Patent Application
20240343550
The present disclosure generally relates to microstructured articles and method of making microstructured articles.
Certain articles with microstructured surfaces have been demonstrated to provide a reduction of microorganism (e.g., bacteria) after cleaning. It can be challenging, however, to achieve strong interfacial adhesion between microstructures and other portions of the article.
In a first aspect, a microstructured article is provided. The microstructured article comprises a thermoplastic polymer shaped to comprise a curve comprising a curvature radius of up to 20 mm, wherein at least a portion of the curve comprises a microstructured surface of utilitarian discontinuities, wherein the microstructured surface comprises peak structures and adjacent valleys, wherein the valleys have a maximum width ranging from 1 micron to 250 microns and the peak structures have a side wall angle of greater than 10 degrees, and wherein the peak structures and the curve are formed of a single piece of the thermoplastic polymer.
In a second aspect, a method of making a microstructured article is provided. The method comprises a) obtaining a tool shaped to comprise at least one of a protrusion or a concavity; b) disposing a microstructured film on at least a portion of the tool including the protrusion and/or the concavity; and c) thermoforming a single piece of thermoplastic polymer onto the tool to form a microstructured article shaped to comprise a curve comprising a curvature radius of up to 20 mm. The curve is an inverse of the protrusion or the concavity of the tool and at least a portion of the curve comprises a microstructured surface of utilitarian discontinuities being an inverse of a surface of the microstructured film. The microstructured surface comprises peak structures and adjacent valleys. The valleys have a maximum width ranging from 1 micron to 250 microns and the peak structures have a side wall angle of greater than 10 degrees.
In a third aspect, the present disclosure provides a tooling article. The tooling article comprises a tool shaped to comprise at least one of a protrusion or a concavity and a microstructured film disposed on at least a portion of the tool including the protrusion and/or the concavity. The microstructured film comprises peak structures and adjacent valleys, wherein the valleys have a maximum width ranging from 1 micron to 250 microns. The peak structures have a side wall angle of greater than 10 degrees.
The above summary of the present disclosure is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The description that follows more particularly exemplifies illustrative embodiments. In several places throughout the application, guidance is provided through lists of examples, which examples may be used in various combinations. In each instance, the recited list serves only as a representative group and should not be interpreted as an exclusive list.
While the above-identified figures set forth various embodiments of the disclosure, other embodiments are also contemplated, as noted in the description. In all cases, this disclosure presents the invention by way of representation and not limitation. The figures are not necessarily to scale. Like numbers used in the figures refer to like components. However, it will be understood that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number.
As used herein, the term “arch” refers to a semicircular shape.
As used herein, “curvature radius” is the reciprocal of the curvature of a curve.
As used herein, “concavity” refers to a surface or an object that has a concave shape.
As used herein, “integral” refers to being made at the same time or being incapable of being separated without damaging one or more of the (integral) parts.
As used herein, “utilitarian” means that the discontinuities provide a positive contribution to the functioning of the article. For instance, easy-clean utilitarian discontinuities provide a positive contribution to the function of cleaning an article easier than an article lacking the utilitarian discontinuities. Representative examples of utilitarian discontinuities include, but are not limited to, cube-corner elements and parallel linear prisms with planar facets.
As used herein, “draw down” as used herein means extending a molten resin as it is being thermoformed. The draw down is characterized by a draw down ratio (DDR), which is the ratio of the surface area of a part to the footprint of the part. In general, the draw-down ratio for thermoplastic materials used herein is suitably from 1.1 to 3.
As used herein, the term “crack” refers to a break in a surface of a material or a change in a thickness of a material, each without complete separation of the material.
As used herein, the term “macrocrack” refers to a crack having at least one dimension that is greater than 250 microns in length.
As used herein, the term “microcrack” refers to a crack in which each dimension is 250 microns in length or shorter.
As used herein, the term “essentially free” in the context of a composition being essentially free of a component, refers to a composition containing less than 1% by weight (wt. %), 0.5 wt. % or less, 0.25 wt. % or less, 0.1 wt. % or less, 0.05 wt. % or less, 0.001 wt. % or less, or 0.0001 wt. % or less of the component, based on the total weight of the composition.
As used herein, “thermoplastic” refers to a polymer that flows when heated sufficiently above its glass transition point and become solid when cooled.
As used herein, “thermoset” refers to a polymer that permanently sets upon curing and does not flow upon subsequent heating. Thermoset polymers are typically crosslinked polymers.
As used herein, the term “glass transition temperature” (Tg), of a polymer refers to the transition of a polymer from a glassy state to a rubbery state and can be measured using Differential Scanning Calorimetry (DSC), such as at a heating rate of 10° C. per minute in a nitrogen stream. When the Tg of a monomer is mentioned, it is the Tg of a homopolymer of that monomer. The homopolymer must be sufficiently high molecular weight such that the Tg reaches a limiting value, as it is generally appreciated that a Tg of a homopolymer will increase with increasing molecular weight to a limiting value. The homopolymer is also understood to be substantially free of moisture, residual monomer, solvents, and other contaminants that may affect the Tg. A suitable DSC method and mode of analysis is as described in Matsumoto, A. et. al., J. Polym. Sci. A., Polym. Chem. 1993, 31, 2531-2539.
The words “preferred” and “preferably” refer to embodiments of the disclosure that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the disclosure.
In this application, terms such as “a”, “an”, and “the” are not intended to refer to only a singular entity, but include the general class of which a specific example may be used for illustration. The terms “a”, “an”, and “the” are used interchangeably with the term “at least one.” The phrases “at least one of” and “comprises at least one of” followed by a list refers to any one of the items in the list and any combination of two or more items in the list.
As used herein, the term “or” is generally employed in its usual sense including “and/or” unless the content clearly dictates otherwise.
The term “and/or” means one or all of the listed elements or a combination of any two or more of the listed elements.
Also herein, all numbers are assumed to be modified by the term “about” and preferably by the term “exactly.” As used herein in connection with a measured quantity, the term “about” refers to that variation in the measured quantity as would be expected by the skilled artisan making the measurement and exercising a level of care commensurate with the objective of the measurement and the precision of the measuring equipment used. Also herein, the recitations of numerical ranges by endpoints include all numbers subsumed within that range as well as the endpoints (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).
As used herein as a modifier to a property or attribute, the term “generally”, unless otherwise specifically defined, means that the property or attribute would be readily recognizable by a person of ordinary skill but without requiring absolute precision or a perfect match (e.g., within +/−20% for quantifiable properties). The term “substantially”, unless otherwise specifically defined, means to a high degree of approximation (e.g., within +/−10% for quantifiable properties) but again without requiring absolute precision or a perfect match. Terms such as same, equal, uniform, constant, strictly, and the like, are understood to be within the usual tolerances or measuring error applicable to the particular circumstance rather than requiring absolute precision or a perfect match.
Although articles with specific microstructure features are useful for reducing the initial formation of a biofilm, particularly for medical articles; in the case of other articles, such microstructured surfaces can be difficult to clean. This is surmised to be due at least in part to the bristles of a brush or fibers of a (e.g., nonwoven) wipe being larger than the space between microstructures. It has been found that some types of microstuctured surfaces exhibit better microorganism (e.g., bacteria) removal when cleaned, even in comparison to smooth surfaces. The article is typically not a sterile implantable medical article. Rather, the microstructured surface typically comes in contact with people and/or animals as well as other contaminants (e.g., dirt). Some representative articles include for example surfaces or component of a medical article, a dental article, an orthodontic article (e.g., an orthodontic aligner), a vehicular article, an electronic article, a personal care article, a cleaning article, an athletic article, a food preparation article, a child care article, or an architectural article.
As noted above, it can be challenging to achieve strong interfacial adhesion between two different material materials, for instance when the materials are thermoformed together. It has been discovered that it is possible to form an article that includes a curved microstructured surface from just one material, using thermoforming. Stated another way, the microstructured surface is integral to the curve of the thermoplastic polymer, as opposed to being a separate microstructured surface that has been attached to the curve of the thermoplastic polymer.
In a first aspect, a microstructured article is provided. The microstructured article comprises a thermoplastic polymer shaped to comprise a curve comprising a curvature radius of up to 20 millimeters (mm). At least a portion of the curve comprises a microstructured surface of utilitarian discontinuities, wherein the microstructured surface comprises peak structures and adjacent valleys, wherein the valleys have a maximum width ranging from 1 micron to 250 microns and the peak structures have a side wall angle of greater than 10 degrees. The peak structures and the curve are formed of a single piece of the thermoplastic polymer.
In contrast to a curved surface, a flat surface has a curvature radius of infinity. In some embodiments, the curve comprises a minimum curvature radius of 0.5 mm, such as 0.5 mm or greater, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.25 mm, 1.5 mm, 1.75 mm, 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.5 mm, 5.0 mm, 5.5 mm, 6.0 mm, 6.5 mm, 7.0 mm, 7.5 mm, 8.0 mm, 8.5 mm, 9.0 mm, 9.5 mm, or 10.0 mm or greater; and 20.0 mm or less, 19.5 mm, 19.0 mm, 18.5 mm, 18.0 mm, 17.5 mm, 17.0 mm, 16.5 mm, 16.0 mm, 15.5 mm, 15.0 mm, 14.5 mm, 14.0 mm, 13.5 mm, 13.0 mm, 12.5 mm, 12.0 mm, 11.5 mm, or 11.0 mm or less.
The microstructured surface typically provides a log 10 reduction of microorganism (e.g., bacteria) of at least 2, 3, 4, 5, 6, 7, or 8 after cleaning. Regardless of whether the microstructured surface is mechanically cleaned with a wipe or brush and/or cleaned by applying an antimicrobial solution to the microstructured surface, the microstructured surface provides improved removal of microorganism (e.g., bacteria) in comparison to surfaces lacking the microstructures.
In a second aspect, a method of making a microstructured article is provided. The method comprises a) obtaining a tool shaped to comprise at least one of a protrusion or a concavity; b) disposing a microstructured film on at least a portion of the tool including the protrusion and/or the concavity; and c) thermoforming a single piece of thermoplastic polymer onto the tool to form a microstructured article shaped to comprise a curve comprising a curvature radius of up to 20 mm. The curve is an inverse of the protrusion or the concavity of the tool and at least a portion of the curve comprises a microstructured surface of utilitarian discontinuities being an inverse of a surface of the microstructured film. The microstructured article can be any article according to the first aspect.
Referring to
Accordingly, a microstructured surface can be imparted to an article having at least one curved surface by thermoforming a single piece of thermoplastic polymer onto a tool having a protrusion, in which a microstructured film is disposed on at least one of a protrusion or a concavity, with the microstructures located on the film opposite the protrusion, the concavity, or both.
Variations in how the steps of the method are performed are contemplated. For instance, the microstructured film may be attached to the thermoplastic polymer and steps b) and c) may be performed at least partially simultaneously. Optionally, the microstructured film is disposed on the tool according to step b) by thermoforming the microstructured film onto the tool simultaneously with step c). In some methods, the microstructured film is attached (e.g., by thermoforming) to an exterior surface of the tool, including over at least a portion of a protrusion and/or a concavity. Suitable methods may comprise thermoforming a thermoplastic polymer onto the microstructured base film at a temperature below the melt temperature of the peak structures of the microstructured (e.g., tooling) film. In some embodiments, vacuum forming may be used in combination with thermoforming, also known as dual vacuum thermoforming (DVT).
Any tool shape can be used to provide a portion of material that extends beyond, above, or below a planar surface, to impart a curve into a final article thermoformed onto at least one of a protrusion or a concavity of the tool, in which the (e.g., first) curve of the article is the inverse of the protrusion or the concavity. One suitable example is a dental arch (see, e.g.,
An advantage of forming a microstructured article according to the present disclosure includes being able to employ a (e.g., standard) microstructured film with any custom-made tool (such as a dental arch prepared for a particular individual), and then create an integral custom article having a microstructured surface. Tools can readily be formed by making one or more molds of a shape of interest, via additive manufacturing (e.g., using a digital scan of the desired shape), or other processes. In certain methods, step a) of the method comprises making the tool using an additive manufacturing process, e.g., stereolithography (SLA).
Referring to
An overall thickness of exemplary microstructured films can vary, such as an average thickness of 25 microns or greater, 30, 40, 50, 60, 70, 80, 90, 100, 120, 140, 160, 180, 200, 220, 240, or 260 microns or greater; and 400 microns or less, 380, 360, 340, 320, 300, 280, 250, 225, 200, 175, or 150 microns or less. In select embodiments, an average thickness of a microstructured film may be 25 to 380 microns or 50 to 260 microns. It was unexpectedly found that in some cases, an average thickness of 380 microns or less contributed to a microstructured film that is more resistant to macrocracks when thermoformed than the same microstructured film having a larger average thickness.
Suitable microstructured films useful as tooling films for methods according to the present disclosure have an inverse microstructure to the desired microstructure of the final microstructured article. Such desired microstructure present on a surface of an article is as described in detail below with respect to
With reference to
In some embodiments, the microstructured surfaces are three-dimensional on a macroscale. However, on a microscale (e.g., surface area that includes at least two adjacent microstructures with a valley or channel disposed between the microstructures) the base layer/base member can be considered planar with respect to the microstructures. The width and length of the microstructures are in the x-y plane and the height of the microstructures is in the z-direction. Further, the base layer is parallel to the x-y plane and orthogonal to the z-plane.
Suitable surfaces are microstructured surfaces comprising microstructures having side wall angles greater than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 degrees. In some embodiments, the side wall angle is at least 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 degrees. In other embodiments, the side wall angle is at least 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 degrees. For example, in some embodiments, the microstructures are cube corner peak structures having a side wall angle of 30 degrees. In other embodiments, the side wall angle is at least 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, or 45 degrees. For example, in some embodiments, the microstructures are prism structures having a side wall angle of 45 degrees. In other embodiments, the side wall angle is at least 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, or 60 degrees. It is appreciated that the microstructured surface would be beneficial even when some of the side walls have lower side wall angles. For example, if half of the array of peak structures have side wall angles within the desired range, about half the benefit of improved microorganism (e.g., bacteria) removal may be obtained. Thus, in some embodiments, less than 50, 45, 40, 35, 30, 25, 20, 15, 10, 5 or 1% of the peak structures have side wall angles less than 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 degree. In some embodiments, less than 50, 45, 40, 35, 30, 25, 20, 15, 10, 5 or 1% of the peak structures have side wall angles less than 30, 25, 20, or 15 degrees. In some embodiments, less than 50, 45, 40, 35, 30, 25, 20, 15, 10, 5 or 1% of the peak structures have side wall angles less than 40, 35, or 30 degrees, at least 50, 60, 70, 80, 90, 95 or 99% of the peak structures have a sufficiently large side wall angle, as described above.
As described for example in PCT Publication No. WO 2013/003373 (Bommarito et al.), microstructures having a cross-sectional dimension no greater than 5 microns are believed to substantially interfere with the settlement and adhesion of target bacteria most responsible for healthcare-associated infections or other biofouling problems such an increased drag, reduced heat transfer, filtration fouling, etc. With reference to
Suitable microstructured surfaces comprise microstructures wherein the maximum width of the valleys is at least 1, 2, 3, or 4 microns and optionally greater than 5, 6, 7, 8, 9, or 10 microns, ranging up to 250 microns. In some embodiments, the maximum width of the valleys is at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 microns. In some embodiments, the maximum width of the valleys is no greater than 1000, 950, 900, 850, 800, 750, 700, 650, 600, 550, 500, 450, 400, 350, 300, 250, 225, 200, 175, 150, 125, 100, 75, or 50 microns. In some embodiments, the maximum width of the valleys is no greater than 45, 40, 35, 30, 25, 20, or 15 microns. It is appreciated that the microstructured surface would be beneficial even when some of the valleys are less than the maximum width. For example, if half of the total number of valleys of the microstructured surface are within the desired range, about half the benefit may be obtained. Thus, in some embodiments, less than 50, 45, 40, 35, 30, 25, 20, 15, 10, 5 or 1% of the valleys have a maximum width of less than 10, 9, 8, 7, 6, or 5 microns. Alternatively, at least 50, 60, 70, 80, 90, 95 or 99% of the valleys have a maximum width, as described above.
In typical embodiments, the maximum width of the microstructures falls within the same ranges as described for the valleys. In other embodiments, the width of the valleys can be greater than the width of the microstructures. Thus, in some favored embodiments, the microstructured surface is typically substantially free of microstructures having a width less than 5, 4, 3, 2, or 1 micron, inclusive of nanostructures having a width less than 1 micron. By substantially free, it is meant that there are none of such microstructures present or that some may be present provided that the presence thereof does not detract from the cleanability properties as will subsequently described.
Although smaller structures including nanostructures can prevent biofilm formation, the presence of a significant number of smaller valleys and/or valleys with insufficient side wall angles can impede cleanability including dirt removal. Further, microstructured surfaces with larger microstructures and valleys can typically be manufactured at a faster rate. Thus, in typical embodiments, each of the dimensions of the microstructures is at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 microns. Further, in certain embodiments, none of the dimensions of at least 50, 60, 70, 80, 90, 95 or 99% microstructures are less than 5, 4, 3, 2, or 1 micron.
The valleys of suitable microstructured surfaces are substantially free of intersecting side walls or other obstructions to the valley. By substantially free, it is meant that there are no side walls or other obstructions present within the valleys or that some may be present provided that the presence thereof does not detract from the cleanability properties. The valleys are typically continuous in at least one direction. This can facilitate the flow of a cleaning solution through the valley. Thus, the arrangement of peaks typically does not define a tortuous pathway.
The peak structures typically have a height (H) ranging from 1 to 250 microns. In some embodiments, the height of the microstructures is at least 2, 3, 4, or 5 microns. In some embodiments, the height of the microstructures is at least 6, 7, 8, 9 or 10 microns. In some embodiments, the height of the microstructures no greater than 225, 200, 175, 150, 125, 100, 90, 80, 70, 60, or 50 microns. In some embodiments, the height of the microstructures is no greater than 45, 40, 35, 30 or 25 microns. In some embodiments, the height of the microstructures is no greater than 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, or 5 microns. In select embodiments, the peak structures each have a height of 10 to 250 microns. It was unexpectedly found that in some cases, a peak structure height of at least 10 microns contributed to a microstructured film that is more resistant to macrocracks when thermoformed than the same microstructured film having a peak structure height of less than 10 microns. In typical embodiments, the height of the valley or channel is within the same range as just described for the peak structures. In some embodiments, the peak structures and valleys have the same height.
The aspect ratio of the valley is the height of the valley (which can be the same as the peak height of the microstructure) divided by the maximum width of the valley. In some embodiments, the aspect ratio of the valley is at least 0.1, 0.15, 0.2, or 0.25. In some embodiments, the aspect ratio of the valley is no greater than 1, 0.9, 0.8, 0.7, 0.6 or 0.5. Thus, in some embodiments, the height of the valley is typically no greater than the maximum width of the valley, and more typically less than the maximum width of the valley.
The base of each microstructure may comprise various cross-sectional shapes including but not limited to parallelograms with optionally rounded corners, rectangles, squares, circles, half-circles, half-ellipses, triangles trapezoids, other polygons (e.g., pentagons, hexagons, octagons, etc., and combinations thereof).
Suitable microstructured surfaces comprise an array of peak structures and adjacent valleys. The valleys preferably have a maximum width ranging from 1 micron to 250 microns. In some embodiments (e.g., for improved cleanability), the peak structures have a side wall angle greater than 10 degrees. The peak structures may comprise two or more facets such as in the case of a linear array of prisms or an array of cube-corners elements. In some embodiments, facets of the peak structures form an apex angle, typically ranging from about 20 to 120 degrees. The facets form continuous or semi-continuous surfaces in the same direction. The valleys typically lack intersecting walls.
The presently described microstructured surface does not prevent microorganisms (e.g., bacteria such as Streptococcus mutans, Staphylococcus aureus, or Pseudomonas aeruginosa) from being present on the microstructured surface, or in other words, does not prevent biofilm from forming. However, such microstructured surfaces have been demonstrated to be easier to clean, providing a low amount of microorganism (e.g., bacteria) present after cleaning. Without intending to be bound by theory, scanning electron microscopy images suggest that large continuous biofilms typically form on a smooth surface. However, even though the peaks and valleys are much larger than the microorganism (e.g., bacteria), the biofilm is interrupted by the microstructured surface. In some embodiments, the biofilm (before cleaning) is present as discontinuous aggregate and small groups of cells on the microstructured surface, rather than a continuous biofilm. After cleaning, biofilm aggregates in small patches cover the smooth surface. However, the microstructured surface was observed to have only small groups of cells and individual cells after cleaning. In favored embodiments, the microstructured surface provides a log 10 reduction of microorganism (e.g., bacteria such as Streptococcus mutans, Staphylococcus aureus, or Pseudomonas aeruginosa) of at least 2, 3, 4, 5, 6, 7 or 8 after cleaning. In some embodiments, the microstructured surface has a mean log 10 of recovered colony forming units of microorganism of less than 6, 5, 4, or 3 after cleaning for a highly contaminated surface.
In some embodiments, the microstructured surface can prevent an aqueous or (e.g., isopropanol) alcohol-based cleaning solution from beading up as compared to a smooth surface comprised of the same polymeric material. When a cleaning solution beads up or in other words dewets, the disinfectant agent may not be in contact with a microorganism for a sufficient duration of time to kill the microorganism. However, it has been found that at least 50, 60, 70, 80, or 90% of the microstructured surface can comprise cleaning solution 1, 2, and 3 minutes after applying the cleaning solution to the microstructured surface.
In one embodiment, the microstructured surface may have the same surface as a brightness enhancing film. As described for example in U.S. Pat. No. 7,074,463 (Jones et al.), backlit liquid crystal displays generally include a brightness enhancing film positioned between a diffuser and a liquid crystal display panel. The brightness enhancing film collimates light, thereby increasing the brightness of the liquid crystal display panel and also allowing the power of the light source to be reduced. Thus, brightness enhancing films have been utilized as an internal component of an illuminated display devices (e.g., cell phone, computer) that are not exposed to microorganisms (e.g., bacteria) or dirt.
With reference to
In another embodiment, the microstructured surface may have the same surface as cube corner retroreflective sheeting. Retroreflective materials are characterized by the ability to redirect light incident on the material back toward the originating light source. This property has led to the widespread use of retroreflective sheeting for a variety of traffic and personal safety uses. With reference to
The microstructured surface 10 of
In another embodiment, depicted in
Other cube corner element structures, described as “full cubes” or “preferred geometry (PG) cube corner elements”, typically comprise at least two non-dihedral edges that are not coplanar as described for example in U.S. Pat. No. 7,188,960 (Smith); incorporated herein by reference. Full cubes are not truncated. In one aspect, the base of full cube elements in plan view are not triangular. In another aspect, the non-dihedral edges of full cube elements are characteristically not all in the same plane (i.e., not coplanar). Such cube corner elements may be characterized as “preferred geometry (PG) cube corner elements”. A PG cube corner element may be defined in the context of a structured surface of cube corner elements that extends along a reference plane. A PG cube corner element means a cube corner element that has at least one non-dihedral edge that: (1) is nonparallel to the reference plane; and (2) is substantially parallel to an adjacent non-dihedral edge of a neighboring cube corner element. A cube corner element with reflective faces that comprise rectangles (inclusive of squares), trapezoids or pentagons are examples of PG cube corner elements.
With reference to
In some embodiments, all the peak structures have the same apex angle θ. For example, the previously described microstructured surface of
As yet another example, as depicted in the cross-section of
In some embodiments, the peak structures typically comprise at least two (e.g., prisms of
When the facets of the microstructures are joined such that the apex and valleys are sharp or rounded, but not truncated, the microstructured surface can be characterized are being free of flat surfaces, that are parallel to the planar base layer. However, wherein the apex and/or valleys are truncated, the microstructured surface typically comprises less than 50, 45, 40, 35, 30, 25, 20, 15, 10, 5 or 1% of flat surface area that is substantially parallel to the planar base layer. In one embodiment, the valleys may have flat surfaces and only one of the side walls of the peaks is angled such as shown in
In each of the embodiments of
In some embodiments, the apex angle of the peak structure is typically two times the wall angle, particularly when the facets of the peak structures are interconnected at the valleys between peak structures. Thus, the apex angle is typically greater than 20 degrees and more typically at least 25, 30, 35, 40, 45, 50, 55, or 60 degrees. The apex angle of the peak structure is typically less than 160 degrees and more typically less than 155, 150, 145, 140, 135, 130, 125 or 120 degrees.
Topography maps can be obtained using confocal laser scanning microscopy (CLSM), e.g., a Keyence VK-X200. CLSM is an optical microscopy technique that scans the surface using a focused laser beam to map the topography of a surface. CLSM works by passing a laser bean through a light source aperture which is then focused by an objective lens into a small area on the surface and image is built up pixel-by-pixel by collecting the emitted photons from the sample. It uses a pinhole to block out-of-focus light in image formation. Dimensional analysis can be used to measure various parameters using SPIP 6.7.7 image metrology software according to the manual (see https://www.imagemet.com/media-library/support-documents).
Surface roughness parameters, Sa (Roughness Average), Sq (Root Mean Square), and Sbi (Surface Bearing Index), Svi (Valley Fluid Retention Index) can be calculated from the topographic images (3D). Prior to calculating roughness, a plane correction is used “Subtract Plane” (1st order planefit form removal).
where M and N are the number of data points X and Y.
Although smooth surfaces can have a Sa approaching zero, the comparative smooth surfaces that were found to have poor microorganism removal after cleaning had an average surface roughness, Sa, of at least 10, 15, 20, 25 or 30 nm. The average surface roughness, Sa, of the comparative smooth surfaces was less than 1000 nm (1 micron). In some embodiments, Sa of the comparative smooth surface was at least 50, 75, 100, 125, 150, 200, 250, 300, or 350 nm. In some embodiments, Sa of the comparative smooth surface was no greater than 900, 800, 700, 600, 500, or 400 nm.
The average surface roughness, Sa, of the microstructured surfaces having improved microorganism removal after cleaning was 1 micron (1000 nm) or greater. In some embodiments, Sa was at least 1100 nm, 1200 nm, 1300 nm, 1400 nm, 1500 nm, 1600 nm, 1700 nm, 1800 nm, 1900 nm, or 2000 nm (2 microns). In some embodiments, Sa of the microstructured surfaces was at least 2500 nm, 3000 nm, 3500 nm, 4000 nm or 5000 nm. In some embodiments, Sa of the microstructured surfaces was at least 10,000 nm, 15,000 nm, 20,000 nm or 25,000 nm. In some embodiments, Sa of the microstructured surfaces having improved microorganism removal after cleaning was no greater than 40,000 nm (40 microns), 35,000 nm, 30,000 nm, 15,000 nm, 10,000 nm, or 5,000 nm.
In some embodiments, Sa of the microstructured surface is at least 2 or 3 times the Sa of a smooth surface. In other embodiments, Sa of the microstructured surface is at least 4, 5, 6, 7, 8, 9, or 10 times the Sa of a smooth surface. In other embodiments, Sa of the microstructured surface is at least 15, 20, 25, 30, 35, 40, 45, 50 times the Sa of a smooth surface. In other embodiments, Sa of the microstructured surface is at least 100, 200, 300, 400, 500, 600, 700, 800, 900, or 1000 times the Sa of a smooth surface.
where M and N are the number of data points X and Y.
Although the Sq values are slightly higher than the Sa values, the Sq values also fall within the same ranges just described for the Sa values.
wherein Z0.05 is the surface height at 5% bearing area.
wherein Vv(h0.80) is the void volume at valley zone within 80-100% bearing area.
As noted in the S Parameters table above, the Sbi/Svi ratio of the comparative smooth samples were 1 and 3. The microstructured surfaces having improved microorganism removal after cleaning had a Sbi/Svi ratio of greater than 3. The microstructured surfaces have a Sbi/Svi ratio of at least 4, 5, or 6. In some embodiments, the microstructured surfaces having improved microorganism removal after cleaning had a Sbi/Svi ratio of at least 7, 8, 9, or 10. In some embodiments, the microstructured surfaces having improved microorganism removal after cleaning had a Sbi/Svi ratio of at least 15, 20, 25, 30, 35, 40 or 45. The microstructured surfaces having improved microorganism removal after cleaning had a Sbi/Svi ratio of less than the comparative square wave microstructured surfaces. Thus, the microstructured surfaces having improved microorganism removal after cleaning had a Sbi/Svi ratio of less than 90, 85, 80, 75, 70 or 65. In some embodiments, the microstructured surfaces having improved microorganism removal after cleaning had a Sbi/Svi ratio of less than 60, 55, 50, 45, 40, 35, 30, 25, 20, or 10.
Topography maps can also be used to measure other features of the microstructured surface. For example, the peak height (especially of a repeating peak of the same height) can be determined from the height histogram function of the software. To calculate the percentage of “flat regions” of a square wave film, the “flat regions” can be identified using SPIP's Particle Pore Analysis feature, which identifies certain shapes (in this case, the “flat tops” of the microstructured square wave film.
Referring now to
In methods of the present disclosure, a microstructured film is disposed on some or all of a tool, including on one or more protrusions or one or more concavities. For example,
By thermoforming a thermoplastic polymer onto the microstructured film (e.g., 800c) present on the dental arch 820, an exemplary microstructured article 830 was formed having a microstructured surface on an interior portion of (at least one) curve of the microstructured article 830. For instance,
An advantage of adding a microstructured film to a tool having one or more protrusions and/or concavities is that it is a straightforward option to dispose the microstructured film on only select portions of the tool. For instance,
In a third aspect, a tooling article is provided. The tooling article comprises:
Further as mentioned above,
The microstructured surface of the microstructured film can be prepared by various microreplication techniques such as coating, injection molding, embossing, laser etching, and extrusion. For example, microstructuring of the (e.g., engineered) film surface can be achieved by at least one of (1) casting a molten thermoplastic using a tool having a microstructured pattern, (2) coating of a fluid onto a tool having a microstructured pattern, solidifying the fluid, and removing the resulting film, (3) passing a thermoplastic film through a nip roll to compress against a tool having a microstructured pattern (i.e., embossing), and/or (4) contacting a solution or dispersion of a polymer in a volatile solvent to a tool having a microstructured pattern and removing the solvent, e.g., by evaporation. The tool can be metallic, such as nickel, nickel-plated copper or brass, or can be a thermoplastic material that is stable under the process conditions, and that preferably has a surface energy that allows clean removal of the polymerized material from the tool. It is to be understood that the microstructured film should comprise a material that will not melt or otherwise deform during the thermoforming process of forming the article such that the utilitarian discontinuities of the microstructured surface of the film maintain their shapes and impart the inverse of their shapes to a surface of the final article.
A tool used for preparing the microstructured film can be formed using any of a number of techniques known to those skilled in the art, selected depending in part upon the tool material and features of the desired topography. Illustrative techniques include etching (e.g., chemical etching, mechanical etching, or other ablative means such as laser ablation or reactive ion etching, etc., and combinations thereof), photolithography, stereolithography, micromachining, knurling (e.g., cutting knurling or acid enhanced knurling), scoring, cutting, etc., or combinations thereof. In some embodiments, the tool is a metal tool. The tool may further comprise a diamond like glass layer, such as described in WO 2009/032815 (David).
Additional information regarding materials and various processes for forming the microstructured tool surface can be found, for example, in PCT Publication No. WO 2007/070310 and US Publication No. US 2007/0134784 (Halverson et al.); US Publication No. US 2003/0235677 (Hanschen et al.); PCT Publication No. WO 2004/000569 (Graham et al.); U.S. Pat. No. 6,386,699 (Ylitalo et al.); US Publication No. US 2002/0128578 (Johnston et al.) and U.S. Pat. Nos. 6,420,622, 6,867,342, and 7,223,364 (Johnston et al.); and U.S. Pat. No. 7,309,519 (Scholz et al.) Such methods may be utilized to form a thermoformable microstructured base member (e.g., sheet or plate), which can then be thermoformed onto a tool comprising a protrusion and/or a concavity.
Useful (optional) base member materials include, for example, styrene-acrylonitrile, cellulose acetate butyrate, cellulose acetate propionate, cellulose triacetate, polyether sulfone, polymethyl methacrylate, polyurethane, polyester, polycarbonate, polyvinyl chloride, polystyrene, polyethylene naphthalate, copolymers or blends based on naphthalene dicarboxylic acids, polycyclo-olefins, polyimides, silicone and fluorinated films, and glass. Optionally, the base material can contain mixtures or combinations of these materials. In an embodiment, the base may be multi-layered or may contain a dispersed component suspended or dispersed in a continuous phase. An example of a useful PET films include photograde polyethylene terephthalate and MELINEX™ PET available from DuPont Films of Wilmington, Del. An example of a useful thermoformable material is polyethylene terephthalate (polyester with glycol) commercially available as VIVAK PETG. Such material is characterized by having a tensile strength ranging from 5000-10,000 psi (ASTM D638) and a flexural strength of 5,000 to 15,000 (ASTM D-790). Such material has a glass transition temperature of 178° F. (ASTM D-3418).
It also is possible and often preferable in order to maintain the fidelity of the microstructures to include a surface energy modifying compound in the composition used to form the microstructures. In some embodiments, the bloom additive may retard or prevent crystallization of the base composition. Suitable bloom additives may be found, for example, in International Publication No. WO 2009/152345 (Scholz et al.) and U.S. Pat. No. 7,879,746 (Klun et al.).
The materials for retroreflective sheeting and brightness enhancing films have been chosen based on the optical properties. Thus, the peak structures and adjacent valleys typically comprise a material having a refractive index of at least 1.50, 1.55, 1.60 or greater. Further, the transmission of visible light is typically greater than 85 or 90%. However, optical properties may not be of concern for many embodiments of the presently described films, methods, and articles. Thus, various other materials may be used having a lower refractive index including colored, light transmissive, and opaque.
As shown in
In some embodiments, the microstructured surface (e.g., at least peak structures thereof) comprise an organic polymeric material with a glass transition temperature (as measured with Differential Scanning Calorimetry) of at least 25° C. In some embodiments, the organic polymeric material has a glass transition temperature of at least 30, 35, 40, 45, 50, 55 or 60° C. In some embodiments, the organic polymeric material has a glass transition temperature no greater than 100, 95, 90, 85, 80, or 75° C.
Referring again to
Thermoformable microstructured base members typically having a thickness of at least 50, 100, 200, 300, 400, or 500 microns. Thermoformable microstructured base members may have thickness up to 3, 4, or 5 mm or greater. The base member can, in some implementations, include discrete pores and/or pores in communication. The thickness of the base member can vary depending on the use.
The organic polymeric materials of the base member can be the same organic polymeric materials previously described for the microstructured surface. In addition, fiber- and/or particle-reinforced polymers can also be used.
Non-limiting examples of suitable non-biodegradable polymers for base members include polyolefins (e.g., polyisobutylene copolymers), styrenic block copolymers (e.g., styrene-isobutylene-styrene block copolymers, such as styrene-isobutylene-styrene tert-block copolymers (SIBS); polyvinylpyrrolidone; polyvinyl alcohols; copolymers of vinyl monomers such as EVA; polyvinyl ethers; polyvinyl aromatics; polyethylene oxides; polyesters such as polyethylene terephthalate; polyamides; polyacrylamides; polyethers such as polyether sulfone; polyolefins such as polypropylene, polyethylene, and high or ultra high molecular weight polyethylene; polyurethanes; polycarbonates; silicones; siloxane polymers; natural based polymers such as optionally modified polysaccharides and proteins including, but not limited to, cellulosic polymers and cellulose esters such as cellulose acetate; and combinations comprising at least one of the foregoing polymers. Combinations may include miscible and immiscible blends as well as laminates.
The base member may be comprised of a biodegradable material. Non-limiting examples of suitable biodegradable polymers include polycarboxylic acid; polyanhydrides such as maleic anhydride polymers; polyorthoesters; poly-amino acids; polyethylene oxide; polyphosphazenes; polylactic acid, polyglycolic acid, and copolymers and mixtures thereof such as poly(L-lactic acid) (PLLA), poly(D,L,-lactide), poly(lactic acid-co-glycolic acid), and 50/50 weight ratio (D,L-lactide-co-glycolide); polydioxanone; polypropylene fumarate; polydepsipeptides; polycaprolactone and co-polymers and mixtures thereof such as poly(D,L-lactide-co-caprolactone) and polycaprolactone co-butylacrylate; polyhydroxybutyrate valerate and mixtures thereof, polycarbonates such as tyrosine-derived polycarbonates and arylates, polyiminocarbonates, and polydimethyltrimethylcarbonates; cyanoacrylate; calcium phosphates; polyglycosaminoglycans; macromolecules such as polysaccharides (including hyaluronic acid, cellulose, and hydroxypropylmethyl cellulose; gelatin; starches; dextrans; and alginates and derivatives thereof, proteins and polypeptides; and mixtures and copolymers of any of the foregoing. The biodegradable polymer can also be a surface erodible polymer such as polyhydroxybutyrate and its copolymers, polycaprolactone, polyanhydrides (both crystalline and amorphous), and maleic anhydride.
Suitable thermoplastic polymers for use in making the microstructured article comprise a material that exhibits a draw down ratio of greater than 1.1, such as 1.2 or more, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 2.1, 2.2, or 2.3 or more; and 3.0 or less, 2.9, 2.8, 2.7, 2.6, 2.5, or 2.4 or less. Optionally, suitable thermoplastic polymers comprise a material that exhibits an elongation at break of 50% or greater, such as 55% or greater, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100% or greater; and 400% or less. Elongation at break can be determined by ASTM D638-10, using test specimen Type V. It is preferred that the thermoplastic polymers possess the following properties: having thermal transition points such as glass transition temperatures between 70° C. and 140° C., an elongation at break greater than 100%, stain resistance, crack resistance, resistance to stress relaxation, and good optical clarity.
Some example suitable thermoplastic polymers include for instance and without limitation, a polypropylene, a polyester, a co-polyester, a polycarbonate, a thermoplastic polyurethane, a polyethylene, a polypropylene and polyethylene copolymer, an acrylic, a cyclic block copolymer, a polyetheretherketone, a polyamide, a polyethylene terephthalate, a polybutylene terephthalate, a polyetherimide, a polyethersulfone, a polytrimethylene terephthalate, silicone urethane copolymer, fluoropolymer, a thermoplastic elastomer, or any combination thereof. Polyurethanes may be formed from aromatic or aliphatic isocyanates combined with polyester or polyether polyols or a combination thereof. In some favored embodiments, the thermoplastic polymer comprises a polypropylene, such as under the trade designation “INVISACRYL C” from Great Lakes Dental Technologies (Tonawanda, NY).
Suitable polyesters include, but are not limited to, copolyesters available under the trade designation TRITAN from Eastman Chemical, Kingsport, TN, polyethylene terephthalate (PET), polyethylene terephthalate glycol (PETg), polycyclohexylenedimethylene terephthalate (PCT), polycyclohexylenedimethylene terephthalate glycol (PCTg), polycarbonate (PC), and mixtures and combinations thereof. Suitable PETg and PCTg resins can be obtained from various commercial suppliers such as, for example, Eastman Chemical, Kingspot, TN; SK Chemicals, Irvine, CA; Dow DuPont, Midiand, MI; Pacur, Oshkosh, WI; and Scheu Dental Tech, Iserlohn, Germany. For example, EASTAR GN071 PETg resins and PCTg VM318 resins from Eastman Chemical have been found to be suitable. Suitable polypropylene or polypropylene copolymer include, but are not limited to, Essix C+ from Dentsply Sirona, Charlotte, NC, and HardCast Material and INVISACRYL C from Great Lakes Dental Technologies, Tonawanda, NY. A suitable thermoplastic elastomer includes Hytrel from DuPont, Wilmington DE, Riteflex from Celanese, Irving, TX, Ecdel from Eastman Chemical Company, Kingsport, TN, Arnitel from DSM, Heerlen, Netherlands, Pelprene from Toyobo Co, Ltd, Osaka, Japan, and Elitel from Unitaka, Osaka, Japan.
The thermoplastic polymer material of the microstructured article may contain other additives such as antimicrobial agents (including antiseptics and antibiotics), dyes, mold release agents, antioxidants, plasticizers, thermal and light stabilizers including ultraviolet (UV) absorbers, fillers, (e.g., for certain applications the fillers are radioopaque), pigments, and the like.
Suitable antimicrobials can be incorporated into or deposited onto the polymers. Suitable preferred antimicrobials include those described in US Publication Nos. 2005/0089539 and 2006/0051384 to Scholz et al. and US Publication Nos. 2006/0052452 and 2006/0051385 to Scholz. The microstructures of articles of the present disclosure also may be coated with antimicrobial coatings such as those disclosed in International Application No. PCT/US2011/37966 to Ali et al.
Typically, the microstuctured surface is not prepared from a low surface energy material (e.g., a fluoropolymer or PDMS) and does not comprise a low surface energy coating, a material or coating that on a flat surface has a receding contact angle with water of greater than 90, 95, 100, 105, or 110 degrees. In this embodiment, the low surface energy of the material is not contributing to the cleanability. Rather, the improvement in cleaning is attributed to the features of the microstructured surface. In this embodiment, the microstructured surface is prepared from a material such that a flat surface of the material typically has a receding contact angle with water of less than 90, 85, or 80 degrees.
Optionally, a low surface energy coating may be applied to the microstructures. Exemplary low surface energy coating materials that may be used include materials such as hexafluoropropylene oxide (HFPO), or organosilanes such as, alkylsilane, alkoxysilane, acrylsilanes, polyhedral oligomeric silsesquioxane (POSS) and fluorine-containing organosilanes, just to name a few. Examples of particular coatings known in the art may be found, e.g., in US Publication No. 2008/0090010 (Zhang et al.), and commonly owned publication, US Publication No. 2007/0298216 (Jing et al.). For embodiments, that include a coating is applied to the microstructures, it may be applied by any appropriate coating method, such as sputtering, vapor deposition, spin coating, dip coating, roll-to-roll coating, or any other number of suitable methods.
In some embodiments, the microstructures or microstructured surface may be modified such that the microstructured surface is more hydrophilic. The microstructured surface generally may be modified such that a flat organic polymer film surface of the same material as the modified microstructured surface exhibits an advancing or receding contact angle of 45 degrees or less with deionized water. In the absence of such modifications, a flat organic polymer film surface of the same material as the microstructured surface typically exhibits an advancing or receding contact angle of greater than 45, 50, 55, or 60 degrees with deionized water.
Any suitable known method may be utilized to achieve a hydrophilic microstructured surface. Surface treatments may be employed such as plasma treatment, vacuum deposition, polymerization of hydrophilic monomers, grafting hydrophilic moieties onto the film surface, corona or flame treatment, etc. For certain embodiments, the hydrophilic surface treatment comprises a zwitterionic silane, and for certain embodiments, the hydrophilic surface treatment comprises a non-zwitterionic silane. Non-zwitterionic silanes include a non-zwitterionic anionic silane, for instance.
In other embodiments, the hydrophilic surface treatment further comprises at least one silicate, for example and without limitation, comprising lithium silicate, sodium silicate, potassium silicate, silica, tetraethylorthosilicate, poly(diethoxysiloxane), or a combination thereof. One or more silicates may be mixed into a solution containing the hydrophilic silane compounds, for application to the microstructured surface.
Since one useful object is to provide an article having a surface with increased microorganism (e.g., bacteria) removal when cleaned, the article is typically not a (e.g., sterile) medical article such as nasal gastric tubes, wound contact layers, blood stream catheters, stents, pacemaker shells, heart valves, orthopedic implants such as hips, knees, shoulders, etc., periodontal implants, dentures, dental crowns, contact lenses, intraocular lenses, soft tissue implants (breast implants, penile implants, facial and hand implants, etc.), surgical tools, sutures including degradable sutures, cochlear implants, tympanoplasty tubes, shunts including shunts for hydrocephalus, post-surgical drain tubes and drain devices, urinary catheters, endotracheal tubes, heart valves, wound dressings, other implantable devices, and other indwelling devices. The medical articles just described may be characterized as single use articles, i.e., the article is used once and then discarded. The above articles may also be characterized as single person (e.g., patient) articles. Thus, such articles are typically not cleaned (rather than sterilized) and reused with other patients.
In contrast, the articles and surfaces described herein include those where the microstructured surface is exposed to the surrounding (e.g., indoor or outdoor) environment and is subject to being touched or otherwise coming in contact with multiple people and/or animals, as well as other contaminants (e.g., dirt).
In some embodiments, the microstructured surface of the article, comes in direct (e.g., skin) contact with (e.g., multiple) people and/or animals during normal use of the article. In other embodiments, the microstructured surface may come is close proximity to (e.g., multiple) people/or animals in the absence of direct (e.g., skin) contact. However, since the microstructured surface comes in close proximity such article surfaces can easily be contaminated with microorganisms (e.g., bacteria) and are therefore cleaned to prevent the spreading of microorganisms to others.
Representative articles that would be cleaned during normal use and/or are amenable for use integrating the microstructured surface into a curved surface of the article include various interior or exterior surfaces or components of a medical article, a dental article, an orthodontic article, a vehicular article, an electronic article, a personal care article, a cleaning article, an athletic article, a food preparation article, a child care article, or an architectural article. More particularly, some examples of representative articles of these categories may include the following:
The microstructured surface is particularly advantageous for congregate living facilities such as military housing, prisons, dorms, nursing homes, apartments, hotels; public places such as offices, schools, arenas, casinos, bowling alleys, golf courses, arcades, gyms, salons, spas, shopping centers, airports, train stations; and public transportation.
In select cases, the article comprises an orthodontic article. Optionally, the microstructured surface of the orthodontic aligner provides a first coefficient of friction that is different than a second coefficient of friction of a curve of the orthodontic aligner that lacks the microstructured surface. For instance, when the coefficient of friction is lower, microstructures can be included in locations of the orthodontic article where the teeth don't need to be moved, for greater comfort when worn by a user. Referring to
The term “microorganism” is generally used to refer to any prokaryotic or eukaryotic microscopic organism, including without limitation, one or more of bacteria (e.g., motile or nonmotile, vegetative or dormant, Gram positive or Gram negative, planktonic or living in a biofilm), bacterial spores or endospores, algae, fungi (e.g., yeast, filamentous fungi, fungal spores), mycoplasmas, and protozoa, as well as combinations thereof. In some cases, the microorganisms of particular interest are those that are pathogenic, and the term “pathogen” is used to refer to any pathogenic microorganism. Examples of pathogens can include, but are not limited to, both Gram positive and Gram negative bacteria, fungi, and viruses including members of the family Enterobacteriaceae, or members of the family Micrococaceae, or the genera Staphylococcus spp., Streptococcus, spp., Pseudomonas spp., Acinetobacter spp., Enterococcus spp., Salmonella spp., Legionella spp., Shigella spp., Yersinia spp., Enterobacter spp., Escherichia spp., Bacillus spp., Listeria spp., Campylobacter spp., Acinetobacter spp., Vibrio spp., Clostridium spp., Klebsiella spp., Proteus spp. Aspergillus spp., Candida spp., and Corynebacterium spp. Particular examples of pathogens can include, but are not limited to, Escherichia coli including enterohemorrhagic E. coli e.g., serotype O157:H7, O129:H111; Pseudomonas aeruginosa; Bacillus cereus; Bacillus anthracis; Salmonella enteritidis; Salmonella enterica serotype Typhimurium; Listeria monocytogenes; Clostridium botulinum; Clostridium perfringens; Staphylococcus aureus; methicillin-resistant Staphylococcus aureus; carbapenem-resistant Enterobacteriaceae, Campylobacter jejuni; Yersinia enterocolitica; Vibrio vulnificus; Clostridium difficile; vancomycin-resistant Enterococcus; Klebsiella pneumonia; Proteus mirabilus and Enterobacter [Cronobacter] sakazakii.
In a first embodiment, the present disclosure provides a microstructured article. The microstructured article comprises a thermoplastic polymer shaped to comprise a curve comprising a curvature radius of up to 20 mm. At least a portion of the curve comprises a microstructured surface of utilitarian discontinuities. The microstructured surface comprises peak structures and adjacent valleys, wherein the valleys have a maximum width ranging from 1 micron to 250 microns and the peak structures have a side wall angle of greater than 10 degrees. The peak structures and the curve are formed of a single piece of the thermoplastic polymer.
In a second embodiment, the present disclosure provides an article according to the first embodiment, wherein the microstructured surface is integral to the curve of the thermoplastic polymer.
In a third embodiment, the present disclosure provides an article according to the first embodiment or the second embodiment, wherein the thermoplastic polymer comprises a material that exhibits a draw down ratio of greater than 1.1.
In a fourth embodiment, the present disclosure provides an article according to any of the first through third embodiments, wherein the thermoplastic polymer comprises a material that exhibits an elongation at break of 50% or greater or 100% or greater.
In a fifth embodiment, the present disclosure provides an article according to any of the first through fourth embodiments, wherein the thermoplastic polymer comprises a polypropylene, a polyester, a co-polyester, a polycarbonate, a thermoplastic polyurethane, a polyethylene, a polypropylene and polyethylene copolymer, an acrylic, a cyclic block copolymer, a polyetheretherketone, a polyamide, a polyethylene terephthalate, a polybutylene terephthalate, a polyetherimide, a polyethersulfone, a polytrimethylene terephthalate, silicone urethane copolymer, fluoropolymer, a thermoplastic elastomer, or any combination thereof.
In a sixth embodiment, the present disclosure provides an article according to the fifth embodiment, wherein the thermoplastic polymer comprises a polypropylene.
In a seventh embodiment, the present disclosure provides an article according to any of the first through sixth embodiments, wherein the thermoplastic polymer is shaped to comprise a second curve that lacks the microstructured surface.
In an eighth embodiment, the present disclosure provides an article according to any of the first through sixth embodiments, wherein the thermoplastic polymer is shaped to comprise a second curve that comprises a microstructured surface.
In a ninth embodiment, the present disclosure provides an article according to any of the first through eighth embodiments, wherein the peak structures each have a height of 10 microns to 250 microns.
In a tenth embodiment, the present disclosure provides an article according to any of the first through ninth embodiments, wherein the article is a medical article, a dental article, an orthodontic article, a vehicular article, an electronic article, a personal care article, a cleaning article, an athletic article, a food preparation article, a child care article, or an architectural article.
In an eleventh embodiment, the present disclosure provides an article according to any of the tenth embodiment, wherein the article is an orthodontic aligner, an orthodontic retainer, or a night guard.
In a twelfth embodiment, the present disclosure provides an article according to the eleventh embodiment, wherein the microstructured surface of the orthodontic aligner provides a first coefficient of friction that is different than a second coefficient of friction of a curve of the orthodontic aligner that lacks the microstructured surface.
In a thirteenth embodiment, the present disclosure provides an article according to any of the first through twelfth embodiments, wherein the portion of the curve comprising the microstructured surface comprises an interior portion.
In a fourteenth embodiment, the present disclosure provides an article according to any of the first through twelfth embodiments, wherein the portion of the curve comprising the microstructured surface comprises an exterior portion.
In a fifteenth embodiment, the present disclosure provides an article according to any of the first through fourteenth embodiments, wherein the peak structures have a height ranging from 1 to 125 microns.
In a sixteenth embodiment, the present disclosure provides an article according to any of the first through fifteenth embodiments, wherein the curve comprises a minimum curvature radius of 0.6 mm.
In a seventeenth embodiment, the present disclosure provides a method of making a microstructured article. The method comprises a) obtaining a tool shaped to comprise at least one of a protrusion or a concavity; b) disposing a microstructured film on at least a portion of the tool including the protrusion and/or the concavity; and c) thermoforming a single piece of thermoplastic polymer onto the tool to form a microstructured article shaped to comprise a curve comprising a curvature radius of up to 20 mm. The curve is an inverse of the protrusion or the concavity of the tool and at least a portion of the curve comprises a microstructured surface of utilitarian discontinuities being an inverse of a surface of the microstructured film. The microstructured surface comprises peak structures and adjacent valleys. The valleys have a maximum width ranging from 1 micron to 250 microns and the peak structures have a side wall angle of greater than 10 degrees.
In an eighteenth embodiment, the present disclosure provides a method according to the seventeenth embodiment, when the microstructured film is attached to the thermoplastic polymer and steps b) and c) are performed at least partially simultaneously.
In a nineteenth embodiment, the present disclosure provides a method according to the eighteenth embodiment, wherein the microstructured film is thermoformed onto the tool simultaneously with step c).
In a twentieth embodiment, the present disclosure provides a method according to any of the seventeenth through nineteenth embodiments, wherein the microstructured film is disposed on only a portion of a thermoforming surface of the tool.
In a twenty-first embodiment, the present disclosure provides a method according to any of the seventeenth through twentieth embodiments, wherein the microstructured film is disposed on 90% or greater of a thermoforming surface of the tool.
In a twenty-second embodiment, the present disclosure provides a method according to the twenty-first embodiment, wherein a portion of the microstructured film is removed from the thermoforming surface of the tool prior to step c).
In a twenty-third embodiment, the present disclosure provides a method according to the twentieth embodiment or the twenty-second embodiment, wherein a geometry of the tool is configured to be smaller in a location where the microstructured film is disposed than in a location where the microstructured film is not disposed.
In a twenty-fourth embodiment, the present disclosure provides a method according to any of the seventeenth through twenty-third embodiments, wherein the tool is formed by additive manufacturing.
In a twenty-fifth embodiment, the present disclosure provides a method according to the twenty-fourth embodiment, wherein step a) comprises making the tool using an additive manufacturing process.
In a twenty-sixth embodiment, the present disclosure provides a method according to any of the seventeenth through twenty-fifth embodiments, wherein the microstructured film has an average thickness of 25 microns to 380 microns.
In a twenty-seventh embodiment, the present disclosure provides a method according to any of the seventeenth through twenty-sixth embodiments, wherein the microstructured film has a land thickness of less than 1 micron, less than 0.5 microns, or less than 0.3 microns.
In a twenty-eighth embodiment, the present disclosure provides a method according to any of the seventeenth through twenty-seventh embodiments, wherein the microstructured article is the microstructured article of any of the first through sixteenth embodiments.
In a twenty-ninth embodiment, the present disclosure provides a tooling article. The tooling article comprises a tool shaped to comprise at least one of a protrusion or a concavity and a microstructured film disposed on at least a portion of the tool including the protrusion and/or the concavity. The microstructured film comprises peak structures and adjacent valleys, wherein the valleys have a maximum width ranging from 1 micron to 250 microns and the peak structures have a side wall angle of greater than 10 degrees.
In a thirtieth embodiment, the present disclosure provides a tooling article according to the twenty-ninth embodiment, wherein the microstructured film is disposed on only a portion of a thermoforming surface of the tool.
In a thirty-first embodiment, the present disclosure provides a tooling article according to the twenty-ninth embodiment or the thirtieth embodiment, wherein the microstructured film is disposed on 90% or greater of a thermoforming surface of the tool.
In a thirty-second embodiment, the present disclosure provides a tooling article according to any of the twenty-ninth through thirty-first embodiments, wherein the tool has a shape of a dental arch.
The following Examples are merely for illustrative purposes and are not meant to be overly limiting on the scope of the appended claims.
Unless otherwise noted or otherwise apparent from the context, all parts, percentages, ratios, and the like in the Examples and the rest of the specification are provided on the basis of weight. Solvents and other reagents used were obtained from Sigma-Aldrich Chemical Company (Milwaukee, WI) unless otherwise noted.
10 mil (0.254 mm) PETG film (obtained under the trade designation “PACUR PETG” Copolyester Sheet from Pacur, LLC, Oshkosh, WI)
5 mil (0.127 mm) and 30 mil (0.762 mm) PETG films were made by extruding pellets of PETG (obtained under the trade designation “EASTAR GN071” from Eastman Chemicals, Kingsport, TN) to 5 mil and 30 mil thicknesses, respectively.
Polypropylene disc, 125 mm diameter, 1.02 mm thick (obtained under the trade designation “INVISACRYL C” from Great Lakes Dental Technologies (formerly Great Lakes Orthodontics), Tonawanda, NY)
PETG disc, 125 mm diameter, 0.75 mm thick (obtained under the trade designation “DURAN REF3413” from Scheu-Dental GmbH, Iserlohn, Germany)
20 mil (0.508 mm) Microstructured Matte Polycarbonate film, (obtained under the trade designation “LEXAN 8B35” from Sabic, Mt. Vernon, IN)
Adhesion promoter (obtained under the trade designation “3M TAPE PRIMER 94” from 3M, St. Paul, MN)
Aliphatic urethane diarylate oligomer (obtained under the trade designation “PHOTOMER 6210” from IGM Resins USA, Inc., Charlotte, NC)
1,6-Hexanediol diacrylate (HDDA), (obtained under the trade designation “SR238” from Sartomer USA (Arkema Group), Exton, PA)
Photoinitiator, 2,4,6-Trimethylbenzoyldiphenylphosphine oxide (obtained under the trade designation “LUCIRIN TPO” from BASF Corporation, Florham Park, NJ)
The articles were visually inspected and examined with a digital microscope (obtained under the trade designation “KEYENCE VHX-1000” from Keyence Corporation of America, Itasca, IL).
A pyramidal microstructured metal tool which had a microstructure described in Example 3 of PCT Pat. Pub. No. 2021/033151 (Connell et al.), but with a peak height of 23 microns, was used to fabricate microstructured tooling films or discs.
A pyramidal microstructured metal tool which had a microstructure described in Example 3 of PCT Pat. Pub. No. 2021/033151 A1 (Connell et al.) with a peak height of 9 microns was used to fabricate microstructure tooling films or discs.
A layer of an adhesion promoter (“3M TAPE PRIMER 94”) was applied to the surface of a film substrate, using a clean brush, for enhancing the adhesion of a coating resin system to the substrate. The primer was allowed to dry at room temperature for 5 minutes before applying a second coating layer to maximize adhesion. The resin system used to cast on the metal tool contained 75 parts oligomer (“PHOTOMER 6210”), 25 parts hexanediol diacrylate (“SR238”), and 0.5 parts of photoinitiator (“LUCIRIN TPO”). The materials were blended with a high-speed mixer, and then heated in an oven set at 160° F. (71° C.) for 24 hours. The compounded resin was subsequently cooled to room temperature. The resin was then applied between the microstructure of the tooling plate and the primed surface of the substrate to form a coating bank, and the assembly was pressed by hand with a rubber hand roller to spread the resin between the tooling plate and the substrate. The sample was cured through the substrate using UV light by passing the sample 2 times through a UV processor having two Hg vapor lamps (obtained under the trade designation model “QC 120233 AN” from RPC Industries, Plainfield, IL) at a rate of 50 feet/minute (15.2 meters/minute) under a nitrogen atmosphere. The microstructure-coated substrate was separated from the tooling plate by hand. A 125 mm diameter hollow punch was used to cut out individual discs from the microstructured tooling film.
The resin prepared in Procedure 1 was coated onto a film substrate using a slot die. The resin-coated film was brought into contact with a tooling having a microstructured surface using pressure provided by a rotating nip roll at a given line speed. While the resin was in contact with the tool, the resin was cured using a high intensity Fusion Systems “D” lamp (from Fusion UV Curing Systems, Rockville, MD) with UV-A (315-400 nm) in the range of 100-1000 mJ/cm2.
To thermoform, a 125 mm diameter substrate was heated for a specific time and then pulled down over a rigid-polymer dental arch model on a pressure molding machine (obtained under the trade designation “BIOSTAR VI” from Scheu-Dental GmbH, Iserlohn, Germany). The specific heating times were set at 14 seconds, 20 seconds, 30 seconds, 45 seconds, and 70 seconds for 5 mil PETG, 10 mil PETG, 30 mil PETG, polycarbonate, and polypropylene, respectively. The BIOSTAR VI chamber behind the film was pressurized to 90 psi (0.62 megapascals) for 15 seconds of cooling time, after which the chamber was vented to ambient pressure and the formed article and arch model were removed from the instrument and cooled down to room temperature under ambient condition. The model with the thermoformed substrate was removed from the machine and excess film was trimmed using an ultrasonic cutter (obtained under the trade designation “SONIC-CUTTER NE80” from Nakanishi Incorporated, Kanuma City, Japan)
A PETG microstructured tooling film was prepared from the 10 mil (0.254 mm) PETG film (“PACUR PETG” Copolyester Sheet) according to Procedure 1 described above, using Microstructured Metal Tool 1 as the tooling plate, and punched into a 125 mm diameter disc. The disc was thermoformed in the pressure molding machine (“BIOSTAR VI”) onto a rigid-polymer dental arch model with its microstructured surface facing away from the dental arch model according to Procedure 3. A polypropylene disc (“INVISACRYL C”) was then thermoformed over the microstructured tooling film on the rigid-polymer dental arch model according to the thermoforming conditions of Procedure 3, to make a tray. After trimming with an ultrasonic cutter (“SONIC-CUTTER NE80”), the polypropylene tray was separated from the tooling film and the dental arch model by hand. The polypropylene tray had a uniform appearance and the inversed structure of the microstructured surface of the tooling film was evident, when examined by microscope, on the surface of the cavity side of the polypropylene tray.
A PETG microstructured tooling film was prepared from the 10 mil (0.254 mm) PETG film (“PACUR PETG” Copolyester Sheet) according to Procedure 1 described above, using Microstructured Metal Tool 1 as the tooling plate, and punched into a 125 mm diameter disc. A polypropylene (“INVISACRYL™ C”) disc was heated for 70 seconds in the pressure molding machine (“BIOSTAR VI”) and then laminated to the PETG tooling film with the microstructured surface of the PETG tooling film in contact with the polypropylene disc under a pressure of 90 psi (0.62 megapascals). The laminated substrate was then thermoformed according to the thermoforming conditions of Procedure 3 on to a rigid-polymer dental arch model with a heating time of 50 seconds, with the tooling film in contact with the dental arch model, to form a tray. After trimming with the ultrasonic cutter (“SONIC-CUTTER NE80”), the polypropylene tray was separated from the tooling film and the dental arch model by hand. The polypropylene tray had uniform appearance and the inversed structure of the microstructured surface of the tooling film was evident, when examined by microscope, on the surface of the cavity side of the polypropylene tray.
A PETG microstructured tooling film was prepared from the 10 mil (0.254 mm) PETG film (“PACUR PETG” Copolyester Sheet) according to Procedure 1 described above, using Microstructured Metal Tool 1 as the tooling plate, and punched into a 125 mm diameter disc. The disc was thermoformed in the pressure molding machine (“BIOSTAR VI”) on to a rigid-polymer dental arch model with its microstructured surface facing away from the dental arch model according to Procedure 3. The tooling film from lateral incisors to central incisors was removed carefully from the dental arch model with a razor blade. A polypropylene disc (“INVISACRYL C”) was then thermoformed over the microstructured tooling film on the rigid-polymer dental arch model by the thermoforming conditions of Procedure 3 to form a tray. After trimming with the ultrasonic cutter (“SONIC-CUTTER NE80”), the polypropylene tray was separated from the tooling film and the dental arch model by hand. The polypropylene tray had differential microstructured appearance and the inverted structure of the microstructured surface of the tooling film was only evident on the surface of the cavity side of the polypropylene tray by microscope for the section where tooling was kept on the dental arch model during the thermoforming operation for the polypropylene disc.
An extrusion replicated matte polycarbonate film (“LEXAN 8B35”) was punched into a 125 mm diameter disc. The disc was thermoformed in the pressure molding machine (“BIOSTAR VI”) to a microstructured tooling film by Procedure 3 and trimmed with the ultrasonic cutter (“SONIC-CUTTER NE80”). The tooling film had good clarity and the matte (microstructured) surface was observed to have been erased by the heating and forming process of the thermoforming operation.
A microstructured PETG disc was prepared by Procedure 1 described above, using Microstructured Metal Tool 1 as the tooling plate, by coating the microstructured layer on a PETG disc (“DURAN REF3413”). The microstructured PETG disc was thermoformed in the pressure molding machine (“BIOSTAR VI”) to a tray by the thermoforming conditions of Procedure 3 and trimmed with the ultrasonic cutter (“SONIC-CUTTER NE80”).
A microstructured PETG film was prepared by Procedure 2 described above, using Microstructured Metal Tool 1 as the tooling plate, from the 30 mil (0.762 mm) PETG film at a line speed of 25 fpm and 15 psi nip pressure and the shore hardness of the rubber nip roll was 95A. The microstructure coated film was punched into a 125 mm disc. The disc was thermoformed and trimmed to a microstructured tooling film by Procedure 3. Referring to
A microstructured PETG film was prepared by Procedure 2 described above, using Microstructured Metal Tool 1 as the tooling plate, from the 10 mil (0.254 mm) PETG film at a line speed of 25 feet per minute (fpm) and 15 psi nip pressure and the shore hardness of the rubber nip roll was 95A. The microstructure coated film was punched into a 125 mm disc. The disc was thermoformed and trimmed to a tooling film by Procedure 3. Referring to
A microstructured PETG film was prepared by Procedure 2 described above, using Microstructured Metal Tool 1 as the tooling plate, from the 10 mil (0.254 mm) PETG film at a line speed of 15 fpm and 30 psi nip pressure and the shore hardness of the rubber nip roll was 90A. The land thickness of coating below the microstructure was approximated by microscope greater than 1.5 micron. The microstructure coated film was punched into a 125 mm disc. The disc was thermoformed and trimmed to a microstructured tooling film by Procedure 3. The thermoformed microstructured tooling film had tiger stripe patterns which are attributed to the macrocracks formed by deformation from the thermoforming operation. Referring to
A microstructured PETG film was prepared by Procedure 2 from the 10 mil (0.254 mm) PETG film from Microstructure Metal Tool 2 at a line speed of 25 fpm and 15 psi nip pressure and the shore hardness of the rubber nip roll was 95A. The microstructure coated film was punched into a 125 mm disc. The disc was thermoformed and trimmed to a microstructured tooling film by Procedure 3. The thermoformed microstructured tooling film had tiger stripe patterns which are attributed to the macrocracks formed by deformation from the thermoforming operation.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2022/058618 | 9/13/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63243855 | Sep 2021 | US | |
| 63402633 | Aug 2022 | US |
