Stretchable articles including a polymeric substrate with a pattern of slits and methods of making same

Abstract

The present disclosure provides a stretchable article. The stretchable article includes a polymeric substrate configured to have a planar unstretched state and a non-planar deformed stretched state. When the polymeric substrate is in the planar unstretched state the polymeric substrate includes a sheet having a first major surface; a second major surface opposite the first major surface; and a plurality of slits that each extend from the first major surface to the second major surface. The plurality of slits are arranged in a Kirigami pattern, which includes at least one feature that is smaller than 500 micrometers. Additionally, a method is provided, including forming a plurality of slits in a polymeric substrate using a microstructured cutting tool.

Description

PA102633W002STRETCHABLE ARTICLES INCLUDING A POLYMERIC SUBSTRATE WITH A PATTERN OF SLITS AND METHODS OF MAKING SAMEField

[0001] The present disclosure relates generally to tension-activated, expanding articles.Summary

[0002] In a first aspect, a stretchable article is provided. The stretchable article comprises a polymeric substrate configured to have a planar unstretched state and a non-planar deformed stretched state. When the polymeric substrate is in the planar unstretched state the polymeric substrate comprises a sheet comprising a first major surface; a second major surface opposite the first major surface; and a plurality of slits that each extend from the first major surface to the second major surface. The plurality of slits are arranged in a Kirigami pattern, which comprises at least one feature that is smaller than 500 micrometers.

[0003] In a second aspect, a method of making a stretchable article is provided. The method comprises forming a plurality of slits in a polymeric substrate using a microstructured cutting tool, thereby forming a polymeric substrate configured to have a planar unstretched state and a non-planar deformed stretched state. When the polymeric substrate is in the planar unstretched state the polymeric substrate comprises a sheet comprising a first major surface; a second major surface opposite the first major surface; and a plurality of slits that each extend from the first major surface to the second major surface. The plurality of slits are arranged in a Kirigami pattern, which comprises at least one feature that is smaller than 500 micrometers.Brief Description of Drawings

[0004] FIG. 1A is a top view schematic drawing of an exemplary double slit pattern.

[0005] FIG. IB is a top view schematic drawing of the primary tension lines of the double slit pattern shown in FIG. 1 A when exposed to tension.

[0006] FIG. 1C is a top view schematic drawing of another exemplary double slit pattern.

[0007] FIG. ID is an image of a modeled exemplary stretchable article having a double slit pattern, in the process of being stretched into a non-planar deformed stretched state.

[0008] FIG. IE is a scanning electron microscopy (SEM) image of a portion of the exemplary stretchable article of Example 1, having a double slit pattern, in a non-planar deformed stretched state.

[0009] FIG. IF is an SEM image of a portion of the exemplary stretchable article of Example 4, in a partially non-planar deformed stretched state.

[0010] FIG. 2A is a top view schematic drawing of an exemplary double slit triple beam pattern.

[0011] FIG. 2B is a nearly side view drawing from a photograph of a material into which the slit pattern of FIG. 2B has been formed after it has been stretched into a non-planar deformed stretched state.

[0012] FIG. 2C is a top view schematic drawing of another exemplary double slit triple beam pattern.

[0013] FIG. 2D is a close-up top view schematic drawing of multibeams in between the double slits in the pattern of FIG. 2C.

[0014] FIG. 2E is an image of a modeled exemplary stretchable article having a double slit triple beam pattern, in the process of being stretched into a non-planar deformed stretched state.

[0015] FIG. 2F is an SEM image of a portion of the exemplary stretchable article of Example 3, having a double slit triple beam pattern, in a partially non-planar deformed stretched state.

[0016] FIG. 2G is a photograph of another exemplary stretchable article having a double slit double beam pattern, in a non-planar deformed stretched state.

[0017] FIG. 2H is a close-up of a portion of the stretchable article of FIG. 2G.

[0018] FIG. 21 is an SEM image of a portion of the exemplary stretchable article of Example 6, having a double slit triple beam pattern, in a partially non-planar deformed stretched state.

[0019] FIG. 3 A is a top view schematic drawing of an exemplary double slit double beam pattern.

[0020] FIG. 3B is a close-up top view schematic drawing of multibeams in between the double slits in the pattern of FIG. 3 A.

[0021] FIG. 3C is an image of a modeled exemplary stretchable article having a double slit double beam pattern, in the process of being stretched into a non-planar deformed stretched state.

[0022] FIG. 3D is an SEM image of a portion of the exemplary stretchable article of Example 2, having a double slit double beam pattern, in a partially non-planar deformed stretched state.

[0023] FIG. 3E is an SEM image of a portion of the exemplary stretchable article of Example 2, having a double slit double beam pattern, in a non-planar deformed stretched state.

[0024] FIG. 3F is an SEM image a portion of the exemplary stretchable article of Example 5, having a double slit double beam pattern, in a partially non-planar deformed stretched state.

[0025] FIG. 3G is a photograph of a portion of the exemplary stretchable article of Example 5, in the process of being stretched.

[0026] FIG. 3H is an SEM image of a portion of the exemplary stretchable article of Example 5, in a non-planar deformed stretched state.

[0027] FIG. 4 is an SEM image of a portion of an exemplary stretchable article to show the precision of the cuts into a polymeric substrate.

[0028] FIG. 5 is an SEM image of a portion of another exemplary stretchable article to show the precision of the cuts into a polymeric substrate.

[0029] FIG. 6 is an SEM image of a portion of a further exemplary stretchable article to show the precision of the cuts into a polymeric substrate.

[0030] FIG. 7 A is a photograph of a portion of the exemplary stretchable article of Example 8, having a single slit pattern, in a planar unstretched state.

[0031] FIG. 7B is an SEM image of a portion of the stretchable article of FIG. 7A (Example 8).

[0032] FIG. 7C is an SEM image of a portion of the stretchable article of Example 8, having a single slit pattern, in a non-planar deformed stretched state.

[0033] FIG. 8 is a photograph of the exemplary stretchable article of Example 7, being separated from a liner.

[0034] FIG. 9 is a generalized schematic side view of an apparatus for making an exemplary stretchable article.

[0035] FIG. 10 is a generalized schematic side view of another apparatus for making an exemplary stretchable article.

[0036] Repeated use of reference characters in the specification and drawings is intended to represent the same or analogous features or elements of the disclosure. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the disclosure. The figures may not be drawn to scale.Detailed Description

[0037] The terms “a”, “an”, “the”, “at least one”, and “one or more” are used interchangeably.

[0038] The term “and / or” means one or both such as in the expression A and / or B refers to A alone, B alone, or to both A and B.

[0039] The term “essentially” means 95% or more.

[0040] 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 specific circumstance rather than requiring absolute precision or a perfect match. Each numerical parameter should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0041] As used herein, “adjacent” means next to or adjoining.

[0042] As used herein, “polymeric” refers to a material prepared from at least one monomer (such as a homopolymer) or to material prepared from two or more monomers (such as a copolymer, a terpolymer, or the like).

[0043] The term “sheet” generally refers to a material with a very high ratio of length or width to thickness. A sheet has two major surfaces defined by a length and a width.

[0044] The term “layer” generally refers to a thickness of material within a sheet that has a relatively consistent chemical composition.

[0045] The term “substrate” encompasses sheets, layers, and articles.

[0046] As used herein, “thickness” refers to the smallest dimension of a substrate or an article, e.g., in a z-axis while a major surface of the substrate or the article is in the x- and y-axes. Thickness may be determined using a micrometer gauge or doing a microscopic analysis of a cross-sectional sample of a substrate or an article.

[0047] The term “planar” with respect to a substrate or article refers to a substrate or article that defines a plane, a longitudinal axis extending along a length of the substrate or article, a transverse axisdisposed in the plane and extending perpendicular to the longitudinal axis, and a thickness normal to the plane.

[0048] The term “Kirigami pattern” refers to a pattern of a plurality of slits cut through the thickness of a substrate.

[0049] The term “stretchable” means a substrate or article whose length may be expanded under tension without tearing of the substrate or an article. The presence of a Kirigami pattern of slits may enable an otherwise non-stretchable substrate or article to become stretchable.

[0050] As used herein, “slit” means a cut through a thickness of a substrate or an article.

[0051] The term “resin” refers to a particulate or viscous liquid polymeric material.

[0052] Stretchable Articles

[0053] In a first aspect, a stretchable article is provided. The stretchable article comprises:

[0054] a polymeric substrate configured to have a planar unstretched state and a non-planar deformed stretched state, wherein when the polymeric substrate is in the planar unstretched state the polymeric substrate comprises:

[0055] a sheet comprising a first major surface; a second major surface opposite the first major surface; and a plurality of slits that each extend from the first major surface to the second major surface, the plurality of slits being arranged in a Kirigami pattern, which comprises at least one feature that is smaller than 500 micrometers.

[0056] It has been discovered that it is possible to provide advanced materials and / or devices with unique properties by creating intricate patterns of cuts in a substrate at a microscopic scale (e.g., micro-kirigami pattern). For instance, high precision permeable scrims and spacers may be made using micro cutting methods in which the substrate is polymeric, e.g., a polymeric sheet. As such, in some cases, when the polymeric substrate is in the non-planar deformed stretched shape the article has a form of a spacer. Similarly, in some cases, when the polymeric substrate is in the non-planar deformed stretched shape the article has a form of a scrim. Optionally, the stretchable article has a form of a roll, which allows sections to be cut from an article having indefinite length.

[0057] Exemplary suitable polymeric substrates may be selected from the group consisting of a polypropylene, a polyester, a polyethylene, a polystyrene, a polymethylmethacrylate, a polyamide, a polycarbonate, a polymethyleneoxide, a polybutyleneterephthalate, a styrene acrylonitrile copolymer, a styrene (methjacrylate copolymer, a styrene maleic anhydride copolymer, a nucleated semi-crystalline polyester, a copolymer of polyethylenenaphthalate, a polyimide copolymer, a polyetherimide, a polyethylene oxides, a copolymer of acrylonitrile, butadiene, and styrene, and blends thereof. In some embodiments, polyethylene terephthalate (PET) is a suitable polyester for use as the polymeric substrate.

[0058] In some embodiments, the polymeric substrate in the planar non-stretched shape has an average thickness of 0.5 micrometers or greater, 1 micrometer, 2 micrometers, 3 micrometers, 4 micrometers, 5 micrometers, 6 micrometers, 7 micrometers, 8 micrometers, 9 micrometers, 10micrometers, 11 micrometers, or 12 micrometers or greater; and 20 micrometers or less, 19 micrometers, 18 micrometers, 17 micrometers, 16 micrometers, 15 micrometers, 14 micrometers, 13 micrometers, 12 micrometers, 11 micrometers, 10 micrometers, 9 micrometers, 8 micrometers, 7 micrometers, 6 micrometers, or 5 micrometers or less. In some cases, the polymeric substrate in the planar non-stretched shape has an average thickness between 0.5 micrometers and 20 micrometers.

[0059] Providing a polymeric substrate having a thickness in the above range enables production of a stretched article such that when the polymeric substrate is in the non-planar deformed stretched shape the article has an average thickness of 5 micrometers or greater, 10 micrometers, 15 micrometers, 25 micrometers, 50 micrometers, 75 micrometers, 100 micrometers, 125 micrometers, 150 micrometers, 175 micrometers, 200 micrometers, 225 micrometers, 250 micrometers, 275 micrometers, 300 micrometers, 325 micrometers, 350 micrometers, 375 micrometers, 400 micrometers, 425 micrometers, 450 micrometers, 475 micrometers, or 500 micrometers or greater; and 800 micrometers or less, 775 micrometers, 750 micrometers, 725 micrometers, 700 micrometers, 675 micrometers, 650 micrometers, 625 micrometers, 600 micrometers, 575 micrometers, 550 micrometers, 525 micrometers, 500 micrometers, 475 micrometers, 450 micrometers, 425 micrometers, 400 micrometers, 375 micrometers, 350 micrometers, 325 micrometers, 300 micrometers, 275 micrometers, 250 micrometers, 225 micrometers, 200 micrometers, 175 micrometers, 150 micrometers, 125 micrometers, 100 micrometers, or 50 micrometers or less. In some cases, when the polymeric substrate is in the non-planar deformed stretched shape the article has an average thickness between 5 micrometers and 800 micrometers. It is noted that following stretching to a non-planar deformed stretched state, it may also be useful to compress the stretchable conductive article to a desired thickness depending on a specific application of the article.

[0060] In some embodiments, suitable Kirigami patterns include single unidirectional patterns or multislit unidirectional patterns.

[0061] A “slit” is defined herein as a narrow cut through the article forming at least one line, which may be straight or curved, having at least two terminal ends. Slits described herein are discrete, meaning that individuals slits do not intersect other slits. A slit is generally not a cut-out, where a “cutout” is defined as a surface area of the sheet that is removed from the sheet when a slit intersects itself. However, in practice, many forming techniques result in the removal of some surface area of the sheet that is not considered a “cut-out” for the purposes of the present application. In particular, many cutting technologies produce a “kerf”, or a cut having some physical width.

[0062] As used herein, the term “single slit pattern” refers to a pattern of individual slits that form individual rows each extending across the sheet transversely, where the rows form a repeating pattern of individual rows along the axial length of the sheet, and the pattern of slits in each row is different than the pattern of slits in the directly adjacent rows. For example, the slits in one row may be axially offset or out of phase with the slits in the directly adjacent rows.

[0063] The term “multi-slit pattern” is defined herein as a pattern of individual slits that form a first set of adjacent rows across the transverse direction y of the sheet, where the individual slits within the firstset of adjacent rows are aligned in the transverse direction y . In a multi-slit pattern, the first set of adjacent rows form a repeating pattern with at least a second row along the axial length of the sheet, where the slits in the first set of adjacent identical rows are offset from the slits in the next row in the transverse direction y. The term "multi-slit pattern" includes double slit patterns, triple slit patterns, quadruple slit patterns, etc.

[0064] As used herein, the term “double slit pattern” refers to a pattern of a plurality of individual slits. The pattern includes a plurality of rows of slits and the individual slits in a first row are substantially aligned with the individual slits in a directly adjacent, second row. A double slit is comprised of a slit in a first row that is substantially aligned with a slit in a second row. A double slit pattern includes at least two sets of double slit rows that are offset from each other in the transverse axis.

[0065] As used herein, the term “triple slit pattern” refers to refers to a pattern of a plurality of individual slits. The pattern includes a plurality of rows of slits and the individual slits in a first row are substantially aligned with the individual slits in a directly adjacent, second row. The slits in the second row are substantially aligned with the individual slits in a directly adjacent, third row. A triple slit is comprised of a slit in a first row that is substantially aligned with a slit in a second row, both of which are substantially aligned with a slit in a third row. Together, these three substantially aligned slits form a triple slit. A triple slit pattern includes at least two sets of triple slit rows that are offset from each other in the transverse axis.

[0066] As used herein, the term “quadruple slit pattern” refers to refers to a pattern of a plurality of individual slits. The pattern includes a plurality of rows of slits and the individual slits in a first row are substantially aligned with the individual slits in a directly adjacent, second row. The slits in the second row are substantially aligned with the individual slits in a directly adjacent, third row. The slits in the third row are substantially aligned with the individual slits in a directly adjacent, fourth row. A quadruple slit is comprised of a slit in a first row that is substantially aligned with a slit in a second row, both of which are substantially aligned with a slit in a third row, all three of which are substantially aligned with a slit in a fourth row. Together, these four substantially aligned slits form a quadruple slit. A quadruple slit pattern includes at least two sets of quadruple slit rows that are offset from each other in the transverse axis.

[0067] The term “multi-slit pattern” includes double slit patterns, triple slit patterns, quadruple slit patterns, etc. Further, the term “multi-slit pattern” is meant to include any slit pattern wherein two or more slits that are each in different, directly adjacent rows substantially align with one another such that their terminal ends substantially align. Substantial alignment of the terminal ends of aligned multi-slits means that if you draw an imaginary line between two aligned terminal ends in two adjacent slits of the multi-slit, the angle of that imaginary line relative to the alignment axis (the axis that is perpendicular to the row(s)) is no greater than + / - 20 degrees. In some embodiments, the length of each slit that forms a multi-slit differs by no more than + / -20% of the total length of the longest or shortest slit. In some embodiments, where the slits are linear, they are substantially parallel to one another. In someembodiments where the slits are not linear, the aligned multi-slits are all substantially aligned parallel to the tension axis within + / - 20 degrees.

[0068] The midpoint 132 of a section of transverse beam 130 can be referred to as the geometric center of that section of the transverse beam (as shown in Fig 1 A). In some embodiments, the individual slits in a row are substantially aligned with the individual slits in more than one and less than a million directly adjacent rows. In some embodiments, the slits are substantially perpendicular to the tension axis (T).

[0069] Double, triple, quadruple, or multi-slit patterns create significantly more out of plane undulation than single slit patterns when exposed to tension along a tension axis. This out of plane undulation of the material has great value for many applications.

[0070] When used herein with respect to single slit patterns and multi-slit patterns (defined above), the term “multibeam slits” is defined as one or more simple slits (in addition to the slits forming the single slit or multi-slit pattern) formed between two adjacent slits, where the two adjacent slits are either in the same row or adjacent rows. For instance, “single beam”, “double beam” or “triple beam” variations of the double slit pattern.

[0071] In FIG. 1, a schematic drawing is provided of an exemplary double slit single beam pattern. The pattern 100 includes a plurality of slits 110 in rows of slits 112. Each slit 110 includes a midpoint 118 between a first terminal end 114 and a second terminal end 116. A first row 112a of slits 110 and a second row 112b of slits 110 each include a plurality of slits 110 that are spaced from one another. The axial space between directly adjacent slits 110 in a row 112 in combination with the adjacent portions of the transverse beam 130 can form an axial beam 120 between adjacent slits 110 in a row 112. In the exemplary embodiment of FIG. 1A, a straight, imaginary line extends between and connects terminal ends 114, 116. In this exemplary embodiment, the straight, imaginary line extending between and connecting the terminal ends of a first slit is substantially colinear with the straight, imaginary line extending between and connecting the terminal ends of a directly adjacent second slit in the same row. In this exemplary embodiment, all of the straight, imaginary lines extending between and connecting the slit terminal ends in a single row are approximately colinear.

[0072] Together, rows 112a, 112b of slits 110 form a transverse beam 130. Transverse beam 130 is bound in the axial direction by slits 110. An overlap beam 136 is directly adjacent to and, in this embodiment, on both sides of each transverse beam 130. Overlap beam 136 is bound in the axial direction by non-aligned slits. The slits in each directly adjacent row 112a, 112b that forms an edge or side of transverse beam 130 are substantially aligned with one another such that they are substantially parallel and their terminal ends 114, 116 are substantially aligned perpendicular to the axis of the row and equidistant to one another. In some embodiments, the slits that are aligned have substantially the same slit length and pitch (pitch being relative to the tension axis).

[0073] Each section of transverse beam 130 bordered by two parallel and substantially aligned slits 110 includes a midpoint 132 that is (1) at the midpoint (transversely) between first terminal end 114 and a second terminal end 116 of the slits 110 that form the sides of transverse beam 130 and (2) at themidpoint (axially) between the two slits 110 that form the sides of transverse beam 130. A midpoint 132a of a first section of transverse beam 130a is out of phase with a midpoint 132b of the directly adjacent section of the directly adjacent transverse beam 130b. In the embodiment of FIG. 1A, the midpoint 132a of a first section of transverse beam 130a substantially aligns axially with midpoint 132c of a first section of transverse beam 130c, which is the second directly adjacent transverse beam from transverse beam 130a.

[0074] FIG. 1 A also shows the tension axis (T) which is substantially parallel to the axial direction and substantially perpendicular to the transverse direction, and the direction of the rows of slits, in the embodiment of FIG. 1A. The tension axis (T) is an axis along which tension can be provided to deploy the material into which the pattern 100 has been formed, which creates the upward and downward movement of transverse beams 130 and rotation of overlap beams 136.

[0075] FIG. IB shows the primary tension lines 140 (e.g., the lines approximating the highest tensile stress path) formed when an article including the slit pattern of FIG. 1 A is deployed with tension along the tension axis T. FIG. IB shows in dashed lines the primary tension lines 140, which are where the greatest tensile stress will occur. Tension lines are imaginary paths through the material that carry the greatest load when tension is applied to the material along the tension axis. When tension is applied along tension axis (T), the primary tension lines 140 move more closely into alignment with the applied tension axis, causing the sheet to distort. When multi-slit patterns are deployed, the activation of tension along the primary tension lines 140 causes substantially all regions of the pattern to experience some tension or compression (tensile stress or compressing stress) and then many of the regions buckle and bend out of the plane of the original two-dimensional film.

[0076] When tension is applied to a material, sheet, or film including a double slit pattern, the portions of the transverse beam 130 between pairs of aligned slits 110 experience primarily compressive stress, which causes the beam 130 to buckle out of the original plane of the sheet forming an undulation or a loop shape, while staying nominally parallel to the tension axis. Overlap beams 136 buckle and bend out of the plane of the original material or sheet as they experience these tensile forces. In the transverse beams 130 only the region between the pairs of slits, called the axial beam 120, experiences the tension (and tensile stress) and transmits it to the next row 112 of slits 110. The axial beam 120 between directly adjacent slits 110 in a single row 112 in combination with the adjacent portions of the transverse beam 130 is marked with dashed lines on the edges where the greatest stress occurs. These tension bearing regions remain relatively flat and parallel to the pretensioned plane of the material or sheet when tension is applied. These tension bearing regions do not tend to rotate because the tension lines through them are substantially parallel to the primary tension axis (T).

[0077] Referring to FIG. 1C, a schematic drawing is provided of another exemplary double slit pattern 100c. The main difference between the double slit pattern of FIG. 1C and the double slit pattern of FIG.1 A is that there is less overlap between the ends of adjacent pairs of slits 110, which results in longer transverse beams 130 and wider axial beams 120 than in the double slit pattern of FIG. 1A. FIG. 1C also shows the tension axis (T) which is substantially parallel to the axial direction and substantiallyperpendicular to the transverse direction, and the direction of the rows of slits, in the embodiment of FIG. 1C.

[0078] FIG. ID provides an image of a modeled exemplary stretchable article lOOd having a double slit pattern, in the process of being stretched into a non-planar deformed stretched state.

[0079] Referring to FIG. IE, a scanning electron microscopy (SEM) image is provided of a portion of an exemplary stretchable article lOOe having a double slit pattern as shown in FIG. 1C, in a non-planar deformed stretched state. This stretchable article lOOe was made according to Example 1 described in detail below. Each of a transverse beam 130, an axial beam 120, and an overlap beam 136 are indicated in the SEM image.

[0080] Referring to FIG. IF, an SEM image is provided of a portion of an exemplary stretchable article, in a partially non-planar deformed stretched state. This stretchable article lOOf was made according to Example 4 described in detail below. Each of a transverse beam 130, an axial beam 120, and an overlap beam 136 are indicated in the SEM image.

[0081] FIG. 2A is a top view schematic drawing of an exemplary double slit triple beam pattern. The beam region, and more specifically the direct path between the closest terminal ends of two adjacent slits in adjacent rows such as ends 216a and 214a of FIG. 2A, experiences the highest concentration of forces when tension is applied to a single slit patterned material. As such, these beam regions experience the greatest stress concentration during deployment (or tension application or activation) of the material. This high stress concentration can result in tearing of the material during deployment. Additional slits added in this region that cross through the direct path between closest terminal ends in adjacent rows can create one or more additional force-carrying paths, or additional beams, which have additional stress concentrating terminal ends that can increase the maximum force bearing capacity of the material. Materials or articles that include multibeam slit patterns have a greater maximum tension force as compared to a material or article with the same pattern of beams but without multibeams. As used herein, the term “maximum tension force” refers to the maximum tensile force that can be applied to a sample of slit-patterned material before it tears. Generally, the maximum tension force occurs just before a slit-patterned material tears. A test method for measuring the maximum tension force is described in U. S. Patent Application No. 62 / 953042, assigned to the present assignee, the entirety of which is incorporated by reference herein. The Maximum Tension Force (e.g., tear force), is the maximum force measured by the load frame as the sample is stretched. This is typically just before the material begins to tear. In some embodiments, materials or articles that include a multibeam slit pattern are capable of withstanding larger tension forces without tearing as compared to a material or article with the same pattern except without multibeams.

[0082] In some embodiments, materials or articles with multibeam slit patterns have the same or lower deployment force. As used herein, the term “deployment force” refers to the force required to substantially deploy the patterned sheet.

[0083] In some embodiments, it is advantageous to have the maximum tension force (the tension force required to tear the slit patterned material during deployment or tensioning along tension axis T) begreater than the deploy force (the force required to deploy the sample). The Max-Deploy Ratio is the ratio of the maximum tension force divided by the deploy force. In some embodiments, it is advantageous for that ratio to be as large as possible such that the force applied to deploy a patterned sheet is much lower than the maximum force that the sheet can sustain. This prevents users of the sheet from accidentally tearing the material when deploying it.

[0084] Multibeam slits 280 (in this embodiment, two multibeam slits) are formed in overlap beam 236. These multibeam slits 280 will enable the formation of multibeams 282 when material 200 is exposed to tension along the tension axis. The multibeam slits 280, and the resulting multibeams 282, of FIGS. 2 A and 2B are substantially linear.

[0085] Those of skill in the art will appreciate that many changes may be made to the pattern while still falling within the scope of the present disclosure. In some embodiments, multi-slit pattern will be a triple slit, quadruple slit, or other multi-slit instead of a double slit pattern. Alternatively, the slit length, slit size, slit thickness, slit shape, row size or shape, transverse beam size or shape, and / or overlap beam size or shape can vary. Further, the degrees of offset or phase offset can vary from what is shown. The slit, row, or beam pitch can vary. The angle between the tension axis and slits can vary. The number, shape, size, etc. of the multibeam slits and / or multibeams can vary. Alternatively, the row size or shape and beam size or shape can vary. Further, the degrees of offset or phase offset can vary from what is shown. Many of these changes could change the deployment pattern.

[0086] There are various features of a Kirigami pattern that may have a size smaller than 500 micrometers. In some embodiments, the at least one feature that is smaller than 500 micrometers comprises one or more of a slit length, an axial beam length, a transverse beam length, a multibeam length, or a distance between two adjacent slits. In certain cases, the feature(s) include a slit length. In certain cases, the feature(s) include an axial beam length. In certain cases, the feature(s) include a transverse beam length. In certain cases, the feature(s) include a multibeam length. In certain cases, the feature(s) include a distance between two adjacent slits.

[0087] FIG. 2B is a drawing created from a photograph of a material including the slit pattern of FIG.2A when exposed to tension along tension axis T. When material 200 is tension activated or deployed along tension axis T, portions of material 200 experience tension and / or compression that causes material 200 to move out of the original plane of material 200 in its non-tensioned format. Portions of transverse beams 230 undulate out of the original plane of the material 200 in its pretensioned state (FIG. 2A) forming loops, while staying nominally parallel to the tension axis. The axial beam 220 between adjacent slits 210 in a row 212 and adjacent portion of transverse beam 230 stays substantially parallel to the original plane of material 200 in its pretensioned state (FIG. 2A). Overlap beams 236 buckle and rotate out of the plane of the original material or sheet. Because of the addition of two multibeam slits 280, each overlap beam 236 is cut into three distinct multibeams 282 that each carry tension and stay nominally parallel to each other and move or rotate as a group. The motion of the overlap beams 236 in combination with the undulation of the transverse beams 230 creates open portions 222.

[0088] When the tension-activated material 200 is wrapped around an article or placed directly adjacent to itself, the loops and undulations interlock with one another and / or opening portions 222, to create an interlocking stmcture. Additional multi-slit patterns are shown in, for example, U.S. Patent Application No. 62 / 952806, assigned to the present assignee, the entirety of which is incorporated herein.

[0089] Referring to FIG. 2C, a schematic drawing is provided of another exemplary double slit triple beam pattern 200c. The main difference between the double slit triple beam pattern of FIG. 2C and the double slit triple beam pattern of FIG. 2 A is that there are more axial beams 120 than in the pattern of FIG. 2A. FIG. 2C also shows the tension axis (T) which is substantially parallel to the axial direction and substantially perpendicular to the transverse direction, and the direction of the rows of slits, in the embodiment of FIG. 2C. FIG. 2D is a close-up top view schematic drawing of adjacent slits (two slits 210 and two multi-beam slits 280) interlaced with 3 beams between them in the pattern of FIG. 2C.

[0090] FIG. 2E provides an image of a modeled exemplary stretchable article 200e having a double slit triple beam pattern, in the process of being stretched into a non-planar deformed stretched state.

[0091] Referring to FIG. 2F, an SEM image is provided of a portion of an exemplary stretchable article 200f having a double slit triple beam pattern as shown in FIG. 2C, in a partially non-planar deformed stretched state. This stretchable article 200f was made according to Example 3 described in detail below. Each of a transverse beam 230, an axial beam 220, and a few multibeams 282 are indicated in the SEM image.

[0092] FIG. 2G is a photograph of another exemplary stretchable article 200g having a double slit double beam pattern, in a non-planar deformed stretched state. FIG. 2H is a close-up of a portion of the stretchable article of FIG. 2G, with each of a transverse beam 230 and an axial beam 220 indicated in the photograph.

[0093] FIG. 21 is an SEM image of a portion of an exemplary stretchable article, having a double slit triple beam pattern, in a partially non-planar deformed stretched state. This stretchable article 200i was made according to Example 6 described in detail below. Each of a transverse beam 230, an axial beam 220, and three multibeams 282 are indicated in the SEM image.

[0094] In some embodiments, a stretchable article has a double slit double beam pattern. FIG. 3 A is a top view schematic drawing of an exemplary double slit double beam pattern 300a. The double slit double beampattem 300a differs from the double slit triple beam patterns described in detail above in having two beams instead of three beams in between the adjacent slits (e.g., 280 in FIGS. 2A, 2C, and 2D). A transverse beam 330 and an axial beam 320 are each indicated in the drawing of the double slit double beam pattern 300a. FIG. 3B is a close-up top view schematic drawing of three adjacent slits (two slits 310 and one multi-beam slit 380) in the pattern of FIG. 3 A.

[0095] FIG. 3 C is an image of a modeled exemplary stretchable article 300c having a double slit double beam pattern, in the process of being stretched into a non-planar deformed stretched state.

[0096] FIG. 3D is an SEM image of a portion of an exemplary stretchable article 300d having a double slit double beam pattern as shown in FIG. 3C, in a partially non-planar deformed stretched state. Thisstretchable article 300d was made according to Example 2 described in detail below. Each of a transverse beam 330, an axial beam 320, and a couple multibeams 382 are indicated in the SEM image.

[0097] Referring to FIG. 3E, an SEM image is provided of a portion of an exemplary stretchable article 300e having a double slit double beam pattern as shown in FIG. 3C, in a non-planar deformed stretched state. This stretchable article 300e was made according to Example 2. Each of a transverse beam 330, an axial beam 320, and a couple multibeams 382 are indicated in the SEM image.

[0098] FIG. 3F is an SEM image of a portion of an exemplary stretchable article, having a double slit double beam pattern, in a partially non-planar deformed stretched state. This stretchable article 300f was made according to Example 5 described in detail below. Each of a transverse beam 330, an axial beam 320, and a couple multibeams 382 are indicated in the SEM image.

[0099] FIG. 3G is a photograph of a portion of the exemplary stretchable article 300g of Example 5, in the process of being stretched.

[0100] FIG. 3H is an SEM image of a portion of an exemplary stretchable article, having a double slit double beam pattern, in a non-planar deformed stretched state. This stretchable article 300h was made according to Example 5. Each of a transverse beam 330, an axial beam 320, and a couple multibeams 382 are indicated in the SEM image.

[0101] It has been discovered that at least certain methods of forming Kirigami patterns in a polymeric substrate on a micrometer scale, such as using a microstructured cutting tool, are capable of forming clean slices through the polymeric substrate. For instance, FIG. 4 is an SEM image of a portion of an exemplary stretchable article 400 that shows examples of the precision of the cuts into a polymeric substrate in the micrometer scale. Three different precise beam edges 450 are indicated in the SEM image, as well as one beam edge defect 460. Similarly, FIG. 5 is an SEM image of a portion of another exemplary stretchable article 500 to show the precision of the cuts into a polymeric substrate. Four different precise beam edges 550 are indicated in the SEM image. FIG. 6 provides an SEM image of a portion of a further exemplary stretchable article to show the precision of the cuts into a polymeric substrate in greater magnification. For instance, an end of a cut piece of polymeric substrate can be seen having a length a little longer than 5 micrometers, with two precise edges 650 indicated and two areas of irregularity 660 in height or thickness indicated.

[0102] A microstructured cutting tool is a tool including a plurality of microstructures, where each microstructure includes at least one cutting edge. The tool is used to form in the polymeric substrate a pattern of cut edges faithfully corresponding to the pattern of the cutting edges of the tool, including cuts that define slits in the polymeric substrate having at least one dimension in a plane of the polymeric substrate in a range of about 0.1 micrometers to about 2000 micrometers. Such tools can be made using conventional micromachining processes. Cutting tools for micromachining and methods of making such cutting tools are described in U.S. Pat. Nos.7, 140,812 (Bryan et al.) and 8,443,704 (Burke et al.), for example. Micro-cutting generally produces sharp cut edges that have a width (e.g., corresponding to the tip width Wt schematically illustrated in FIG.19 of PCT Application Publication No. WO 2022 / 243772 (Johnston et al.)) substantially less (e.g., at least a factor of 2, or at least a factor of 4, or at least a factorof 8 less) than a smallest lateral dimension (e.g., the width W1 schematically illustrated in FIG.19 of WO 2022 / 243772 (Johnston et al.)) of the elements formed by micro-cutting. Advantageously, by using a microstructured cutting tool, the edges of the formed slits do not get chemically modified, unlike the edges of slits in substrates that are cut using lasers or ion beams.

[0103] FIG. 7A is a photograph of a portion of an exemplary stretchable article 700a having a single slit pattern, in a planar unstretched state. The single slit pattern includes a plurality of substantially parallel rows of multiple individual linear slits. Each of the individual linear slits in a given row is out of phase with each of the individual linear slits in the directly adjacent and substantially parallel row. In the specific construction of FIG. 7A, the adjacent rows are out of phase by approximately one half of the horizonal spacing. The pattern forms an array of slits and rows, and the array has a regular, repeating pattern across the array. Between directly adjacent rows of slits are formed beams of material.

[0104] FIG. 7B is an SEM image of a portion 700b of the stretchable article 700a of FIG. 7A. For instance, the pattern includes a plurality of substantially parallel rows 712 of multiple individual linear slits 710. Each of the individual linear slits 710 in a given row 712 is out of phase with each of the individual linear slits 710 in the directly adjacent and substantially parallel row 712. The pattern forms an array of slits 710 and rows 712, and the array has a regular, repeating pattern across the array.Between directly adjacent rows 712 of slits 710 are formed beams 730 of material and between linear slits are formed axial beams 720. This stretchable article 700a was made according to Example 8 described in detail below. The high magnification of the SEM image shows that the microscale of the slits and the single slit pattern results in gaps between adjacent beams 730 that have similar widths as the beams 730 themselves. For example, several measurements are indicated on the SEM image of FIG. 7B. First is a length 1 of a slit 710 that was measured to be 256.9 micrometers. A width 2 of a slit 710 in an adjacent row was measured to be 13.9 micrometers while a width 3 of a slit 710 in the next adjacent row was measured to be 12.4 micrometers. Regarding beam width, a width 4 of one beam 730 was measured to be 19.9 micrometers and a width 5 of another beam 730 was measured to be 20.7 micrometers. Additionally, a length 6 of an axial beam 720 was measured to be 27.9 micrometers. FIG. 7C is an SEM image of a portion of a stretchable article 700c having a single slit pattern, in a non-planar deformed stretched state. This stretchable article 700c was made according to Example 8. Due to the deformation, there are large spaces 770 inbetween the stretched beams 730 and axial beams 720.

[0105] In some embodiments of a stretchable article having any of the Kirigami patterns disclosed herein, a portion of the polymeric substrate between two adjacent slits has a width of 10 micrometers or greater, 11 micrometers, 12 micrometers, 13 micrometers, 14 micrometers, 15 micrometers, 15 micrometers, 16 micrometers, 17 micrometers, 18 micrometers, 19 micrometers, 20 micrometers, 21 micrometers, 22 micrometers, 23 micrometers, 24 micrometers, or 25 micrometers or greater; and 30 micrometers or less, 29 micrometers, 28 micrometers, 27 micrometers, 26 micrometers, 25 micrometers, 24 micrometers, 23 micrometers, 22 micrometers, 21 micrometers, 20 micrometers, 19 micrometers, 18 micrometers, 17 micrometers, 16 micrometers, or 15 micrometers or less. In certain cases of astretchable article, a portion of the polymeric substrate between two adjacent slits has a width between 10 micrometers and 30 micrometers.

[0106] In some embodiments, each of the plurality of slits independently has a certain average width and a portion of the polymeric substrate between two adjacent slits has a certain width. For instance, each of the plurality of slits independently may have an average width of 10 micrometers or greater, 20 micrometers, 30 micrometers, 40 micrometers, 50 micrometers, 60 micrometers, 70 micrometers, 80 micrometers, 90 micrometers, or 100 micrometers or greater; and 150 micrometers or less, 140 micrometers, 130 micrometers, 120 micrometers, 110 micrometers, 100 micrometers, 90 micrometers, 80 micrometers, 70 micrometers, 60 micrometers, or 50 micrometers or less. Simultaneously, a portion of the polymeric substrate between two adjacent slits has a width of 10 micrometers or greater, 20 micrometers, 30 micrometers, 40 micrometers, 50 micrometers, 60 micrometers, 70 micrometers, 80 micrometers, 90 micrometers, or 100 micrometers or greater; and 150 micrometers or less, 140 micrometers, 130 micrometers, 120 micrometers, 110 micrometers, 100 micrometers, 90 micrometers, 80 micrometers, 70 micrometers, 60 micrometers, or 50 micrometers or less. In some cases, each of the plurality of slits independently has an average width between 10 micrometers and 150 micrometers and wherein a portion of the polymeric substrate between two adjacent slits has a width between 10 micrometers and 150 micrometers.

[0107] Referring to FIG. 8, a photograph is provided of an exemplary stretchable article 800 being separated from a liner 890. This stretchable article 800 was made according to Example 7 described in detail below. The polymeric substrate is polyethylene terephthalate (PET) having a thickness of 6 micrometers and can be seen in the photograph to appear flexible due at least to the beam Kirigami pattern cut into the PET substrate.

[0108] Methods of Making a Stretchable Article

[0109] In a second aspect, a method of making a stretchable article is provided. The method comprises:

[0110] forming a plurality of slits in a polymeric substrate using a microstructured cutting tool, thereby forming a polymeric substrate configured to have a planar unstretched state and a non-planar deformed stretched state, wherein when the polymeric substrate is in the planar unstretched state the polymeric substrate comprises:

[0111] a sheet comprising a first major surface; a second major surface opposite the first major surface; and a plurality of slits that each extend from the first major surface to the second major surface, the plurality of slits being arranged in a Kirigami pattern, which comprises at least one feature that is smaller than 500 micrometers.

[0112] In certain embodiments, the microstructured cutting tool is a rotary cutting tool. In some embodiments, the stretchable article is formed using roll-to-roll processing. Two suitable apparatuses for roll-to-roll processing are depicted in FIGS. 9 and 10. FIG. 9 is a generalized schematic side view of an apparatus 9000 for making an exemplary stretchable article. The apparatus 9000 includes at least a nip roll 9100 having an exterior surface 9110, a patterned roll 9200 including an exterior surface 9210on which are formed cutting blades 9215 that will cut a Kirigami pattern into a polymeric substrate, and a strip off roll 9300 having an exterior surface 9310. The patterned roll 9200 with cutting blades 9215 may be referred to as a microstructured cutting tool or more specifically as a microstructured rotary cutting tool. This apparatus 9000 further includes a die 9400 configured to coextrude a polymeric substrate material 9500 and a backing material 9600. After coextrusion, the polymeric substrate material 9500 and a backing material 9600 get fed through the exterior surface 9110 of the nip roll 9000 and exterior surface 9210 of the patterned roll 9200, where rotation of the patterned roll 9200 cuts slits having a Kirigami pattern into polymeric substrate material 9500. The polymeric substrate material 9500 and the backing material 9600 solidify before and / or during the cutting step. The resulting cut polymeric substrate 9550 on a backing layer 9650 is then passed over the exterior surface 9310 of the strip off roll 9300 and the polymeric substrate 9550 having a Kirigami pattern 9555 is optionally separated from the backing layer 9650 at that time, forming a stretchable article.

[0113] FIG. 10 is a generalized schematic side view of another apparatus for making an exemplary stretchable article. The apparatus includes at least a nip roll 10100 having an exterior surface 10110, a patterned roll 10200 including an exterior surface 10210 on which are formed cutting blades 10215 that will cut a Kirigami pattern into a polymeric substrate, and a strip off roll 10300 having an exterior surface 10310. The patterned roll 10200 with cutting blades 10215 may be referred to as a microstructured cutting tool or more specifically as a microstructured rotary cutting tool. Instead of a die, a polymeric substrate 10520 and a backing layer 10620 get fed through the exterior surface 10110 of the nip roll 10100 and the exterior surface 10210 of the patterned roll 10200, where rotation of the patterned roll 10200 cuts slits having a Kirigami pattern into the polymeric substrate 10520. The resulting cut polymeric substrate 10550 on the backing layer 10620 is then passed over the exterior surface 10310 of the strip off roll 10300 and the polymeric substrate 10550 having a Kirigami pattern 10555 is optionally separated from the backing layer 10650 at that time, forming a stretchable article.

[0114] As exemplified in the two general apparatuses of FIGS. 9 and 10, in some cases of roll-to-roll processing, a layer is disposed adjacent to the polymeric substrate opposite the microstructured cutting tool during the forming of the plurality of slits, e.g., between a nip roll and the polymeric substrate. In some cases, such a layer is an extruded backing and optionally the polymeric substrate is formed by coextruding a polymeric resin with the backing and forming the plurality of slits in the polymeric substrate while the polymeric substrate is on the backing. Often, the backing is removed from the cut polymeric substrate, although the stretchable article may be stored / transported before final use while still attached to another layer (e.g., a backing layer). The layer is not restricted to the example of a backing layer, but optionally the layer is selected from the group consisting of a backing, a carrier, and a liner. Some suitable backings, carriers, and liner are described below.

[0115] Backings

[0116] Suitable backing layers may broadly include an organic polymeric film, a metal coated film, a metallic foil, a paper, a foam, or a (e.g., woven or non-woven) fibrous web. In some embodiments, the substrate is a woven (including knitted) or (e.g., spunbond or melt blown) nonwoven fibrous web. Incertain embodiments, the backing layer comprises a cyclic olefin polymer, a polycarbonate, a polyethylene terephthalate, or a polyethylene terephthalate coated with an acrylic layer.

[0117] Carriers

[0118] Exemplary materials useful as the carrier include, but are not limited to, polyolefins such as polyethylene, polypropylene (including isotactic polypropylene and high impact polypropylene), polystyrene, polyester, including polyethylene terephthalate), polyvinyl chloride, poly(butylene terephthalate), poly(caprolactam), polyvinyl alcohol, polyurethane, poly(vinylidene fluoride), cellulose and cellulose derivatives, such as cellulose acetate and cellophane, and wovens and nonwovens.Commercially available carrier film include kraft paper (available from Monadnock Paper, Inc.); spun-bond poly(ethylene) and polypropylene), such as those available under the trade designations “TYVEK” and “TYPAR” (available from The Chemours Co.); and porous films obtained from poly(ethylene) and polypropylene), such as those available under the trade designations “TESLIN” (available from PPG Industries, Inc.), and “CELLGUARD” (available from Hoechst-Celanese).

[0119] L / ner5

[0120] Suitable (e.g., release) liners may comprise flexible paper and polymeric films having sufficient dimensional stability to hold layers formed thereon in position without excessive stretching. Suitable paper liners include, but are not limited to, densified Kraft paper (commercially available from, for example, Loparex North America, Willowbrook, IL), poly -coated paper such as polyethylene coated Kraft paper, and the like. Suitable polymeric film / liners include, but are not limited to, thermoplastic polymer films including polyalkylenes, e.g., polyethylene and polypropylene; polybutadiene, polyisoprene; polyalkylene oxides, e.g., polyethylene oxide; polyesters, e.g., PET andPBT; polyamides; polycarbonates, polystyrenes, block copolymers of any of the proceeding polymers, and combinations thereof. Other suitable polymeric materials include polyimide, polysilicone, polytetrafluoroethylene, polyethylenephthalate, polyvinylchloride, or combinations thereof. Polymer blends of any of the above may also be employed, and nonwoven or woven liners may also be used.

[0121] In some embodiments, any or all of the major surfaces of a release liner may include a release coating, which may be the same or different, to tune or otherwise modify their release values. In various embodiments, which are not intended to be limiting, the release coatings applied to the major surfaces of the release liners may be selected from a fluorine-containing material, a silicone-containing material, a fluoropolymer, a silicone polymer, or a poly(meth)acrylate ester derived from a monomer including an alkyl (methjacrylate having an alkyl group with 12 to 30 carbon atoms. In one embodiment, the alkyl group on the alkyl (methjacrylate can be branched. Illustrative examples of useful fluoropolymers and silicone polymers can be found in U.S. Patent No. 4,472,480 (Olson), U.S. Patent No. 4,567,073 andU.S. Patent No. 4,614,667 (both Larson et al), incorporated herein by reference in their entireties. Illustrative examples of useful poly(meth)acrylate esters can be found in U.S. Patent Appl. Publ. No. 2005 / 0118352 (Suwa), incorporated herein by reference in its entirety.

[0122] It is expressly contemplated that the resulting stretchable article made according to such methods may be according to any embodiment of the first aspect described in detail above.

[0123] Select Embodiments of the Disclosure

[0124] In a first embodiment, the present disclosure provides a stretchable article. The stretchable article comprises a polymeric substrate configured to have a planar unstretched state and a non-planar deformed stretched state. When the polymeric substrate is in the planar unstretched state the polymeric substrate comprises: a sheet comprising a first major surface; a second major surface opposite the first major surface; and a plurality of slits that each extend from the first major surface to the second major surface. The plurality of slits is arranged in a Kirigami pattern, which comprises at least one feature that is smaller than 500 micrometers.

[0125] In a second embodiment, the present disclosure provides a stretchable article according to the first embodiment, wherein the polymeric substrate is selected from the group consisting of a polypropylene, a polyester, a polyethylene, a polystyrene, a polymethylmethacrylate, a polyamide, a polycarbonate, a polymethyleneoxide, a polybutyleneterephthalate, a styrene acrylonitrile copolymer, a styrene (methjacrylate copolymer, a styrene maleic anhydride copolymer, a nucleated semi-crystalline polyester, a copolymer of polyethylenenaphthalate, a polyimide copolymer, a polyetherimide, a polyethylene oxides, a copolymer of acrylonitrile, butadiene, and styrene, and blends thereof.

[0126] In a third embodiment, the present disclosure provides a stretchable article according to the first embodiment or the second embodiment, wherein the polymeric substrate in the planar non-stretched shape has an average thickness between 0.5 micrometers and 20 micrometers.

[0127] In a fourth embodiment, the present disclosure provides a stretchable article according to any of the first through third embodiments, wherein when the polymeric substrate is in the non-planar deformed stretched shape the article has an average thickness between 5 micrometers and 800 micrometers.

[0128] In a fifth embodiment, the present disclosure provides a stretchable article according to any of the first through fourth embodiments, wherein the at least one feature that is smaller than 500 micrometers comprises one or more of a slit length, an axial beam length, a transverse beam length, a multibeam length, or a distance between two adjacent slits.

[0129] In a sixth embodiment, the present disclosure provides a stretchable article according to any of the first through fifth embodiments, wherein each of the plurality of slits independently has an average width between 10 micrometers and 150 micrometers and wherein a portion of the polymeric substrate between two adjacent slits has a width between 10 micrometers and 150 micrometers.

[0130] In a seventh embodiment, the present disclosure provides a stretchable article according to any of the first through sixth embodiments, wherein the Kirigami pattern is selected from the group consisting of single unidirectional patterns and multi-slit unidirectional patterns.

[0131] In an eighth embodiment, the present disclosure provides a stretchable article according to any of the first through seventh embodiments, comprising a portion of the polymeric substrate between two adjacent slits having a width between 10 micrometers and 30 micrometers.

[0132] In a ninth embodiment, the present disclosure provides a stretchable article according to any of the first through eighth embodiments, wherein when the polymeric substrate is in the non-planar deformed stretched shape the article has a form of a spacer.

[0133] In a tenth embodiment, the present disclosure provides a stretchable article according to any of the first through eighth embodiments, wherein when the polymeric substrate is in the non-planar deformed stretched shape the article has a form of a scrim.

[0134] In an eleventh embodiment, the present disclosure provides a stretchable article according to any of the first through tenth embodiments, having a form of a roll.

[0135] In a twelfth embodiment, the present disclosure provides a method of making a stretchable article. The method comprises forming a plurality of slits in a polymeric substrate using a microstructured cutting tool, thereby forming a polymeric substrate configured to have a planar unstretched state and a non-planar deformed stretched state. When the polymeric substrate is in the planar unstretched state the polymeric substrate comprises: a sheet comprising a first major surface; a second major surface opposite the first major surface; and a plurality of slits that each extend from the first major surface to the second major surface. The plurality of slits is arranged in a Kirigami pattern, which comprises at least one feature that is smaller than 500 micrometers.

[0136] In a thirteenth embodiment, the present disclosure provides a method of making a stretchable article according to the twelfth embodiment, wherein the stretchable article is formed using roll-to-roll processing.

[0137] In a fourteenth embodiment, the present disclosure provides a method of making a stretchable article according to the thirteenth embodiment, wherein a layer is disposed adjacent to the polymeric substrate opposite the microstructured cutting during the forming of the plurality of slits, wherein the layer is selected from the group consisting of a backing, a carrier, and a liner.

[0138] In a fifteenth embodiment, the present disclosure provides a method of making a stretchable article according to the twelfth embodiment, wherein the layer comprises a cyclic olefin polymer, a polycarbonate, a polyethylene terephthalate, or a polyethylene terephthalate coated with an acrylic layer.

[0139] In a sixteenth embodiment, the present disclosure provides a method of making a stretchable article according to the fourteenth embodiment or the fifteenth embodiment, wherein the layer is an extruded backing.

[0140] In a seventeenth embodiment, the present disclosure provides a method of making a stretchable article according to the sixteenth embodiment, further comprising forming the polymeric substrate by coextruding a polymeric resin with the backing and forming the plurality of slits in the polymeric substrate while the polymeric substrate is on the backing.

[0141] In an eighteenth embodiment, the present disclosure provides a method of making a stretchable article according to the seventeenth embodiment, further comprising removing the backing.

[0142] In a nineteenth embodiment, the present disclosure provides a method of making a stretchable article according to any of the twelfth through eighteenth embodiments, wherein the microstructured cutting tool is a rotary cutting tool.

[0143] In a twentieth embodiment, the present disclosure provides a method of making a stretchable article according to any of the twelfth through nineteenth embodiments, wherein the stretchable article is according to any of the first through eleventh embodiments.EXAMPLES

[0144] Unless otherwise noted or readily apparent from the context, all parts, percentages, ratios, etc. in the Examples and the rest of the specification are by weight. Table 1 (below) lists materials used in the examples and their sources. In the Tables, "NA" means not applicable. In the examples:TABLE 1. Materials List

[0145] Example 1-3 - 3 Different Double Slit micro -Kirigami patterns were cut in a 5-10 micrometers thick and 75 mm wide PP film using microstructured rotary cutting tools. The uncut PP film with a 75 micrometers thick NSNF polymeric liner at the back was fed into the tool against a backing roll and force up to 4000 lb was applied to cut the PP film. The microstructured rotary tool blades were oriented in the machine direction.1. Double Slit Single Beam (FIG. IE). The microstructured rotary cutting tool was manufactured to cut a pattern as illustrated in FIG.1C and designed to cut slits that are 1400 micrometers long, spaced 150 micrometers apart in the transverse direction and 700 micrometers apart in the longitudinal direction. The 150 micrometer spacing of adjacent slits is a feature of the Kirigami pattern that is smaller than 500 micrometers.2. Double Slit Double Beam (FIGS. 3D and 3E). The microstructured rotary cutting tool was manufactured to cut a pattern as illustrated in FIG. 3 A and designed to cut slits that are 1400 micrometers long, spaced 150 micrometers apart in the transverse direction and 700micrometers apart in the longitudinal direction. The smaller slit that creates the double beam feature between the bigger slits was 500 micrometers in length and spaced equally at 75 micrometers from the bigger slits. The 150 micrometer spacing of adjacent slits and the 75 micrometer spacing between adjacent multibeam slits are both features of the Kirigami pattern that are smaller than 500 micrometers.3. Double Slit Triple Beam (FIG. 2F). The micro structured rotary cutting tool was manufactured to cut a pattern as illustrated in FIG.2C and designed to cut slits that are 1400 micrometers long and spaced 150 micrometers apart in the transverse direction and 700 micrometers apart in the longitudinal direction. The two smaller slits that create the triple beam feature between the bigger slits were 500 micrometers in length and spaced equally 50 micrometers apart and from the bigger slits. The 150 micrometer spacing of adjacent slits and the 50 micrometer spacing between adjacent multibeam slits are both features of the Kirigami pattern that are smaller than 500 micrometers.

[0146] Example 4-6 - 3 Different Double Slit micro -Kirigami pattern were cut in a 4.5 micrometer thick and 75 or 200 mm wide PET film using microstructured rotary cutting tools. The uncut PET film with a 75 micrometers thick NSNF polymeric liner at the back was fed into the tool against a backing roll and force up to 4000 lb was applied to cut the PET film. The microstructured rotary tool blades were oriented in the machine direction.4. Double Slit Single Beam (FIG. IF). The microstructured rotary cutting tool was manufactured to cut a pattern as illustrated in FIG.1C was designed to cut slits that are 1400 micrometers long and spaced 150 micrometers apart in the transverse direction and 700 micrometers apart in the longitudinal direction. The 150 micrometer spacing of adjacent slits is a feature of the Kirigami pattern that is smaller than 500 micrometers.5. Double Slit Double Beam (FIGS. 3F-3H) The microstructured rotary cutting tool was manufactured to cut a pattern as illustrated in FIG.3 A and designed to cut slits that are 1400 micrometers long and spaced 150 micrometers apart in the transverse direction and 700 micrometers apart in the longitudinal direction. The smaller slit that creates the double beam feature between the bigger slits is 500micrometers in length and spaced equally at 75 micrometers from the bigger slits. The 150 micrometer spacing of adjacent slits and the 75 micrometer spacing between adjacent multibeam slits are both features of the Kirigami pattern that are smaller than 500 micrometers.Double Slit Triple Beam (FIG. 2I)The microstructured rotary cutting tool was manufactured to cut a pattern as illustrated in FIG. 2C and designed to cut slits that are 1400 micrometers long and spaced 150 micrometers apart in the transverse direction and 700 micrometers apart in the longitudinal direction. The two smaller slits that create the triple beam feature between the bigger slits were 500 micrometers in length and spaced equally 50 micrometers apart from the bigger slits and each other. The 150 micrometer spacing of adjacent slits and the 50 micrometer spacing between adjacent multibeam slits are both features of the Kirigami pattern that are smaller than 500 micrometers.Example 7 (FIGS. 2G, 2H, and 8) - Double Slit Double Beam micro-Kirigami pattern was cut in a Vital PET film. Vital 2700B copolyester from Boston Inc. was solvent cast with toluene onto NSNF liner to result in a 6 micrometers thick layer. A 200 mm wide film was used. The uncut Vital PET film with a 75 micrometers thick NSNF polymeric liner at the back was fed into the tool against a backing roll and force up to 4000 lb was applied to cut the PET film. The microstructured rotary tool blades were oriented in the machine direction. The micro structured rotary cutting tool was manufactured to cut a pattern as illustrated in FIG. 3 A and designed to cut slits that are 1400 micrometers long and spaced 150 micrometers apart in the transverse direction and 700 micrometers apart in the longitudinal direction. The smaller slit that creates the double beam feature between the bigger slits is 500 micrometers in length and spaced equally at 75 micrometers from the bigger slits. The 150 micrometer spacing of adjacent slits and the 75 micrometer spacing between adjacent multibeam slits are both features of the Kirigami pattern that are smaller than 500 micrometers.Example 8 (FIGS. 7A-7C) - A Single Slit micro-Kirigami pattern was cut in 4.5 micrometers thick and 37.5 mm wide PET film. The uncut PET film with a 75 micrometers thick NSNF polymeric liner at the back was fed into the tool against a backing roll and force up to 1500 lb was applied to cut the PET film. The rotary tool blades were oriented in the machine direction. The microstructured rotary cutting tool was manufactured to cut a pattern with slits that are ~250 micrometers long and spaced 50 micrometers apart in the longitudinal (along the slits) direction with a spacing of 38 micrometers between adjacent rows. The slit length of 250 micrometers, distance between adjacent slits of 50 micrometers, and distance between adjacent rows of 38 micrometers are all features of the Kirigami pattern that are smaller than 500 micrometers.

[0147] Other modifications and variations to the present disclosure may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present disclosure, which is more particularly set forth in the appended claims. It is understood that aspects of the various embodiments may be interchanged in whole or part or combined with other aspects of the various embodiments. All cited references, patents, or patent applications in the above application for letters patent are herein incorporated by reference in their entirety in a consistent manner. In the event of inconsistencies or contradictions between portions of the incorporated references and this application, the information in the preceding description shall control. The preceding description, given in order to enable one of ordinary skill in the art to practice the claimed disclosure, is not to be construed as limiting the scope of the disclosure, which is defined by the claims and all equivalents thereto.

Claims

What is claimed is:

1. A stretchable article comprising a polymeric substrate configured to have a planar unstretched state and a non-planar deformed stretched state, wherein when the polymeric substrate is in the planar unstretched state the polymeric substrate comprises:a sheet comprising a first major surface; a second major surface opposite the first major surface; and a plurality of slits that each extend from the first major surface to the second major surface, the plurality of slits being arranged in a Kirigami pattern, which comprises at least one feature that is smaller than 500 micrometers.

2. The stretchable article of claim 1, wherein the polymeric substrate is selected from the group consisting of a polypropylene, a polyester, a polyethylene, a polystyrene, a polymethylmethacrylate, a polyamide, a polycarbonate, a polymethyleneoxide, a polybutyleneterephthalate, a styrene acrylonitrile copolymer, a styrene (methjacrylate copolymer, a styrene maleic anhydride copolymer, a nucleated semi-crystalline polyester, a copolymer of polyethylenenaphthalate, a polyimide copolymer, a polyetherimide, a polyethylene oxides, a copolymer of acrylonitrile, butadiene, and styrene, and blends thereof.

3. The stretchable article of claim 1 or claim 2, wherein the polymeric substrate in the planar nonstretched shape has an average thickness between 0.5 micrometers and 20 micrometers.

4. The stretchable article of any of claims 1 to 3, wherein when the polymeric substrate is in the non-planar deformed stretched shape the article has an average thickness between 5 micrometers and 800 micrometers.

5. The stretchable article of any of claims 1 to 4, wherein the at least one feature that is smaller than 500 micrometers comprises one or more of a slit length, an axial beam length, a transverse beam length, a multibeam length, or a distance between two adjacent slits.

6. The stretchable article of any of claims 1 to 5, wherein each of the plurality of slits independently has an average width between 10 micrometers and 150 micrometers and wherein a portion of the polymeric substrate between two adjacent slits has a width between 10 micrometers and 150 micrometers.

7. The stretchable article of any of claims 1 to 6, wherein the Kirigami pattern is selected from the group consisting of single unidirectional patterns and multi-slit unidirectional patterns.

8. The stretchable article of any of claims 1 to 7, comprising a portion of the polymeric substrate between two adjacent slits having a width between 10 micrometers and 30 micrometers.

9. The stretchable article of any of claims 1 to 8, wherein when the polymeric substrate is in the non-planar deformed stretched shape the article has a form of a spacer.

10. The stretchable article of any of claims 1 to 8, wherein when the polymeric substrate is in the non-planar deformed stretched shape the article has a form of a scrim.

11. The stretchable article of any of claims 1 to 10, having a form of a roll.

12. A method of making a stretchable article, the method comprising:forming a plurality of slits in a polymeric substrate using a microstructured cutting tool, thereby forming a polymeric substrate configured to have a planar unstretched state and a non- planar deformed stretched state, wherein when the polymeric substrate is in the planar unstretched state the polymeric substrate comprises:a sheet comprising a first major surface; a second major surface opposite the first major surface; and a plurality of slits that each extend from the first major surface to the second major surface, the plurality of slits being arranged in a Kirigami pattern, which comprises at least one feature that is smaller than 500 micrometers.

13. The method of claim 12, wherein the stretchable article is formed using roll-to-roll processing.

14. The method of claim 13, wherein a layer is disposed adjacent to the polymeric substrate opposite the microstructured cutting tool during the forming of the plurality of slits, wherein the layer is selected from the group consisting of a backing, a carrier, and a liner.

15. The method of claim 14, wherein the layer comprises a cyclic olefin polymer, a polycarbonate, a polyethylene terephthalate, or a polyethylene terephthalate coated with an acrylic layer.

16. The method of claim 14 or claim 15, wherein the layer is an extruded backing.

17. The method of claim 16, further comprising forming the polymeric substrate by coextruding a polymeric resin with the backing and forming the plurality of slits in the polymeric substrate while the polymeric substrate is on the backing.

18. The method of claim 17, further comprising removing the backing.

19. The method of any of claims 12 to 18, wherein the microstructured cutting tool is a microstructured rotary cutting tool.

20. The method of any of claims 12 to 19, wherein the stretchable article is of any of claims 1 to 11.

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