Cushioning articles including a polyurethane

Abstract

The present disclosure provides a cushioning article including a cushioning layer having a structured major surface and an opposing second major surface. The structured major surface includes a land region and a plurality of engineered structures. The cushioning layer has a free volume of greater than 50% and includes a polyurethane containing 5 to 25 weight percent units derived from hydroquinone bis (2-hydroxyethyl) ether. A battery assembly is also provided, including a battery cell and a cushioning layer adjacent to the battery cell.

Description

CUSHIONING ARTICLES INCLUDING A POLYURETHANEField

[0001] The present disclosure generally relates to the field of cushioning articles.Background

[0002] There is a need for cushioning articles that can provide high pressures against swelling and deswelling, e.g., of a battery during use.Summary

[0003] In a first aspect, a cushioning article is provided. The cushioning article comprises a cushioning layer having a structured major surface and an opposing second major surface. The structured major surface comprises a land region and a plurality of engineered structures. The cushioning layer has a free volume of greater than 50% and comprises a polyurethane containing 5 weight percent (wt.%) to 25 wt.% units derived from hydroquinone bis (2-hydroxyethyl) ether.

[0004] In a second aspect, a battery assembly is provided. The battery assembly comprises a battery cell and a cushioning layer adjacent to the battery cell. The cushioning layer is preferably according to any embodiment of the first aspect.Brief Description of Drawings

[0005] FIGS. 1A, IB, and 1C are each a schematic perspective view of a single unit cell of a cushioning layer, according to some embodiments of the present disclosure.

[0006] FIG. 2A is a generalized schematic top view of a unit cell of a hexagonal lattice geometry of a cushioning layer, according to some embodiments of the present disclosure.

[0007] FIG. 2B is a schematic cross-sectional view of the engineered structure and the land region of the unit cell of FIG. 2A.

[0008] FIG. 3 is a generalized schematic perspective view of an exemplary cushioning article including continuous parallel rib engineered structures and a land region, according to some embodiments of the present disclosure.

[0009] FIG. 4 is a generalized schematic perspective view of an exemplary cushioning article including discontinuous cylindrical engineered structures and a land region, according to some embodiments of the present disclosure.

[0010] FIG. 5 is a generalized schematic perspective view of a single engineered structure extending from a land region at a 45 degree angle, according to some embodiments of the present disclosure.

[0011] FIG. 6 is a generalized schematic perspective view of an exemplary cushioning article including a land region and a plurality of engineered structures, according to some embodiments of the present disclosure.

[0012] FIG. 7 is a generalized schematic exploded perspective view of an exemplary cushioning article including two optional films adjacent to opposing major surfaces of the cushioning layer, according to some embodiments of the present disclosure.

[0013] FIG. 8A is a generalized schematic top view of a unit cell of a frustum pattern of a cushioning layer, according to some embodiments of the present disclosure.

[0014] FIG. 8B is a generalized schematic cross-sectional view of the engineered structure and the land region of the unit cell of FIG. 8 A.

[0015] FIG. 9A is a generalized schematic top view of a unit cell of a cylinder pattern of a cushioning layer, according to some embodiments of the present disclosure.

[0016] FIG. 9B is a generalized schematic cross-sectional view of the engineered structure and the land region of the unit cell of FIG. 9 A.

[0017] FIG. 10 is a photograph of the exemplary cushioning article of Example 2 of the present disclosure.

[0018] FIG. 11 is generalized schematic perspective view of a battery assembly, according to some embodiments of the present disclosure.

[0019] FIG. 12 is a generalized schematic top view of an exemplary battery assembly including at least one cushioning article or layer between adjacent battery cells, according to some embodiments of the present disclosure.

[0020] 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

[0021] The terms “a”, “an”, “the”, “at least one”, and “one or more” are used interchangeably.

[0022] 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.

[0023] The term “essentially” means 95% or more.

[0024] The term “equivalents” refers to the number of moles of a functional group (e.g., OH groups, isocyanate groups, etc.) per molecule of a polymer chain or per mole of a different functional group. The term “equivalent” means “moles” in this case, thus the isocyanate content in a material (in terms of equivalents / moles) is divided by the weight of the entire formulation to give a value of equivalents per kilograms.

[0025] The term “alkyl” refers to a monovalent radical of an alkane. Suitable alkyl groups can have up to 50 carbon atoms, up to 40 carbon atoms, up to 30 carbon atoms, up to 20 carbon atoms, up to 16 carbon atoms, up to 12 carbon atoms, up to 10 carbon atoms, up to 8 carbon atoms, up to 6 carbon atoms, up to 4 carbon atoms, or up to 3 carbon atoms. The alkyl groups can be linear, branched, cyclic, or a combination thereof. Linear alkyl groups often have 1 to 30 carbon atoms, 1 to 20 carbon atoms, 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms. Branched alkyl groups often have 3 to 50carbon atoms, 3 to 40 carbon atoms, 4 to 20 carbon atoms, 3 to 10 carbon atoms, or 3 to 6 carbon atoms. Cyclic alkyl groups often have 3 to 50 carbon atoms, 5 to 40 carbon atoms, 6 to 20 carbon atoms, 5 to 10 carbon atoms, or 6 to 10 carbon atoms.

[0026] The term “alkylene” refers to a divalent group that is a radical of an alkane. The alkylene can be straight-chained, branched, cyclic, or combinations thereof. The alkylene typically has 1 to 20 carbon atoms. In some embodiments, the alkylene contains 4 to 14 carbon atoms, 1 to 10 carbon atoms, 1 to 8 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms. The radical centers of the alkylene can be on the same carbon atom (i.e., an alkylidene) or on different carbon atoms. In certain embodiments, the alkylene can be substituted with an OH group.

[0027] The term “hydroxyl group” means a monovalent group of formula -OH.

[0028] The term “isocyanate group” means a monovalent group of formula -N=C=O.

[0029] The term “carbamate ester” refers to a divalent group in a polyurethane having the general formula (-R-O-C(O)-NH-R’-).

[0030] The term “aryl” refers to a monovalent group that is radical of an arene, which is a carbocyclic, aromatic compound. The aryl can have one to five rings that are connected to or fused to the aromatic ring. The other ring structures can be aromatic, non-aromatic, or combinations thereof. Examples of aryl groups include, but are not limited to, phenyl, biphenyl, terphenyl, naphthyl, acenaphthyl, anthraquinonyl, phenanthryl, anthracenyl, pyrenyl, perylenyl, and fluorenyl.

[0031] The term “aralkyl” refers to a monovalent group of formula -R-Ar where R is an alkylene and Ar is an aryl group. That is, the aralkyl is an alkyl substituted with an aryl.

[0032] The term “aralkylene” refers to a divalent group of formula -R-Ar3- where R is an alkylene and Ar3is an arylene (i.e., an alkylene is bonded to an arylene).

[0033] The term “arylene” refers to a divalent group that is carbocyclic and aromatic. The group has one to five rings that are connected, fused, or combinations thereof. The other rings can be aromatic, non-aromatic, or combinations thereof. In some embodiments, the arylene group has up to 5 rings, up to 4 rings, up to 3 rings, up to 2 rings, or one aromatic ring. For example, the arylene group can be phenylene. The term “alkarylene” refers to a divalent group that is an arylene group substituted with an alkyl group or an arylene group attached to an alkylene group. Unless otherwise indicated, the alkarylene group typically has from 1 to 20 carbon atoms, 4 to 14 carbon atoms, 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms. Unless otherwise indicated, for both groups, the alkyl or alkylene portion typically has from 1 to 20 carbon atoms, 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms. Unless otherwise indicated, for both groups, the aryl or arylene portion typically has from 6 to 20 carbon atoms, 6 to 18 carbon atoms, 6 to 16 carbon atoms, 6 to 12 carbon atoms, or 6 to 10 carbon atoms. In certain embodiments, the arylene group or the alkarylene group has 4 to 14 carbon atoms.

[0034] The term “diisocyanate” refers to a compound having the general formula O=C=N — R — N=C=O. Preferred R groups include alkylene and arylene groups.

[0035] The term “diol” refers to a compound with two OH groups.

[0036] The term “(meth)acrylate” means acrylate or methacrylate.

[0037] The term “triamine” refers to a compound with three amino groups.

[0038] The term “polyester” refers to repeating difunctional polymer wherein the repeat units are joined by ester linkages. Ester groups have the general formula -R — C(O) — OR’. The term “polyether” refers to repeating difunctional alkoxy radicals having the general formula -O-R-. Preferred R and R’ groups have the general formula -CnEbn- and include, for example, methylene, ethylene and propylene (including n-propylene and i-propylene) or a combination thereof. Combinations of R and R’ groups may be provided, for example, as random or block type copolymers.

[0039] The term “polyol” refers to a compound with two or more hydroxyl (i.e., OH) groups.

[0040] The term “polymeric material” refers to any homopolymer, copolymer, terpolymer, and the like, as well as any diluent.

[0041] The term “ambient temperature” refers to a temperature in the range of 20 degrees Celsius to 25 degrees Celsius, inclusive.

[0042] The terms “cure” and “curable” refer to joining polymer chains together by covalent chemical bonds, usually via crosslinking molecules or groups, to form a network polymer. Therefore, in this disclosure the terms “cured” and “crosslinked” may be used interchangeably. A cured or crosslinked polymer is generally characterized by insolubility, but may be swellable in the presence of an appropriate solvent.

[0043] The term “backbone” refers to the main continuous chain of a polymer.

[0044] 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.

[0045] By definition, the total weight percentages of all ingredients in a composition equals 100 weight percent.

[0046] As used herein, “adjacent” encompasses both in direct contact (e.g., directly adjacent) and having one or more intermediate layers present between the adjacent materials.

[0047] The term “film” or “layer” refers to a single stratum within a multilayer film or article.

[0048] The term “sheet” refers to a stmcture that is generally a single plane, having a major surface in the x- and y-axes and minor surface in the z-axis. A sheet may be flexible.

[0049] As used herein, “thickness” refers to the smallest dimension of a film or layer, e.g., in a z-axis while a major surface of the film or layer is in the x- and y-axes. Thickness may be determined using a micrometer gauge. Average thickness of an article may be determined by taking a thickness measurement every 2-4 inches (5-10 centimeters) across a width of the article and taking a thickness measurement every 2 inches (5 centimeters) or l / 50thof the total length, whichever is greater, down a length of the article. The width is either equal to or shorter than the length. The individual measurements are then averaged to provide an average thickness of the article.

[0050] As used herein, a “foam” refers to a polymer that has a cellular structure with numerous, generally uniformly distributed bubbles (e.g., cells) throughout the material. Closed cell foams have isolated bubbles while open cell foams have a network of interconnected cells. An open cell foam can include up to about 30% closed cells.

[0051] As used herein, an “engineered structure” refers to a shape that has a deliberate design, which is contrast to a random stmcture. Engineered structures encompass structures that have some defects due to the manufacturing process (e.g., some gas generation during curing).

[0052] Cushioning articles may be used in many applications. For example, a cushioning article may be used to support fragile elements in packaging applications, may be used for personal padding, or may be used to provide an approximately constant pressure on an element as that element changes size or shape. One exemplary application for cushioning articles is a replacement for foam that is conventionally used with flexographic printing plates to control the pressure that the plate exerts when pressed on a paper or fdm. Another exemplary application for cushioning articles is in battery packs for electric vehicles or energy storage for mini-grid or home storage, for example, where a cushioning article can be utilized to provide an appropriate pressure to electrochemical cells as their volumes change during their charging and discharging cycles.

[0053] To improve the range and efficiency of electric vehicles, the current industry trend is to increase battery pack-level energy density through consolidated cell formats and higher energy -density lithium battery cell chemistries. Maintaining battery cell pressure and pressure uniformity for pouch and prismatic cells during the volume change of charge-discharge cycles is desired for battery life and failure mode avoidance. Foams have been used in past attempts to provide the desired pressure profiles.Longer-term, there is a general trend toward all solid-state battery cells, which have even higher energy density (e.g., 500 Wh / kg) than conventional lithium (Li) ion batteries and are safer. However, stack pressure uniformity beyond what conventional foam materials can provide is desired for maintaining the integrity of the Li-solid-state electrolyte interfaces for low contact resistance during cell cycling. This presents a significant challenge to the successful implementation of long-life solid-state battery cells in electric vehicles.

[0054] Cushioning Articles

[0055] In a first aspect, a cushioning article is provided. The cushioning article comprises a cushioning layer having a structured major surface and an opposing second major surface. The structured major surface comprises a land region and a plurality of engineered structures. The cushioning layer has a free volume of greater than 50% and comprises a polyurethane containing 5 weight percent (wt.%) to 25 wt.% units derived from hydroquinone bis (2-hydroxy ethyl) ether (HQEE).

[0056] In some cases, the polyurethane contains greater than 5 wt.% units derived from HQEE, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, 10 wt.%, 11 wt.%, 12 wt.%, 13 wt.%, 14 wt.%, 15 wt.%, 16 wt.%, 17 wt.%, 18 wt.%, 19 wt.%, or greater than 20 wt.%; and 25 wt.% or less, 24 wt.%, 23 wt.%, 22 wt.%, 21 wt.%, 20 wt.%, 19 wt.%, 18 wt.%, 17 wt.%, 16 wt.%, 15 wt.%, 14 wt.%, 13 wt.%, 12 wt.%, 11 wt.%, or 10 wt.% or less. It is to be understood that the weight percent solely includes the HQEE residue, not any othermaterial that may have been combined with the HQEE, such as a diisocyanate. One commercially available hydroquinone bis (2 -hydroxyethyl) ether is from Monument Chemical (Indianapolis, IN).

[0057] It has been discovered that cushioning articles derived from polyurethanes containing a HQEE chain extender provide improved performance compared to cushioning articles made with other polyurethanes. Urethanes based on HQEE are commercially available materials. However, most HQEE materials are specifically suitable for injection molding processes, and they are not recommended for extrusion processes because the material tends to readily change from too stiff to process to too runny to extrude. Because the HQEE resins are explicitly not recommended for extrusion, it was surprising that such injection-molding grade resins could be successfully employed in the extrusion processes of at least certain embodiments of the present disclosure. Compared to standard extrusion-grade urethane resins derived from butanediol, the resins derived from HQEE produce better resilience, which manifests as desirable higher forces upon unloading in a compression / decompression cycle.

[0058] Some prior cushioning articles have been made of a foamed polymer. Typically, the polyurethanes of the present disclosure do not have a form of a foam. A foam includes a cellular structure with numerous, generally uniformly distributed bubbles (e.g., cells) throughout the material. While air pocket defects may be present in cushioning articles of the present disclosure due to some gas generation during curing, such air pockets are not distributed throughout the material. Additionally, polyurethanes of the present disclosure preferably exhibit a density of greater than 0.8 grams per milliliter (g / mL), greater than 0.9 g / mL, or greater than 1.0 g / mL. The density can be measured by liquid pycnometry, preferably in water, such that the water contacts the exterior sample surface but generally does not wet small pores in the sample. Foams have densities lower than 0.8 g / mL due to the significantly greater volume of cells in the polyurethane material. The polyurethane of the cushioning article is solid (other than any minor defects), so a line that passes through the opposing second major surface, the base of an engineered structure, and a distal end of the engineered structure, would only pass through polyurethane material until going beyond the distal end of the engineered structure and / or the opposing second major surface. In contrast, a line that passed through a foam cushioning article of the same configuration would pass through polymeric material, (e.g., air) bubbles, more polymeric material, more bubbles, etc., between the opposing second major surface, base of the engineered structure, and distal end of the engineered stmcture.

[0059] In some preferred embodiments, the polyurethane exhibits a glass transition temperature that is below 20 °C, 19 °C, 18 °C, 17 °C, 16 °C, 15 °C, 14 °C, 13 °C, 12 °C, 11 °C, 10 °C, 9 °C, 8 °C, 7 °C, 6 °C, or even below 5 °C. As used herein, the terms “glass transition temperature” and “Tg” are used interchangeably and refer to the glass transition temperature of a material or a mixture. Unless otherwise indicated, glass transition temperature values are determined by Differential Scanning calorimetry (DSC). The low Tg provides a wider working temperature range for the battery, especially by limiting the stiffening of the cushion at subambient temperatures.

[0060] In some embodiments, the polyurethane exhibits a hardness of Shore 70A or greater, Shore 20D, Shore 80 A, Shore 40D, Shore 90 A, Shore 50D, or Shore 100A or greater; and Shore 70D or less, Shore60D, Shore 90 A, Shore 80A, or Shore 20D or less. Stated another way, the polyurethane may exhibit a hardness between Shore 70A and Shore 70D. Hardness may be measured using a durometer.

[0061] In some applications, including battery applications, compression is required to operate within a specified working pressure range. Therefore, is useful for the article to be able to be compressed over a large distance while staying within that working pressure range. The working compression distance can often be maximized by increasing the overall thickness of the structured compressible layer. However, it is also useful for the structured compressible layer to be as thin as possible to allow for compact constructions that employ the structured compressible layer. Therefore, the objectives of maximizing the working compression distance and minimizing the overall thickness (T) of the structured compressible layer are often opposing each other. The balance of working compression distance and the overall thickness can be quantified with a concept of cushioning efficiency. As used herein, cushioning efficiency is the working cushioning distance divided by the thickness of the structured compressible layer at the lowest pressure of the specified working pressure range. The cushioning efficiency can be measured in a compression test where the structured compressible layer is loaded to highest pressure value of the target pressure range and then unloaded to at least the lowest pressure value of the target pressure range. The change in the thickness (T) of the structured compressible layer between the highest pressure value and lowest pressure value is then divided by the thickness of the structured compressible layer at the lowest pressure value to provide

[0062] The preferred cushioning efficiency value can vary based on the designated range of working pressures. In some embodiments, maximum working pressures include 6.0, 5.5, 5.0, 4.5, 4.0, 3.5, or even 3.0 MPa. In some embodiments, minimum working pressures include 0.5, 1.0, or even 1.5 MPa. With a working pressure range of 0.5 MPa to 4.0 MPa, in some embodiments, the cushioning efficiency is preferably at least 24, 25, 26, 28, 30, 32, or even 35% with higher efficiencies being preferred.

[0063] An alternative metric to evaluate the performance of the structured compressible layer is to determine the compression displacement that occurs within a designated working pressure range. The compressible layer is loaded to the peak working pressure and then unloaded to the minimum working pressure. The span of the working pressure range is then divided by the change in compressive strain observed between the peak loading pressure and the minimum loading pressure. This value can be defined as the average slope of the stress / strain curve within the designated working pressure range. The slope is preferred to be as low as possible. For example, the average slope observed within a working pressure range of 4 MPa to 0.5 MPa is preferably less than 30 MPa or less than 20 MPa or less than 15 MPa.

[0064] Cushioning articles according to at least some embodiments of the present disclosure will deform in a way that maintains compressive stresses between about 0.5 MPa and 4 MPa as they undergo significant compression displacements. It is also preferrable for the cushioning articles to occupy relatively small volumes (e.g., in a battery assembly design), so the cushioning article thickness is preferably small. Therefore, a suitable metric to evaluate the performance of these cushions is to determine the compression displacement that occurs between 0.5 MPa and 4 MPa upon unloading afterinitially loading to 4 MPa since the unloading step in the cycle is the more challenging portion for maintaining high stresses. This value is then divided by the total thickness of the cushioning article. This can also be stated as the average slope of the stress / strain curve between 4 MPa and 0.5 MPa. The slope is preferred to be as low as possible, and slopes of less than 30 MPa or less than 20 MPa are particularly preferred.

[0065] Cushioning articles used in battery assemblies should maintain consistent levels of stress over long periods of time to enable long battery lifetimes. Therefore, the materials of such cushioning articles will preferably undergo minimal stress relaxation. One way to characterize the stress stability of these designs is to compare the unloading curves between the first compression cycle and the third compression cycle in the test method above. Samples with good stress stability will show a minimal change in strain at a benchmark stress level - for example, 1 MPa. Samples with poor stress stability will show a more significant difference in strain between the first and third cycles at that stress level. Therefore, the difference in strain between the first cycle and third cycle at 1 MPa stress upon unloading - i.e., “AeiMPa” can be used as a parameter to gauge performance in these cushions, with lower values being desirable. Values below 0.015 (e.g., 1.5% strain) are preferred.

[0066] In select embodiments, the cushioning layer advantageously exhibits an unload slope of less than 30 megapascals (MPa), 25 MPa, 20 MPa, or even less than 15 MPa, determined according to the Compression Test Method described in detail in the Examples. Cushioning articles may achieve such low slopes by having patterned stmctures that are compressed. The material itself is substantially non-compressible, so the volume of the material must be substantially maintained as the sample is compressed. Therefore, it is preferrable to design the cushioning articles with adequate initial free volume to accommodate the material deformation as it is compressed. If the desired peak stress (e.g., 4 MPa) is not reached before the free volume is substantially all consumed by the deformation of the structures, then the sample undergoes a densification phenomenon with a sharp increase in slope in the stress / strain profile. This densification leads to undesirable large average slopes upon unloading.Generally, cushioning articles with an initial free volume fraction of at least 50% are preferrable, and 60% is more preferred. The initial free volume fraction is determined by calculating the volume of the polymer in at least one unit cell of a cushioning article design and by calculating the volume of the simple prism that fully contains the same unit cell(s). The polymer volume is subtracted from the total volume to obtain the free volume, and this is divided by the total volume to obtain the free volume fraction. As noted above, the cushioning layer has a free volume of greater than 50%, such as 55%, 60%, 65%, or even greater than 70%; and 80% or less.

[0067] Referring to FIGS. 1 A and IB, a single unit cell (100a, 100b) is depicted. In FIG. 1 A, the unit cell 100a includes a land region 110 and an engineered structure 120. The engineered structure extends away from the land region 110, in this case orthogonally from a surface 112 of the land region 110. The engineered structure 120 in these figures has a generally oblong cylindrical shape with a maximum width (widthmax) across an x-axis, a minimum width (widthmm) across a y-axis, and a height H across a z-axis. FIG. IB includes dashed lines 101 delineating boundaries within which to calculate the volume of asimple prism that fully contains the unit cell 100b. Also shown in FIG. IB are a base 122 of the engineered structure 120, and end 124 distal to the base 122, and a wall 126 between the base 122 and the end 124. In certain embodiments, the engineered structures do not all have the same height, but rather engineered structures on the same cushioning layer may have two or more different heights.

[0068] Compression of these engineered structures is preferred over bending or buckling. The aspect ratio of the engineered structure contributes to the potential buckling or bending behavior. The aspect ratio is defined in this case as the height of an engineered structure (distance from a surface of the land region to the end (i.e., point of the engineered structure farthest from the surface of the land region)) divided by the width of the engineered structure at half-height. Width is defined as the smallest dimension of the engineered structure that goes through a center of the structure in a plane parallel to the land region. High aspect ratio engineered structures tend to undergo buckling or bending. Even after buckling, these high aspect ratio engineered structures can sometimes achieve the target stresses by being compressed after fully bending over, which might be the case with aspect ratios between about 2 and 5. However, in some embodiments it is preferable to provide engineered structures the undergo compression initially without bending. This might be the case with aspect ratios below about 2.

[0069] At another extreme, engineered structures with low aspect ratio are not preferred. In general, it is preferrable for structures to be close together - for example, less than 10 millimeters (mm) between adjacent engineered structures, less than 5 mm, or less than 2 mm between adjacent engineered structures. Engineered structures that are spaced far apart lead to poor uniformity of force distribution across the working surface, with areas adjacent to engineered structures having high forces and areas not adjacent to engineered structures having low forces. Therefore, it is desirable to have closer spacing of engineered structures, which leads to smaller distances between force extremes. With a fixed structure height, low aspect ratio engineered structures have a larger area than high aspect ratio engineered structures. If the low aspect ratio engineered structures are closely spaced, then their relatively large area leads to a poor free volume fraction that leads to densification and high slopes upon unloading. If the low aspect ratio engineered structures are spaced farther apart to accommodate their relatively high area, then the force distribution becomes poor. Therefore, the preferred aspect ratio is 0.25 or greater.

[0070] It is not necessary for every engineered stmcture to have the same aspect ratio. In some embodiments, at least 80% of the total number of engineered structures on a cushioning article have an aspect ratio of 0.25 or greater; 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.00, 1.05, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40, 1.45, 1.50, 1.55, 1.60, 1.65, 1.70, 1.75.1.80.1.85.1.90, 1.95, or 2.00 or greater; and 5.00 or less, 4.95, 4.90, 4.85, 4.80, 4.75, 4.70, 4.65, 4.60, 4.55, 4.50, 4.45, 4.40, 4.35, 4.30, 4.25, 4.20, 4.15, 4.10, 4.05, 4.00, 3.95, 3.90, 3.85, 3.80, 3.75, 3.70, 3.65, 3.60, 3.55, 3.50, 3.45, 3.40, 3.35, 3.30, 3.25, 3.20, 3.15, 3.10, 3.05, 3.00, 2.95, 2.90, 2.85, 2.80, 2.75, 2.70, 2.65, 2.60, 2.55, 2.50, 2.45, 2.40, 2.35, 2.30, 2.25, 2.20, 2.15, 2.10, 2.05, 2.00, 1.95, 1.90, 1.85, 1.80, 1.75, 1.70, 1.65, 1.60, 1.55, 1.50, 1.45, 1.40, 1.35, 1.30, 1.25, 1.20, 1.15, 1.10, 1.05, 1.00, 0.95, 0.90, 0.85, or 0.80 or less. In certain embodiments, at least 80% of the total number of engineered structures on a cushioning article have an aspect ratio between 0.25 and 5.0. In selectembodiments, at least 80% of the total number of engineered structures on a cushioning article have an aspect ratio between 0.5 and 1.2.

[0071] The engineered structures of the present disclosure can be continuous or discontinuous. Broadly, the engineered structures may include shapes such as a curvilinear shape, a polygonal shape, or any combination thereof. For example, suitable continuous structures could include interconnected linear structures like a square lattice or a hexagonal lattice (e.g., a honeycomb shape). For instance, FIGS. 2A and 2B depict a hexagonal lattice geometry. FIG. 2 A is a generalized schematic top view of a unit cell 200a having a length 1. The continuous engineered structure 220 has a generally Y-shape centered on the land region 210. FIG. 2B provides a cross-sectional view of the engineered structure 220 and the land region 210. The aspect ratio (h / m) is defined as the height of the wall (“h”) of the engineered structure 220 divided by the width of the wall of the engineered structure 220 at half-height (“m”). The free volume (“FV”) is calculated as 1 minus the volume of polymer in the land region 210 and the walls of the engineered structure 220 of a unit cell 200a divided by the total volume of the hexagonal prism that contains the unit cell 200a of the land region 210 and the walls of the engineered structure 220.

[0072] Similarly, referring to FIG. 1C, an engineered structure 134 extends from a land region 132, which has an opposing second surface 133. To calculate the free volume, an imaginary box 140 is drawn which extends from the opposing second surface 133 upward to the height of the engineered structure 134. This imaginary box is represented by lines 141, 142, and 143. The volume of polymer within imaginary box 140 (represented by the shaded portions in FIG. 1C) is subtracted from the volume of box 140 (length of 141 x 142 x 143) to determine the free volume of an individual unit cell. This difference is divided by the total volume of the box to obtain the free volume fraction, which can be reported as a percentage.

[0073] Continuous structures can also include non-connected linear structures, such as parallel rib structures. The cross-sectional wall profile of the linear structures can have straight sides or curved sides and optionally has a draft angle between 0 degrees and 60 degrees. For instance, FIG. 3 is a generalized schematic perspective view of a cushioning article 300 including a structured major surface 305 having continuous parallel rib engineered structures 320 and a land region 310. Also indicated are a major surface 312 of the land region 310 and an opposing major surface 314 of the cushioning article 300. Although these ribs are straight, it is expressly contemplated that the parallel ribs could have other designs, e.g., an undulating pattern along a length of the continuous ribs. During molding, continuous structures advantageously provide a pathway for air to escape as the features are filled, which can lead to reduced defects from air entrapment.

[0074] Discontinuous structures can include cylindrical shapes, conical shapes, frustoconical shapes, and other shapes with full axial symmetry. For instance, FIG. 4 is a generalized schematic perspective view of a cushioning article 400 including a structured major surface 405 having discontinuous cylindrical engineered structures 420 and a land region 410. Also indicated is an opposing major surface 414 of the cushioning article 400. Discontinuous structures can also include structures with lower degrees of symmetry, such as triangular prisms, square prisms, hexagonal prisms, pyramids, tetrahedrons, and othergeometries. Compared to continuous stmctures, discontinuous structures can advantageously provide a more uniform distribution of force on the structured surface and a more uniform distribution of stress within the polymer as the cushioning article is compressed. The engineered stmctures 420 of FIG. 4 extend orthogonally from a major surface 412 the land region 410, however, in some cases, the engineered structures extend outwardly from the land region at an angle other than 90 degrees. For instance, FIG. 5 is a generalized schematic perspective view of a single engineered structure 520 extending from a land region 510 at a 45 degree angle. Also indicated are a major surface 512 of the land region 510 and an opposing major surface 514 of the cushioning article 500.

[0075] Optionally, a cushioning layer includes a plurality of engineered structures extending from opposing major surfaces of the land region. For instance, FIG. 6 is a generalized schematic perspective view of a cushioning article 600 including a structured major surface 605 having a land region 610 and a plurality of engineered structures 620. The land region 610 has a first major surface 612 and a second major surface 614. Engineered structures 620 extend outwardly from each of the first major surface 612 and a second major surface 614 of the land region 610. In this case, the opposing second major surface of the cushioning layer is also a structured major surface 607. The presence of two structured surfaces that oppose each other provides individual structures with a lower aspect ratio when compared to a case where taller structures exist on a single surface to provide an equivalent total cushion thickness. The lower aspect ratio of the individual structures can limit undesirable buckling or bending behavior.

[0076] In some embodiments, a suitable average thickness for a cushioning layer is 1 millimeter (mm) or greater, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, 3.0 mm, 3.1 mm, 3.2 mm, 3.3 mm, 3.4 mm, 3.5 mm, 3.6 mm, 3.7 mm, 3.8 mm, 3.9 mm, 4.0 mm, 4.1 mm, 4.2 mm, 4.3 mm, 4.4 mm, 4.5 mm, 4.6 mm, 4.7 mm, 4.8 mm, 4.9 mm, 5.0 mm, 5.1 mm, 5.2 mm, 5.3 mm, 5.4 mm, 5.5 mm, 5.6 mm, 5.7 mm, 5.8 mm, 5.9 mm, 6.0 mm, 6.1 mm, 6.2 mm, 6.3 mm, 6.4 mm, 6.5 mm, 6.6 mm, 6.7 mm, 6.8 mm, 6.9 mm, 7.0 mm, 7.1 mm, 7.2 mm, 7.3 mm, 7.4 mm, 7.5 mm, 7.6 mm, 7.7 mm, 7.8 mm, 7.9 mm, or 8.0 mm or greater; and 10.0 mm or less, 9.9 mm, 9.8 mm, 9.7 mm, 9.6 mm, 9.5 mm, 9.4 mm, 9.3 mm, 9.2 mm, 9.1 mm, 9.0 mm, 8.9 mm, 8.8 mm, 8.7 mm, 8.6 mm, 8.5 mm, 8.4 mm, 8.3 mm, 8.2 mm, 8.1 mm, 8.0 mm, 7.9 mm, 7.8 mm, 7.7 mm, 7.6 mm, 7.5 mm, 7.4 mm, 7.3 mm, 7.2 mm, 7.1 mm, 7.0 mm, 6.9 mm, 6.8 mm, 6.7 mm, 6.6 mm, 6.5 mm, 6.4 mm, 6.3 mm, 6.2 mm, 6.1 mm, 6.0 mm, 5.9 mm, 5.8 mm, 5.7 mm, 5.6 mm, 5.5 mm, 5.4 mm, 5.3 mm, 5.2 mm, 5.1 mm, 5.0 mm, 4.9 mm, 4.8 mm, 4.7 mm, 4.6 mm, 4.5 mm, 4.4 mm, 4.3 mm, 4.2 mm, 4.1 mm, 4.0 mm, 3.9 mm, 3.8 mm, 3.7 mm, 3.6 mm, 3.5 mm, 3.4 mm, 3.3 mm, 3.2 mm, 3.1 mm, 3.0 mm, 2.9 mm, 2.8 mm, 2.7 mm, 2.6 mm, 2.5 mm, 2.4 mm, 2.3 mm, 2.2 mm, 2.1 mm, and 2.0 mm. Stated another way, in some cases the cushioning layer has an average thickness of 1 to 10 millimeters.

[0077] Optionally, a cushioning article has a form of a sheet, which may be flexible. A sheet is in contrast, for example, to a rounded article such as a vehicle tire having tread structures on a major surface.

[0078] The compression forces provided by the patterned films are produced by the individual features of the pattern. When the patterned film is compressed, the local pressure directly adjacent to a compressed feature will therefore be higher than the average pressure over the entire array of features. The local pressure directly adjacent to the spaces between compressed features can be much lower than the average pressure over the entire array of features. In some cases, these local variations in applied pressure are not desirable. For example, in some battery cushioning applications, these local variations in pressure can lead to damage within a battery cell. To alleviate local variations in pressure, it can be useful to provide a pressure distribution layer to distribute the pressure from individual compressed features over the entire area between individual features. Referring to FIG. 7, a generalized schematic exploded perspective view is provided of an exemplary cushioning article 800 including two optional films 730a, 730b that can serve as pressure distribution layers. The first film 730a is adjacent to the second major surface 714 of the cushioning layer and the second film 730b is adjacent to the plurality of engineered structures 720. Also indicated are the structured major surface 705 of the cushioning article 700 and the first major surface 712 of the land region 710 of the cushioning article 700. Suitable materials for use in a film includes for instance and without limitation, a polyester, a polyimide, a polyamide, a polyvinyl chloride (PVC), a fiber-reinforced polymer composite, a polyethylene terephthalate (PET), a mica, a glass, or a metal. When a polymer is employed, it is preferably a high modulus polymer. In select cases, a PET may be selected that does not bum or hold a flame (e.g., classified as V0). This pressure distribution layer must resist bending to prevent the localized transmission of concentrated pressures, so stiff layers are preferred over compliant layers. The stiffness of the pressure distribution layer can be quantified by the flexural rigidity. The flexural rigidity (D) of a flat sheet can be calculated by the equation D= EH3 / (12(l-v2)) where E is the Young’s modulus, H is the layer thickness, and v is the Poisson ratio. To distribute the pressure effectively, the flexural rigidity of the stiffening layer should preferably be greater than 3xl0'3Pa m3(Pascal meters3), more preferably greater than 5xl0'3Pa m3, and even more preferably greater than 6xl0'3Pa m3. The pressure distribution layer can be a polymer, a metal, a ceramic, or other materials including composites and mixtures. The pressure distribution layer may be in the form of a continuous sheet, a woven, or a nonwoven material. For example, the pressure distribution layer may be, but is not limited to, a metal mesh, metal sheeting, woven glass, woven silica, mica sheet, mica with glass reinforcement, silicone impregnated wovens, nonwoven ceramics, carbon fiber wovens and nonwovens.

[0079] Polyurethanes containing units derived from HQEE are commercially available, such as from Covestro (Leverkusen, Germany) under the trade designation “DESMOPHAN 453”, from Huntsman (The Woodlands, TX) under the trade designation “IROGRAN A95 K4977”. Alternatively, polyurethanes containing units derived from HQEE may be synthesized using at least a polyol, a diisocyanate, and HQEE. Components used in polymerizable compositions to prepare such polyurethanes are described below.

[0080] Polyols

[0081] The polyol is not particularly limited. In some embodiments, the polyurethane contains units derived from a polyester or a poly ether, e.g., polycaprolactone, adipate polyester diol, or poly(tetramethylene ether) glycol (PTMEG). In some embodiments, the poly(tetramethylene ether) glycol has an average molecular weight less than 3000 g / mol or less than 2100 g / mol or less than 1900 g / mol to limit crystallinity in the resulting polyurethane.

[0082] In some cases, the polyester comprises a reaction product of at least one diacid and at least two different diols. One suitable polyester that is a reaction product of at least one diacid and at least two different diols is poly(butylene-co-ethylene adipate). In other such cases, the polyester comprises a reaction product of at least two different diacids and at least one diol. Some suitable polyesters that are a reaction product of at least two different diacids and at least one diol include polyethylene adipate-co-phthalate), poly(butylene adipate-co-phthalate), or poly(hexamethylene adipate-co-phthalate).

[0083] Polyester

[0084] Polyesters may be formed as the reaction product of diacids and diols. For example, terephthalic acid (a diacid) and ethylene glycol (a diol) can be reacted to form polyethylene terephthalate (PET). More generally, one or more diacids and one or more diols can be reacted, in equal molar portions of total diacids and total diols, to form a polyester comprising residues of the diacids and residues of the diols. The term residue when used in reference to the components of a polyester, refers to the moiety in the polyester resulting from the reaction of a corresponding monomer. In some cases, polyesters are formed from the reaction of diesters with diols by transesterification. In this reaction, instead of replacement of a hydrogen atom with a hydrocarbon group, it involves replacement of a hydrocarbon group (such as a methyl group) with a different hydrocarbon group (a diol).

[0085] A polyester can be prepared by preparing a reaction mixture, heating the reaction mixture with stirring, and removing the water byproduct of the condensation reaction. Typically, the water or alcohol byproduct is removed at a reduced pressure. In addition to the reactants noted above, the reaction mixture may contain optional reactive or non-reactive additives such as at least one catalyst selected from the acetate, phosphate, acid, or oxide form of antimony, zinc, cobalt, titanium, iron, potassium, calcium, and combinations thereof; or stabilizing agents selected from primary antioxidant, secondary antioxidant, antiozonant, UV absorber, hindered amine stabilizer, phosphate stabilizer, acid scavenger, heat stabilizer, and combinations thereof.

[0086] A wide range of diacids are suitable for use in a reaction mixture to form a polyester. In general, the diacids are of general Formula 1 below:

[0087] HO2C-A-CO2H Formula I

[0088] wherein A comprises a divalent group comprising an alkylene, arylene, heteroalkylene, heteroarylene, aralkylene, cyclic, branched, or a combination thereof. The selection of diacids depends upon the specific properties desired for the polyester copolymer.

[0089] In some embodiments, at least one of the diacids comprises an alkylene diacid of general Formula 1A below:

[0090] HO2C-(CH2)n-CO2H Formula 1A

[0091] wherein n is an integer from 1-12. Examples of suitable alkylene diacids include: malonic acid (n =1); succinic acid (n = 2); glutaric acid (n = 3); adipic acid (n = 4); pimelic acid (n = 5); suberic acid (n = 6); azelaic acid (n = 7); sebacic acid (n = 8); undecanedioc acid (n = 9); and dodecanedioc acid (n = 10). Particularly suitable alkylene diacids include adipic acid, suberic acid and sebacic acid.

[0092] In some embodiments, at least one of the diacids is an arylene diacid, where the arylene is substituted or unsubstituted. Examples of suitable arylene diacids include: phthalic acid; terephthalic acid; isophthalic acid; dibenzoic acid; and 2,6-napththalenedicarboxylic acid.

[0093] A wide range of diols are suitable for use in a reaction mixture to form a polyester. In general, the diols are of general Formula 2 below:

[0094] HO-B-OH Formula 2

[0095] wherein B comprises a divalent group comprising an alkylene, arylene, heteroalkylene, heteroarylene, aralkylene, cyclic, branched, or a combination thereof. The selection of diols depends upon the specific properties desired for the polyester copolymer.

[0096] In some embodiments, at least one of the diols comprises an alkylene diol of general Formula 2A below:

[0097] HO-(CH2)n-OH Formula 2A

[0098] wherein n is an integer from 2-12. Examples of suitable alkylene diols include: ethylene glycol (n = 2); 1, 4-butane diol (n = 4); 1,5-pentane diol (n = 5); 1,6-hexane diol ( n = 6); 1,8-octane diol (n = 8); and 1,10-decane diol (n = 10). Besides these straight chain diols, other 1, 2-diols, also called vicinal diols, are suitable such as are described by general Formula 2B below:

[0099] HO-(CRaH-CRbH)-OH Formula 2B

[0100] wherein each Raand Rbindependently comprises a hydrogen atom or an alkyl group with a 1-6 carbon atoms. In some embodiments, Rais H and Rbis a methyl group, and the compound is 1,2-propane diol. In other embodiments, Raand Rbare both methyl and the compound is 2,3 -butane diol.

[0101] In some embodiments, the diol of Formula 2 is a cycloalkylene diol. In these embodiments, the B group comprises a cycloalkylene group. Particularly suitable cycloalkylene diols are those with 6-membered cycloalkylene rings, such as CHDM (1,4-cyclohexane dimethanol. In some embodiments, the diol of Formula 2 is branched diol, such as neopentyl glycol (2,2-dimethylpropane-l,3-diol).

[0102] In some embodiments, at least one of the diols is an arylene diol, where the arylene is substituted or unsubstituted. Examples of suitable arylene diols include the isomers of dihydroxybenzenes: 1,2-dihydroxybenzene commonly referred to as catechol; 1,3 -dihydroxybenzene commonly referred to as resorcinol; 1,4 -dihydroxybenzene commonly referred to as hydroquinone; and chain extended phenols such as bisphenol A and bisphenol F.

[0103] Polypropylene Glycol and Poly (tetramethylene ether) Glycol

[0104] Examples of suitable polyoxyalkylene polyols include polyoxyalkylene polyols with an alkylene portion having from 1 to 6 carbons, and preferably from 2 to 4 carbons. In some cases, the molecular weight of the polyoxyalkylene polyol is preferably from 100 to 10000, or from 500 to 5000. As the polyoxyalkylene polyol, a polyoxyalkylene diol can be used, and a polyoxyalkylene diol having analkylene portion with from 2 to 6 carbons is preferable. Examples of this type of compound include polyoxyethylene glycol (polyethylene glycol), polyoxypropylene glycol (polypropylene glycol), and polyoxytetramethylene glycol (poly(tetramethylene ether) glycol).

[0105] Diisocyanate

[0106] Examples of diisocyanates include 4,4'-methylenediphenylenediisocyanate (MDI), 2,4-toluenediisocyanate, 2,6-toluene diisocyanate, o, m, and p-xylylene diisocyanate, 4,4'-diisocyanatodiphenylether, 3,3 '-dichloro-4,4'-diisocyanatodiphenylmethane, 4,4'-diphenyldiisocyanate, 4,4'-diisocyanatodibenzyl, 3,3'-dimethoxy-4,4'-diisocyanatodiphenyl, 3,3'-dimethyl-4,4'-diisocyanatodiphenyl, 2,2'-dichloro-5,5'-dimethoxy-4,4'-diisocyanato diphenyl, 1,3-diisocyanatobenzene, 1,2-naphthylene diisocyanate, 4-chloro-l,2-naphthylene diisocyanate, 1,3 -naphthylene diisocyanate, and l,8-dinitro-2,7-naphthylene diisocyanate; alicyclic diisocyanates such as 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate; 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate; aliphatic diisocyanates such as 1,6-hexamethylenediisocyanate, 2,2,4-trimethyl-l,6-hexamethylenediisocyanate, and 1,2-ethylenediisocyanate; cyclic diisocyanates such as isophorone diisocyanate (IPDI) and dicyclohexylmethane-4,4'-diisocyanate.

[0107] In some embodiments, the diisocyanate can be provided in the form of an isocyanate prepolymer. The isocyanate prepolymer can be the reaction product of an alcohol with a molar excess of diisocyanate. In some embodiments, the prepolymer is the reaction product of a polyester diol with a diisocyanate. In some embodiments, the isocyanate prepolymer is the reaction product of a polyether diol with a diisocyanate. In select cases, the polyurethane contains 20 wt.% or more units derived from a reaction product of 4,4'-methylenediphenyl diisocyanate (MDI) with an alcohol, 22 wt.%, 24 wt.%, 26 wt.%, 28 wt.%, 30 wt.%, 32 wt.%, 34 wt.%, 36 wt.%, 38 wt.%, 40 wt.%, 42 wt.%, 44 wt.%, 46 wt.%, 48 wt.%, or 50 wt.% or more units derived from a reaction product of MDI with an alcohol; and 60 wt.% or less units derived from a reaction product of MDI with an alcohol, 58 wt.%, 56 wt.%, 54 wt.%, 52 wt.%, 50 wt.%, 48 wt.%, 46 wt.%, 44 wt.%, 42 wt.%, 40 wt.%, 38 wt.%, 36 wt.%, 34 wt.%, 32 wt.%, 30 wt.%, 28 wt.%, 26 wt.%, or 24 wt.% or less units derived from a reaction product of MDI with an alcohol. Stated another way, the polyurethane may contain 20 wt.% to 60 wt.% units derived from a reaction product of 4,4'-methylenediphenyl diisocyanate with an alcohol.

[0108] Catalyst

[0109] Optionally, a catalyst is present in polymerizable compositions to form polyurethanes according to the present disclosure. For instance, in certain embodiments the polyurethane is derived from a reaction product of a polyol, a diisocyanate, and HQEE, in the presence of a catalyst. In some embodiments, the catalyst comprises an amine catalyst or a metal catalyst. For example, suitable catalysts can include amines or organometallic catalysts such as tin compounds, bismuth compounds, zinc compounds, and zirconium compounds. Optionally, a bismuth carboxylate may be a suitable catalyst, for instance bismuth neodecanoate and / or bismuth ethylhexanoate. In select embodiments, the compositions are free of catalysts that contain tin. Suitable amine catalysts include cyclohexyldimethylamine, 2-dimethylaminoethanol, 4-ethylmorpholine, N,N,4-trimethylpiperazine-l -ethylamine, 1,4-dimethylpiperazine, 3 -aminopropyldimethylamine, 2,2'-iminodiethanol, 1 -methylimidazole, 1,2-dimethylimidazole, 2-propyl imidazole, 2-butyl imidazole, 2-benzyl imidazole, 2-benzyl-4-methyl imidazole, 2-butyl-4-methyl imidazole, imidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, l-benzyl-2-methylimidazole, 2,4-dimethylimidazole, 2,4,5-trimethylimiazole, 2-ethy limidazole, 2- [[2 -(dimethy lamino)ethy 1] methylamino] ethanol, N- [3 -(dimethy lamino)propy 1] -N,N’,N’-trimethylpropane-l,3-diamine, formic acid, compound with 2,2'-oxybis[N,N-dimethylethylamine] (2:1), l,r-[[3-(dimethylamino)propyl]imino]bispropan-2-ol, 2-[(2-[2-(dimethylamino)ethoxy]ethyl)methylamino] ethanol, benzyldimethylamine 4-methylmorpholine, N,N,N’,N’ -tetramethylhexamethylenediamine, 2-[2-(dimethylamino)ethoxy]ethanol, 1,4-diazabicyclooctane, bis(2-dimethylaminoethyl)(methyl)amine, N,N,N’,N’-tetramethyl-2,2'-oxybis(ethylamine, 2,2'-dimorpholinyldiethyl ether, l,8-diazabicyclo[5.4.0]undec -7-ene, N’-[3-(dimethylamino)propyl]-N,N-dimethylpropane-l,3-diamine, N,N,N’,N’,N”,N”-hexamethyl-l,3,5-triazine- 1 ,3 ,5(2H,4H,6H)-tripropanamine, N,N-bis[3 -(dimethy lamino)propyl] -N’ ,N’ -dimethylpropane-1,3 -diamine.

[0110] One or more catalysts may be present in a polymerizable composition in an amount of at least O.02 wt.%, based on a combined weight of the polyol, diisocyanate, HQEE, and the catalyst, such as at least 0.03 wt.%, 0.04 wt.%, 0.05 wt.%, 0.06 wt.%, 0.07 wt.%, 0.08 wt.%, 0.09 wt.%, 0.10 wt.%, 0.12 wt.%, 0.14 wt.%, 0.16 wt.%, 0.18 wt.%, 0.20 wt.%, 0.25 wt.%, 0.30 wt.%, 0.35 wt.%, 0.40 wt.%, 0.45 wt.%, or at least 0.50 wt.%; and 5 wt.% or less, 4.5 wt.%, 4 wt.%, 3.5 wt.%, 3 wt.%, 2.5 wt.%, 2 wt.%, 1.5 wt.%, 1 wt.%, 0.9 wt.%, 0.8 wt.%, 0.7 wt.%, 0.6 wt.%, 0.5 wt.%, 0.4 wt.%, 0.3 wt.%, or 0.2 wt.% or less, based on a combined weight of the polyol, diisocyanate, HQEE, and the catalyst. In select embodiments, the catalyst is present in an amount of 0.02 wt.% to 5 wt.%, based on a combined weight of the polyol, diisocyanate, HQEE, and the catalyst.

[0111] Additives

[0112] The polymerizable composition may further comprise one or more additives, e.g., plasticizers, non-reactive diluents, toughening agents, fillers, flow control agents, colorants (e.g., pigments and dyes), adhesion promoters, UV stabilizers, flexibilizers, fire retardants, antistatic materials, thermally and / or electrically conductive particles, antioxidants, abrasive granules, thermal degradation stabilizers, light stabilizers, conductive particles, tackifiers, flow agents, bodying agents, flatting agents, inert fillers, binders, fungicides, bactericides, surfactants, thixotropic agents (e.g., ultra-fine silica powder), surfactants, antifoamers, antistatic agents, or metal deactivators. These additives, if present, are added in an amount effective for their intended purpose. The amount and type of such additives may be selected by one skilled in the art, depending on the intended end use of the composition.

[0113] Battery Assemblies

[0114] In a second aspect, a battery assembly is provided. The battery assembly comprises a battery cell and a cushioning layer adjacent to the battery cell. The cushioning layer is preferably according to any embodiment of a cushioning layer of the cushioning article described in detail above.

[0115] FIG. 11 illustrates an exemplary generic assembled battery module 11100 which includes a plurality of electrochemical cells or battery cells 11160 separated from each other by a gap, and a plurality of cushioning layers 11150 positioned in the gaps between the battery cells 11160, according to some embodiments. FIG. 11 shows a battery assembly 11100 in which the cushioning layers 11150 have two opposing major surfaces which contact adjacent battery cells 11160.

[0116] FIG. 12 is a generalized schematic top-down view of an exemplary battery assembly module with cushioning article(s), according to some embodiments. In the embodiment of FIG. 12, the battery assembly 12600 includes cylindrical battery cells 12060 with a cushioning article 12650 extending non-linearly (e.g., weaving in and out) between battery cells 12060. The cushioning article 12650 of FIG. 12 can schematically represent any cushioning article or layer, or any stacks of cushioning articles or layers, of the present disclosure.

[0117] Select Embodiments of the Disclosure

[0118] In a first embodiment, the present disclosure provides a cushioning article. The cushioning article comprises a cushioning layer having a stmctured major surface and an opposing second major surface. The structured major surface comprises a land region and a plurality of engineered structures. The cushioning layer has a free volume of greater than 50% and comprises a polyurethane containing 5 weight percent (wt.%) to 25 wt.% units derived from hydroquinone bis (2 -hydroxyethyl) ether.

[0119] In a second embodiment, the present disclosure provides a cushioning article according to the first embodiment, further comprising a film attached to the structured major surface and / or to the second major surface.

[0120] In a third embodiment, the present disclosure provides a cushioning article according to the second embodiment, wherein the film comprises a polyester, a polyimide, a polyamide, a polyvinyl chloride (PVC), a fiber-reinforced polymer composite, a polyethylene terephthalate (PET), a mica, a glass, or a metal.

[0121] In a fourth embodiment, the present disclosure provides a cushioning article according to any of the first through third embodiments, wherein at least 80% of the plurality of engineered structures has an aspect ratio between 0.25 and 5.0.

[0122] In a fifth embodiment, the present disclosure provides a cushioning article according to any of the first through fourth embodiments, wherein at least 80% of the plurality of engineered structures has an aspect ratio between 0.5 and 1.2.

[0123] In a sixth embodiment, the present disclosure provides a cushioning article according to any of the first through fifth embodiments, wherein the cushioning layer has an average thickness of 1 to 10 millimeters.

[0124] In a seventh embodiment, the present disclosure provides a cushioning article according to any of the first through sixth embodiments, wherein the polyurethane exhibits a density of greater than 0.8 grams per milliliter (g / mL), greater than 0.9 g / mL, or greater than 1.0 g / mL.

[0125] In an eighth embodiment, the present disclosure provides a cushioning article according to any of the first through seventh embodiments, wherein the plurality of engineered structures comprises a continuous interconnected structure.

[0126] In a ninth embodiment, the present disclosure provides a cushioning article according to any of the first through seventh embodiments, wherein the plurality of engineered structures comprises a plurality of continuous unconnected structures.

[0127] In a tenth embodiment, the present disclosure provides a cushioning article according to any of the first through eighth embodiments, wherein the plurality of engineered structures comprises a plurality of discontinuous structures.

[0128] In an eleventh embodiment, the present disclosure provides a cushioning article according to any of the first through tenth embodiments, wherein the plurality of engineered structures comprises shapes selected from the group consisting of a curvilinear shape, a polygonal shape, and combinations thereof.

[0129] In a twelfth embodiment, the present disclosure provides a cushioning article according to any of the first through eighth embodiments, wherein the plurality of engineered structures has shapes selected from the group consisting of cylindrical shapes, conical shapes, frustoconical shapes, triangular prisms, square prisms, hexagonal prisms, pyramids, tetrahedrons, and combinations thereof.

[0130] In a thirteenth embodiment, the present disclosure provides a cushioning article according to any of the first through twelfth embodiments, having a form of a sheet.

[0131] In a fourteenth embodiment, the present disclosure provides a cushioning article according to any of the first through thirteenth embodiments, wherein the polyurethane contains 20 wt.% to 60 wt.% units derived from a reaction product of 4,4'-methylenediphenyl diisocyanate with an alcohol.

[0132] In a fifteenth embodiment, the present disclosure provides a cushioning article according to any of the first through fourteenth embodiments, wherein the polyurethane contains units derived from a polyester or a polyether.

[0133] In a sixteenth embodiment, the present disclosure provides a cushioning article according to the fifteenth embodiment, wherein the polyester or polyether comprises poly caprolactone, adipate polyester diol, or poly(tetramethylene ether) glycol (PTMEG).

[0134] In a seventeenth embodiment, the present disclosure provides a cushioning article according to any of the first through sixteenth embodiments, wherein the polyurethane exhibits a glass transition temperature that is below 20 °C.

[0135] In an eighteenth embodiment, the present disclosure provides a cushioning article according to any of the first through seventeenth embodiments, wherein the polyurethane exhibits a hardness between Shore 70A and Shore 70D.

[0136] In a nineteenth embodiment, the present disclosure provides a cushioning article according to any of the first through eighteenth embodiments, wherein the cushioning layer exhibits an unload slope of less than 30 megapascals (MPA), determined according to the Compression Test Method.

[0137] In a twentieth embodiment, the present disclosure provides a cushioning article according to any of the first through nineteenth embodiments, wherein the plurality of engineered structures comprises two or more different heights.

[0138] In a twenty -first embodiment, the present disclosure provides a cushioning article according to any of the first through twentieth embodiments, wherein the plurality of engineered structures extend outwardly from the land region at an angle other than 90 degrees.

[0139] In a twenty-second embodiment, the present disclosure provides a battery assembly comprising a battery cell and a cushioning layer adjacent to the battery cell.

[0140] In a twenty -third embodiment, the present disclosure provides a battery assembly according to the twenty-second embodiment, wherein the cushioning layer is according to any of the first through twenty-first embodiments.EXAMPLES

[0141] 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.

[0142] Preparatory Example:

[0143] A polyurethane was prepared by dissolving HQEE (3.37 grams) in hot Fomrez G24-56 (23.5 g). Rubinate 1234 was added (13.1 grams), and the reactive mixture was mixed on a speed mixer for 10 seconds. 15 mL of the reactive mixture was transferred to an MCI 5 microcompounder (obtained from Xplore Instruments, Sittard, The Netherlands) set at 210 °C. This was mixed for 10 minutes at 100 RPM while polymerization occurred. The material was then dispensed between polytetrafluoroethylene (PTFE) sheets and pressed into a flat sheet in a hydraulic press set at about 400 °F (204 °C).

[0144] Comparative Example 1 and Examples 2-6. Honeycomb Geometry Samples

[0145] Samples were prepared by extruding thermoplastic polyurethane resins shown into polymeric tooling with varied geometries according to the details in Table 2. The aspect ratio (h / m) is defined as the height of the wall (“h”) divided by the width of the wall at half-height (“m”). The free volume (“FV”) is calculated as 1 minus the volume of polymer in the backing and the walls of a unit cell divided by the total volume of the hexagonal prism that contains the unit cell of the backing and the walls.

[0146] Example 7.

[0147] A first aluminum sheet (305 mm x 152 mm x 0.5 mm) was provided with an array of holes (9 holes x 36 holes) with centers spaced 2.7 mm apart. A cutting bit with a 30° taper angle was used such that each of the holes had a taper from a diameter of 2.0 mm on one face of the plate to a diameter of 1.5 mm on the opposite face of the plate (See FIGS. 8A-8B). A second aluminum sheet (20 cm x 13 cm x 0.024 cm) was provided with a rectangular opening (2.5 cm x 15 cm). This was placed over the first patterned sheet, and both were treated with a silicone release spray.

[0148] 17 grams of A95 K4977 was mixed in an MC15 microcompounder at 220 °C and 100 RPM for three minutes. A portion of that molten resin was then deposited into the rectangular opening of thesecond aluminum sheet and onto the patterned area of the first aluminum sheet. The sheets were placed between PTFE films and pressed in a hydraulic press with more than 10,000 pound-force (Ibf) for 30 seconds at 440 °F (226.67 °C). After cooling, the patterned polyurethane sample was removed with the geometry described in Table 3. Referring specifically to FIGS. 8A and 8B, FIG. 8A is a generalized schematic top view of a unit cell 800a of a cushioning layer including a land region 810 and a frustoconical engineered structure 802. FIG. 8B is a generalized schematic cross-sectional view of the engineered structure 820 and the land region 810 of the unit cell of FIG. 8A.

[0149] Example 8.

[0150] A first stainless steel sheet (15 cmx 15 cmx 0.050 cm) was provided with a staggered array of 119 holes with 0.06 inches (1.5 mm) in diameter and spaced 0.18 inches (4.6 mm) apart (center to center, see FIGS. 9A-9B). The holes covered an area of 1 inch (25.4 mm) x 3.25 inches (82.55 mm). A second stainless steel sheet (15 cm x 15 cm x 0.037 cm) was provided with a rectangular opening (2.5 cm x 8.3 cm). This was placed over the first patterned sheet and both were treated with a silicone release spray.

[0151] 17 grams of A95 K4977 was mixed in an MC-15 microcompounder at 220 °C and 100 RPM for three minutes. A portion of that molten resin was then deposited into the rectangular opening of the second stainless steel sheet and onto the patterned area of the first stainless steel sheet. The sheets were placed between PTFE films and pressed in a hydraulic press with more than 10,000 Ibf for 30 seconds at 440 °F (226.67 °C). After cooling, the patterned polyurethane sample was removed with the geometry described in Table 3. Referring specifically to FIGS. 9A and 9B, FIG. 9A is a generalized schematic top view of a unit cell 900a of a cushioning layer including a land region 910 and a cylindrical engineered structure 920. FIG. 9B is a generalized schematic cross-sectional view of the engineered structure 920 and the land region 910 of the unit cell of FIG. 9 A.

[0152] Example 9:

[0153] A first aluminum sheet (18 cmx 13 cmx 0.25 cm) was provided with a staggered array of 84 holes with a 3.9 mm diameter and spaced 11.1 mm apart (center to center, see FIGS. 9A-9B). The holes covered an area of 11 cm x 8 cm. A second aluminum sheet (20 cm x 13 cm x 0.05 cm) was provided with a rectangular opening (15 cm x 8 cm). This was placed over the first patterned sheet and both were treated with a silicone release spray.

[0154] 17 grams of A95 K4977 was mixed in an MC-15 microcompounder at 220 °C and 100 RPM for three minutes. A portion of that molten resin was then deposited into the rectangular opening of the second aluminum sheet and onto the patterned area of the first aluminum sheet. The sheets were placed between PTFE films and pressed in a hydraulic press with more than 10,000 Ibf for 30 seconds at 440 °F (226.67 °C). After cooling, the patterned polyurethane sample was removed with the geometry described in Table 3.

[0155] FIG. 10 is a photograph of the exemplary cushioning article of Example 9. More particularly, the photograph shows a cushioning article 10000 including a structured major surface 10005 having a landregion 10010 with a plurality of cylindrical engineered structures 10200 extending from the surface 10012 of the land region 10010. The cushioning article 10000 also has an opposing major surface 10014.

[0156] Example 10.

[0157] The first aluminum sheet from Example 7 was placed under a stainless steel sheet (20 cm x 15 cm x 0.010 cm) with a rectangular opening (2.5 cm x 15 cm). Both sheets were treated with silicone oil as a release agent. 1.8 grams of the polymer from the preparatory example was placed in the rectangular opening of the stainless steel sheet. The sheets were placed between PTFE films and pressed in a hydraulic press with more than 10,000 Ibf for 30 seconds at 400 °F (204.44 °C). After cooling, the patterned polyurethane sample was removed with the geometry described in Table 3.

[0158] Example 11.

[0159] An aluminum plate (152 mm x 152 mm x 1.5 mm) was provided with a hexagonal array of holes drilled through the plate. The holes had a diameter of approximately 2.6 mm with straight sides. The array was concentric hexagonal rings of 30, 24, 18, 12, 6 and 1 holes with the holes spaced 4.6 mm on center. In addition, a stainless steel sheet (23 cm x 7.5 cm x 0.016 cm) was provided with a circular opening (5 cm diameter). This was placed over the first patterned sheet and both were treated with a silicone release spray. 2.5 grams of the polymer from the preparatory example was placed in the opening of the stainless steel sheet. The sheets were placed between PTFE films and pressed in a hydraulic press with more than 10,000 Ibf for 30 seconds at 400 °F (204.44 °C). After cooling, the patterned polyurethane sample was removed with the geometry described in Table 3.

[0160] Comparative Example 12.

[0161] The preparation of Example 11 was repeated, except 2.5 grams ofEstane 58309 was used.

[0162] Example 13.

[0163] An aluminum plate (152 mm x 152 mm x 2.5 mm) was provided with an array of holes drilled through the plate. The holes had a diameter of 2.6 mm with straight sides. The array was a generally square arrangement of hexagonally packed holes in 25 rows having alternately 22 holes or 21 holes in each row. The holes were spaced 4.65 mm on center. A stainless steel sheet (23 cm x 7.5 cm x 0.016 cm) with a circular opening (5 cm diameter) was placed over the aluminum plate sheet and both were treated with a silicone release spray. 3 grams of Des 453 was placed in the opening of the stainless steel sheet. The sheets were placed between PTFE films and pressed in a hydraulic press with more than 10,000 Ibf for 30 seconds at 400 °F (204.44 °C). After cooling, the patterned polyurethane sample was removed with the geometry described in Table 3.

[0164] Example 14.

[0165] A sample of dried pellets of DES 487 resin was pressed between PTFE liners at 390 °C to make a precursor film of DES 487. The tooling plate of Example 8 was treated with TEF-2 dry lubricant release agent. 1 gram of the DES 487 film was placed on Tool 2, and PTFE liners were placed on both sides of the assembly. The stack was pressed in a hydraulic press with 30,000 Ibf for 30 seconds at 390 °F. After cooling, the resulting patterned polyurethane sample was removed from tool and trimmed to a rectangular area 27 mm x 62 mm.Table 3: Details of Samples with Post Geometries

[0166] Compression Test Method

[0167] Compression testing was done on a load frame equipped with compression platens (frame selected from either a model C43-504EYfrom MTS, Eden Prairie, MN, or a model 5969 from Instron, Norwood, MA). The compliance of the load frame was measured by compressing a metal platen with a force ramp from 0 kiloNewtons (kN) to 40 kN. The displacement observed as a function of load was then subtracted from subsequent tests to account for the compliance in the load frame. The sample was loaded between the platens of the load frame and compressed at 0.5 mm / minute until reaching a compression stress of 4 megapascals (MPa). The sample was immediately unloaded at the same rate to the initial displacement. The load / unload cycle was repeated twice for a total of three cycles.

[0168] The cushioning efficiency observed on the third cycle was calculated by the equation:Platen Gap at 0.5 MPa — Platen Gap at 4.0 MPa Cushioning Efficiency = - - - - - Platen Gap at 0.5 MPaThe generalized slope of the third unload cycle was calculated by the equation:3.5 MPaUnload Slope = - - —— - - - - „ >Strain at 4 MPa — Strain at 0.5 MPa

[0169] These parameters characterize the ability of the sample to provide cushioning pressure in the desired range (e.g., 0.5 MPa to 4.0 MPa) over a relatively long distance (preferably), with higher efficiencies being preferred over lower efficiencies and lower slope values (<20 MPa) being preferred over higher slope values (>20 MPa).

[0170] The results are shown in Table 4.

[0171] As the data in Table 4 show, the best slopes are achieved when the aspect ratio is less than 6.0. It is believed that aspect ratios above about 6.0 lead to initial bending of the features rather than compression of the features, and that bending deformation does not produce the stresses in the desired range (>1 MPa). Once bending is complete, the densified features lead to a rapid, steep development of stress that is not preferred.

[0172] In addition, that data in Table 4 show that the best slopes are achieved when the free volume of the samples is greater than about 40%. At low free volumes, the features are able to be pressed into the backing without development of stress in the desired range (>1 MPa). Once the feature is fully pressed into the backing and the sample densified, the sample undergoes rapid, steep development of stress that is not preferred.

[0173] Pressure Distribution Layers

[0174] To demonstrate the effects of added pressure distribution layers, examples were tested with a pencil rubbing technique. A pressure distribution layer was placed over the patterned urethane film, and a piece of 20 lb copy paper was placed over the pressure distribution layer. The paper was then marked by hand with a number 2 pencil over a continuous area of at least 4 square centimeters. The downforce on the pencil was about 0.5 kilograms-force (kgf), and the area of pencil contacting the paper was about 6 mm2 for a contact pressure of about 0.8 MPa. The clarity of any resulting pattern corresponding to the underlying pattern of features was qualitatively recorded in Table 5. Inability to observe the underlying pattern in the pencil markings demonstrates the ability of the pressure distribution layer to distribute pressure. Four pressure distribution layers were tested: Aluminum Foil (Ultra-Clean Supremium Aluminum Foil, Available as Product 3545 from Control Company, Friendswood, TX.), Oriented PET Film 0.18 mm thick (Melinex 462 from Tekra, LLC, New Berlin, WI), Oriented PET film 0.25 mm thick (Melinex 462 from Tekra), and Stainless Steel 0.076 mm thick (Product 22175 from Precision Brand, Downers Grove, IL). Tests were done on both the tops of selected examples (directly on patterns) and on the bottoms of the examples (on the surface of the land area opposite the patterned surface). With flexuralrigidity values of 2.2xl0'3Pa m3or less, the pattern was easily observed in the rubbings, while values of 6.3xl0'3Pa m3or more produced significantly diminished patterns.

[0175] In addition, that data in Table 4 show that the best slopes are achieved when the free volume of the samples is greater than about 40%. At low free volumes, the features are able to be pressed into the backing without development of stress in the desired range (>1 MPa). Once the feature is fully pressed into the backing and the sample densified, the sample undergoes rapid, steep development of stress that is not preferred.

[0176] 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 cushioning article comprising a cushioning layer having a structured major surface and an opposing second major surface, wherein the stmctured major surface includes a land region and a plurality of engineered structures, wherein the cushioning layer has a free volume of greater than 50%, and wherein the cushioning layer comprises a polyurethane containing 5 weight percent (wt.%) to 25 wt.% units derived from hydroquinone bis (2 -hydroxyethyl) ether.

2. The cushioning article of claim 1, further comprising a film attached to the structured major surface and / or to the second major surface.

3. The cushioning article of claim 2, wherein the film comprises a polyester, a polyimide, a polyamide, a polyvinyl chloride (PVC), a fiber-reinforced polymer composite, a polyethylene terephthalate (PET), a mica, a glass, or a metal.

4. The cushioning article of any of claims 1 to 3, wherein at least 80% of the plurality of engineered structures has an aspect ratio between 0.25 and 5.0.

5. The cushioning article of any of claims 1 to 4, wherein at least 80% of the plurality of engineered structures has an aspect ratio between 0.5 and 1.2.

6. The cushioning article of any of claims 1 to 5, wherein the cushioning layer has an average thickness of 1 to 10 millimeters.

7. The cushioning article of any of claims 1 to 6, wherein the polyurethane exhibits a density of greater than 0.8 grams per milliliter (g / mL), greater than 0.9 g / mL, or greater than 1.0 g / mL.

8. The cushioning article of any of claims 1 to 7, wherein the plurality of engineered structures comprises a continuous interconnected structure.

9. The cushioning article of any of claims 1 to 7, wherein the plurality of engineered structures comprises a plurality of continuous unconnected structures.

10. The cushioning article of any of claims 1 to 8, wherein the plurality of engineered structures comprises a plurality of discontinuous structures.

11. The cushioning article of any of claims 1 to 10, wherein the plurality of engineered structures comprises shapes selected from the group consisting of a curvilinear shape, a polygonal shape, and combinations thereof.

12. The cushioning article of any of claims 1 to 8, wherein the plurality of engineered structures has shapes selected from the group consisting of cylindrical shapes, conical shapes, frustoconical shapes, triangular prisms, square prisms, hexagonal prisms, pyramids, tetrahedrons, and combinations thereof.

13. The cushioning article of any of claims 1 to 12, having a form of a sheet.

14. The cushioning article of any of claims 1 to 13, wherein the polyurethane contains 20 wt.% to 60 wt.% units derived from a reaction product of 4,4'-methylenediphenyl diisocyanate with an alcohol.

15. The cushioning article of any of claims 1 to 14, wherein the polyurethane contains units derived from a polyester or a polyether.

16. The cushioning article of claim 15, wherein the polyester or polyether comprises polycaprolactone, adipate polyester diol, orpoly(tetramethylene ether) glycol (PTMEG).

17. The cushioning article of any of claims 1 to 16, wherein the polyurethane exhibits a glass transition temperature that is below 20 °C.

18. The cushioning article of any of claims 1 to 17, wherein the polyurethane exhibits a hardness between Shore 70 A and Shore 70D.

19. The cushioning article of any of claims 1 to 22, wherein the cushioning layer exhibits an unload slope of less than 30 megapascals (MPA), determined according to the Compression Test Method.

20. The cushioning article of any of claims 1 to 19, wherein the plurality of engineered structures comprises two or more different heights.

21. The cushioning article of any of claims 1 to 20, wherein the plurality of engineered structures extend outwardly from the land region at an angle other than 90 degrees.

22. A battery assembly comprising a battery cell and a cushioning layer adjacent to the battery cell.

23. The battery assembly of claim 22, wherein the cushioning layer is according to any of claims 1 to 21.

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