Liquid crystal elastomer adhesive and articles including the same

Abstract

Provided are articles including a substrate and a curable composition comprising 50 to 81 weight percent of a liquid crystal monomer, 1 to 24 weight percent of a chain extender, 6 to 26 weight percent of a crosslinker, and 0 to 1.5 weight percent of an initiator, wherein the curable composition is adjacent to the substrate, and wherein the curable composition is in the form of a continuous or discontinuous layer. Also provided are articles including a substrate and a cured composition of a curable composition comprising 50 to 81 weight percent of a liquid crystal monomer, 1 to 24 weight percent of a chain extender, 6 to 26 weight percent of a crosslinker, and 0 to 1.5 weight percent of an initiator, wherein the curable composition is adjacent to the substrate, wherein the curable composition is in the form of a continuous or discontinuous layer, and wherein the cured composition comprises a liquid crystal elastomer comprising a monodomain.

Description

[0001] LIQUID CRYSTAL ELASTOMER ADHESIVES AND ARTICLES INCLUDING THE SAME

[0002] BACKGROUND

[0003] Adhesives are used in a variety of marking, holding, protecting, sealing, and masking applications. One type of adhesive, a pressure-sensitive adhesive, is particularly preferred for many applications. Pressure-sensitive adhesives (“PSAs") are well known to persons of ordinary skill in tire relevant arts to possess certain properties at room temperature (e.g., 23 °C), including: (1) aggressive and permanent tack, (2) adherence with no more than finger pressure, (3) sufficient ability to hold onto an adherend, and (4) sufficient cohesive strength. Materials that have been found to function well as pressure-sensitive adhesives are polymers designed and formulated to exhibit the requisite viscoelastic properties resulting in a desired balance of tack, peel adhesion, and shear strength. Characteristics of PSAs are described, for example, in the Encyclopedia of Polymer Science and Engineering, Vol. 13, Wiley -Interscience Publishers (New York. 1988) and the Encyclopedia of Polymer Science and Technology, Vol. 1. Interscience Publishers (New York, 1964).

[0004] SUMMARY

[0005] The present disclosure provides articles including a pressure-sensitive adhesive derived from a liquid crystal elastomer (“LCE”) using thiol-ene chemistry. LCEs are lightly crosslinked polymer networks that contain mesogen (i.e., liquid crystal) phases that can be oriented via processing such that the aligmnent of the mesogen phases can impart anisotropic mechanical properties to the LCE. By introducing these alignment effects to the LCE PSA, the adhesive may have a peel force that depends on the direction in which it is peeled.

[0006] In one aspect, provided herein are articles including a substrate and a curable composition comprising 50 to 81 weight percent of a liquid crystal monomer, 1 to 24 weight percent of a chain extender, 6 to 26 weight percent of a crosslinker, and 0 to 1.5 weight percent of an initiator, wherein the weight percent values arc based on a total weight of the curable composition, wherein the curable composition is adjacent to the substrate, and wherein the curable composition is in the form of a continuous or discontinuous layer.

[0007] In another aspect, provided herein are articles including a substrate and a cured composition of a curable composition, the curable composition comprising 50 to 81 weight percent of a liquid crystal monomer, 1 to 24 weight percent of a chain extender, 6 to 26 weight percent of a crosslinker, and 0 to 1.5 weight percent of an initiator, wherein the weight percent values are based on a total weight of the curable composition, wherein the curable composition is adjacent to the substrate, wherein the curable composition is in the form of a continuous or discontinuous layer, and wherein the cured composition comprises a liquid crystal elastomer comprising a monodomain. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. la is a graph showing the effect of mesogen orientation on peel strength.

[0009] FIG. lb shows an LCE having a parallel mesogen orientation peeled from a substrate.

[0010] FIG. 1c shows an LCE having a perpendicular mesogen orientation peeled from a substrate.

[0011] DETAILED DESCRIPTION

[0012] Reference will now be made to various embodiments of the disclosed subject matter. While the disclosed subject matter will be described in conjunction with the enumerated claims, it will be understood that the exemplified subject matter is not intended to limit the claims to the disclosed subject matter.

[0013] The terms “a,” “an,” or “the” are used to include one or more than one unless the context clearly dictates otherwise. The term “or” is used to refer to a nonexclusive "or” unless otherwise indicated. In addition, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for description only and not of limitation. Any use of section headings is intended to aid reading of the document and is not to be interpreted as limiting; information that is relevant to a section heading may occur within or outside of that section.

[0014] In many applications involving bonding interactions between an adhesive and a substrate it may be beneficial to control the strength of the adhesive-substrate bond. This can involve, for example, some fonn of "debond- or bond-on-demand" functionality that enables the adhesive to adhere with appropriate strength to the substrate while also allowing for ease of separation under certain conditions. In some adhesive-substrate constructions an external stimulus (e.g., heat, electricity, light) may be required to change the adhesion strength. However, in some applications the ability to apply an external stimulus is limited. To address at least these issues, the present disclosure provides articles including a pressuresensitive adhesive (“PSA”) derived from a liquid crystal elastomer (“LCE”). LCEs are known to those of ordinary skill in the relevant arts and are described, for example, by Herbert et al., “Synthesis and Alignment of Liquid Crystalline Elastomers.” Nature Reviews Materials, Nature Research. January 1, 2022, pp 23-38.

[0015] LCEs are lightly crosslinked polymer networks that contain mesogen (i.e.. liquid crystal) phases that can be oriented into monodomains via processing, such as. for example, by exposure to polarized light or by applying some order or orientation to the substrate on which they are applied, such as, for example, by rubbing a surface to form aligned "scratches" that the mesogens align to. The alignment of the mesogen phases into one or more monodomains can impart anisotropic mechanical properties to the LCE and by introducing these alignment effects to the LCE PSA, the adhesive may have a peel force drat depends on the direction in which it is peeled. For example, in an unaligned case, the tacky LCE PSA has some baseline strength of adhesion, which can be controlled by conventional means (e.g., crosslinking density, modulus, glass transition temperature). However, if the LCE is oriented during and / or prior to use through processing, the strength of the adhesion to a substrate can be changed, for example as illustrated by the graph in FIG. la, to be weaker than the baseline in the parallel mesogen direction (FIG. lb) and stronger than the baseline in the perpendicular mesogen direction (FIG. 1c).

[0016] Use of LCE PSAs in bonded articles allows for sophisticated bond design, such as, for example, articles where die bonding strength increases in a first direction, while allowing for easy removal when debonding along a second direction. Directional peel force is an advantageous property for enabling on- demand disbondment of an adhesive, where its holding power it optimized along its principal usage direction but the user could remove it with minimal force by peeling it along some other direction. Applications that could benefit from such a property could include adhesives used for temporary bonding, such as those used in pick-and-place manufacturing: static applications like supporting wall-mounted brackets where the usage direction is fixed, but release and repositioning can be achieved quickly by removing it along an alternative direction; and adhesives for access panels where ease of removal aids in repair of a device. These characteristics can be further exploited by changing mesogen orientation, for example, by exposure of the bonded article to heat or light, thereby allowing the adhesive strength to be tuned throughout the life the article. Articles including patterned LCE PSAs, where the mesogen orientation can be locally tuned to provide complex bonding profiles, are also contemplated.

[0017] In one aspect, provided are articles comprising a substrate and a curable composition including 50 to 81 weight percent of a liquid crystal monomer, 1 to 24 weight percent of a chain extender. 6 to 26 weight percent of a crosslinker, and 0 to 1.5 weight percent of an initiator, wherein the weight percent values are based on a total weight of the curable composition, wherein the curable composition is adjacent to the substrate, and wherein the curable composition is in the form of a continuous or discontinuous layer. In some embodiments, the substrate comprises a polyester terephthalate film. In some embodiments, the liquid cry stal monomer is represented by the structure

[0018] In some embodiments, the chain extender is represented by the structure In some embodiments, die crosslinker is represented by the structure

[0019] In some embodiments, the initiator comprises a photoinitiator. In some embodiments, the article further comprises a primer layer between the substrate and the curable composition. In some embodiments, the primer layer comprises a polyamide resin.

[0020] In another aspect, provided are articles comprising a substrate and a cured composition of a curable composition, the curable composition including 50 to 81 weight percent of a liquid crystal monomer, 1 to 24 weight percent of a chain extender, 6 to 26 weight percent of a crosslinker, and 0 to 1.5 weight percent of an initiator, wherein the weight percent values are based on a total weight of the curable composition, wherein the curable composition is adjacent to the substrate, wherein the curable composition is in the form of a continuous or discontinuous layer, and wherein the cured composition comprises a liquid crystal elastomer comprising a monodomain. In some embodiments, the cured composition comprises a pressuresensitive adhesive. In some embodiments, the cured composition is a pressure-sensitive adhesive, the substrate is a backing, and the article is an adhesive tape. In some embodiments, the substrate comprises a tape backing. In some embodiments, wherein the liquid crystal monomer is represented by the structure

[0021] In some embodiments, the chain extender is represented by the structure In some embodiments, die crosslinker is represented by the structure

[0022] In some embodiments, the initiator comprises a photoinitiator. In some embodiments, the article further comprises a primer layer between the substrate and the curable composition. In some embodiments, the primer layer comprises a polyamide resin. In some embodiments, the article comprises a plurality of monodomains. In some embodiments, the ratio of Average Peel Strength Orthogonal to Nematic Director of LCE: Average Peel Strength Parallel to Nematic Director of LCE is 1.1:1 to 100:1; optionally 1.1 :1 to 75:1; optionally 1.1:1 to 50:1; optionally 1.1:1 to 40:1; optionally 1.1:1 to 30:1; 1.1:1 to 25:1; optionally 1.1 :1 to 20:1; optionally 1.1:1 to 15: 1; optionally 1.1:1 to 10: 1; optionally 1.2:1 to 100:1, optionally 1.3: 1 to 100:1, optionally 1.4:1 to 100:1, optionally 1.4:1 to 9:1 as determined by the Peel Test.

[0023] Objects and advantages of this disclosure are further illustrated by the following non-limiting examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this disclosure.

[0024] EXAMPLES

[0025] Materials l.l'-(2-Methyl-l,4-phenylene) bis[4-[(6-mercaptohexyl)oxy]benzoate] (RM2SH) (CAS Registry Number 1803269-66-0) was obtained from AlphaMicron Incorporated. Kent, OH. Glyoxal bis(diallyl acetal) (GBDA) (CAS Registry' Number 16646-44-9) and trimethylolpropane diallyl ether (TMPDAE) (CAS Registry Number 682-09-7) were obtained from the Sigma-Aldrich Company, St. Louis, MO. IRGACURE 369 photoinitiator was obtained from IGM Resins, Charlotte, NC. ELV AMIDE 8023R polyamide resin was obtained from the DuPont Corporation. Wilmington, DE.

[0026] Methods

[0027] Gel Fraction Determination

[0028] A dry sample of LCE film was weighed and then submerged in cyclopentane for a minimum of 72 hours. The film sample was then removed from the cyclopentane and dried by placing on a hot plate set at 75 °C for 5 hours. The dried sample was removed from the hot plate, cooled to room temperature, and then weighed. The weight of the sample after the cyclopentane submersion / drying process was compared to the original recorded weight of the sample to calculate the gel fraction, defined as the weight fraction of the remaining insoluble portion.

[0029] Polarized Optical Microscopy

[0030] Surface alignment of LCE films was imaged using a Nikon Eclipse Ci-POL polarized light microscope (Nikon Instruments, Melville, NY) in reflection mode at 20x magnification.

[0031] Wide Angle X-ray Scattering (WAXS) Analysis

[0032] LCE film samples were imaged with a Xenocs Xeuss 3.0 SAXS / WAXS beamline (Xenocs, Inc., Holyoke, MA). Patterns were collected with vacuum in transmission geometry using a copper source with x-ray energy at 8 keV. Scan times were 60 seconds per sample.

[0033] Example 1. Preparation of Liquid Crystal Elastomer (LCE) Film

[0034] Rectangular glass slides (38 mm (x-axis) by 25 mm (y-axis)) were plasma cleaned for 10 minutes under vacuum using a Harrick PDC-32G (115 V) basic plasma cleaner (Harrick Plasma. Ithaca, NY). ELVAMIDE 8023R polyamide resin (6-10 drops. 0.125 weight percent in methanol) was spin-coated onto the plasma coated surface of one side of each glass slide (10 seconds at 1500 rpm. 500 rpm / second acceleration, followed by 50 seconds at 3500 rpm. 1200 rpm / second acceleration) using a Laurell WS-650- 23B Spin Coater (Laurell Technologies. Lansdale. PA). To create an alignment surface for mesogens, the resulting resin coated surface of each slide was rubbed a minimum of 10 times in a single, linear direction (i.e., y-axis direction of the glass slide) using a velvet cloth with hand pressure. The velvet cloth was wrapped around a round glass vial. A first glass slide was placed on a solid horizontal surface with the rubbed surface exposed. A second slide was placed on top of the first slide with 30 micron glass bead spacers used to create a gap separating the slides. The rubbed surface of the second slide faced the rubbed surface of the first slide and the slides were edge aligned so as to have the same direction of surface rubbing.

[0035] The monomers RM2SH (50 mg), GBDA (5.32 microliters), and TMPDAE (9.40 microliters) were combined with the IRGACURE 369 photoinitiator (0.64 mg) in a vial. The molar ratio of GBDA:TMPDAE was about 1:2. The mixture was melt-mixed at 110 °C with vortexing to form a homogeneous mixture. The glass plate assembly was placed on a hot plate set at 110 °C. The melted mixture was applied to the edge of the heated glass plate assembly using a pipette so that the gap volume between the slides was filled with the mixture by capillary action. The assembly was then placed on a hot plate set at 75 °C to reach the nematic liquid crystal state and the monomer mixture was photopolymerized at 75 °C with 10 minutes of exposure to 100 mW / cm2 of 365 mn light (Dymax BlueWave MX-25 curing system, Dymax Company, Torrington, CT). The glass slide assembly was then submerged in room temperature water overnight, followed by removal of the resulting LCE film from the assembly. The film was dabbed with a dry paper towel to remove residual water. The gel fraction of the LCE film was 90.1%. Polarized optical microscopy images of the LCE film showed birefringence. The wide angle x-ray scatering (WAXS) image of the LCE film showed prominent eyebrow features consistent with monodomain LCE aligmnent.

[0036] Comparative Example A. Polydomain LCE Polymer Film

[0037] The same procedure as reported in Example 1 was followed with the exception that the polyamide resin coated surfaces of tire glass slides were not rubbed to create an alignment surface.

[0038] Example 2. Preparation of LCE Film with More GBDA Cross-Linker than in Example 1

[0039] The same procedure as described in Example 1 was followed with the exception that the monomer mixture contained RM2SH (50 mg), GBDA (7.45 microliters), and TMPDAE (5.64 microliters) were combined with the IRGACURE 369 photoinitiator (0.63 mg) in a vial. The molar ratio of GBDA:TMPDAE was about 1:1. The gel fraction of the LCE film was 91.9%. Polarized optical microscopy images of the LCE film showed birefringence. The wide angle x-ray scatering (WAXS) image of the LCE film showed prominent eyebrow features consistent with monodomain LCE alignment.

[0040] Comparative Example B. Polydomain LCE Polymer Film

[0041] The same procedure as reported in Example 2 was followed with the exception that the polyamide resin coated surfaces of the glass slides were not rubbed to create an alignment surface.

[0042] Example 3. Preparation of LCE Film with More GBDA Cross-Linker than in Example 2

[0043] The same procedure as described in Example 1 was followed with the exception that the monomer mixture contained RM2SH (50 mg), GBDA (9.58 microliters), and TMPDAE (1.88 microliters) were combined with the IRGACURE 369 photoinitiator (0. 1 mg) in a vial. The molar ratio of GBDA:TMPDAE was about 4.5:1. The gel fraction of the LCE film was 87.1%. Polarized optical microscopy images of the LCE film showed birefringence. The wide angle x-ray scatering ( AXS) image of the LCE film show ed prominent eyebrow features consistent with monodomain LCE aligmnent.

[0044] Comparative Example C. Polydomain LCE Polymer Film

[0045] The same procedure as reported in Example 3 was followed with the exception that the polyamide resin coated surfaces of tire glass slides were not rubbed to create an alignment surface.

[0046] Example 4. Tensile Testing of Examples 1-3 and Corresponding Comparative Examples A-C

[0047] A DMA850 Dynamic Mechanical Analyzer (TA Instruments, New Castle, DE) was operated at room temperature for tensile testing of LCE film strips (cut to about 10 mm length and 2.5 mm width). For LCE films of Examples 1-3, sets of strips were cut in two different orientations. In the first set, strips were cut with the lengthwise direction of the strip parallel to the nematic director of the LCE film (i.e., cut in the direction of surface rubbing). In the second set. strips were cut with the lengthwise direction of the strip perpendicular to the nematic director of the LCE fihn (i.e., cut in the direction orthogonal to the direction of surface rubbing). The applied strain was 10% / minutc. The Young’s modulus was taken in the linear regime in the stress-strain curve between 1-3% strain. Test strips were prepared from at least 3 different batches of each LCE film with at least 3 samples taken per batch. The average values determined for “stress at fracture” (MP), “strain at fracture” and “Young’s modulus” (with standard error of the mean (SE)) are presented in Tables 1-3.

[0048] Table 1.

[0049] N / A = Not Applicable

[0050] Table 2.

[0051] N / A = Not Applicable Table 3.

[0052] N / A = Not Applicable

[0053] Example 5. Peel Test

[0054] Peel tests (180°) were performed using a TA.XTplus Texture Analyzer with a 500 g load cell (Stable Micro Systems, Surrey, England). ASTM Standard D3330 ‘Standard Test Method for Peel Adhesion of Pressure-Sensitive Tape’ was used as a guide for the procedure. Samples for peel testing were prepared by heat pressing an LCE film selected from Examples 1-3 and corresponding Comparative Examples A-C to the primed surface of a polyester terephthalate film (thickness of 51 microns) at 80 °C for 10 minutes. The resulting backed films were cut into strips (15 mm length by 2-4 mm width). For backed films prepared from LCE films of Examples 1-3, sets of strips were cut in two different orientations. In the first set, strips were cut with the lengthwise direction of the strip parallel to the nematic director of the LCE film (i.e., cut in the direction of surface rubbing). In the second set, strips were cut with the lengthwise direction of the strip perpendicular to the nematic director of the LCE film (i.e.. cut in the direction orthogonal to the direction of surface rubbing).

[0055] Each strip had an overhang of the backing that was then taped onto a glass slide for attachment to a grip of the instrument. The exposed LCE surface was placed onto a piece of plasma-cleaned glass and maintained at 80 °C for one hour to ensure maximum conformality of the surface. The samples were then cooled to room temperature. Adherence pressure was standardized by rolling each sample 5 times with a weighted roller. The 180° peel tests were performed at room temperature at a velocity of 0.5 mm / second for 20 mm or until the entire sample strip was unpeeled. The peel force reading was normalized by the test sample width. Peel strength measurements were averaged across a plateau of force to record the steadystate peel force. For each peel test sample, the average peel strength (with standard error of the mean(SE)) was determined using LCE film prepared from at least three different batches and a minimum of 15 total strip measurements were conducted. The peel strength results (N / min) arc reported in Tables 4 and 5.

[0056] Table 4. Peel Strength Measurements N / A = Not Applicable

[0057] Table 5. Peel Strength Calculation

[0058] N / A = Not Applicable

[0059] Example 6. Preparation and Peel Testing of a Pressure Sensitive Adhesive with a Patterned LCE Surface Rectangular glass slides (38 mm (x-axis) by 25 mm (y-axis)) were plasma cleaned and coated with

[0060] ELVAMIDE 8023R polyamide resin (0.125 weight percent in methanol) according to the method described in Example 1. The method of rubbing the resin coated surface was changed from Example 1 to create two sections (each section being 19 mm (x-axis) by 25 mm (y-axis)) with different (orthogonal) directions of rubbing. In the first section, the resin coated surface was rubbed a minimum of 10 times in the x-axis direction only using a velvet cloth with hand pressure. The velvet cloth was wrapped around a round glass vial. In the second section, the resin coated surface was rubbed a minimum of 10 times in the y-axis direction only using the velvet cloth. These sectioned glass slides were used to prepare a patterned LCE film according to the photopolymerization procedure described in Example 2. The resulting LCE film was obser ed under cross polarizers and a prominent light scattering difference was evident for the tw o sections indicating that the nematic directors of the LCE film sections w ere aligned based on the direction of rubbing. The first LCE section (from rubbing the polyamide contact surface in die x-direction) was more opaque than the second LCE section (from rubbing the polyamide contact surface in the y-direction).

[0061] A backing w as adhered to the LCE film according to the procedure described in Example 5. A sample strip (30 mm (x-axis direction) by 3.8 mm (y-axis direction) was cut from the backed film. The upper half of the strip (15 mm by 3.8 mm) was from the section of the slide in which the polyamide resin was rubbed in the x-axis direction and the lower half of the strip (15 mm by 3.8 mm) was from the section of the slide in which the polyamide resin was rubbed in the y-axis direction.

[0062] The peel test (180°) of the sample strip was conducted as described in Example 5 with the peel direction being parallel to the direction of rubbing used for aligning the upper LCE film section. The two sections of the patterned sample had significantly different peel strengths. The peel strength of the upper section was 0.09 N / mm. while the peel strength of the lower section was 0.49 N / mm (>5 times the peel strength of the upper section of the pattern).

[0063] All cited references, patents, and 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. An article comprising: a substrate; and a curable composition comprising a) 50 to 81 weight percent of a liquid crystal monomer; b) 1 to 24 weight percent of a chain extender; c) 6 to 26 weight percent of a crosslinker; d) 0 to 1.5 weight percent of an initiator, wherein the weight percent values are based on a total weight of the curable composition, wherein the curable composition is adjacent to the substrate, and wherein the curable composition is in the form of a continuous or discontinuous layer.

2. The article of claim 1. wherein the substrate comprises a polyester terephthalate film.

3. The article of claim 1, wherein the liquid crystal monomer is represented by the structure4. The article of claim 1, wherein the chain extender is represented by the structure5. The article of claim 1. wherein the crosslinker is represented by the structure6. The article of claim 1, wherein the initiator comprises a photoinitiator.

7. The article of claim 1, further comprising a primer layer between the substrate and the curable composition.

8. The article of claim 7, wherein the primer layer comprises a polyamide resin.

9. An article comprising: a substrate; and a cured composition of a curable composition, the curable composition comprising: a) 50 to 81 weight percent of a liquid cry stal monomer; b) 1 to 24 weight percent of a chain extender; c) 6 to 26 weight percent of a crosslinker; d) 0 to 1.5 weight percent of an initiator, wherein the weight percent values are based on a total weight of the curable composition, wherein the curable composition is adjacent to the substrate, wherein the curable composition is in the form of a continuous or discontinuous layer, and wherein the cured composition comprises a liquid crystal elastomer comprising a monodomain.

10. The article of claim 9. wherein the cured composition comprises a pressure-sensitive adhesive.

11. The article of claim 9, wherein the cured composition is a pressure-sensitive adhesive, the substrate is a backing, and the article is an adhesive tape.

12. The article of claim 9, wherein the substrate comprises a tape backing.

13. The article of claim 9, wherein the liquid cry stal monomer is represented by the structure14. The article of claim 9, wherein the chain extender is represented by the structure15. The article of claim 9, wherein the crosslinker is represented by the structure16. The article of claim 9, wherein the initiator comprises a photoinitiator.

17. The article of claim 9, further comprising a primer layer between the substrate and the curable composition.

18. The article of claim 17, wherein the primer layer comprises a polyamide resin.

19. The article of claim 9 comprising a plurality of monodomains.

20. The article of claim 9, wherein the ratio of Average Peel Strength Orthogonal to Nematic Director of LCE: Average Peel Strength Parallel to Nematic Director of LCE is 1.1:1 to 100:1; optionally 1.1:1 to75:1; optionally 1.1:1 to 50:1; optionally 1.1:1 to 40:1; optionally 1.1:1 to 30:1; 1.1:1 to 25:1; optionally 1.1:1 to 20:1; optionally 1.1:1 to 15:1; optionally 1.1:1 to 10:1; optionally 1.2:1 to 100:1, optionally 1.3:1 to 100:1, optionally 1.4:1 to 100:1, optionally 1.4:1 to 9:1 as determined by the Peel Test.

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