Silicone adhesive tapes useful for high temperature applications

Abstract

An adhesive tape comprising a backing having a first major surface and a second major surface opposite the first major surface, a first tie layer disposed on the first major surface of the backing, and a first silicone adhesive disposed on the first tie layer. The first silicone adhesive includes a first polymerized product of a first reaction mixture. The first reaction mixture comprises a first MQ silicate resin tackifier, and a first silicone elastomer having the formula where R1 and R2 are independently selected from alkyl, allyl, phenyl, alkenyl, silyl, and hydrogen, where R3 and R4 are independently selected from alkyl, allyl, phenyl, and alkenyl, and where n is from 100 to 100000. The backing comprises at least one of woven or nonwoven inorganic fibers. The adhesive tape passes the Torch-Flame Test (TFT) Method.

Description

SILICONE ADHESIVE TAPES USEFUL FOR HIGH TEMPERATURE APPLICATIONSBackground

[0001] Expanding markets exist for hybrid or fully electric vehicles fueled by rechargeable batteries, such as the lithium-ion battery. Such batteries are typically made up of several battery modules, and each battery module comprises many interconnected individual battery cells. When one cell in a battery module is damaged or faulty in its operation (e.g., improper cell use, puncture, exposure to extreme external temperatures, or manufacturing defects), the temperature within the cell may increase faster than heat can be removed. If the temperature increase remains unchecked, a catastrophic phenomenon called thermal runaway can occur resulting in a fire and blasts of particles as hot as 1000 °C or more. The resulting fire can spread very quickly to neighboring cells and subsequently to cells throughout the entire battery as a chain reaction. These fires can be potentially massive and can spread to surrounding structures if not properly contained.Summary

[0002] The thermal runaway process can be accelerated by the ejection of conductive gases, liquids, and / or particulates that short circuit adjacent cells. The short circuiting is facilitated by metal surfaces that make up many of the components within the battery.

[0003] The present disclosure provides dielectric silicone adhesive tapes that can be applied to metal surfaces to reduce or eliminate short circuit events during a thermal runaway, delaying the spread of the fire and reducing potential harm and / or damage. Unlike dielectric coatings applied to metal surfaces, dielectric tapes can be quickly applied to the metal surfaces on site and can be reworked and / or repositioned as needed. However, most commercial electrical tapes, including glass cloth tapes and Mica tapes, use acrylic adhesives that decompose (e.g., oxidize to CO2) under a torch flame and / or temperatures of 550 °C, resulting in significant adhesion drop and adhesion failure under the conditions anticipated in athermal runaway event. The dielectric silicone adhesive tapes of the present disclosure adhere to metal surfaces and can outperform conventional solutions (e.g, acrylic adhesives) at high temperature applications, thus making them a suitable solution for use as an electrical insulator in electric vehicle batteries.

[0004] In one embodiment, the present disclosure provides an adhesive tape comprising: a backing having a first major surface and a second major surface opposite the first major surface, the backing comprising at least one of woven or nonwoven inorganic fibers; a first tie layer disposed on the first major surface of the backing; and a first silicone adhesive disposed on the first tie layer. The first silicone adhesive includes a first polymerized product of a first reaction mixture. The first reaction mixture comprises a first MQ silicate resin tackifier and a first silicone elastomer having the formulaR4where Ri and R2 are independently selected from alkyl, allyl, phenyl, alkenyl, silyl, and hydrogen, where Rs and R4 are independently selected from alkyl, allyl, phenyl, and alkenyl, and where n is from 100 to 100000. The adhesive tape passes the Torch-Flame Test (TFT) Method set forth herein.

[0005] The backing may further comprise a sizing agent, wherein at least a portion of the sizing agent is disposed on the first major surface of the backing, and where the first tie layer comprises the sizing agent disposed on the first major surface of the backing. Such sizing agents may include a polymeric carbohydrate, a starch-oil based binder, a poly(vinyl alcohol), a reactive silane, or combinations thereof. Alternatively, or in addition thereto, the tie layer may comprise a primer. Such primers may include an epoxy-silane, a polydimethylsiloxane with vinyl groups, or combinations thereof.

[0006] In another embodiment, the adhesive tape of the present disclosure further comprises a second tie layer disposed on the second major surface of the backing and a second silicone adhesive disposed on the second tie layer, wherein the second tie layer is sandwiched between the second major surface of the backing and the second silicone adhesive. The second silicone adhesive comprises a second polymerized product of a second reaction mixture. The second reaction mixture comprises a second MQ silicate resin tackifier, and a second silicone elastomer having the formulaR / R / O — f— ~ Si— ~ RAwhere R and R2’ are independently selected from alkyl, allyl, phenyl, alkenyl, silyl, and hydrogen, where R3’ and Rf are independently selected from alkyl, allyl, phenyl, and alkenyl, and where n is from 100 to 100000.

[0007] The compositions of the first and second silicone adhesives may be the same or different. The compositions of the first and second primers may be the same or different.

[0008] In a further embodiment, the present disclosure provides a method of making the adhesive tapes described above, the method comprising applying a primer to the first major surface of the backing, drying the primer to form the first tie layer, applying the first reaction mixture to the first tie layer, and curing the first reaction mixture by e-beam radiation to form the first silicone adhesive.

[0009] In yet a further embodiment, the present disclosure provides another method a making the adhesive tapes described above, the method comprising: applying the first reaction mixture to the first major surface of the backing, the backing comprising a sizing agent, at least a portion of the sizing agentdisposed on the first major surface of the backing between the backing and the first reaction mixture; and curing the reaction mixture by e-beam radiation to form the first silicone adhesive.

[0010] The above summary of the present disclosure is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The description that follows more particularly exemplifies illustrative embodiments.Brief Description of Drawings

[0011] FIG. 1 is a schematic cross-sectional view of a single-sided adhesive tape in the present disclosure; and

[0012] FIG. 2 is a schematic cross-section view of a double-sided adhesive tape in the present disclosure.Detailed Description

[0013] In the following description of illustrative embodiments, reference is made to the accompanying figures of the drawings which form a part hereof, and in which are shown, by way of illustration, specific embodiments. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.

[0014] As used herein:

[0015] The term “comprises” and variations thereof do not have a limiting meaning where these terms appear in the description and claims. Such terms will be understood to imply the inclusion of a stated step or element or group of steps or elements but not the exclusion of any other step or element or group of steps or elements. By “consisting of’ is meant including, and limited to, whatever follows the phrase “consisting of.” Thus, the phrase “consisting of’ indicates that the listed elements are required or mandatory, and that no other elements may be present. By “consisting essentially of’ is meant including any elements listed after the phrase, and limited to other elements that do not interfere with or contribute to the activity or action specified in the disclosure for the listed elements. Thus, the phrase “consisting essentially of’ indicates that the listed elements are required or mandatory, but that other elements are optional and may or may not be present depending upon whether or not they materially affect the activity or action of the listed elements.

[0016] The terms “a,” “an,” and “the” are used interchangeably with “at least one” to mean one or more of the components being described.

[0017] The term “and / or” means one or all of the listed elements or a combination of any two or more of the listed elements.

[0018] The term “some embodiments” means that a particular feature, configuration, composition, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Thus, the appearances of such phrases in various places throughout this specification are not necessarily referring to the same embodiment of the disclosure. Furthermore, the particular features, configurations, compositions, or characteristics may be combined in one or more embodiments.

[0019] The terms “preferred” and “preferably” refer to embodiments of the disclosure that may afford certain benefits, under certain circumstances; however, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the disclosure.

[0020] All numbers are assumed to be modified by the term “about”. As used herein in connection with a measured quantity, the term “about” refers to that variation in the measured quantity as would be expected by the skilled artisan making the measurement and exercising a level of care commensurate with the objective of the measurement and the precision of the measuring equipment used.

[0021] The recitations of numerical ranges by endpoints include all numbers subsumed within that range as well as the endpoints (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.). The phrase “up to” a number (e.g., up to 50) includes the number (e.g., 50).

[0022] Ther term “disposed on” means to extend over so as to a least partially cover and directly contact another layer or element.

[0023] An exemplary single-sided adhesive tape of the present disclosure is illustrated in FIG. 1. Generally, the adhesive tape 100 comprises a backing 110 having a first major surface 112 and a second major surface 114 opposite the first major surface 112. The backing 110 typically comprises woven and / or nonwoven inorganic fibers. A first tie layer 116 is disposed on the first major surface 112 of the backing 110. A first silicone adhesive 118 is disposed on the first tie layer 116. Optionally, a release liner 120 is reversibly applied to the first silicone adhesive 118 to protect the adhesive during manufacture, shipping and / or handling. Each of the components making up the adhesive tape are described in greater detail below.

[0024] Backing

[0025] The backings for the adhesive tapes disclosed herein are electrically insulative (or dielectric) and perform well against the blasts of particles and high temperatures associated with thermal runaways. Preferably, the backings are also flexible for ease of application and conformability to nonplanar substrates.

[0026] The backings typically comprise a plurality of inorganic fibers. The inorganic fibers may include glass fibers, ceramic fibers, glass-ceramic fibers, or combinations thereof.

[0027] Exemplary inorganic fibers include silica-based glass fibers such as A-glass, C-glass, D-glass, E-glass, M-glass, R-glass, S-glass, ECR-glass, AR-glass, HR-glass, and basalt fibers; pure (> 99%) silica fibers (e.g. Astroquartz fibers); silicon carbide fibers; alumina fibers (also known as aluminum oxide fiber), Nextel fibers; or combinations thereof. In some embodiments, the inorganic fibers may be chemically treated. In some particular embodiments, the backing comprises E-glass fibers. E-glass, also known as electrical glass, is typically made from oxides of silicon, aluminum, calcium magnesium, and boron.

[0028] The inorganic fibers may be woven and / or nonwoven. The inorganic fibers can be configured into a sheet or mat, including fabrics and papers, using any of a number of well-knowntechniques. For example, in some embodiments, the backing may be a single layer cloth, knitted fabric, interlaced fabric, crocheted fabric, wet or dry-laid nonwoven paper, or combinations thereof. In other embodiments, the backing may be a multilayer fabric comprising woven and / or nonwoven layers bonded together by stitching, needle punching, mechanical entanglement, or a combination thereof.

[0029] Optionally, sizing agents (e.g., a starch-like substances) may be added to the fibers to enhance the mechanical properties of the woven and / or nonwoven backing. The sizing agent is distributed among the fibers in the backing, improving the overall strength and handling of the fibrous backing. Exemplary sizing agents include polymeric carbohydrates, starch-oil based binders, poly(vinyl alcohol), inorganic binders (e.g., water glass, bentonite, kaolinite, cement, lime, gypsum), or combinations thereof.

[0030] The overall thickness of the backing should be sufficient to reduce the potential for short circuits in a battery during thermal runaway but still sufficiently flexible to conform to metal substrates to which they are applied. In some embodiments, the backing has a thickness ranging from 0.02 to 1.5 mm. In some embodiments, the backing has a basis weight of 13 to 1,500 g / m2. In some embodiments, the diameter of the inorganic fibers range from 4 micrometers to 13 micrometers.

[0031] Commercially available backings comprise E-glass cloth obtained under the trade designation JPS 1162 from JPS Composite Materials in Anderson, South Carolina, USA and E-glass cloth obtained under the trade designation BWI 1291 from Bedford Weaving, Inc. in Bedford, Virginia, USA.

[0032] Tie Layer

[0033] A tie layer is disposed on a major surface of the backing to improve adhesion between the backing and the silicone adhesive, particularly at the higher temperatures associated with thermal runaway events. The tie layer may be comprised of a single layer of material, multiple layers of material, or a gradient of two or more materials (e.g., when two materials mix at an interface so that there is no well-defined line of demarcation).

[0034] In some embodiments, the tie layer comprises a sizing agent used in making the fibrous backing, where at least a portion of the sizing agent is disposed on a major surface of the backing. In some embodiments, the tie layer is the sizing agent. Exemplary sizing agents that can function as a tie layer for purposes of the present disclosure include a polymeric carbohydrate, a starch-oil based binder, a poly(vinyl alcohol), a reactive silane, or combinations thereof. In some embodiments, the sizing agent comprises a polymeric carbohydrate, a starch-oil based binder, and a poly(vinyl alcohol). In some embodiments, the sizing agent comprises a reactive silane.

[0035] Polymeric carbohydrates, also known as polysaccharides, are long chains of monosaccharide units bonded together. Suitable polymeric carbohydrates include starch (a storage polysaccharide in plants), glycogen (a storage polysaccharide in animals), cellulose (a structural polysaccharide in the cell walls of plants), chitin (a structural polysaccharide found in the exoskeletons of arthropods and the cell walls of fungi), pectin (a polysaccharide found in the cell walls of plants), agar (gelatinous substancederived from red algae), hyaluronic acid (a polysaccharide found in connective tissues), or combinations thereof. Exemplary starches include those extracted from com, tapioca, potato, or combinations thereof.

[0036] Suitable poly(vinyl alcohol)s include polyethanol homopolymer, polyethanolvinylacetate copolymer, partial hydrolyzed polyvinylacetate, or combinations thereof.

[0037] Reactive silanes are organosilanes that have a reactive group and hydrolysable alkoxy groups. Suitable reactive silanes include vinyl triacetoxysilane, acryloyl propyl triethoxysilane, glycidoxypropyl trimethoxy silane, 2-(3,4-epoxycyclohexyl)ethylmethyldiethoxysilane, or combinations thereof.

[0038] In some embodiments, the tie layer comprises a primer that is disposed on a major surface of the backing. In some embodiments, the tie layer is the primer (e.g., the backing may not comprise a sizing agent, or the sizing agent is not disposed on a major surface of the backing). In other embodiments, the tie layer comprises both a sizing agent disposed on a major surface of the backing and a primer. The primer may be applied to the backing in solvent or in pure form using any suitable technique, including, for example, hand spreading, roll coating, knife coating, curtain coating, gravure coating, or spraying. The primer is typically dried prior to application of the silicone adhesive as described below. The primer may be applied in one or more coatings. Further, more than one type of primer (i.e., primers of different compositions) may be applied to the same surface. Suitable primers include epoxy-silanes, polydimethylsiloxanes with vinyl groups, and a combination thereof. In some embodiments, the primer is an epoxy-silane. In other embodiments, the primer is a polydimethylsiloxane with vinyl groups. Commercially available primers include those obtained under the trade designation ELASTOSIL LR 3003 / 30 A / B (Part B only) from Wacker in Adrian, Michigan, USA.

[0039] In some embodiments, the tie layer comprises a primer, and the primer comprises an epoxy silane. In other embodiments, the tie layer is a primer, and the primer is an epoxy silane. In some embodiments, the tie layer comprises a primer, and the primer comprises a polydimethylsiloxane with vinyl groups. In other embodiments, the tie layer is a primer, and the primer is a polydimethylsiloxane with vinyl groups.

[0040] In some embodiments, the tie layer comprises a sizing agent and a primer, wherein the sizing agent comprises a polymeric carbohydrate, a starch-oil based binder, a poly(vinyl alcohol), a reactive silane, or combinations thereof, and wherein the primer is an epoxy silane, a polydimethylsiloxane with vinyl groups, or a combination thereof. In other embodiments, the tie layer is a sizing agent and a primer, where the sizing agent is a polymeric carbohydrate, a starch-oil based binder, a poly(vinyl alcohol), a reactive silane, or combinations thereof, and where the primer is an epoxy silane, a polydimethylsiloxane with vinyl groups, or a combination thereof. The sizing agent and primer may form distinct, separate layers within the tie layer. Alternatively, the binder and the primer may form concentration gradients throughout the thickness of the layer, where mixing of materials occurs most at the interface between the layers.

[0041] The tie layer is disposed on at least one major surface of the backing. Typically, the tie layer does not form a continuous film over the entire surface of the backing but rather forms a discontinuouscoating on the surface fibers that make up the backing, preserving at least some of the porosity of the fibrous backing. In some preferred embodiments, the tie layer covers substantially all of the surface fibers on at least one major surface of the backing. The term “substantially all” in this context means that the tie layer covers at least 90%, or at least 91%, or at least 92%, or at least 93%, or at least 94%, or at least 95%, or at least 96%, or at least 97%, or at least 98%, or at least 99% or 100% of the fibers on a surface of the backing.

[0042] For purposes of this disclosure, the tie layer may be on the first and / or second major surfaces of the backing. In some embodiments, a first tie layer is disposed on the first major surface of the backing. In some preferred embodiments, such as in the case of a two-side tape, a second tie layer is disposed on the second major surface of the backing. The compositions of the first and second tie layers may be the same or different.

[0043] Silicone Adhesive

[0044] The silicone adhesives of the present disclosure are generally pressure sensitive adhesives. As used herein, a “pressure sensitive adhesive” or “PSA” satisfies the Dahlquist criteria for tackiness, which means that the storage modulus is typically 3x 105Pa (300 kPa) or less when measured at 25 °C and 1 Hertz (6.28 radians / second). PSAs typically exhibit adhesion, cohesion, compliance, and elasticity at room temperature.

[0045] The silicone adhesives of the present disclosure comprise a polymerized product of a reaction mixture comprising a silicone elastomer and a MQ silicate resin tackifier. Generally, the silicone elastomers are polysiloxanes (i.e., materials comprising a polysiloxane backbone) described by Formula I, below:R.O-eSi -O^R,r4(i)where Ri and R2 are independently selected from alkyl, allyl, phenyl, alkenyl, silyl, and hydrogen; R3and R4 are independently selected from alkyl, allyl, phenyl, and alkenyl; and n is from 100 to 100000.

[0046] Suitable alkyl groups include those having the formula -(CITjnCHs where n is 0 to 7.Examples include a methyl, an ethyl, or a propyl group. In some embodiments, each of R3 and Ros a methyl group. Allyl groups include -CH2-HC=CH2. Phenyl groups include -C H . Suitable alkenyl groups include -GTEn-i, where n is 2 to 8. Silyl groups include -Si(CH3)3.

[0047] In some embodiments, the silicone elastomer has a kinematic viscosity of at least 30000 mm2 / sec (30000 cSt), at least 50000 mm2 / sec (50000 cSt), at least 75000 mm2 / sec (75000 cSt), at least 100000 mm^ / sec (100000 cSt), at least 200000 mm^ / sec (200000 cSt), at least 300000 mm^ / sec (300000 cSt), at least 400000 mm^ / sec (400000 cSt), at least 500000 mm^ / sec (500000 cSt), at least 600000 mm^ / sec (600000 cSt), at least 700000 mm^ / sec (700000 cSt), 800000 mm^ / sec (800000 cSt), at least 900000 mm^ / sec (900000 cSt), or even at least 1000000 mm^ / sec (1000000 cSt). Kinematic viscosity ofsilicone elastomers can be determined according to ASTM D4283-98 (Reapproved 2015), "Standard Test Method for Viscosity of Silicone Fluids".

[0048] Commercially available silicone elastomers include those under the trade designation AK 1000000, AK300000, AK 100000, AK60000, AK30000 from Wacker Chemie AG in Adrian, Michigan USA.

[0049] The MQ silicate resin tackifiers are cage-like molecules having a shell of R^SiOj^ units (“M” units) around SiC>4 / 2 units (“Q” units) in a core, where the M units are bonded to the Q units, each of which is bonded to one Q unit. Some of the SiC>4 / 2 units (“Q” units) are bonded to hydroxyl groups resulting in HOSiC>3 / 2 units ("'p O7FT units), thereby accounting for the silicon-bonded hydroxyl content of the MQ silicate resin tackifier, and some are bonded only to other SiC>4 / 2 units. These silicate resin tackifiers usually have a number average molecular weight in the range of 100 to 50,000 grams / mole or in the range of 500 to 15,000 grams / mole and generally have methyl R' groups.

[0050] MQ silicate resin tackifiers are described in, for example, Encyclopedia of Polymer Science and Engineering, vol. 15, John Wiley & Sons, New York, (1989), pp. 265-270, and U.S. Pat. Nos.2,676,182 (Daudt et al.), 3,627,851 (Brady), 3,772,247 (Flannigan), and 5,248,739 (Schmidt et al.). Other examples are disclosed in U.S. Pat. No. 5,082,706 (Tangney). The above-described MQ silicate resin tackifiers are generally prepared in solvent. Dried or solventless MQ silicate resin tackifiers can be prepared, as described in U.S. Pat. Nos. 5,319,040 (Wengrovius et al.), 5,302,685 (Tsumura et al.), and 4,935,484 (Wolfgruber et al.).

[0051] Certain MQ silicate resin tackifiers can be prepared by the silica hydrosol capping process described in U.S. Pat. No. 2,676,182 (Daudt et al.) as modified according to U.S. Pat. No. 3,627,851 (Brady), and U.S. Pat. No. 3,772,247 (Flannigan). These modified processes often include limiting the concentration of the sodium silicate solution, and / or the silicon-to-sodium ratio in the sodium silicate, and / or the time before capping the neutralized sodium silicate solution to generally lower values than those disclosed by Daudt et al. The neutralized silica hydrosol is often stabilized with an alcohol, such as 2-propanol, and capped with R3 S iO | / 2 siloxane units as soon as possible after being neutralized, wherein R represents an alkyl group. The level of silicon bonded hydroxyl groups (i.e., silanol) on the MQ resin may be reduced to no greater than 1.5 weight percent, no greater than 1.2 weight percent, no greater than 1.0 weight percent, or no greater than 0.8 weight percent based on the weight of the MQ silicate resin tackifier. This may be accomplished, for example, by reacting hexamethyldisilazane with the siloxane tackifying resin. Such a reaction may be catalyzed, for example, with trifluoroacetic acid. Alternatively, trimethylchlorosilane or trimethylsilylacetamide may be reacted with the silicate resin tackifier, a catalyst not being necessary in this case.

[0052] Suitable MQ silicate resin tackifiers are commercially available from sources such as Dow Coming, Momentive Performance Materials, Bluestar Silicones, NuSil, and Wacker Chemie AG.Examples of useful MQ silicate resin tackifiers include those available under the trade designations SR-545 and SR- 1000, both of which are commercially available from Momentive Performance Materials,PRO-2780 available from NuSil, and TMS-803 available from Wacker Chemie AG. Such resins are generally supplied in organic solvent and may be employed as received, or they may be diluted. In some embodiments, it may be desirable to utilize the silicate resin tackifier as a solid, so the resin solution may be dried to form solid or, in some embodiments, the silicate resin may be obtained as a solid powder.

[0053] When the MQ silicate resin tackifiers are used as a solution, typically the resin solutions are further diluted from the concentration in which they are obtained. In some embodiments, the 100% solid of silicate resin tackifier solutions are used as powders or flakes and fed into a twin screw extruder.

[0054] In some embodiments, the reaction mixture comprises at least 20 wt.%, at least 25 wt.%, at least 30 wt.%, at least 35 wt.%, at least 40 wt.%, at least 50 wt.%, or at least 55 wt.% MQ silicate resin tackifier. In the same or different embodiments, the reaction mixture comprises no greater than 80 wt.%, no greater than 75 wt.%, no greater than 70 wt.%, or no greater than 65 wt.% MQ silicate resin tackifier. In some embodiments, the reaction mixture comprises 20 to 80 wt.%, 20 to 60 wt.%, 40 to 70 wt.%, 58 to 62 wt.%, or 60 wt.% MQ silicate resin tackifier.

[0055] In some embodiments, the reaction mixture comprises at least 20 wt.%, at least 25 wt.%, at least 30 wt.%, or at least 35 wt.% silicone elastomer. In the same or different embodiments, the reaction mixture comprises no greater than 80 wt.%, no greater than 75 wt.%, no greater than 70 wt.%, no greater than 65 wt.%, no greater than 60 wt.%, no greater than 55 wt.%, or no greater than 50 wt.% silicone elastomer. In some embodiments, the reaction mixture comprises 20 to 80 wt.%, 20 to 60 wt.%, 30 to 50 wt.%, 38 to 42 wt.%, or 40 wt.% silicon elastomer.

[0056] The silicone elastomer may be combined with the MQ silicate resin tackifier and chemically crosslinked. In some embodiments, the weight ratio of silicone elastomer to MQ silicate resin tackifier is 20:80 to 80:20, 30:70 to 50:50, or 38:62 to 42:58.

[0057] Additives may optionally be added to the reaction mixture to impart additional properties to the silicone adhesive. Optional additives include inorganic fillers (e.g., glass, ceramic, clay, silicate, mineral or combinations thereof), flame retardant agents, heat stabilizers, smoke suppression agents, endothermic agents, rheology modifiers, or combinations thereof.

[0058] In some embodiments, the reaction mixture comprises 0 wt.%, at least 0.5 wt.%, at least 1 wt.%, at least 1.5 wt.%, at least 2 wt.%, at least 2.5 wt.%, at least 3 wt.%, at least 3.5 wt.%, at least 4 wt.%, at least 4.5 wt.%, or at least 5 wt.% of additives. In some embodiments, the reaction mixture comprises up to 10 wt.%, up to 9 wt.%, up to 8 wt.%, up to 7 wt.%, up to 6 wt.%, up to 5 wt.% , up to 4 wt.%, or up to 3 wt.% additives. In some embodiments, the coating comprises 0 wt.% to 10 wt.%, 0.5 wt.% to 10 wt.%, 0.5 wt.% to 5 wt.%, or 1 wt.% to 3 wt.% additives.

[0059] The reaction mixture that forms the silicone adhesive is typically coated onto the tie layer by a hot melt coating method. Such methods are preferable to solution coating methods, where the solvent(s) have a tendency to dissolve or leach out the sizing agent from the backing, reducing the effectiveness of the tie layer. The silicone elastomer, MQ silicate resin tackifier, and any optional additives may be combined by any of a wide variety of known means prior to being hot melt coated onto the first (or second) tie layer and cured. The various components may be pre-blended using commonequipment such as mixers, blenders, mills, extruders, and the like. In some embodiments, the hot melt coating process is extrusion. For example, the silicone elastomer, MQ silicate resin tackifier, and optional additives are mixed by a twin screw extruder, wherein the twin screw extruder has multiple ports for raw material feedings. Preferably the silicone elastomer and MQ silicate resin tackifier are fed into a twin screw extruder from different ports. Optionally at least one port is connected to vacuum pump to devolatilize low molecule weight silicones. In some embodiments, the elastomer / tackifier mixture is coated directly on to the tie layer using a die (e.g., a rotary rod die, slot die, or drop die).

[0060] Subsequently to coating, the reaction mixture is irradiated with an electron beam (i.e., e-beam) to provide a crosslinked silicone pressure-sensitive adhesive. In some embodiments, reaction mixture compounding, coating, and curing are carried out sequentially as a continuous process. The e-beam cured silicone adhesive can be laminated to a release liner. The lamination may be operated in the continuous process described above, or it may be carried out independently. The surface of the silicone adhesive opposite the liner can then be laminated to the tie layer on a backing.

[0061] Elevated temperatures in multiple zones of twin screw extruder can be used to reduce the viscosity of mixtures. If desired, a small amount of organic solvent (e.g., one or more hydrocarbon solvents) may be added to further reduce viscosity. Although the silicone PSA mixture could be crosslinked through addition cure, peroxide cure, UV radical cure, or UV cationic cure, crosslinking is preferably accomplished by exposure to electron beam (e-beam) radiation. Advantageously, e-beam radiation can be used without need of added catalysts and / or initiators (i.e., the mixture may be free of catalysts and / or initiators).

[0062] A variety of procedures for E-beam curing are well-known. The cure depends on the specific equipment used to deliver the electron beam, and those skilled in the art can define a dose calibration model for the equipment used. Commercially available electron beam generating equipment is readily available. For the examples described herein, the radiation processing was performed on a Model CB-300 electron beam generating apparatus (available from Energy Sciences, Inc., Wilmington, Massachusetts). Generally, a support film (e.g., polyester terephthalate support film) runs through an inert chamber. In some embodiments, the reaction mixture is covered by a release liner prior to e-beam radiation (e.g., as described herein “closed face" radiation) and conveyed at a fixed speed of about 6.1 meters / min (20 feet / min). In some embodiments, the reaction mixture is radiated with e-beam before laminating to a release liner("open face" radiation).

[0063] The crosslink density is generally affected by the dose of e-beam radiation applied. The higher e-beam dose, the higher the crosslinking density. The e-beam source voltage will typically depend on the thickness of the coated mixture to have high enough radiation penetration. Selection of appropriate conditions is within the capability of those skilled in the art. Further details concerning preparation of crosslinked silicone pressure -sensitive adhesives is described in U.S. Pat. No. 9,359,529 (Liu et al), the disclosure of which is incorporated herein by reference.

[0064] In some preferred embodiments, the extrusion of the reaction mixture is performed at high temperature with high agitation and high vacuum to remove any residual cyclosiloxanes that may bepresent in the reaction mixture. This can reduce the amount of volatile organic compounds, more particularly cyclosiloxanes, in the silicone adhesive and the tape derived therefrom. In particular, this process can remove cyclosiloxanes having three repeating siloxane units (D3), four repeating siloxane units (D4), five repeating siloxane units (D5), and six repeating siloxane units (D6). In some embodiments, the adhesive tapes of the present disclosure contain less than 100 parts per million (ppm), less than 5 ppm, or even less than 2 ppm of D3-, D4-, D5- and D6-cyclosiloxanes, as measured using the combination of gas chromatography and mass spectrometry. For example, approximately 1200 milligrams of silicone adhesive is combined with 7.0 milliliter acetone in a vial. The vial is placed on a wrist-action shaker overnight. Triplicates are analyzed. Standards of octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane are analyzed with the samples by GCMS using an Agilent 8890 GC instrument with a DB-5MS, 30 meters x 0.25 millimeters, 0.25 micrometer film column, 1 microliter, 10: 1 slit, 250°C inlet, helium carrier at 1.0 milliliter / minute constant flow, 10°C / minute oven ramp rate from 2 minutes at 40°C up to 320°C for 4 minutes, and an FID 350°C detection.

[0065] Release Liners

[0066] A release liner may be releasably adhered to the pressure-sensitive adhesive layer to protect it during storage and shipping.

[0067] In some preferred embodiments, the release liners are non-fluorinated release liners.Examples of commercially available non-fluorinated release liners include a non-silicone release liner under the trade designation Cerapeel PJ271 from Toray Industries, Inc. in Tokyo, Japan and a silicon release liner under the trade designation 78B from Laufenberg GMBH in Krefeld-Htils, Germany.

[0068] Other exemplary release liners include those that comprise a fluorinated compound but are free of silicone moieties (e.g., as in poly(dimethylsiloxane) or a fluorosilicone.

[0069] In some embodiments, the release liner can be unitary. One such embodiments is an extruded fdm comprising a non-fluorinated thermoplastic and a fluorinated melt additive as described in U.S. Patent Application Publication No. 2020 / 0207948 (Teverovskiy), the disclosure of which is incorporate herein by reference.

[0070] Exemplary fluorinated melt additives according to the present disclosure are represented by general formula II, below:

[0071] represents a linear alkylene group having from 1 to 18 carbon atoms, preferably from 2 to 12 carbon atoms, and more preferably from 2 to 8 carbon atoms, and even more preferably 2 to 6 carbon atoms. Exemplary groupsinclude ethylene, propane-1, 3-diyl, butane- 1,4-diyl, pentane-l,5-diyl, hexane- 1,6-diyl, octane- 1,8-diyl, decane- 1, 10-diyl, dodecane- 1, 12-diyl, hexadecane- 1,16-diyl, and octadecane -1,18 -diyl .n represents an integer from 1 to 4, inclusive (i.e., n = 1, 2, 3, or 4).Rf’ represents a monovalent group represented by the general formula, - < O / \ II— N N-S-Rf\ / II' -(Owherein Rf represents a perfluorinated group having from 3 to 5 carbon atoms, preferably Rfhas 4 carbon atoms. Examples of groups Rf include perfluoro-n-pentyl, perfluoro-n-butyl, perfluoro-n-propyl, perfluoroisopropyl, and perfluoroisobutyl.

[0072] Compounds according to general formula II can be made by any suitable method. One relatively convenient method involves reaction of one acyl chloride group from each of two terephthaloyl chloride molecules with a diol to create an extended diacyl chloride, which is then reacted with two equivalents of a fluorinated piperazine represented by the general formula III, below: / - \ °H-N N-S-Rf(III)\ / II' -fOto form the corresponding melt additive compound. Examples of suitable diols include ethylene glycol, 1,3 -propanediol, 1,4-butanediol, 1,5 -pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, 1-16-hexadecanediol, and 1,18 -octadecanediol. Such diols are available from commercial sources.

[0073] Fluorinated piperazines according to general formula III can be prepared using known organic reactions such as, for example, those disclosed in U.S. Pat. No. 5,451,622 (Boardman et al.). An exemplary method of preparation is by the reaction of fluoroaliphatic sulfonyl fluorides, RfSC^F, with piperazine.

[0074] The fluorinated melt additives can be combined with an extrudable polymer and extruded to form a release liner (e.g., as a film). Typically, the amount of melt additive co-extruded with the extrudable polymer is an amount of from 0.01 to 5 weight percent, preferably 0.1 to 3 weight percent, and more preferably 0.3 to 1.5 weight percent, based on the total weight of the extruded release liner, however other amounts may also be used.

[0075] Advantageously, melt additive compounds according to the present disclosure may still be receptive to dyes (e.g., textile dyes), while displaying a reasonable degree of water and oil repellency. Accordingly, melt additive compounds according to the present disclosure may be suitable for textile applications including carpet and woven, nonwoven or knit fabrics, for example.

[0076] Examples of extrudable polymers include thermoplastic polymers (preferably nonfluorinated) such as polyesters (e.g., polyethylene terephthalate, polybutylene terephthalate, and polycaprolactone), cellulosics (e.g., cellulose acetate and cellulose butyrate), polyamides (e.g., Nylon 6 and Nylon 6,6), polyimides, polyolefins (e.g., polyethylenes, polypropylenes, and polybutylenes), polyetherketone (PEK), polyetheretherketone (PEEK), polycarbonates, and polyacrylics (e.g., polyacrylonitrile and polymethyl methacrylate), and combinations thereof.

[0077] Extruded release liners may contain other ingredients such as for example, fdlers, antioxidants, conductive materials, fdlers, lubricants, pigments, plasticizers, processing aids, and UV-light stabilizers.

[0078] In some embodiments, the release liner can be a composite liner. For example, a perfluoropolyether release material can be coated onto a backing that together comprise a composite liner, where the perfluoropolyether surface is in contact with the silicone adhesive. As used herein, the term "perfluoropolyether" refers to any compound that includes a perfluoropolyether segment.Exemplary perfluoropolyethers have divalent segments represented by to following formula:— CF2O(CF2CF2O)m(CF2O)nCF2—where m and n denote randomly distributed repeating units and the ratio m / n is 0.2: 1 to 5: 1, and each segment has a number average molecular weight of 800 to 10,000 grams / mole.

[0079] Suitable composite release liners can be prepared by coating a backing with a perfluoropolyether or a polymerizable precursor thereof followed by polymerization to form a perfluoropolyether. Coating may be out of solvent or in pure form. Any suitable coating technique can be used including, for example, roll coating, knife coating, curtain coating, gravure coating, or spraying.

[0080] Double-Sided Tapes

[0081] Adhesive tapes of the present disclosure may be single-sided adhesive tapes, as illustrated in FIG. 1 or converted to double-sided tapes. A double-sided tape of the present disclosure is illustrated in FIG. 2. The tape is similar to that illustrated in FIG. 1, where like numerals offset by 100 (e.g., 210 and 110, or 216 and 116) have the same features described above in FIG. 1. Additionally, the tape in FIG. 2 comprises a second tie layer 226 disposed on the second major surface 214 of the backing 210 and a second silicone adhesive 228 disposed on the second tie layer 226, where the second tie layer 226 is sandwiched between the second major surface 214 of the backing 210 and the second silicone adhesive 228. Optionally, a release liner 230 is reversibly applied to the second silicone adhesive 228 to protect the adhesive during manufacture, shipping and / or handling. In some embodiments, the double-sided tape has a single release liner on either the first silicone adhesive 218 or second silicone adhesive 228. The double-sided tape can then be rolled up on itself so that the exposed first or second silicone adhesive contacts the back of the release liner adhered to the other (first or second) silicone adhesive. Rolling the adhesive tape in this way may be beneficial for processing, shipping and / or dispensing.

[0082] The composition and features of the second tie layer, second silicone adhesive, and second release liner are the same as those described above for the first tie layer, first silicone adhesive, and first release liner, respectively. In some embodiments, the first and second tie layers are the same or different compositions. In some embodiments, the first and second silicone adhesives are the same or different compositions. In some embodiments, the optional first and second release liners are the same or different compositions. For example, in some embodiments, the first and second tie layers comprise sizing agent disposed on the first and second major surfaces of the backing, the first silicone adhesive is different from the second silicone adhesive, and the first release liner is different from the second release liner. Inanother embodiment, the first and second tie layers comprise different primers, the first and second silicone adhesives are different, and the first and second release liners are the same.

[0083] Applications

[0084] The adhesive tapes of the present disclosure can be applied to metal surfaces to reduce or eliminate short circuit events during athermal runaway.

[0085] Typically, the adhesive tapes exhibit good adhesion to metal surfaces at both room temperature and a testing temperature of 550 °C, as evidenced by the Peel Adhesion (90°) Test Method and the Hot Block Test Method, respectively, each described in detail in the Examples section. In some embodiments, the adhesive tapes of the present disclosure have a peel adhesion of at least 2.5 N / cm, at least 3.0 N / cm, at least 3.5 N / cm, at least 4.0 N / cm or at least 4.5 N / cm when tested in accordance with the Peel Adhesion (90°) Test Method set forth herein. In some embodiments, the adhesive tapes have a peel adhesion in the range of 2.5 to 6.0 N / cm, 2.5 to 4.60 N / cm, or 2.9 to 4.6 N / cm. In some embodiments, the adhesive tapes of the present disclosure have an HBT peel value of greater than 5.0 N / cm, greater than 5.5 N / cm, greater than 6.0 N / cm, greater than 6.5 N / cm, greater than 7.0 N / cm, or even greater than 7.5 N / cm when tested in accordance with the Hot Block Test (HBT) Method set forth herein. In some embodiments, the adhesive tapes have an HBT peel value in the range of 5.0 N / cm to 10.0 N / cm, 5.0 N / cm to 8.0 N / cm, or 5.1 N / cm to 6.9 N / cm.

[0086] Further, in some embodiments, the adhesive tapes of the present disclosure can withstand up to 1200 °C for at least 20 seconds in the Torch-Flame Test Method described in detail in the Examples section.

[0087] Even further, the tapes of the present disclosure may exhibit good resistance to direct current dielectric breakdown voltages (DCDBV) as demonstrated in the Direct Current Dielectric Breakdown Voltage (DCDBV) Test Method disclose in the Examples section. In some embodiments, the adhesive tapes have a direct current breakdown strength of at least 4.0 kV, at least 4.5 kV, at least 5.0 kV in accordance with the Direct Current Dielectric Breakdown Voltage (DCDBV) Test Method set forth herein. In some embodiments, the adhesive tapes have a direct current breakdown strength in the range of 4.0 kV to 12.0 kV, more particularly, 4.5 kV to 10.0 kV, or even more particularly 4.3 kV to 9.2 kV.

[0088] Additionally, the adhesive tapes disclosed herein may exhibit sufficient releasability as demonstrated with the Adhesion to Backing (ATB) Test Method described in the Examples Section. This may be particularly advantageous in forming rolls of the adhesive tapes where adhesion should be sufficient to maintain the roll form but not too strong as to damage the roll when unwound. In some embodiments, the adhesive tapes have an adhesion to backing value of no greater than 20 ozf / inch, no greater than 18 ozf / inch, no greater than 17 ozf / inch, no greater than 16 ozf / inch, no greater than 15 ozf / inch, no greater than 14 ozf / inch, no greater than 13 ozf / inch, no greater than 12 ozf / inch, no greater than 11 ozf / inch, or no greater than 10 ozf / inch when tested in accordance with the Adhesion to Backing Test Method set forth herein. In the same or different embodiments, the adhesive tapes have an adhesion to backing value of at least 4 ozf / inch, at least 5 ozf / inch, at least 6 ozf / inch, at least 7 ozf / inch, at least 8 ozf / inch, at least 9 ozf / inch. In some embodiments, the adhesive tapes have an adhesion to backing value ranging from 4 to 20 ozf / inch, 4.5 to 15 ozf / inch, or 4.9 to 8.2 ozf / inch.

[0089] Further, in some embodiments, the adhesive tapes disclosed herein may have a 2-Bond Value of at least 30 ozf / 0.5 inches, at least 35 ozf / 0.5 inches, at least 40 ozf / 0.5 inches, at least 45 ozf / 0.5 inches, at least 50 ozf / 0.5 inches, or at least ozf / 0.5 inches according to the 2-Bond Test Method in the Examples Section. In some embodiments, the adhesive tapes have a 2-Bond Value ranging from 30 to 75 ozf / 0.5 inches, 30 to 55 ozf / 0.5 inches, or 33.7 to 52.4 ozf / 0.5 inches.

[0090] Adhesive tapes of the present application may be used in a variety of high impact, high temperature applications. For example, the adhesive tapes of the present disclosure may be used as impact resistant thermal barriers disposed in the gap between battery cells in an electric vehicle battery (e.g., in a battery module or a batter pack) and / or between individual battery modules in a battery pack. In addition, or alternatively, the adhesive tapes of the present disclosure may be disposed on the inner surface of the casing of a battery pack (e.g., a battery module or a battery pack), including the inner surface of a compartment lid or the inner surface of vent passages for exhaust gas. Further, the adhesive tapes of the present disclosure may be used for Cell Connection Systems where reworkability or repositionability of the dielectric material is often required by automotive OEMs.Examples

[0091] Objects and advantages of this invention are further illustrated by the following examples. These examples are merely for illustrative purposes only and are not meant to be limiting on the scope of the appended claims.

[0092] Unless otherwise noted, all parts, percentages, ratios, etc. in the Examples Section and the rest of the specification are by weight. If not specified below, reagents are available from fine chemical vendors or may be synthesized by known methods.

[0093] The following abbreviations are used in the Example Section: g = gram; mm = millimeter; cm = centimeter; in = inch; ozf = ounce-force; sqm = square meters; min = minute; sec = seconds; °C = degrees Celsius; °F = degrees Fahrenheit; mrad = millirad; kV = kilovolt; N = Newton; % = percent; wt.% = weight percent; and cSt = centistokes.Table 1. Materials Used in the ExamplesAbbreviation DescriptionAKIM Polydimethylsiloxane, methyl-terminated, obtained under the trade designation WACKER AK1000000 from Wacker Chemie AG in Adrian, Michigan, USA.AK60k Polydimethylsiloxane, methyl-terminated, obtained under the trade designation WACKER AK 60000 from Wacker in Adrian, Michigan, USA.R3003-B Polydimethylsiloxane with vinyl groups and auxiliary, obtained under the trade designation ELASTOSIL LR 3003 / 30 A / B (Part B only) from Wacker in Adrian, Michigan, USA.MQ Co-hydrolysis product of tetraalkoxysilane (Q unit) and trimethylethoxysilane (M unit), obtained under the trade designation MQ TMS 803 TF from Wacker Chemie AG in Adrian, Michigan, USA.E-glass cloth, 0.14 mm thick, 137 g / m2obtained from JPS CompositeJPS 1162Materials in Anderson, South Carolina, USA.BWI 1291 e-glass cloth, 0.14 mm thick, 137 g / m2, obtained from Bedford Weaving, Inc. in Bedford, Virginia, USA.TPGE 3-(Trimethoxysilyl)Propyl Glycidyl EtherIPA Isopropyl alcohol solvent69 Tape Glass cloth electrical tape, 0.127 mm thick glass backing, silicone adhesive, 0.178 mm total thickness, obtained under the trade designation 3M Glass Cloth Electrical Tape 69 from 3M Company in St. Paul, Minnesota, USA.79 Tape Glass cloth electrical tape, 0.127 mm thick glass cloth backing, acrylic pressure-sensitive adhesive, 0.178 mm total thickness, obtained under the trade designation 3M Glass Cloth Electrical Tape 79 from 3M Company in St. Paul, Minnesota, USA.Aluminum panel 0.025 inch, 3003-H14 Bare Aluminum, obtain from Q-Lab in Cleaveland, Ohio, USA.Steel panel 2" x 5" type 304 AISI, bright annealed finish. Surface roughness 2.0 + / - 1.0 micro inch.PVA Polyvinyl alcohol is a synthetic polymer used as a glass fiber sizing.IMASS Imass TL-2300 Intermediate Speed Range Slip / Peel Tester, long bed, 10 lbLoad Cell, available from IMASS, Inc. in Strongsville, Ohio, USA.Test MethodsPeel Adhesion (90°) Test Method

[0094] Peel adhesion was measured at room temperature (23 °C) using an IMASS slip / peel tester. A tape sample (1 inch wide by 8 inches long) was laminated to an aluminum panel (2.5 inches wide by 6 inches long) by applying the tape sample to the aluminum panel and passing a 4.5 lb weight roller, without application of additional pressure, over the backing of the tape lengthwise, twice in each direction, at a rate of approximately 300 mm / min (12 in / min). Prior to application of the tape sample, the surface of the aluminum panel was cleaned with ethyl acetate, acetone, and n-heptane, sequentially, by using lint-free wipes. The laminated tape was aged at room temperature (23 °C) and 50% relativehumidity for 20 minutes prior to testing. The aluminum panel with the laminated tape sample was then mounted in the IMASS and the tape was pulled off at a 90° angle and a speed of 300 mm / min (12 in / min). The results were measured in ounce-force, and converted to N / cm (i.e., 0.1095 N / cm = 1 ozf / in). Hot Block Test (HBT) Method

[0095] Two tape samples (1 inch wide by 8 inches long) were each laminated to an aluminum panel (2.5 inches wide by 6 inches long) by applying the tape sample to the aluminum panel and passing a 4.5 lb weight roller, without application of additional pressure, over the backing of the tape lengthwise, twice in each direction, at a rate of approximately 300 mm / min (12 in / min). Prior to application of the tape samples, the surfaces of the aluminum panels were cleaned with ethyl acetate, acetone, and n-heptane, sequentially, by using lint-free wipes. The laminated tapes were aged at room temperature (23 °C) and 50% relative humidity for 20 minutes prior to testing.

[0096] An aluminum hot block having a flat surface (approximately 6 inches by 8 inches) and total weight of approximately 1100 g, including a handle, was conditioned in an oven to a testing temperature of 550 °C.

[0097] The two laminated tapes were placed side-by-side on a mica (insulating) sheet. The hot block was carefully removed from the oven and placed onto the backings of the two tape samples for 20 seconds. After 20 seconds, the hot block was carefully removed from the tape samples, and the tape samples were allowed to equilibrate to room temperature.

[0098] The tape samples were tested according to the Peel Adhesion Test Method (above) and the result were reported as the HBT peel value (N / cm).Torch-Flame Test (TFT) Method

[0099] A tape sample (1.5 inches wide by 4 inches long) was laminated to an aluminum panel (1.5 inches wide by 6 inches long) by applying the tape sample to the aluminum panel and passing a 4.5 lb weight roller, without application of additional pressure, over the backing of the tape lengthwise, twice in each direction, at a rate of approximately 300 mm / min (12 in / min). The tape sample and panel were configured so that the short edges (bottoms) aligned. Prior to application of the tape sample, the surface of the aluminum panel was cleaned with ethyl acetate, acetone, and n-heptane, sequentially, by using lint-free wipes. The laminated tape was aged at room temperature (23 °C) and 50% relative humidity for 20 minutes prior to testing.

[0100] After 20 minutes, the laminated tape was hung vertically. A 1200 °C torch, with a horizontal flame orientation, was applied to the center of the tape laminate for 20 seconds. After 20 seconds, the torch was removed and the specimen observed for the following: Did the tape slip or fall off the aluminum panel (yes or no)? Did the torch bum through or melt the aluminum panel (yes or no)? A “Pass” occurs if both questions are “no”. Slip is the vertical movement of the tape sample on the aluminum panel.Direct Current Dielectric Breakdown Voltage (DCDBV) Test Method

[0101] Direct current dielectric breakdown voltages (DCDBV) were recorded after testing was performed according to ASTM D3755.Adhesion to Backing (ATB) Test Method

[0102] A first tape sample (2 inches wide by 6 inches long) was laminated to a steel panel (2.5 inches wide by 6 inches long) by applying the first tape sample to the steel panel and passing a 4.5 lb weight roller, without application of additional pressure, over the backing of the tape lengthwise, twice in each direction, at a rate of approximately 300 mm / min (12 in / min). Prior to application of the first tape sample, the surface of the steel test panel was cleaned with ethyl acetate, acetone, and n-heptane, sequentially, by using lint-free wipes.

[0103] A second tape sample (1 inch wide by 6 inches long) was laminated to the backing of the first tape sample opposite the surface attached to the steel panel by applying the second tape sample to the backing of the first tape sample and passing a 4.5 lb weight roller, without application of additional pressure, over the backing of the tape lengthwise, twice in each direction, at a rate of approximately 300 mm / min (12 in / min). The resultant double laminate (second tape sample / first tape sample / steel panel) was aged at room temperature (23 °C) and 50% relative humidity for 20 minutes prior to testing.

[0104] The steel panel with the tape samples was then mounted in the IMASS and the second tape sample was pulled at a 180° angle and a speed of 90 inches / minute. The force required to remove the second tape sample from the first tape sample was recorded as the ATB peel value (ozf / inch).2-Bond Test Method

[0105] The backing of a 1 inch (2.54 cm) wide tape sample was fastened, adhesive side up, to one side of a steel panel (2.5 inches wide) covered with 3M Plate Mounting Tape 411 (“411 Tape”) available from 3M Company in St. Paul, Minnesota, USA. The steel panel is the same construction as listed in Table 1 except a different size. Prior to application of the 411 Tape, the surface of the steel panel was cleaned with ethyl acetate, acetone, and n-heptane, sequentially, by using lint-free wipes. Two strips of thin masking tape were applied at each end of the tape sample to secure it in place on the steel panel without compromising the adhesive.

[0106] A 0.5 inch wide sample of 3M Polyester Tape 8403 (“8403 Tape”) available from 3M Company was applied (adhesive side down) to the adhesive side of the tape sample, and a 4.5 lb weight roller was passed backing and forth over the laminate at a rate of approximately 300 mm / min (12 in / min), twice in each direction without application of additional pressure. The laminate was allowed to sit for 20 minutes, after which a 180° peel of the 8403 Tape was conducted at a rate of 300 mm / min and the force required to remove the 8403 Tape from the tape sample was recorded as the 2-Bond Value.Preparatory SamplePreparation of Silicone Adhesives (PE1-PE3) and Tie Layers (PE4-PE7)

[0107] The ingredients listed in Table 2 were blended to achieve a homogenous mixture. Mixing was accomplished by twin screw extrusion (TSE) in PE1-PE3, speed mixers and a blade mixer for PE4.Table 2. Preparatory Examples for Adhesives and Tie LayersPreparatoryWater IPA AKIM AK60k MQ TPGE R3003-B Example(Wt.%) (Wt.%) (Wt.%) (Wt.%) (Wt.%) (Wt.%) (Wt.%) (PE)PEI 0 0 40 0 60 0 0PE2 0 0 42 0 58 0 0PE3 0 0 38 0 62 0 0PE4 45-55 40-55 0 0 0 <1 0PE5 0 0 100 0 0 0 0PE6 0 0 0 100 0 0 0PE7 0 0 0 0 0 0 100ExamplesRadiation Curing Process Used in Examples 1-7 (EXS 1-7)

[0108] Samples of uncured material were attached to a support fdm and passed through an inert chamber comprising nitrogen at a fixed speed of 6.1 meters / minute (20 fee / minute), where the uncured material was exposed to electron beam (e-beam) radiation from a Model CB-300 electron beam generating apparatus (available from Energy Sciences, Inc. in Wilmington, Massachusetts, USA) according to the radiation parameters specified below.Example 1 (EXI)

[0109] PEI was mixed by twin screw extrusion (“TSE”) at 400 °F, extruded onto JPS 1162 glass cloth (1 inch by 6 inches), and cured by e-beam radiation with 8 Mrads at 280 kV. The targeted net coating weight of the silicone adhesive was 0.33 g / (1 inch by 6 inches). The total sample weight including backing was 0.91 g / (1 inch by 6 inches).Example 2 (EX2)

[0110] PE2 was mixed by TSE at 400 °F, extruded onto JPS 1162 glass cloth (1 inch by 6 inches), and cured by e-beam radiation with 8 Mrads at 280 kV. The targeted net coating weight of the silicone adhesive was 0.33 g / (1 inch by 6 inches). The total sample weight including backing was 0.91 g / (1 inch by 6 inches).Example 3 (EX3)

[0111] PE3 was mixed by TSE at 400 °F, extruded onto JPS 1162 glass cloth (1 inch by 6 inches), and cured by e-beam radiation with 8 Mrads at 280 kV. The targeted net coating weight of the silicone adhesive was 0.33 g / (1 inch by 6 inches). The total sample weight including backing was 0.91 g / (1 inch by 6 inches).Example 4 (EX4)

[0112] PEI was mixed by TSE at 400 °F, extruded onto JPS 1162 glass cloth (1 inch by 6 inches), and cured by e-beam radiation with 7 Mrads at 280 kV. The targeted net coating weight of the silicone adhesive was 0.33 g / (1 inch by 6 inches). The total sample weight including backing was 0.91 g / (1 inch by 6 inches).Example 5 (EX5)

[0113] PEI was mixed by TSE at 400 °F, extruded onto JPS 1162 glass cloth (1 inch by 6 inches), and cured by e-beam radiation with 9 Mrads at 280 kV. The targeted net coating weight of the silicone adhesive was 0.33 g / (1 inch by 6 inches). The total sample weight including backing was 0.91 g / (1 inch by 6 inches).Example 6 (EX6)

[0114] PE4 was roll-coated onto BWI 1291 glass cloth (1 inch by 6 inches) and dried at 300 °F. PEI was mixed by TSE at 400 °F, subsequently extruded on to the PE4-coated glass cloth, and cured by e-beam radiation with 8 Mrads at 280 kV. The targeted net coating weight of the silicone adhesive was 0.33 g / (1 inch by 6 inches). The total sample weight including backing was 0.91 g / (1 inch by 6 inches).Example 7 (EX7)

[0115] PE7 was extruded onto JPS 1162 glass cloth (1 inch by 6 inches) and allowed to infiltrate the glass cloth for 24 hours. PEI was mixed by TSE at 400 °F, subsequently extruded on to the PE7-coated glass cloth, and cured by e-beam radiation with 8 Mrads at 280 kV. The targeted net coating weight of the silicone adhesive was 0.33 g / (1 inch by 6 inches). The total sample weight including backing was 0.91 g / (1 inch by 6 inches).Comparative Example 1 (CE1)

[0116] 3M Glass Cloth Electrical Tape 69.Comparative Example 2 (CE2)

[0117] 3M Glass Cloth Electrical Tape 79.Comparative Example 3 (CE3)

[0118] PE5 was hand spread onto JPS 1162 glass cloth (1 inch by 6 inches). PEI was mixed by TSE at 400 °F, subsequently coated on to the PE5-coated glass cloth, and cured by e-beam radiation with 8 Mrads at 280 kV. The targeted net coating weight of the silicone adhesive was 0.33 g / (1 inch by 6 inches). The total sample weight including backing was 0.91 g / (1 inch by 6 inches).Comparative Example 4 (CE4)

[0119] PE6 was hand spread onto JPS 1162 glass cloth (1 inch by 6 inches). PEI was mixed by TSE at 400 °F, subsequently coated onto the PE6-coated glass cloth, and cured by e-beam radiation with 8Mrads at 280 kV. The targeted net coating weight of the silicone adhesive was 0.33 g / (1 inch by 6 inches). The total sample weight including backing was 0.91 g / (1 inch by 6 inches).Table 3. Properties of Tape ExamplesSample 90° HBT TFT DCDBV ATB #2-Bond(N / cm) (N / cm) (Pass / (kV) (ozf / in) (ozf / 0.5 in)Fail)CE1 1.9 5.0 Fail 3.3 24.5 39.83CE2 3.2 0.6 Fail 4.8 16.92 53.13EXI 4.0 5.2 Pass 5.2 6.27 36.63EX2 4.11 5.12 Pass 4.3 8.19 33.68EX3 2.88 5.69 Pass 5.1 4.87 41.13EX4 3.68 5.39 Pass 4.6 7.18 39.08EX5 3.03 5.19 Pass 4.6 5.61 38.98EX6 4.60 6.9 Pass 5.5 6.39 52.44EX7 3.98 5.2 Pass 9.2 5.11 38.78CE3 4.59 7.39 Fail 5.9 10.80 55.25CE4 4.35 7.17 Fail 5.8 14.99 49.14

[0120] Thus, the present disclosure provides, among other things, silicone adhesive tapes for use in high temperature applications. Various features and advantages of the present disclosure are set forth in the following claims.

Claims

What is claimed is:

1. An adhesive tape comprising:a backing having a first major surface and a second major surface opposite the first major surface, the backing comprising at least one of woven or nonwoven inorganic fibers;a first tie layer disposed on the first major surface of the backing; anda first silicone adhesive disposed on the first tie layer, the first silicone adhesive including a first polymerized product of a first reaction mixture comprising aa first MQ silicate resin tackifier, anda first silicone elastomer having the formulaR3I^OfSi -O^RjR4where R1 and R2 are independently selected from alkyl, allyl, phenyl, alkenyl, silyl, and hydrogen,R3 and R4 are independently selected from alkyl, allyl, phenyl, and alkenyl, and n is from 100 to 100000,wherein the adhesive tape passes the Torch-Flame Test (TFT) Method set forth herein.

2. The adhesive tape of claim 1, wherein the adhesive tape has a peel adhesion of at least 2.5 N / cm when tested in accordance with the Peel Adhesion (90°) Test Method set forth herein.

3. The adhesive tape of claim 1 or claim 2, wherein the adhesive tape has an HBT peel value of greater than 5.0 N / cm when tested in accordance with the Hot Block Test (HBT) Method set forth herein.

4. The adhesive tape of any one of the preceding claims, wherein the adhesive tape has a direct current breakdown strength of at least 4.0 kV in accordance with the Direct Current Dielectric Breakdown Voltage (DCDBV) Test Method set forth herein.

5. The adhesive tape of any one of the preceding claims, where in the inorganic fibers comprise glass fibers, ceramic fibers, glass-ceramic fibers or combinations thereof6. The adhesive tape of any one of the preceding claims, wherein the inorganic fibers are selected from the group consisting of A-glass, C-glass, D-glass, E-glass, M-glass, R-glass, S-glass, ECR-glass, AR-glass, HR-glass, and basalt fibers; pure (> 99%) silica fibers; silicon carbide fibers; alumina fibers, Nextel fibers; or combinations thereof.

7. The adhesive tape of any one of the preceding claims, wherein the first reaction mixture comprises 20 - 80 wt.% MQ silicate resin tackifier.

8. The adhesive tape of any one of the preceding claims, where the first reaction mixture comprises 20 - 80 wt.% silicone elastomer.

9. The adhesive tape of any one of the preceding claims, wherein the first reaction mixture further comprises inorganic fillers, flame retardant agents, heat stabilizers, smoke suppression agents, endothermic agents, rheology modifiers, or combinations thereof.

10. The adhesive tape of any one of the preceding claims where the backing further comprises a sizing agent, wherein at least a portion of the sizing agent is disposed on the first major surface of the backing, and where the first tie layer comprises the sizing agent disposed on the first major surface of the backing.

11. The adhesive tape of claim 10, wherein the sizing agent comprises a polymeric carbohydrate, starch-oil based binder, a poly( vinyl alcohol), a reactive silane, or combinations thereof.

12. The adhesive tape of claim 10, wherein the sizing agent comprises a polymeric carbohydrate, starch-oil based binder, a poly(vinyl alcohol), or combinations thereof.

13. The adhesive tape of any one of the preceding claims, wherein the first tie layer comprises a primer, and the primer comprises an epoxy-silane.

14. The adhesive tape of any one of claims 1 to 13, wherein the first tie layer comprises a primer, and the primer comprises a polydimethylsiloxane with vinyl groups.

15. The adhesive tape of any one of the preceding claims, further comprising a second tie layer disposed on the second major surface of the backing and a second silicone adhesive disposed on the second tie layer, wherein the second tie layer is sandwiched between the second major surface of the backing and the second silicone adhesive, and wherein the second silicone adhesive comprises a second polymerized product of a second reaction mixture comprising:a second MQ silicate resin tackifier, anda second silicone elastomer having the formulawhere R and R2’ are independently selected from alkyl, allyl, phenyl, alkenyl, silyl, and hydrogen,Rs’ and Rf are independently selected from alkyl, allyl, phenyl, and alkenyl, and n’ is from 100 to 100000.

16. The adhesive tape of claim 15, wherein the compositions of the first and second silicone adhesives are the same.

17. The adhesive tape of claim 15, wherein the compositions of the first and second silicone adhesives are different.

18. The adhesive tape of any one of the preceding claims, further comprising a liner on at least one of the first and second silicone adhesives.

19. The adhesive tape of claim 18, wherein the liner comprises a non-fluorinated material.

20. The adhesive tape of any one of the preceding claims, wherein the adhesive tapes of the present disclosure contain less than 100 parts per million (ppm) of D3-, D4-, D5- and D6-cyclosiloxanes.

21. A method of making a silicone adhesive tape of any one of the preceding claims, the method comprising:applying a primer to the first major surface of the backing;drying the primer which becomes part of the first tie layer;applying the first reaction mixture to the first tie layer; andcuring the first reaction mixture by e-beam radiation to form the first silicone adhesive.

22. The method of claim 21, wherein the first reaction mixture is applied to the first tie layer by hot melt coating.

23. A method of making a silicone adhesive tape of any one of claims 1 to 20, the method comprising:applying the first reaction mixture to the first major surface of the backing, the backing comprising a sizing agent, at least a portion of the sizing agent disposed on the first major surface of the backing between the backing and the first reaction mixture; andcuring the reaction mixture by e-beam radiation to form the first silicone adhesive.

24. The method of claim 23, wherein the first reaction mixture is applied to the first major surface of the backing by hot melt coating.

Images