Security film and forced-entry resistant window

Abstract

A security film includes a substrate including thermoplastic polyurethane; an optically clear pressure sensitive adhesive layer disposed on the substrate; and a polymeric liner releasably attached to the substrate via the optically clear pressure sensitive adhesive layer. The substrate, the optically clear pressure sensitive adhesive layer, and the polymeric liner are substantially coextensive with one another. The substrate includes an outermost major surface of the security film and has a thickness in a range of 480 to 760 micrometers and a Graves tear resistance of greater than 2.75 joules with a maximum extension of greater than 7.5 cm as determined according to ASTM D1004-21 except with an initial grip separation of 3.8 cm and with a strain rate of 1.27 m / min. The security film can increase forced-entry resistance of a window. A forced-entry resistant window includes the security film, with the polymeric liner removed, laminated to a glass pane.

Description

[0001] SECURITY FILM AND FORCED-ENTRY RESISTANT WINDOW

[0002] TECHNICAL FIELD

[0003] The present description relates generally to security films useful for increasing the forced-entry resistance of windows.

[0004] BACKGROUND

[0005] A security film can be used to provide an additional substrate to a glass window to provide added protection against smash and grab burglaries, for example.

[0006] SUMMARY

[0007] In some aspects, the present description provides a security film for increasing forced-entry resistance of a window. The security film includes a substrate comprising thermoplastic polyurethane; an optically clear pressure sensitive adhesive layer disposed on the substrate; and a polymeric liner releasably attached to the substrate via the optically clear pressure sensitive adhesive layer. The substrate, the optically clear pressure sensitive adhesive layer, and the polymeric liner can be substantially coextensive with one another. The substrate comprises an outermost major surface of the security film and has a thickness in a range of 480 to 760 micrometers and a Graves tear resistance of greater than 2.75 joules with a maximum extension of greater than 7.5 cm as determined according to ASTM DI 004-21 except with an initial grip separation of 3.8 cm and with a strain rate of 1.27 m / min.

[0008] In some aspects, the present description provides a security film for increasing forced-entry resistance of a window. The security film includes a substrate comprising thermoplastic polyurethane; an optically clear pressure sensitive adhesive layer disposed on the substrate; and a polymeric liner releasably attached to the substrate via the optically clear pressure sensitive adhesive layer. The substrate, the optically clear pressure sensitive adhesive layer, and the polymeric liner can be substantially coextensive with one another. The substrate comprises an outermost major surface of the security film and has a thickness in a range of 480 to 760 micrometers. When the polymeric liner is removed and the substrate is laminated to a glass via the optically clear pressure sensitive adhesive layer to form a laminate, the laminate has a blunt impact forced entry time of at least 100 seconds as determined according to ASTM Fl 233 -21 except that a 0.7 kg smooth-faced framing hammer is used as a blunt impacting tool and the smooth face of the framing hammer strikes the glass side of the laminate along a Z pattern having horizontal edges that are each 76 cm wide and having a diagonal length of 102 cm. Forced entry is defined as breaking through the laminate along the entire Z pattern. The glass has in-plane dimensions of 86 by 86 cm and a thickness of 3.2 mm. The substrate can be substantially coextensive with the glass. The glass is tempered glass as specified by ASTM C1048-18.

[0009] In some aspects, the present description provides a forced-entry resistant window including at least one pane of glass; and a security film laminated to an outermost major surface of the at least one pane of glass. The security film including a substrate comprising thermoplastic polyurethane. The substrate comprises an outermost major surface of the security film. The substrate has a thickness in a range of 480 to 760 micrometers and a Graves tear resistance of greater than 2.75 joules with a maximum extension of greater than 7.5 cm as determined according to ASTM D1004-21 except with an initial grip separation of 3.8 cm and with a strain rate of 1.27 m / min.

[0010] These and other aspects will be apparent from the following detailed description. In no event, however, should this brief summary be construed to limit the claimable subject matter.

[0011] BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 is a schematic cross-sectional view of a security film, according to some embodiments.

[0013] FIG. 2 is a plot of graves tear resistance versus maximum extension for various exemplary and comparative substrates.

[0014] FIG. 3 is a plot of tear force versus extension for various exemplary and comparative substrates.

[0015] FIG. 4 is a schematic cross-sectional view of a forced-entry resistant window, according to some embodiments.

[0016] FIG. 5 is a schematic illustration of a pattern of blunt impacts used to determine a blunt impact forced entry time, according to some embodiments.

[0017] FIG. 6 is a plot of blunt impact forced entry time of forced-entry resistant windows versus thickness of the substrates of various exemplary and comparative security films.

[0018] FIGS. 7-8 are schematic cross-sectional views of substrates of security films, according to some embodiments.

[0019] DETAILED DESCRIPTION

[0020] In the following description, reference is made to the accompanying drawings that form a part hereof and in which various embodiments are shown by way of illustration. The drawings are not necessarily to scale. It is to be understood that other embodiments are contemplated and may be made without departing from the scope or spirit of the present description. The following detailed description, therefore, is not to be taken in a limiting sense.

[0021] Security films can be used to provide an additional substrate to a glass pane of a window in order to slow a break-and-entry attempt, provide protection against physical impacts, and / or reduce the number of free-flying shards in the case of an otherwise glass-shattering event, for example. For example, a security film can include a polymeric substrate that may be laminated to an inner surface of a glass window in order to form a forced-entry resistant window having a substantially increase forced entry time, for example, compared to the unprotected glass window. According to some embodiments of the present description, it has been surprisingly found that when the substrate comprises thermoplastic polyurethane having properties described elsewhere herein, that the forced entry time to break through the forced-entry resistant window rapidly increases when the substrate thickness is increased to at least 480 micrometers. The properties of the thermoplastic polyurethane which has been found to lead to the increased forced entry time include a high Graves tear resistance (e.g., greater than 2.75 joules) with a high maximum extension (e.g., greater than 7.5 cm) when the Graves tear resistance and maximum extension are determined according to a modified ASTM D 1004-21 test (e.g., modified to utilize an initial grip separation of 3.8 cm and a strain rate of 1.27 m / min) as described further elsewhere herein. Other useful properties of the thermoplastic polyurethane have been found to include, for example, a high elongation at break (e.g., at least 500%) and a low tensile stress at 300% elongation (e.g., no more than 15 MPa).

[0022] FIG. 1 is a schematic cross-sectional view of a security film 100, according to some embodiments. In some embodiments, security film 100 includes a substrate 110 comprising thermoplastic polyurethane; an optically clear pressure sensitive adhesive layer 120 disposed on the substrate 110; and a polymeric liner 140 releasably attached to the substrate 110 via the optically clear pressure sensitive adhesive layer 120. In some embodiments, the substrate 110, the optically clear pressure sensitive adhesive layer 120, and the polymeric liner 140 are substantially coextensive with one another. In some embodiments, the substrate 110 comprises an outermost major surface 112 of the security fdm 100. In some embodiments, the substrate 110 has a thickness T in a range of 480 to 760 micrometers. In some embodiments, the thickness T is at least 500, 520, 540, 560, 580, 590, 600, or 610 micrometers. In FIG. 1, the security fdm extends generally in the x-y plane and the thickness is measured along the z-axis. Generally, a higher thickness (e.g., 480 micrometers or even thicker) is preferred for improved blunt impact forced entry time. In some embodiments, the thickness T is no more than 740, 720, 700, 680, 660, 640, or 620 micrometers. Generally, a lower thickness (e.g., 760 micrometers or even thinner) is preferred for improved manufacturability and cost, for example. In some embodiments, the thickness T is in a range of 500 to 740 micrometers, or 520 to 720 micrometers, or 540 to 700 micrometers, or 560 to 680 micrometers, or 580 to 660 micrometers, or 590 to 640 micrometers, for example. In some embodiments, the thickness T is about 610 micrometers, for example. It has been found that a substrate thickness in a range of 480 to 760 micrometers, or in another of these ranges, can provide a substantially improved blunt impact forced entry time compared to thinner substrates (see, e.g., FIG. 6) when the substrate has a high Graves tear resistance with high maximum extension, for example. The security fdm 100 can be for increasing forced-entry resistance of a window. For example, the polymeric liner can be removed, and the substrate laminated to a glass pane of the window via the optically clear pressure sensitive adhesive to result in a forced-entry resistant window as described further elsewhere herein.

[0023] Layers or elements can be described as substantially coextensive with each other if at least about 60% by area of each layer or element is coextensive with at least about 60% by area of each other layer or element. Here, area refers to the area of a major surface of the layer or element (e.g., area in x-y plane). In some embodiments, for layers or elements described as substantially coextensive, at least about 70%, or at least about 80%, or at least about 90%, or at least about 95% by area of each layer or element is coextensive with at least about 70%, or at least about 80%, or at least about 90%, or at least about 95% by area of each other layer or element. Layers or elements that are substantially coextensive with each other may be coextensive with one another with the possible exception of edge regions of the layers or elements. For example, in some embodiments, for a security fdm substantially coextensive with a pane of glass, the security fdm is coextensive with the pane of glass except for edges of the pane that may not include the security fdm and that may be hidden under a window frame.

[0024] The polymeric liner 140 can be made from any suitable polymer such as a polyester. In some embodiments, the polymeric liner is a surface-treated polyethylene terephthalate (PET) liner, for example. The PET, or other polymer layer, can include a release coating (on the face of the liner 140 facing the adhesive layer 120). The release coating can be a silicone or natural wax coating, for example. The surface of the polymeric liner 140 facing the adhesive layer 120 can be smooth. For example, this surface can be optically smooth (e.g., having a surface roughness Ra small compared to wavelengths of visible light) so that the liner does not transfer optically significant roughness to the adhesive layer. For example, the surface roughness Ra can be less than 200, 150, 100, or 50 nm. The polymeric liner 140 can be between 25 and 100 micrometers thick, for example.

[0025] In some embodiments, optically clear pressure sensitive adhesive 120 is selected such that it is compatible with both the substrate 110 and an expected glass window surface to which it will be applied. In some embodiments, optically clear pressure sensitive adhesive 120 may be selected for its physical characteristics, such as its softness or hardness (elastic modulus) or its flowability. In some embodiments, optically clear pressure sensitive adhesive 120 may be selected for its optical characteristics, such as its transparency, or, more specifically its optical clarity (high), optical transmission (high), and optical haze (low). The optically clear pressure sensitive adhesive layer 120 can have a luminous transmittance of greater than 80, 85, or 90 percent and / or can have a haze less than 5, 4, 3, or 2 percent, for example. Luminous transmittance and haze can be determined according to ASTM DI 003- 13, for example. In some embodiments, optically clear pressure sensitive adhesive 120 may be an acrylic adhesive. In some embodiments, optically clear pressure sensitive adhesive 120 may be between 1 and 25 micrometers thick, between 25 and 50 micrometers thick, between 50 and 75 micrometers thick, between 75 and 100 micrometers thick, or between 100 and 500 micrometers thick. The adhesive layer may be formed through any suitable means, and then dispensed or provided onto the substrate by any suitable method, such as through solvent or extrusion coating, or via a transfer tape or the lamination of a release liner carrying the adhesive layer. Suitable optically clear pressure sensitive adhesives with polymeric liners include 3M Optically Clear Adhesives 8211, 8212, 8213, 8214, and 8215, for example.

[0026] Graves tear resistance and the corresponding maximum extension of the substrate can be determined according to the ASTM DI 004-21 tear resistance test. In this test standard, a sample geometry is specified where the sample has an approximately V-shaped portion between approximately rectangular end portions that having a sample width of 1.9 cm (0.75 inches). Grips are attached to the end portions and are pulled apart at a specified strain rate causing the sample to tear, typically in the V-shaped portion. The force versus displacement is measured and the area under the force vs displacement is determined as the Graves tear resistance and the maximum extension when the sample finally fails can also be determined. The maximum extension is a change in the grip separation from the initial separation to the final separation at failure (e.g., a change from an initial separation of 3.8 cm to a final separation at break of 11.3 cm is a 7.5 cm maximum extension). In some embodiments, this ASTM standard is modified by specifying a different strain rate, a different initial grip separation, and / or a different sample width. Two such modifications have been found to be useful in characterizing the substrate of a security film. In one modification, the ASTM DI 004-21 standard is used except with an initial grip separation of 3.8 cm and with a strain rate of 1.27 m / min. In another modification, the ASTM DI 004-21 standard is used except with an initial grip separation of 5. 1 cm, with a strain rate of 1.27 m / min, and with a sample width of 3.8 cm. When the sample width is increased, the shape of the approximately V-shaped portion remains as specified in the ASTM DI 004-21 standard.

[0027] In some embodiments, the substrate 110 has a Graves tear resistance of greater than 2.75, 3, 3.25,

[0028] 3.5, 3.75, 4, 4.25, 4.5, 4.75, 5, 5.25, 5.5, 5.75, 6, or 6.25 joules with a maximum extension of greater than 7.5 cm as determined according to ASTM D1004-21 except with an initial grip separation of 3.8 cm and with a strain rate of 1.27 m / min. In some embodiments, this Graves tear resistance may be up to 15, 12, 10, or 8 joules, for example. In some embodiments, this maximum extension is greater than 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, or 12 cm. In some embodiments, this maximum extension may be up to 18, 16, or 14 cm, for example. FIG. 2 is a plot of Graves tear resistance versus maximum extension in this Graves tear resistance test for various exemplary and comparative substrates having thicknesses from 124 micrometers (4.9 mils) to 699 micrometers (27.5 mils) as described further in the Examples. It has been found, according to some embodiments, that substrates in the upper right portion (e.g., Graves tear resistance greater than 2.75 joules and maximum extension greater than 7.5 cm or Graves tear resistance greater than 3 joules and maximum extension greater than 8.5 cm) of this plot give better break and entry resistance than substrates in other portions of the plot. The Graves tear resistance can be increased from the values shown in this figure by increasing the thickness of the substrate since it generally takes a greater energy to tear a thicker substrate. The maximum extension can be adjusted by adjusting relative amounts and types of hard and soft segments of the polyurethane as described further elsewhere herein (e.g., increasing the soft segment content can increase the maximum extension, but may sacrifice tear force unless the substrate is also made thicker; and soft segments based on polycaprolactone or polycarbonate have been found to give desired tear resistance with desired maximum extension).

[0029] In some embodiments, the substrate 110 has a Graves tear resistance of greater than 9, 9.5, 10,

[0030] 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, or 15 joules with a maximum extension of greater than 9 cm as determined according to ASTM DI 004-21 except with an initial grip separation of 5. 1 cm, with a strain rate of 1.27 m / min, and with a sample width of 3.8 cm. In some embodiments, this Graves tear resistance may be up to 30, 25, 20, or 18 joules, for example. In some embodiments, this maximum extension is greater than 9.5, 10, 10.5, 11, 11.5, 12, 12.5, or 13 cm. In some embodiments, this maximum extension may be up to 22, 20, 18, 17, 16 or 15 cm, for example. FIG. 3 is a plot of force versus extension determined in this Graves tear resistance test for various thermoplastic polyurethane substrates as described further in the Examples.

[0031] Other useful properties of the substrate include, according to some embodiments, elongation at break and / or tensile stress at 300% elongation, for example. In some embodiments, the substrate has an elongation at break of at least 500%, 550%, 600%, 650%, 675%, or 700%. In some such embodiments, or in other embodiments, the substrate has a tensile stress at 300% elongation of no more than 15, 14, 13, 12, or 11 MPa. The elongation at break may be up to 1200%, 1100%, 1000%, 950%, or 900%, for example. The tensile stress at 300% elongation may be at least 5, 6, 7, 8, 9, or 10 MPa, for example. The thermoplastic polyurethane of FIG. 3 labeled Substrate C, for example, had an elongation at break of 741% and a tensile stress at 300% elongation of 10.7 MPa (1550 psi). The elongation at break and / or tensile strength at a given elongation (e.g., 300%) can be determined according to ASTM D882-18 or according to D882-18 but modified to utilize a test speed of 30.5 cm / min (12 in / min), a sample width of 1.3 cm (0.5 inches), and an initial grip separation of 2.5 cm (1 inch), for example.

[0032] FIG. 4 is a schematic cross-sectional view of a forced-entry resistant window 200, according to some embodiments. The forced-entry resistant window 200 includes at least one pane of glass 160; a security film 100' laminated to an outermost major surface 162 of the at least one pane of glass 160. The at least one pane of glass 160 can be a single pane of glass, or may be double or triple, for example, planes of glass. The at least one pane of glass can define an interior surface (e.g., surface facing an interior of a house) and an exterior surface (e.g., surface facing an outside of a house). The outermost major surface 162 may be the interior surface or the exterior surface. Typically, the outermost major surface 162 is the interior surface (i.e., the security film 100' is laminated to the interior surface). However, in some cases, the outermost major surface 162 may be the exterior surface. The security film 100' can be substantially coextensive with the at least one pane of glass 160 (e.g., the security film 100' can be coextensive with the at least one plane of glass 160 with the possible exception that edge regions of the at least one pane of glass 160 may not be covered by the security film 100').

[0033] The security film 100' can correspond to security film 100 with the polymeric liner 140 removed. The security film 100' includes a substrate 110 comprising thermoplastic polyurethane. The substrate 110 comprises an outermost major surface 112 of the security film 100' and has a thickness T in a range of 480 to 760 micrometers (or in a range described elsewhere herein). The substrate 110 can have a Graves tear resistance with a maximum extension in the respective ranges described elsewhere herein. For example, in some embodiments, the substrate 110 can have a Graves tear resistance of greater than 2.75 joules (or in a range described elsewhere herein) with a maximum extension of greater than 7.5 cm (or in a range described elsewhere herein) as determined according to ASTM D 1004-21 except with an initial grip separation of 3.8 cm and with a strain rate of 1.27 m / min. In some embodiments, the substrate 110 of the security film 100' has an elongation at break of at least 500% (or in a range described elsewhere herein) and a tensile stress at 300% elongation of no more than 15 MPa (or in a range described elsewhere herein). In some embodiments, the substrate 110 has a haze of less than 5%, 4%, 3%, or 2% (e.g., as determined according to ASTM D1003-13). In some embodiments, the forced-entry resistant window 200 has a haze of less than 5%, 4%, 3%, or 2% (e.g., as determined according to ASTM D1003-13). In some embodiments, the substrate 110 has a luminous transmittance of greater than 80, 85, or 90 percent (e.g., as determined according to ASTM D1003-13). In some embodiments, the forced-entry resistant window 200 has a luminous transmittance of greater than 80, 85, or 90 percent (e.g., as determined according to ASTM D1003-13).

[0034] In some embodiments, the forced-entry resistant window 200 is characterized by a blunt impact forced entry time. FIG. 5 is a schematic illustration of a pattern of blunt impacts used to determine a blunt impact forced entry time, according to some embodiments. In some embodiments, the forced-entry resistant window 200 has a blunt impact forced entry time of at least 100, 110, 120, 130, 140, 150, 160, 170, or 180 seconds as determined according to ASTM F1233-21 except that a 0.7 kg smooth-faced framing hammer 670 is used as a blunt impacting tool and the smooth face 672 of the framing hammer strikes the glass side (side opposite the security film 100') of the forced-entry resistant window along a Z pattern having horizontal edges that are each 76 cm wide (width W) and a having diagonal length D of 102 cm, where forced entry is defined as breaking through the forced-entry resistant window along the entire Z pattern. Framing hammers generally include a striking face that can be a milled face (also referred to as a checkered face or a waffle face) or a smooth face. The smooth face generally does not include any texture deliberately formed in the face.

[0035] In some embodiments, the security film 100 is characterized by a blunt impact forced entry time of a laminate formed by removing the polymeric liner 140 and laminating the substrate 110 to a standardized glass (e.g., being a standardized tempered glass having standardized dimensions) via the optically clear pressure sensitive adhesive layer 120. In some embodiments, when the polymeric liner 140 is removed and the substrate 110 is laminated to a glass 160 via the optically clear pressure sensitive adhesive layer 120 to form a laminate (e.g., corresponding to forced-entry resistant window 200), the laminate has a blunt impact forced entry time of at least 100, 110, 120, 130, 140, 150, 160, 170, or 180 seconds as determined according to ASTM F1233-21 except that a 0.7 kg smooth-faced framing hammer is used as a blunt impacting tool and the smooth face of the framing hammer strikes the glass side of the laminate along a Z pattern having horizontal edges that are each 76 cm wide (width W) and a having diagonal length D of 102 cm, where forced entry is defined as breaking through the laminate along the entire Z pattern and where the glass is tempered glass as specified by ASTM Cl 048- 18 and has in-plane dimensions of 86 by 86 cm and a thickness of 3.2 mm. The substrate 110 can be substantially coextensive with the glass 160 in the laminate.

[0036] In some embodiments, the forced-entry resistant window 200 or the laminate is characterized by the number of hits resulting in forced entry in the blunt impact forced entry test. In some embodiments, the number of hits is at least 100, 120, 140, or 150. The number of hits can be up to 200, 180, or 170, for example. FIG. 6 is a plot of blunt impact forced entry time versus total substrate thickness. Data is shown for polyurethane (PU) substrates, for polyethylene terephthalate (PET) substrates, for a substrate including PU and PET layers (Hybrid PET / PU), and for the case where a PU substrate is applied to both sides of the window glass (Half in / Half out). Results for conventional security fdm substrates (e.g., PET substrates), and for PU substrates having a thickness of 460 micrometers or less or having a higher thickness but not having the desired properties (e.g., Graves Tear energy and Graves tear extension) described elsewhere herein, fall in the channel between the two parallel lines 401 and 402. The two parallel lines 401 and 402 are separated by about 50.4 seconds along the forced entry time axis. In some embodiments, the security fdm of the present description results in a forced entry time above the upper line 401. The equation for the upper line 401 is FET = 0.116 T + 28.2, where FET is the forced entry time in seconds and T is the thickness of the substrate in micrometers. In some embodiments, for the laminate or for the forced-entry resistant window including a security fdm, the blunt impact forced entry time in seconds is greater than 0.116 T + 30, or greater than 0.116 T + 50, or greater than 0.116 T + 70, or greater than 0. 116 T + 90, or greater than 0.116 T + 110, or greater than 0. 116 T + 120, or greater than 0.116 T + 130, or greater than 0.116 T + 140, or greater than 0.116 T + 150, where T is the thickness of the substrate in micrometers.

[0037] In some embodiments, the thermoplastic polyurethane comprises at least 85, 90, 92, 93, 94, or 95 percent of a total volume of the substrate 110. In some embodiments, the substrate 110 comprises a single layer of the thermoplastic polyurethane having a thickness of at least 480, 500, 520, 540, 560, 580, 600, or 610 micrometers. In other embodiments, the substrate 110 can include two or more layers of the thermoplastic polyurethane where each pair of adjacent polyurethane layers can be separated by an adhesive layer.

[0038] FIGS. 7-8 are schematic cross-sectional views of substrates of security fdms, according to some embodiments. Substrates 210 and 310 can correspond to substrate 110 and can have any of the properties (e.g., Graves tear resistance, maximum extension, elongation at break, and / or stress at 300% strain) described elsewhere herein for substrate 110. In some embodiments, the substrate 210 or 310 includes at least one layer 211 or 314 of the thermoplastic polyurethane and further includes at least one other polymeric layer 212 or 315. The at least one other polymeric layer 212 may be or include another thermoplastic polyurethane layer, for example. The at least one other polymeric layer may be a clear coat layer, for example. In some embodiments, the thermoplastic polyurethane 110 or 211 comprises the outermost major surface 112 or 212 of the security fdm. In other embodiments, a different polymeric layer 315 comprises the outermost major surface 312 of the security fdm.

[0039] In some embodiments, the substrate 210 includes at least two layers 211, 212 of the thermoplastic polyurethane separated by an adhesive layer 220 and having a total thickness (T1 + T2) of at least 480, 500, 520, 540, 560, 580, 600, or 610 micrometers. In some embodiments, T1 and T2 are approximately equal (e.g., equal to within 20, 15, or 10 percent). In other embodiments, T1 and T2 are substantially different. In some embodiments, each of the at least two layers 211, 212 is attached to an adjacent layer of the at least two layers via an adhesive layer 220.

[0040] In some embodiments, the substrate 310 includes a clear coat layer 315 comprising the outermost major surface 312 of the security fdm. In some embodiments, the clear coat layer has a thickness (T2 in FIG. 8) in a range of 0.5 to 10, 8, 6, or 5 micrometers. A thinner (e.g., no more than 10 micrometers thick) clear coat layer can provide an easy clean functionality, for example, without sacrificing tear resistance or forced entry time for example. The clear coat layer 315 can comprise a silicone or other low surface energy material, for example. A thicker (e.g., at least 0.5 micrometers thick) clear coat layer can be readily manufactured by conventional means. The clear coat layer 315 and / or the entire substrate 310 can have a haze of less than 5% (or in a range described elsewhere herein) and a luminous transmittance of greater than 80% (or in a range described elsewhere herein). In some embodiments, the clear coat thickness is at least 1 micrometer. In some embodiments, the substrate 310 includes a thermoplastic polyurethane layer 314 having a thickness T1 of at least 480, 500, 520, 540, 560, 580, 600, or 610 micrometers.

[0041] A thermoplastic polyurethane can be formulated to provide the mechanical properties described herein. Principles of polyurethane formulation are known in the art and are described, for example, in Chapter 1 of Felipe M. de Souza, Pawan K. Kahol, Ram K. Gupta (2021); Polyurethane Chemistry: Renewable Polyols and Isocyanates,' ACS Symposium Series, Vol. 1380; and in Chapter 7 of Kumbar, Sangamesh G. Laurencin, Cato T. Deng, Meng (2014); Natural and Synthetic Biomedical Polymers,' Elsevier. Thermoplastic polyurethanes are typically block copolymers comprising a plurality of alternating hard and soft segments. Polyurethanes can be formed as a reaction product of a formulation comprising at least one isocyanate and at least one polyol. The at least one isocyanate can define the hard segments of the polyurethane and the at least on polyol can include diols of long-chain molecules of polyether, polyesters, polysiloxane, and / or polycarbonate, for example, to define the soft segments. Mechanical properties of polyurethanes can be varied by suitably selecting the hard and soft segments and / or by varying the ratio of the soft and hard segments. Generally, increasing the hard segment fraction increases strength of the polyurethane while increasing the soft segment fraction increases the elasticity of the polyurethane. In some embodiments, the thermoplastic polyurethane comprises hard segments in a range of 30 to 60, or 35 to 50, or 40 to 45 weight percent. It has been found, according to some embodiments, that suitably thick polyurethanes with hard and segment content in these ranges can provide desired Graves tear strength and maximum extension, for example, as described elsewhere herein.

[0042] In some embodiments, the thermoplastic polyurethane is or comprises an aliphatic polyurethane. In other embodiments, the thermoplastic polyurethane is or comprises an aromatic polyurethane. According to some embodiments, aromatic polyurethanes may give better performance (e.g., better break- in performance and / or better Graves tear performance) than many aliphatic polyurethanes, but aliphatic polyurethanes may be preferred for some applications since such polyurethanes typically exhibit less yellowing upon exposure to ultraviolet (UV) light than exhibited by aromatic polyurethanes. In some embodiments, the substrate 110 includes light stabilizers such as UV absorbers which may be dispersed in the thermoplastic polyurethane. Alternatively, or in addition, the adhesive layer 120 can include light stabilizers. Suitable light stabilizers include those available from BASF (Ludwigshafen, Germany) under the tradename TINUVIN. The light stabilizers may be included in the thermoplastic polyurethane layer, and / or in the adhesive layer, at 0.2 to 4 weight percent, for example.

[0043] In some embodiments, the thermoplastic polyurethane comprises a reaction product of a formulation comprising at least one isocyanate and at least one polyol. In some embodiments, each of the at least one isocyanate is an aliphatic isocyanate. In some embodiments, each of the at least one polyol is an aliphatic polyol. In other embodiments, the at least isocyanate comprises an aromatic isocyanate and / or the at least one polyol comprises an aromatic polyol. It has been found, according to some embodiments, that desired properties can be obtained from using polycarbonate and / or polycaprolactone polyols. Accordingly, in some embodiments, the at least one polyol comprises a polycarbonate polyol, a polycaprolactone polyol, or a combination thereof.

[0044] In some embodiments, the at least one polyol comprises a polycarbonate polyol. In some embodiments, the formulation comprises the polycarbonate polyol at 20 to 75 weight percent. In some embodiments, the formulation comprises the polycarbonate polyol at no less than 30, 40, 50, or 55 weight percent. In some embodiments, the formulation comprises the polycarbonate polyol at no more than 70 or 65 weight percent. In some embodiments, the polycarbonate polyol is a polycarbonate diol. In some embodiments, the polycarbonate polyol is an aliphatic polycarbonate polyol such as an aliphatic polycarbonate diol. In other embodiments, an aromatic polycarbonate polyol is used. Suitable polycarbonate polyols include those available from UBE Corporation (Tokyo, Japan) under the ETERNACOLL tradename. Such polycarbonate polyols include ETERNACOLL UH 100 which is an aliphatic polycarbonate diol.

[0045] In some embodiments, the at least one polyol comprises at least one diol and at least one triol. Triol(s) may be included to add branching in the resulting polyurethane. In some embodiments, the formulation comprises the at least one diol at 20 to 75 weight percent and comprises the at least one triol at 0.2 to 5 weight percent, for example. In some embodiments, the formulation comprises the at least one diol at no less than 30, 40, 50, or 55 weight percent. In some embodiments, the formulation comprises the at least one diol at no more than 70 or 65 weight percent. In some embodiments, the formulation comprises the at least one triol at 0.3 to 2 weight percent.

[0046] In some embodiments, the at least one polyol comprises a polycaprolactone polyol having a molecular weight of less than 2500, 2000, 1500, 1200, 1000, 800, 600, 400 g / mole. In some embodiments, the molecular weight is at least 100, 150, 200, or 250 g / mole. In some embodiments, the formulation comprises the polycaprolactone polyol at 15 to 75, or 20 to 60, or 25 to 65 weight percent. In some embodiments, the poly caprolactone polyol is an aliphatic polycaprolactone polyol. In some embodiments, the at least one polyol comprises a first polycaprolactone polyol having a molecular weight in a range of 800 to 2500 g / mole and a second poly caprolactone polyol having a molecular weight in a range of 200 to 400 g / mole. In some embodiments, the formulation comprises the first polycaprolactone polyol at 45 to 70 weight percent and comprises the second poly caprolactone polyol at 0.2 to 5 weight percent, or 0.3 to 2 weight percent. In some embodiments, the first polycaprolactone polyol is a diol and the second polycaprolactone polyol is a triol. In some embodiments, each of the first and second polycaprolactone polyols is an aliphatic poly caprolactone polyol. In other embodiments, at least one of the first and second polycaprolactone polyols is an aromatic poly caprolactone polyol. Suitable polycaprolactone polyols include those available from Ingevity (North Charleston, SC) under the CAPA tradename. Such poly caprolactone polyols include CAPA 2203 A which is a polycaprolactone diol having a molecular weight of 2000 g / mole, CAPA 2101 A which is a polycaprolactone diol having a molecular weight of 1000 g / mole, and CAPA 3031 which is a poly caprolactone triol having a molecular weight of 300 g / mole.

[0047] In some embodiments, the at least one isocyanate comprises a cycloaliphatic diisocyanate. The formulation may include the cycloaliphatic diisocyanate at 25 to 60 weight percent, or 30 to 55, 50, or 45 weight percent, for example. Suitable cycloaliphatic diisocyanates include dicyclohexylmethane diisocyanate, for example, which is available from Covestro LLC (Pittsburgh, PA) under the tradename DESMODURW.

[0048] In some embodiments, the formulation includes a prepolymer comprising a reaction product of isocyanate and polyester polyol. Suitable prepolymers include those available from Huntsman (The Woodlands, TX) under the RUBINATE tradename. An example is RUB INATE 1234 which is a low- functionality prepolymer (functionality = 2.01) produced by reacting 4,4'-diphenylmethane diisocyanate (Pure MDI) with polyester polyols. The formulation may include the prepolymer at 40 to 65 weight percent, for example.

[0049] In some embodiments, the formulation comprises at least one chain extender having a molecular weight less than 250, 200, or 150 g / mole. The molecular weight can be at least 40, 50, or 60 g / mole, for example. In some embodiments, the formulation comprises the at least one chain extender at 3 to 25, or 4 to 22, or 5 to 20 weight percent. Suitable chain extenders include aliphatic diols such as 1,4 butanediol.

[0050] In some embodiments, the formulation comprises a crosslinking or gelling catalyst such as dibutyltin dilaurate. The formulation may include the crosslinking or gelling catalyst at 0.01 to 0.1 weight percent, for example. EXAMPLES

[0051] TEST METHODS

[0052] Graves Tear Test Method 1

[0053] Graves tear resistance and the corresponding maximum extension were determined according to ASTM DI 004-21 except with an initial grip separation of 1.5 inches (3.8 cm) and with a strain rate of 500 in / min (1.27 m / min).

[0054] Graves Tear Test Method 2

[0055] Graves tear resistance and the corresponding maximum extension were determined according to ASTM DI 004-21 except with an initial grip separation of 2 inches (5.1 cm), with a strain rate of 500 in / min (1.27 m / min), and with a sample width of 1.5 inches (3.8 cm).

[0056] Tensile Stress and Elongation at Break

[0057] Elongation at break and tensile stress at various elongations were determined according to ASTM D882-18 except with a test speed of 12 in / min (30.5 cm / min), a sample width of 0.5 inches (1.3 cm), and an initial grip separation of 1 inch (2.5 cm).

[0058] Break and Entry Test

[0059] The substrate of the security film was laminated to a glass via the optically clear pressure sensitive adhesive layer to form a laminate. The substrate was coextensive with the glass. If the security film included a polymeric liner, the liner was removed before the lamination. The glass had in-plane dimensions of 33.75 by 33.75 inches (86 by 86 cm) and a thickness of 1 / 8 inch (3.2 mm). The glass was tempered glass as specified by ASTM C1048-18. The blunt impact forced entry time and number of hits were determined according to ASTM F1233-21 except that a 0.7 kg smooth-faced framing hammer was used as a blunt impacting tool with the smooth face of the framing hammer striking the glass side of the laminate along a Z pattern having horizontal edges that are each 30 inches (76 cm) wide and a having diagonal length of 40 inches (102 cm). Forced entry was defined as breaking through the laminate along the entire Z pattern.

[0060] MATERIALS

[0061] Unless otherwise noted, all parts, percentages, ratios, etc. in the examples and the rest of the specification are by weight. Materials used in the examples are available from commercial suppliers and / or can be made by known methods, unless indicated otherwise.

[0062] SECURITY FILMS

[0063] Materials listed in the following table were reaction extruded into polyurethane substrates.

[0064] Various formulations were made into security film substrates and tested as described under “Graves Tear Test Method 1”. Results are reported in the following table and in FIG. 2. Samples of thermoplastic polyurethane (TPU) pellets were obtained and extruded into security fdm substrates. The substrates had thicknesses and properties indicated in the table below. In some cases, substrates were formed by laminating together two of the extruded substrates. The properties in the following table were measured as described under “Tensile Stress and Elongation at Break”.

[0065] Various substrates were laminated to glass with an optically clear pressure sensitive adhesive and were tested as described under “Break and Entry Test”. The optically clear adhesive (PSA) layer was a 3M Window Film PSA having a thickness of 20 to 30 micrometers and a 180 degree peel fore on glass of greater than 10 N / in (3.94 N / cm) at a peel speed of 12 in / min (30.5 cm / min). Results are provided in the following table and in FIG. 6. Three PET substrates were tested for comparison as indicated in the table. Some of these substrates were tested as described under “Graves Tear Test Method 1”. Results are provided in the following table and in FIG. 2.

[0066] Various substrates were tested as described under “Graves Tear Test Method 2”. Results are provided in the following table and in FIG. 3.

[0067] Terms such as “about” will be understood in the context in which they are used and described in the present description by one of ordinary skill in the art. If the use of “about” as applied to quantities expressing feature sizes, amounts, and physical properties is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “about” will be understood to mean within 10 percent of the specified value. A quantity given as about a specified value can be precisely the specified value. For example, if it is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, a quantity having a value of about 1, means that the quantity has a value between 0.9 and 1. 1, and that the value could be 1.

[0068] Terms such as “substantially” will be understood in the context in which they are used and described in the present description by one of ordinary skill in the art. If the use of “substantially” with reference to a property or characteristic is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description and when it would be clear to one of ordinary skill in the art what is meant by an opposite of that property or characteristic, the term “substantially” will be understood to mean that the property or characteristic is exhibited to a greater extent than the opposite of that property or characteristic is exhibited. All references, patents, and patent applications referenced in the foregoing are hereby incorporated herein 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. Descriptions for elements in figures should be understood to apply equally to corresponding elements in other figures, unless indicated otherwise. Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and / or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations, or variations, or combinations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.

Claims

What is claimed is:

1. A security film for increasing forced-entry resistance of a window, the security film comprising: a substrate comprising thermoplastic polyurethane; an optically clear pressure sensitive adhesive layer disposed on the substrate; and a polymeric liner releasably attached to the substrate via the optically clear pressure sensitive adhesive layer, the substrate, the optically clear pressure sensitive adhesive layer, and the polymeric liner being substantially coextensive with one another, wherein the substrate comprises an outermost major surface of the security film; and wherein the substrate has a thickness in a range of 480 to 760 micrometers and a Graves tear resistance of greater than 2.75 joules with a maximum extension of greater than 7.5 cm as determined according to ASTM DI 004-21 except with an initial grip separation of 3.8 cm and with a strain rate of 1.27 m / min.

2. The security film of claim 1, wherein when the polymeric liner is removed and the substrate is laminated to a glass via the optically clear pressure sensitive adhesive layer to form a laminate, the laminate has a blunt impact forced entry time of at least 100 seconds as determined according to ASTM Fl 233 -21 except that a 0.7 kg smooth-faced framing hammer is used as a blunt impacting tool and the smooth face of the framing hammer strikes the glass side of the laminate along a Z pattern having horizontal edges that are each 76 cm wide and having a diagonal length of 102 cm, forced entry being defined as breaking through the laminate along the entire Z pattern, the glass having in-plane dimensions of 86 by 86 cm and a thickness of 3.2 mm, the substrate being substantially coextensive with the glass, the glass being tempered glass as specified by ASTM C1048-18.

3. The security film of claim 1 or 2, wherein the substrate has a Graves tear resistance of greater than 9 joules with a maximum extension of greater than 9 cm as determined according to ASTM DI 004-21 except with an initial grip separation of 5. 1 cm, with a strain rate of 1.27 m / min, and with a sample width of 3.8 cm.

4. The security film of any one of claims 1 to 3, wherein the substrate has an elongation at break of at least 500% and a tensile stress at 300% elongation of no more than 15 MPa.

5. The security film of any one of claims 1 to 4, wherein the thermoplastic polyurethane comprises a reaction product of a formulation comprising at least one isocyanate and at least one polyol, the at least one polyol comprising a poly caprolactone polyol having a molecular weight of less than 2500 g / mole.

6. The security film of any one of claims 1 to 4, wherein the thermoplastic polyurethane comprises a reaction product of a formulation comprising at least one isocyanate and at least one polyol, the at least one polyol comprising a polycarbonate polyol.

7. The security film of claim 5 or 6. wherein the formulation comprises at least one chain extender having a molecular weight less than 250 g / mole.

8. The security film of any one of claims 1 to 7, wherein the thermoplastic polyurethane comprises hard segments in a range of 30 to 60 weight percent.

9. A security film for increasing forced-entry resistance of a window, the security film comprising: a substrate comprising thermoplastic polyurethane; an optically clear pressure sensitive adhesive layer disposed on the substrate; and a polymeric liner releasably attached to the substrate via the optically clear pressure sensitive adhesive layer, the substrate, the optically clear pressure sensitive adhesive layer, and the polymeric liner being substantially coextensive with one another, wherein the substrate comprises an outermost major surface of the security film; and wherein the substrate has a thickness in a range of 480 to 760 micrometers, and wherein when the polymeric liner is removed and the substrate is laminated to a glass via the optically clear pressure sensitive adhesive layer to form a laminate, the laminate has a blunt impact forced entry time of at least 100 seconds as determined according to ASTM Fl 233 -21 except that a 0.7 kg smooth-faced framing hammer is used as a blunt impacting tool and the smooth face of the framing hammer strikes the glass side of the laminate along a Z pattern having horizontal edges that are each 76 cm wide and having a diagonal length of 102 cm, forced entry being defined as breaking through the laminate along the entire Z pattern, the glass having in-plane dimensions of 86 by 86 cm and a thickness of 3.2 mm, the substrate being substantially coextensive with the glass, the glass being tempered glass as specified by ASTM C 1048-18.

10. The security film of claim 9, wherein the thermoplastic polyurethane comprises hard segments in a range of 30 to 60 weight percent.

11. The security film of claim 9 or 10, wherein the blunt impact forced entry time in seconds is greater than 0. 116 T + 30, T being the thickness of the substrate in micrometers.

12. A forced-entry resistant window, comprising: at least one pane of glass; anda security fdm laminated to an outermost major surface of the at least one pane of glass, the security fdm including a substrate comprising thermoplastic polyurethane, wherein the substrate comprises an outermost major surface of the security fdm; wherein the substrate has a thickness in a range of 480 to 760 micrometers and a Graves tear resistance of greater than 2.75 joules with a maximum extension of greater than 7.5 cm as determined according to ASTM DI 004-21 except with an initial grip separation of 3.8 cm and with a strain rate of 1.27 m / min.

13. The forced-entry resistant window of claim 12, wherein the forced-entry resistant window has a blunt impact forced entry time of at least 100 seconds as determined according to ASTM F1233-21 except that a 0.7 kg smooth-faced framing hammer is used as a blunt impacting tool and the smooth face of the framing hammer strikes the glass side of the forced-entry resistant window along a Z pattern having horizontal edges that are each 76 cm wide and having a diagonal length of 102 cm, forced entry being defined as breaking through the forced-entry resistant window along the entire Z pattern.

14. The forced-entry resistant window of claim 13, wherein the blunt impact forced entry time in seconds is greater than 0.116 T + 30, T being the thickness of the substrate in micrometers.

15. The forced-entry resistant window of any one of claims 12 to 14, wherein the substrate of the security fdm has an elongation at break of at least 500% and a tensile stress at 300% elongation of no more than15 MPa.

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