Piezoelectric (METH)acrylate adhesive laminate tapes

Abstract

The present invention relates to a piezoelectric (meth)acrylate adhesive laminate tape assembly. The adhesive laminate tape demonstrates excellent adhesive properties while maintaining good piezoelectric response.

Description

2024P00381PIEZOELECTRIC (METH)ACRYLATE ADHESIVE LAMINATE TAPESBACKGROUNDField

[0001] The present invention relates to a piezoelectric (meth)acrylate adhesive laminate tape assembly. The adhesive laminate tape demonstrates excellent adhesive properties while maintaining good piezoelectric response.Brief Description of Related Technology

[0002] To date, piezoelectric materials have been incorporated into adhesive resins and matrices, although with different objectives. Two common ones are: composites with piezoelectric ceramics and combination of piezoelectric and nonpiezoelectric polymers.

[0003] Piezoelectric ceramics have been mixed with polymeric resins to form composite materials. While this approach is widely known, in many cases, the polymeric resin is not used for its adhesive properties but rather as a binder. In this regard, the polymeric resin can improve the mechanical properties (otherwise, too brittle) and the processability of the piezoelectric systems (otherwise, difficult to process in general). See generally R.E. Newnham et al., “Connectivity and piezoelectric-pyroelectric composites”, Mat. Res. Bull., Vol. 13(5), pp. 525-36 (May 1978) and K. Uchino, “Piezoelectric Composites”, Reference Module in Materials Science and Materials Engineering. Oxford: Elsevier, pp. 1 -12 (2016).

[0004] Piezoelectric compositions are known to belong to a variety of different configurations. For instance, [0,3] composites, which can be cast or applied like paints, ordinarily contain a fluorinated polymer and piezoelectric particles. These composites may be cured and thereafter poled (such as under exposure to 3-5 kV / mm for a period of 10 minutes) prior to evaluating the piezoelectric properties. These composites show a piezoelectric coefficient (dss), oftentimes as high as about2024P0038130 pC / N. But, to the extent they once did, once cured the composites no longer show structural adhesive capabilities.

[0005] In addition, poling [0,3] composites can be complex and challenging. For instance, contact poling requires the use of a high applied electric field due to differences in constant (K) between the piezo particles (high K) and the surrounding polymer matrix (low K). These differences mean that the low dielectric polymer matrix shields the ceramic particles from the applied electric field, which translates to the required use of very high applied electric fields to pole the ceramic particles. The use of such high applied poling electric fields increases the likelihood of dielectric breakdown of the polymer matrix and of dielectric breakdown due to presence of defects (air bubbles, voids, fish eye, dust particles and the like) which will result in electrical shorting.

[0006] In addition, these high applied poling electric fields require a test specimen to be immersed in a silicone oil bath to minimise risk of dielectric breakdown in air. Because of this, limitations on the size of specimens and scale and practicality of contact poling a [0,3] composite film are imposed. Thus, contact poling can only be performed conveniently on small sample areas / thin films. Larger composite film areas require the use of larger applied poling electric fields, which increase the chances of shorting via defects found in larger area film.

[0007] Contact poling also requires the placement of electrodes on the composite surface. That is, a conductive metal electrode must be in full contact with the area of the composite to be poled. This can involve further difficult and expensive processing steps (such as metal (gold or silver) sputtering or use of gold metallised low roughness PET which is then pressure sandwiched onto the composite surface to ensure good surface contact of electrodes to composites). These additional processing steps preclude the use of the composite as an adhesive as the poling electrode cannot be in contact with the metal substrate to be adhesively bonded.

[0008] From a practical standpoint, it is difficult to reach an applied electric field sufficiently high enough to pole the piezo particles (typically the applied electric field2024P00381 must be much greater than the coercive field of the piezo particle to pole efficiently) which leaves the [0,3] composite with poor piezoelectric activity.

[0009] One may reduce the difference in dielectric constant of the piezo particles and the surrounding polymer matrix by for instance increasing the volume fraction of the piezo particles in the polymer matrix. But processing / dispersing such large amounts of filler into the polymer creates viscosity issues and wetting issues. These issues influence the possibility of air entrapment / voids at the fi Iler-poly mer interface, which can lead to film defects and porosity creation. These defects and porosity creation can result in dielectric breakdown and thus poor poling performance. Moreover, highly filled composites are more difficult to process, become brittle / reduced flexibility, and suffer from reduced design flexibility.

[0010] Piezoelectric materials are widely used in industry as receiver sensors (accelerometers, gyroscopes, shock wave sensors, impact sensors, stress-strain sensors and receiver transducers) and as emitters (level sensors, ultrasonic distance sensors, flow rate measurement sensors, transducers for non-destructive evaluation- SHM, sonar, hydrophones, for high intensity ultrasonic cleaning, for high intensity ultrasonic welding and as actuators). Piezoelectric materials are widely used in medical diagnosis (e.q., ultrasonic scan) and as medical tools (e.q., surgical knives, bubble detectors, aerosol production for inhalers, shock wave lithotripsy or as a cleaning tool). Consumer market applications for piezoelectric materials include speakers, pick-ups for instruments, microphones, lighters, keypads, printers, and the newly developed energy harvesters.

[0011] All of these applications have used piezoelectric materials (e.q., ceramics or polymers), which are then attached separately with adhesives.

[0012] Prior efforts in this connection include:

[0013] German Patent Document No. DE 10104605, which discloses an adhesive bond for structural members comprising a piezo particle (see the title, the abstract, claim 1) and which exemplifies the use of 56.2 percent of piezo particles and 43.8 percent of a thermoplastic polymer.2024P00381

[0014] International Patent Publication No. WO 2014 / 162976 discloses an electroacoustic transduction film, comprising a polymer composite piezoelectric body in which piezoelectric body particles are dispersed in a viscoelastic matrix formed of a polymer material having viscoelasticity at a normal temperature; and electrode layers disposed to interpose the polymer composite piezoelectric body therebetween, wherein an area fraction of the piezoelectric body particles in a contact surface with respect to the electrode layer is less than or equal to 50 percent (see the abstract, claim 1). The PCT ‘976 document exemplifies a composition comprising 75 percent of piezoelectric particles, 7.5 percent of a viscoelastic matrix and 17.5 percent of a solvent.

[0015] European Patent Document No. EP 3235016 is directed to and claims a piezoelectric adhesive composition comprising: a) from 3 percent to 30 percent of an adhesive matrix; b) from 5 to 85 percent of a piezoelectric component; and c) from 30 percent to 90 percent of a solvent, where all weight percentages are based on weight of the total weight of the composition, and where said piezoelectric component is in a piezoelectric phase.

[0016] International Patent Publication No. WO2016 / 097077 is directed to and claims an adhesive composition comprising: a) from 2 to 50 percent of an adhesive matrix; b) from 5 to 85 percent of a piezoelectric component selected from the group consisting of polyvinylidene difluoride (PVDF), polyvinylidene difluoride trifluoroethylene (P(VDF-TrFE)), polyvinylidene difluoride hexafluoropropylene (P(VDF-HFP)), polyvinylidene difluoride trifluoroethylene chlorofluoroethylene (P(VDF-TrFE-CFE)), where all weight percentages are based on weight of the total weight of the composition.

[0017] With respect to the PCT ‘077 document, observation of piezoelectric performance requires poling of the composition. And in this connection poling occurs after curing of the adhesive matrix. Once the adhesive matrix is cured no meaningful structural adhesive properties are retained. In other words, while the composition2024P00381 exhibits piezoelectric performance it no longer demonstrates any meaningful adhesive properties.

[0018] Similar to the PCT ‘077 document, U.S. Patent Application Publication No. US 2020 / 00303621 describes in sum and substance a [0,3] piezoelectric polymer composites prepared by polymerising a formulation of a dispersion of barium titanate piezo filler in a MMA monomer / HEMA monomer blend containing a radical initiator and an ionic liquid. The formulations are cast as films, allowed to cure at 60°C and corona poled, either after curing or as curing is occurring. Again, as with the PCT ‘077 document this course produces a piezoelectric polymer composite that demonstrates no meaningful adhesive properties.

[0019] JP2015186909, EP4331838, JP2020165887 and JP2015101673 each describe laminated sheets having a piezoelectric component. JP2015186909 describes a laminated sheet having a cured adhesive product which acts as a pressure-sensitive adhesive composition. In JP2015186909, the adhesive is present in an already cured state. And while such cured adhesives may function as pressure sensitive adhesives, once the adhesive is cured, they are no longer in a curable form and as such cannot cure to form bonds having structural strength. EP4331838 describes a piezoelectric laminated film with a transparent adhesive sheet for use in touch panels. JP2020165887 describes a piezoelectric laminate sheet comprising a first conductive layer, a piezoelectric layer, an adhesive layer, a release layer, and a second conductive layer. JP2015101673 describes a double-sided pressure-sensitive adhesive sheet for piezoelectric films, which has pressure-sensitive adhesive layers which acts as a pressure-sensitive adhesive composition. In these disclosures, the stickiness and viscoelastic properties of the adhesive layers provide a tack. This tackiness gives adhesion but the bonds formed provide no structural strength, such as sufficient shear or tensile strength. No meaningful structural adhesive properties are possible.

[0020] Thus, it is seen that the state of the art fails to provide a piezoelectric structure which includes an adhesive composition, where the piezoelectric structure2024P00381(1) adheres to a substrate on its own without using a separate adhesive to adhere it and (2) is able to act as an adhesive, sealant or coating, particularly a structural adhesive having good adhesion strength, while at the same time providing good piezoelectric response.SUMMARY

[0021] A solution to that failure has been provided here.

[0022] The present invention relates to a curable adhesive laminate tape comprising: a first release liner; a first adhesive composition; a piezoelectric polymer film or piezoelectric polymer composite film having: a film thickness of from about 1 pm to about 500 pm, from about 10 pm to about 150 pm, from about 20 pm to about 110 pm, or from about 25 pm to about 75 pm, a piezoelectric coefficient d33 value of from about 5 to about 40 picocoulombs / Newton (pC / N), from about 10 to about 35 pC / N, or from about 20 to about 30 pC / N, each measured according to National Physical Laboratory Measurement Good Practice Guide No. 44: Measuring Piezoelectric d33 Coefficients Using Direct Method (2001), a modulus of from about 2,000 to about 2,700 Pascals (Pa), and a dielectric constant of from about 8 to about 50, such as about 12.5 to about 13; a second adhesive composition; and a second release liner.

[0023] In the curable adhesive laminate tape of the invention, the first and / or second adhesive composition is a curable adhesive composition. Desirably each is a curable adhesive composition. Here at least one, desirably each, of the first adhesive composition and the second adhesive composition is based on a (meth)acrylate2024P00381 matrix. The (meth)acrylate matrix that forms the adhesive layer(s) of the present invention is (are each) a curable (meth)acrylate matrix. In particular, the (meth)acrylate matrix takes the form of a curable (meth)acrylate composition within a matrix. A matrix is desirably formed by at least one film former together with the curable (meth)acrylate composition. The film former imparts a matrix form within which the curable (meth)acrylate composition remains curable. In other words, once the film former has formed a film, the (meth)acrylate composition remains curable. Therefore, once assembled in the curable adhesive laminate tape according to the invention, the film former in the (meth)acrylate adhesive composition will have already formed a film. In the laminate of the invention the film former is typically in film form. Suitable (meth)acrylates for use in the adhesive layer(s) / (meth)acrylate matrix of the present invention are set out below. Desirably the (meth)acrylates used in the adhesive layer(s) / (meth)acrylate matrix of the present invention are (meth)acrylate monomers.

[0024] When only one of the adhesive layers is a (meth)acrylate matrix, the other adhesive layer may be a curable epoxy matrix or a curable cyanoacrylate matrix. Such curable epoxy matrix or curable cyanoacrylate matrix is desirably formed by at least one film former together with a curable epoxy composition or a curable cyanoacrylate composition. The film former imparts a matrix form within which the curable epoxy composition or the curable cyanoacrylate composition remains curable. In the laminate of the invention the film former is typically in film form.

[0025] In practice, the piezoelectric polymer film or piezoelectric polymer laminate film should be electroded at the upper and lower surfaces of the film.

[0026] When cured the adhesive laminate tape demonstrates one or more of the following physical properties:• lap shear strength on stainless steel of from about 1 .0 to about 11 (N / mm2or MPa), when measured according to ASTM D1002-10(2019),2024P00381• after exposure to room temperature aging conditions for a period of time of up to 6 weeks, lap shear strength on stainless steel of from about 1 .0 to about 11 (N / mm2or MPa), when measured according to ASTM D1002-10(2019),• after exposure to accelerated aging conditions of 80°C for a period of time of up to 6 weeks, lap shear strength on stainless steel of from about 3.5 to about 9 (N / mm2or MPa), when measured according to ASTM D1002-10(2019),• after exposure to accelerated aging conditions of 40°C and 98% relative humidity for a period of time of up to 6 weeks, lap shear strength on stainless steel of from about 4.0 to about 8.0 (N / mm2or MPa), when measured according to ASTM D1002-10(2019),• up to 180 percent adhesion retention on stainless steel after exposure to accelerated aging conditions of 80°C for a period of time of up to 6 weeks;• up to 71 percent d33 coefficient retention on stainless steel after exposure to accelerated aging conditions of 80°C for a period of time of up to 6 weeks;• up to 110 percent adhesion retention on stainless steel after exposure to accelerated aging conditions of 40°C and 98% relative humidity for a period of time of up to 6 weeks;• up to 173 percent d33 coefficient retention on stainless steel after exposure to accelerated aging conditions of 40°C and 98% relative humidity for a period of time of up to 6 weeks;• when disposed and cured between stainless steel substrates a d33 coefficient across the stainless steel substrates of from about 1 .5 to about 11 , such as about a d33 coefficient of about 8 for (meth)acrylate-based adhesive layers after exposure to room temperature aging conditions for a period of time of 2 weeks, when measured according to National Physical Laboratory Measurement Good Practice Guide No. 44: Measuring Piezoelectric d33 Coefficients Using Direct Method (2001).2024P00381

[0027] The present invention relates to the use of the curable adhesive laminate tape as described herein as a sensor to monitor structural health of adhesively bonded structures.

[0028] In addition, the present invention relates to the use of a piezoelectric adhesive laminate tape as an adhesive, sealant or coating with sensorised properties suitable for condition monitoring the structural health of adhesively bonded / sealed / coated industrial assets. For example, the present invention relates to the use of a piezoelectric adhesive laminate tape as an adhesive, sealant or coating with sensorised properties suitable for condition monitoring the structural health of fluid flow pathways such as pipes. The present invention also relates to the use of a piezoelectric adhesive laminate tape according to the invention in a monitoring system, such as for fluid flow pathways, for example for monitoring pipes. Such systems comprise monitoring equipment which can detect changes to the substrate to which it is attached, for example to fluid flow pathway(s), where those changes are communicated to the monitoring equipment through the piezoelectric adhesive laminate tape according to the invention. In such cases the piezoelectric adhesive laminate tape according to the invention may be considered to be a sensor where piezoelectric changes are detected. Monitoring may be local or remote and may be wireless.

[0029] Further, the present invention also encompasses a device comprising a piezoelectric adhesive laminate tape disposed between two conductive elements.

[0030] Accordingly, an adhesive laminate tape with piezoelectric properties brought about through pre-corona poling and electroding of the piezoelectric component is provided. In this way, once constructed the adhesive tape film does not require poling to exhibit piezoelectric properties while at the same time exhibiting adhesive properties.

[0031] The present invention also encompasses a method for monitoring assets, such as in a fluid flow pathway(s), the method comprising:2024P00381 applying the laminate tape according to the invention to a surface of a portion of an asset such as a fluid flow pathway for example a pipe; providing monitoring equipment, such as a remote device, to receive signals generated by the piezoelectric layer of the laminate tape, and receiving generated signals for monitoring and reporting conditions in the fluid flow pathway(s). In order to apply the laminate tape according to the invention to a surface of a portion of an asset, the first and / or second release liner must be removed.

[0032] The present invention also encompasses a system for monitoring assets such as in a fluid flow pathway(s) for example in pipes. The system comprises the application of the inventive curable adhesive laminate tape, which comprises: a first release liner; a first adhesive composition (which may comprise a (meth)acrylate matrix); a piezoelectric polymer film or piezoelectric polymer composite film having: a film thickness of from about 1 pm to about 500 pm, a piezoelectric coefficient d33 value of from about 5 to about 40 picocoulombs / Newton (pC / N), from about 10 to about 35 pC / N, or from about 20 to about 30 pC / N, each when measured according to National Physical Laboratory Measurement Good Practice Guide No. 44: Measuring Piezoelectric d33 Coefficients Using Direct Method (2001), a modulus of from about 2,000 to about 2,700 Pascals (Pa), and a dielectric constant of from about 8 to about 50; a second adhesive composition (which may comprise a (meth)acrylate matrix); and a second release liner, to a surface of a portion of a substrate such as an industrial asset including a fluid flow pathway for example a pipe. Prior to application of the inventive curable adhesive laminate tape, the first and / or second release liner must be removed. The system may include monitoring equipment, such as a remote device, to receive signals2024P00381 generated by the piezoelectric layer of the laminate tape. The monitoring equipment will typically receive generated signals and utilise those for monitoring and reporting conditions in the substrate such as in an asset including a fluid pathway for example a pipe.BRIEF DESCRIPTION OF THE FIGURES

[0033] FIG. 1 illustrates a schematic diagram of a piezoelectric adhesive laminate tape according to the present invention.

[0034] FIG. 2 depicts visually a bar chart representing adhesive strength coupled with a curve showing piezoelectric coefficient d33 value, each over time when aged at room temperature, using a piezoelectric laminated tape comprising a piezoelectric layer of 30 pm and a fixed (meth)acrylate adhesive layer of 50 pm.

[0035] FIG. 3 depicts visually a bar chart representing adhesive strength coupled with a curve showing piezoelectric coefficient d33 value, each over time when aged at room temperature, using a piezoelectric laminated tape comprising a piezoelectric layer of 50 pm and a fixed (meth)acrylate adhesive layer of 50 pm.

[0036] FIG. 4 depicts visually a bar chart representing adhesive strength coupled with a curve showing piezoelectric coefficient d33 value, each over time when aged at room temperature, using a piezoelectric laminated tape comprising a piezoelectric layer of 80 pm and a fixed (meth)acrylate adhesive layer of 50 pm.

[0037] FIG. 5 depicts visually a bar chart representing adhesive strength coupled with a curve showing piezoelectric coefficient d33 value, each over time when aged at room temperature, using a piezoelectric laminated tape comprising a piezoelectric layer of 110 pm and a fixed (meth)acrylate adhesive layer of 50 pm.

[0038] FIG. 6 depicts visually a bar chart representing adhesive strength coupled with a curve showing piezoelectric coefficient d33 value, each over a period of time of 6 weeks when aged at room temperature, with a piezoelectric layer of 80 pm for the (meth)acrylate adhesive layers at a thickness of 30 pm.

[0039] FIG. 7 depicts visually a bar chart representing adhesive strength coupled with a curve showing piezoelectric coefficient d33 value, each over a period of2024P00381 time of 6 weeks when aged at room temperature, with a piezoelectric layer of 80 pm for the (meth)acrylate adhesive layers at a thickness of 50 pm.

[0040] FIG. 8 depicts visually a bar chart representing adhesive strength coupled with a curve showing piezoelectric coefficient, each over time, at a piezoelectric layer of 80 pm for the (meth)acrylate adhesive layers at a thickness of 100 pm.

[0041] FIG. 9 depicts visually a bar chart representing adhesive strength coupled with a curve showing piezoelectric coefficient, each over time at a temperature of 40°C and a relative humidity of 98%, at a piezoelectric layer of 80 pm for the (meth)acrylate adhesive layers at a thickness of 30 pm.

[0042] FIG. 10 depicts visually a bar chart representing adhesive strength coupled with a curve showing piezoelectric coefficient, each over time at a temperature of 80°C, at a piezoelectric layer of 80 pm for the (meth)acrylate adhesive layers at a thickness of 30 pm.

[0043] FIG. 11 depicts a schematic of a system for monitoring assets. The system comprises monitoring equipment, such as signal harvesting circuitry, for use with the inventive piezoelectric adhesive laminate tape of the invention. The piezoelectric adhesive laminate tape of the invention is depicted bonded between two metal substrates (8, 9). The release I iner(s) is(are) removed such that the adhesive layer(s) in use ordinarily bonds to (or, together) one or two substrates e.g. a metal substrate as in FIG 11. In this Example, the inventive piezoelectric adhesive laminate tape of the invention is depicted as sandwiched between two metal substrates (8, 9) and comprises: a first adhesive composition (an adhesive composite layer 2); a piezoelectric polymer film or piezoelectric polymer composite film 4; a second adhesive composition (an adhesive composite layer 6). In this Example, the piezoelectric polymer film or piezoelectric polymer composite film is electroded at the upper and lower surfaces of the film via conductive electrode layers (3,5).2024P00381DETAILED DESCRIPTION

[0044] As noted above, the present invention relates to a piezoelectric adhesive laminate tape. The piezoelectric adhesive laminate tape demonstrates adhesive properties and piezoelectric properties. And the piezoelectric adhesive laminate tape is curable and once cured demonstrates adhesive properties and piezoelectric properties. The piezoelectric adhesive laminate tape may also demonstrate coating and / or sealant properties depending on the application to which the laminate tape is placed. As described herein, a curable adhesive laminate tape of the invention adheres to a substrate. The substrate may be a metallic substrate, for example, steel, aluminium, copper, iron, brass, bronze, titanium, nickel, tin, zinc or lead. (Adhering to one of more substrate(s) requires removal of the first and / or second release liner.)

[0045] The piezoelectric adhesive laminate tape comprises: a first release liner 1; a first adhesive composition 2; a piezoelectric polymer film or piezoelectric polymer composite film 3; a second adhesive composition 2’; and a second release liner T. (See FIG. 1 .)

[0046] Here at least one, desirably each, of the first adhesive composition and the second adhesive composition is based on a (meth)acrylate composition, desirably a curable (meth)acrylate composition.

[0047] When only one of the adhesive layers is a (meth)acrylate composition, the other adhesive layer may be a cyanoacrylate matrix or an epoxy matrix, desirably a curable cyanoacrylate matrix or a curable epoxy matrix..

[0048] In practice, the piezoelectric polymer film or piezoelectric polymer composite film should be electroded at the upper and lower surfaces of the film. (See FIG. 1 , 3,5 and FIG. 11 , 3, 5.) The electrodes may be constructed from conductive materials that do not substantially interfere with the performance of the adhesive layer(s). For instance, the electrodes may be constructed from conductive materials that do not appreciably participate in RedOx reactions, such as conductive organic2024P00381 polymers. Examples of such conductive organic polymers include PEDOT-PSS (blend of two distinct polymers: poly(3,4-ethylenedioxythiophene) (“PEDOT”) and polystyrene sulfonate (“PSS”)), surface treated conductive metals or conductive carbon nanostructures.

[0049] The piezoelectric polymer film or piezoelectric polymer composite film should have:• a film thickness of from about 1 pm to about 500 pm, such as from about 10 pm to about 150 pm, desirably from about 20 pm to about 110 pm, particularly from about 25 pm to about 75 pm, optionally the film thickness may be about 30 pm, further optionally the film thickness may be about 50 pm, further optionally the film thickness may be about 80 pm, further optionally the film thickness may be about 110 pm,• a piezoelectric coefficient d33 value of from about 5 to about 40 picocoulombs / Newton (pC / N), such as from about 10 to about 35 pC / N, desirably from about 20 to about 30 pC / N, each measured according to National Physical Laboratory Measurement Good Practice Guide No. 44: Measuring Piezoelectric d33 Coefficients Using Direct Method (2001), optionally the piezoelectric coefficient d33 value is from about 2 to about 20 pC / N, further optionally the piezoelectric coefficient d33 value is from about 2 to about 15 pC / N,• a modulus of from about 2,000 to about 2,700 Pascals (Pa), and• a dielectric constant of from about 8 to about 50, such as about 12.5 to about 13.

[0050] At least one of the first adhesive composition or the second adhesive composition of the piezoelectric adhesive laminate tape is curable, and when cured the adhesive laminate tape demonstrates one or more of the following physical properties:• lap shear strength on stainless steel of from about 1 .0 to about 11 (N / mm2or MPa), when measured according to ASTM D1002-10(2019),2024P00381• after exposure to room temperature aging conditions for a period of time of up to 6 weeks, lap shear strength on stainless steel of from about 1 .0 to about 11 (N / mm2or MPa), when measured according to ASTM D1002-10(2019),• after exposure to accelerated aging conditions of 80°C for a period of time of up to 6 weeks, lap shear strength on stainless steel of from about 3.5 to about 9 (N / mm2or MPa), when measured according to ASTM D1002-10(2019),• after exposure to accelerated aging conditions of 40°C and 98% relative humidity for a period of time of up to 6 weeks, lap shear strength on stainless steel of from about 4.0 to about 8.0 (N / mm2or MPa), when measured according to ASTM D1002-10(2019),• up to 180 percent adhesion retention on stainless steel after exposure to accelerated aging conditions of 80°C for a period of time of up to 6 weeks;• up to 71 percent d33 coefficient retention on stainless steel after exposure to accelerated aging conditions of 80°C for a period of time of up to 6 weeks;• up to 110 percent adhesion retention on stainless steel after exposure to accelerated aging conditions of 40°C and 98% relative humidity for a period of time of up to 6 weeks;• up to 173 percent d33 coefficient retention on stainless steel after exposure to accelerated aging conditions of 40°C and 98% relative humidity for a period of time of up to 6 weeks;• when disposed and cured between stainless steel substrates a d33 coefficient across the stainless steel substrates of from about 1 .5 to about 11 , such as about a d33 coefficient of about 8 for (meth)acrylate-based adhesive layers after exposure to room temperature aging conditions for a period of time of 2 weeks, when measured according to National Physical Laboratory Measurement Good Practice Guide No. 44: Measuring Piezoelectric d33 Coefficients Using Direct Method (2001).2024P00381

[0051] When cured (i.e. when the at least one curable (meth)acrylate adhesive composition has cured to a substrate), the adhesive laminate tape demonstrates one or more of the following physical properties:• lap shear strength on stainless steel of from about 1 .0 to about 11 (N / mm2or MPa), when measured according to ASTM D1002-10(2019), o The lap shear strength on stainless steel may be from about 2.0 to about 5.0 (N / mm2or MPa) when the laminate tape comprises at least one adhesive composition layer(s) (such as an adhesive composition comprising a (meth)acrylate matrix) of 50 pm with a piezoelectric polymer film or piezoelectric polymer composite film (e.g. PVDF layer) of 30 pm. o The lap shear strength on stainless steel may be from about 1 .5 to about 3.0 (N / mm2or MPa) when the laminate tape comprises at least one adhesive composition layer(s) (such as an adhesive composition comprising a (meth)acrylate matrix) of 50 pm with a piezoelectric polymer film or piezoelectric polymer composite film (e.g. PVDF layer) of 50 pm. o The lap shear strength on stainless steel may be from about 2.0 to about 5.0 (N / mm2or MPa) when the laminate tape comprises at least one adhesive composition layer(s) (such as an adhesive composition comprising a meth(acrylate) matrix) of 50 pm with a piezoelectric polymer film or piezoelectric polymer composite film (e.g. PVDF layer) of 80 pm. o The lap shear strength on stainless steel may be from about 1 .5 to about 4.0 (N / mm2or MPa) when the laminate tape comprises at least one adhesive composition layer(s) (such as an adhesive composition comprising a (meth)acrylate matrix) of 50 pm with a piezoelectric polymer film or piezoelectric polymer composite film (e.g. PVDF layer) of 110 pm.2024P00381 o The lap shear strength on stainless steel may be from about 3.0 to about 7.0 (N / mm2or MPa) when the laminate tape comprises at least one adhesive composition layer(s) (such as an adhesive composition comprising a (meth)acrylate matrix) of 30 pm with a piezoelectric polymer film or piezoelectric polymer composite film (e.g. PVDF layer) of 80 pm. o The lap shear strength on stainless steel may be from about 4.0 to about 6.5 (N / mm2or MPa) when the laminate tape comprises at least one adhesive composition layer(s) (such as an adhesive composition comprising a (meth)acrylate matrix) of 50 pm with a piezoelectric polymer film or piezoelectric polymer composite film (e.g. PVDF layer) of 80 pm. o The lap shear strength on stainless steel may be from about 4.0 to about 6.0 (N / mm2or MPa) when the laminate tape comprises at least one adhesive composition layer(s) (such as an adhesive composition comprising a (meth)acrylate matrix) of 100 pm with a piezoelectric polymer film or piezoelectric polymer composite film (e.g. PVDF layer) of 80 pm.• after exposure to room temperature aging conditions for a period of time of up to 6 weeks, lap shear strength on stainless steel of from about 1 .0 to about 11 (N / mm2or MPa), when measured according to ASTM D1002-10(2019), o The lap shear strength on stainless steel after exposure to room temperature aging conditions for a period of time of up to 6 weeks may be from about 2.0 to about 5.0 (N / mm2or MPa) when the laminate tape comprises at least one adhesive composition layer(s) (such as an adhesive composition comprising a (meth)acrylate matrix) of 50 pm with a piezoelectric polymer film or piezoelectric polymer composite film (e.g. PVDF layer) of 30 pm.2024P00381 The lap shear strength on stainless steel after exposure to room temperature aging conditions for a period of time of up to 6 week may be from about 1 .5 to about 3.0 (N / mm2or MPa) when the laminate tape comprises at least one adhesive composition layer(s) (such as an adhesive composition comprising a (meth)acrylate matrix) of 50 pm with a piezoelectric polymer film or piezoelectric polymer composite film (e.g. PVDF layer) of 50 pm. The lap shear strength on stainless steel after exposure to room temperature aging conditions for a period of time of up to 6 weeks may be from about 2.0 to about 5.0 (N / mm2or MPa) when the laminate tape comprises at least one adhesive composition layer(s) (such as an adhesive composition comprising a (meth)acrylate matrix) of 50 pm with a piezoelectric polymer film or piezoelectric polymer composite film (e.g. PVDF layer) of 80 pm. The lap shear strength on stainless steel after exposure to room temperature aging conditions for a period of time of up to 6 week may be from about 1 .5 to about 4.0 (N / mm2or MPa) when the laminate tape comprises at least one adhesive composition layer(s) (such as an adhesive composition comprising a (meth)acrylate matrix) of 50 pm with a piezoelectric polymer film or piezoelectric polymer composite film (e.g. PVDF layer) of 110 pm. The lap shear strength on stainless steel after exposure to room temperature aging conditions for a period of time of up to 6 week may be from about 3.0 to about 7.0 (N / mm2or MPa) when the laminate tape comprises at least one adhesive composition layer(s) (such as an adhesive composition comprising a (meth)acrylate matrix) of 30 pm with a piezoelectric polymer film or piezoelectric polymer composite film (e.g. PVDF layer) of 80 pm.2024P00381 o The lap shear strength on stainless steel after exposure to room temperature aging conditions for a period of time of up to 6 week may be from about 4.0 to about 6.5 (N / mm2or MPa) when the laminate tape comprises at least one adhesive composition layer(s) (such as an adhesive composition comprising a (meth)acrylate matrix) of 50 pm with a piezoelectric polymer film or piezoelectric polymer composite film (e.g. PVDF layer) of 80 pm. o The lap shear strength on stainless steel after exposure to room temperature aging conditions for a period of time of up to 6 week may be from about 4.0 to about 6.0 (N / mm2or MPa) when the laminate tape comprises at least one adhesive composition layer(s) (such as an adhesive composition comprising a (meth)acrylate matrix) of 100 pm with a piezoelectric polymer film or piezoelectric polymer composite film (e.g. PVDF layer) of 80 pm.• after exposure to accelerated aging conditions of 80°C for a period of time of up to 6 weeks, lap shear strength on stainless steel of from about 3.5 to about 9 (N / mm2), when measured according to ASTM D1002-10(2019), o The lap shear strength on stainless steel after exposure to accelerated aging conditions of 80°C for a period of time of up to 6 weeks may be from about 4.0 to about 8.0 (N / mm2or MPa) when the laminate tape comprises at least one adhesive composition layer(s) (such as an adhesive composition comprising a (meth)acrylate matrix) of 30 pm with a piezoelectric polymer film or piezoelectric polymer composite film (e.g. PVDF layer) of 80 pm.• after exposure to accelerated aging conditions of 40°C and 98% relative humidity for a period of time of up to 6 weeks, lap shear strength on stainless steel of from about 4.0 to about 8.0 (N / mm2or MPa), when measured according to ASTM D1002-10(2019)2024P00381 o The lap shear strength on mild steel after exposure to accelerated aging conditions of 40°C and 98% relative humidity for a period of time of up to 6 weeks may be from about 4.0 to about 7.0 (N / mm2or MPa) when the laminate tape comprises at least one adhesive composition layer(s) (such as an adhesive composition comprising a (meth)acrylate matrix) of 30 pm with a piezoelectric polymer film or piezoelectric polymer composite film (e.g. PVDF layer) of 80 pm.• up to 180 percent adhesion retention on stainless steel after exposure to accelerated aging conditions of 80°C for a period of time of up to 6 weeks;• up to 71 percent d33 coefficient retention on stainless steel after exposure to accelerated aging conditions of 80°C for a period of time of up to 6 weeks;• up to 110 percent adhesion retention on stainless steel after exposure to accelerated aging conditions of 40°C and 98% relative humidity for a period of time of up to 6 weeks;• up to 173 percent d33 coefficient retention on stainless steel after exposure to accelerated aging conditions of 40°C and 98% relative humidity for a period of time of up to 6 weeks;• when disposed and cured between stainless steel substrates a d33 coefficient across the stainless steel substrates of from about 1 .5 to about 11 , such as about a d33 coefficient of about 8 for (meth)acrylate-based adhesive layers after exposure to room temperature aging conditions for a period of time of 2 weeks, when measured according to National Physical Laboratory Measurement Good Practice Guide No. 44: Measuring Piezoelectric d33 Coefficients Using Direct Method (2001).

[0052] The piezoelectric adhesive laminate tape according to the present invention thus demonstrates adhesive properties and piezoelectric properties.

[0053] Components of the piezoelectric adhesive laminate tape are described in detail below.2024P00381Piezoelectric Component

[0054] A piezoelectric adhesive laminate tape according to the present invention comprises an organic or inorganic piezoelectric component. The piezoelectric component is sandwiched as a layer between two adhesive layers, each of whose outer surfaces which prior to use is disposed under a release liner. When the release liner(s) is(are) removed the adhesive layer(s) in use ordinarily bond to(together) one or two substrates.

[0055] In practice, the piezoelectric polymer film or piezoelectric polymer laminate film should be electroded at the upper and lower surfaces of the film. By placement of the electrodes at the respective surfaces, an electrical signal arising as a result of an applied mechanical stress / strain on the cured piezoelectric adhesive composite or bonded / sealed / coated asset may be harvested. This may be beneficial in the commercial context of monitoring fluid flow pathways. It may also be beneficial within other monitoring systems such as those monitoring industrial assets.

[0056] As noted above, the electrodes may be constructed from conductive materials that do not substantially interfere with the performance of the adhesive layer(s). For instance, the electrodes may be constructed from conductive materials that do not appreciably participate in RedOx reactions, such as conductive organic polymers. Examples of such conductive organic polymers include poly(3,4- ethylenedioxythiophene) (“PEDOT”) and polystyrene sulfonate (“PSS”) (“PEDOT- PSS”), surface treated conductive metals or conductive carbon nanostructures. The electrodes may be constructed from copper or silver, such as in the form of a copper tape or film, or as a coating.

[0057] The piezoelectric components provide novel properties to the adhesive laminate tape. Yet in carrying out the present invention, unlike technology that existed heretofore, exposure of the inventive adhesive laminate tape to poling conditions is unnecessary to achieve the so-described piezoelectric properties.

[0058] The piezoelectric component may be formed as a layer in a variety of thicknesses. For instance, the piezoelectric component may be used in a film2024P00381 thickness of from about 1 m to about 500 pm, from about 10 pm to about 150 pm, from about 20 pm to about 110 pm, or from about 25 pm to about 75 pm. Certain thicknesses - e.q., 30 pm, 50 pm, 80 pm, 100 pm or 120 pm -- are particularly desirable. Each of these film thicknesses for PVDF is available from PolyK Technologies, LLC, State College, PA, US. Other commercially available sources include one or more of Alfa Chemistry Fluoropolymers: PVDF Piezoelectric Film with 100 nm thick Aluminum Electrode - Fluoropolymers / Alfa Chemistry; Precision acoustics: PVDF - Precision Acoustics: GoodFellow: Piezo-electric Film PVDF Film I Goodfellow: T.E. Connectivity: Piezo Film Sheets I TE Connectivity: Arkema Piezotech; and Kureha.

[0059] In some instances, it may be desirable to include in the piezoelectric layer a piezoelectric filler, such as a ceramic powder or a polymer, which may be dissolved or dispersed, and which may have a treated surface.

[0060] The type and quantity of the piezoelectric filler added to the piezoelectric layer can have an effect on the piezoelectric response of the piezoelectric adhesive laminate tape.

[0061] Suitable commercially available piezoelectric fillers to be used in the present invention are for example PZT from T & Partners Praha and PVDF Kynar 740 from Arkema. Additional piezoelectric components may be sourced from PolyK Technologies, LLC, State College, PA, US.

[0062] The piezoelectric component comprises a piezoelectric polymer film or piezoelectric polymer composite film constructed from one or more fluorinated polymers, such as any one of the following polymers (listed here together with their respective dielectric constants): polyvinylidene difluoride -12-13 polyvinylidene difluoride trifluoroethylene -8 polyvinylidene difluoride hexafluoropropylene -10 polyvinylidene difluoride chlorofluoroethylene -20-502024P00381 polyvinylidene fluoride-co-trifluoroethylene-co- ~4.5 hexafluoropropylene polyvinylidene fluoride-co-trifluoroethylene-co- -20-50 chlorofluoroethylene

[0063] The piezoelectric component is desirably constructed from polyvinylidene difluoride. The piezoelectric component may be constructed from polyvinylidene difluoride having a thickness of 30 pm. The piezoelectric component may be constructed from polyvinylidene difluoride having a thickness of 50 pm. The piezoelectric component may be constructed from polyvinylidene difluoride having a thickness of 80 pm. The piezoelectric component may be constructed from polyvinylidene difluoride having a thickness of 110 pm.Adhesive Layerts)

[0064] A piezoelectric adhesive laminate tape according to the present invention comprises at least two adhesive layers. The adhesive layer(s) sandwich the piezoelectric component in the form of a layer. The adhesive layer(s) may be provided at a thickness of about 10 pm to about 200 pm, preferably about 20 pm to about 150 pm. The adhesive layer(s) may be provided at a thickness of about 30 pm. The adhesive layer(s) may be provided at a thickness of about 50 pm. The adhesive layer(s) may be provided at a thickness of about 100 pm.

[0065] The adhesive layer(s) used in the piezoelectric adhesive laminate tape may be selected from (meth)acrylate, such as an anaerobic curable system or a light curable adhesive system. At least one, desirably each, of the adhesive layer(s) used in the piezoelectric adhesive laminate tape may be selected from a (meth)acrylate matrix. In the piezoelectric adhesive laminate tape of the invention, the (meth)acrylate matrix is a curable (meth)acrylate matrix. In particular, the (meth)acrylate matrix takes the form of a curable (meth)acrylate composition within a matrix. A matrix is desirably formed by at least one film former together with the curable (meth)acrylate composition. The film former imparts a matrix form within2024P00381 which the curable (meth)acrylate composition remains curable. In other words, once the film former has formed a film, the (meth)acrylate composition remains curable. Therefore, once assembled in the curable adhesive laminate tape according to the invention, the film former in the (meth)acrylate adhesive composition will have already formed a film. Desirably the (meth)acrylates used in the adhesive layer(s) / (meth)acrylate matrix of the present invention are (meth)acrylate monomers.

[0066] In this regard, the (meth)acrylate matrix can be pre-applied to an article and then later cured. The (meth)acrylate matrix may be tacky when uncured. When only one of the adhesive layers is an (meth)acrylate matrix, the other adhesive layer may be a cyanoacrylate matrix or an epoxy matrix, desirably a curable cyanoacrylate matrix or a curable epoxy matrix. Such curable cyanoacrylate matrix or curable epoxy matrix is desirably formed by at least one film former as described herein together with a curable cyanoacrylate matrix or a curable epoxy composition.

[0067] Suitable (meth)acrylates for use in the present invention are selected from aliphatic, cycloaliphatic, and aromatic (meth)acrylates, and hydrogenated aromatic (meth)acrylates. The (meth)acrylates may be mono-(meth)acrylates or poly(meth)acrylates.

[0068] Examples of suitable (meth)acrylates include triethylene glycol dimethacrylate (“TGM”), alkoxylated hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tricyclodecane dimethanol diacrylate, dicyclopentadienyl methacrylate, ethoxylated bisphenol A di(meth)acrylate, tris (2-hydroxy ethyl) isocyanurate triacrylate, polybutadiene urethane dimethacrylate and polybutadiene dimethacrylate and epoxy acrylate resins, which are all commercially available from Sartomer Company, Inc.

[0069] Other suitable (meth)acrylates include 2-[3-(2H-benzotriazol-2-yl)-4- hydroxyphenyl]ethyl methacrylate, 2-(diethylamino)ethyl acrylate, 2-N- morpholinoethyl methacrylate, 2-(dimethylamino)ethyl methacrylate, 2- (diethylamino)ethyl methacrylate, ethyl 3-(2-amino-3-pyridyl)-acrylate, (E)-methyl 3-2024P00381(2-arnino-5-methylpyridin-3-yl)acrylate, methyl 3-(2-amino-4-methoxypyridin-3- yl)acrylate, which are all commercially available from Aldrich.

[0070] (Meth)acrylated polyurethanes and novolac polysters may be used as well.

[0071] (Meth)acrylated polyurethanes may be used, an example of which includes:where n is an integer from 2 to 10 for example a compound of the above formula having a molecular weight of about 6,000 g / mol may have a melting point of about 75 to about 85°C.

[0072] Novolac vinyl esters may be used, an example of which includes:where n is an integer from 2-10. For example a compound of the above formula having a molecular weight of about 6,000 g / mol may have a melting point of about 75 to about 85°C.

[0073] And further (meth)acrylates include hydroxypropyl methacrylate (“HPMA”), hydroxyethylmethacrylate (“HEMA”), tetrahydrofurfuryl acrylate, zinc acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethyl hexyl (meth)acrylate, isodecyl (meth)acrylate, n-lauryl (meth)acrylate, alkyl (meth)acrylate, tridecyl(meth)acrylate, n-stearyl (meth)acrylate, cyclohexyl(meth)acrylate, tetrahydrofurfuryl-(meth)acrylate, 2-phenoxy ethyl(meth)acrylate,2024P00381 isobornyl(meth)acrylate, 1 ,4-butanediol di(meth)acrylate, 1 ,6-hexanediol di(meth)acrylate, 1 ,9-nonandiol di(meth)acrylate, perfluorooctylethyl (meth)acrylate, 1 ,10-decandiol di(meth)acrylate, nonylphenol polypropoxylate (meth)acrylate, and polypentoxylate tetrahydrofurfuryl acrylate, which are all commercially available from Kyoeisha Chemical Co.

[0074] Additional suitable (meth)acrylates include polycarbonate urethane diacrylate available from Negami Chemical Industries Co., Ltd; acrylated aliphatic urethane oligomers available from Radcure Specialities, Inc; and polyester acrylate oligomers available from Radcure Specialities, Inc.

[0075] Referring back to (meth)acrylated polyurethanes, some may be termed (meth)acrylate-functionalized urethane resins, which may be made with an isophorone diisocyanate segment. For instance, a polyester of hexanedioic acid, diethylene glycol, terminated with isophorone diisocyanate, capped with 2- hydroxyethyl acrylate (CAS 72121-94-9) and a hydroxy terminated polybutadiene terminated with isophorone diisocyanate, capped with 2-hydroxyethyl acrylate are appropriate examples.

[0076] Other (meth)acrylate-functionalized urethane resins may be made more generally. For instance, the (meth)acrylate-functionalized urethane resins may be formed by reacting a polyol with a diisocyanate, to form a polyurethane comprising free isocyanato groups, and subsequently reacting the so-formed polyurethane comprising free isocyanoto groups with a hydroxyl functionalised (meth)acrylate component, to form a (meth)acrylate-functionalized urethane resin.

[0077] The (meth)acrylate-functionalized urethane resins may be in the solid state and in which case has a molecular weight in the range of from about 5,000 g / mol to about 35,000 g / mol, and has a melting point in the range of from about 50°C to about 80°C. The term “solid” means in a solid state within the temperature range of from about 5°C to 40°C, suitably in a solid state at room temperature and at atmospheric pressure. Solid state is defined as the state of matter in which materials are not fluid but retain their boundaries without support, the atoms or molecules2024P00381 occupying fixed positions with respect to each other and unable to move freely. Desirably, the (meth)acrylate is in the solid phase at room temperature.

[0078] Suitably, the polyol has a molecular weight in the range of from 1 ,000 to 10,000 g / mol. For example, the polyol may be a polyester polyol, such as the reaction product of a polybasic carboxylic acid selected from a dibasic to a tetrabasic carboxylic acid with a polyhydric alcohol selected from a dihydric, trihydric, tetrahydric or pentahydric alcohol.

[0079] Suitably, the polyol is a polyester polyol having a molecular weight in the range of from 1 ,500 g / mol to about 4,500 g / mol, such as from about 2,000 g / mol to about 4,500 g / mol, for example from about 3,250 g / mol to about 3,750 g / mol.

[0080] The polyester polyol may have a hydroxyl number in the range of from 25 to 55, such as from about 27 to 54, for example from 27 to 34, as determined in accordance with DIN EN ISO 4629-2.

[0081] Suitably, the polyester polyol has a melting point in the range of from 45°C to 75°C, such as from 55°C to 75°C, preferably from 60°C to 75°C as determined by DSC.

[0082] The polyol may have a viscosity at 80°C in the range of from 0.3 to 2.3 Pa.s as determined using a parallel plate method. The method used to determine viscosity at above room temperature is based on BS5350 Part B8 “Methods of test for adhesives. Determination of Viscosity”.

[0083] The diisocyanate component is suitably an aromatic diisocyanate. For example, the diisocyanate may be selected from toluene diisocyanate, methylene phenyl diisocyanate and aliphatic diisocyanates selected from isophorone diisocyanate, hexamethylene diisocyanate and methylene bis(4- cyclohexylisocyanate).

[0084] The (meth)acrylate component which is reacted with the polyurethane may be selected from acrylic acid, hydroxyethylacrylate, hydroxyproprylacrylate, hydroxyethylmethacrylate, hydroxypropylmethacrylate, methacrylic acid, phthalic acid2024P00381 monoethyl methacrylate, maleic monoethyl methacrylate and succinic monoethyl maleate.

[0085] In addition, some of these (meth)acrylate-functionalized urethane resins may be commercially available. Examples of commercially available resins include those from Dymax Corporation, such as BR-345 (promoted by Dymax in its 2018 “BOMAR Oligomers Selected Guide,” page 12 as a polyether urethane acrylate “[i]deal for 3D printing resins” with a nominal viscosity of 46,000 at 25°C and a Tg by DMA of -57°C), BR-302, BR 374-744B or BR-900. With respect to at least BR-345, see also A. Prabhakar et al., “Structural Investigations of Polypropylene glycol (PPG) and Isophorone diisocyanate (IPDI)-based Polyurethane Prepolymer by 1 D and 2D NMR Spectroscopy”, J. Polym. Sci.: Part A: Polym. Chem., 43, 1196-1209 (2005).

[0086] The (meth)acrylate for use in the adhesive layer(s) of the present invention may include hydroxyethyl methacrylate (BISOMER) and / or acrylic acid, glacial, which is reacted with urethane methacrylate resin.

[0087] The adhesive layers may be rendered in a solid form for instance by using a blend of solid (meth)acrylate resins with liquid (meth)acrylate resins, or by addition of film formers.

[0088] The film former can be blended by any means known to those skilled in the art, such as melt blending or dissolution in an appropriate solvent or reactive diluent, by way of example. Solvent-borne systems can be coated and dried to yield the (meth)acrylate adhesive film layer; melt blends can be extruded or hot melt coated. Advantageously, the laminate adhesive tape of the invention is in solid form as the film former imparts the solid form. The (meth)acrylate matrix is desirably provided in solid form. In the laminate tape of the invention, the (meth)acrylate matrix remains curable. The film former may also be referred to as a film forming polymer component or a film forming component.

[0089] The film can also be formed by using a UV step on an epoxy- (meth)acrylate blend, where the UV step cures the epoxy portion to give a reactive (meth)acrylate film. The film can also be formed by using a blend of epoxy-2024P00381 functionalized (meth)acrylate(s) and a cationic photoinitiator, followed by a UV step as above.

[0090] The film former may contain functionality that is reactive with the (meth)acrylate resin. Alternatively, the film former may be non-reactive.

[0091] Film formers oftentimes are dissolved in a solvent, reactive diluent or other suitable liquid carrier to permit processing the (meth)acrylate into an adhesive layer. The processing may be done by solvent casting the (meth)acrylate and subsequently removing the solvent, either actively or passively. Suitable solvents include those that do not substantially interfere with the performance of the adhesive layer(s), such as acetone, ethyl acetate, and methyl ethyl ketone (“MEK”). The solvent may desirably be ethyl acetate.

[0092] The (meth)acrylate and the film former should be used in a relative amount of at least about 1 : 1 by weight ratio, desirably up to about a 3: 1 by weight ratio (meth)acrylate:film former, such as about a 2:1 by weight ratio (meth)acrylate:film former

[0093] Typical film formers for use with the (meth)acrylate matrix include polyesters, polyurethanes, polyimides, siloxane polyimides, polyamides, rubbers such as styrene-butadiene rubber (“SBR”), nitrile rubber (“NBR”), carboxy-terminal nitrile rubber (“CTBN”), ethylene-propylene-diene monomer copolymer (“EPDM”), polybutadiene rubber, polyisoprene rubber, poly(styrene-butadiene-styrene) block copolymer (“SBS”), poly(styrene-isoprene-styrene) block copolymer (“SIS”), styrene- b-ethylene-co-butylene-b styrene block copolymer (“SEBS”), styrene-b-ethylene-co- propylene-b-styrene block copolymer (“SEPS”), ethylene co-vinyl acetate, polyvinyl butyrals (such as those available commercially under the trade name BUTVAR), and cellulose-based film formers, as well as acrylic polymers, all by way of example. The film former may contain functionality that is reactive with the (meth)acrylate matrix. Alternatively, the film former may be non-reactive. Polyester resins, such as those available under the trade names DYNACOLL (available from Evonik) and VITEL (available from Bostik), are particularly desirable.2024P00381

[0094] Solid thermoplastic polyurethane resins may also be used as the film former in this connection. The solid thermoplastic polyurethane resin should have a molecular weight in the range of from 40,000 g / mol to 100,000 g / mol and a melting point in the range of from 40°C to 80°C. The film forming polymer component may alternatively or additionally comprise a thermoplastic polyurethane which is activatable by UV radiation, for example a thermoplastic polyurethane that comprises at least one acrylate group, at least one methacrylate group or at least one acrylamide group.

[0095] The solid thermoplastic polyurethane resin may be present in an amount of from about 20 percent by weight to about 75 percent by weight, based on the total weight of the curable composition, suitably in an amount of from about 35 percent by weight to about 65 percent by weight based on the total weight of the curable composition, such as from about 38 percent by weight to about 62 percent by weight based on the total weight of the curable composition.

[0096] The solid thermoplastic polyurethane resin should have a molecular weight in the range of from 40,000 g / mol to 100,000 g / mol, wherein the molecular weight Mw is as determined in accordance with ASTM D5296-05 (Standard Test Method for Molecular Weight Averages and Molecular Weight Distribution of Polystyrene by High Performance Size-Exclusion Chromatography), and a melting point in the range of from 40°C to 80°C; and a curing component for curing the anaerobically curable components. Suitable solid thermoplastic polyurethane resins include those available under the PEARLBOND tradename, such as PEARLBOND 100, PEARLBOND 106, PEARLBOND 120, PEARLBOND 122, PEARLBOND 180, and under the PEARLSTICK tradename, such as PEARLSTICK 5712, PEARLSTICK 5714 and PEARLSTICK 40-70 / 08 which are commercially available from Lubrizol (Barcelona, Spain).

[0097] If the molecular weight of the solid thermoplastic polyurethane resin is below about 40,000 g / mol the cured compositions tend to be brittle. If the molecular2024P00381 weight range is greater than about 100,000 g / mol the compositions tend to be tacky and achieving dry-to-touch is difficult.

[0098] A solid thermoplastic polyether polyurethane resin is one form of the thermoplastic polyurethane resin that may also be used.

[0099] The solid thermoplastic polyether polyurethane resin may have a molecular weight Mw in the range of from about 180,000 g / mol to about 260,000 g / mol, suitably in the range of from about 200,000 g / mol to about 240,000 g / mol, such as about 215,000 g / mol to 230,000 g / mol for example 220,000 g / mol to 225,000 g / mol for example about 223,000 g / mol, wherein the molecular weight Mw is as determined in accordance with ASTM D5296-05 (Standard Test Method for Molecular Weight Averages and Molecular Weight Distribution of Polystyrene by High Performance Size-Exclusion Chromatography). Unless otherwise specified all molecular weight(s) Mw are determined in accordance with this ASTM.

[0100] The solid thermoplastic polyether polyurethane resin may have a melting point in the range of from 160°C to 200°C, such as from 165°C to 190°C, for example from 170°C to 180°C.

[0101] The solid thermoplastic polyether polyurethane resin may be present in an amount of from about 10 percent by weight to about 30 percent by weight, based on the total weight of the curable composition, suitably in an amount of from about 18 percent by weight to about 25 percent by weight based on the total weight of the curable composition, such as about 20 percent by weight based on the total weight of the curable composition.

[0102] The solid thermoplastic polyether polyurethane resin may have molecular weight Mw in the range of from about 180,000 g / mol to about 260,000 g / mol, suitably in the range of from about 200,000 g / mol to about 240,000 g / mol, such as about 215,000 g / mol to 230,000 g / mol for example 220,000 g / mol to 225,000 g / mol like about 223,000 g / mol, wherein the molecular weight Mw is as determined in accordance with ASTM D5296-05. The solid thermoplastic polyether polyurethane resin may have a melting point from 160°C to 200°C, such as from 165°C to 190°C2024P00381 for example from 170°C to 180 °C. Suitable solid thermoplastic polyether polyurethane resins include PEARLBOND 960, available from Lubrizol (Barcelona, Spain). PEARLBOND 960 is a solid thermoplastic polyether polyurethane resin having a Mw of 222,906 as determined in accordance with D5296-05 (Standard Test Method for Molecular Weight Averages and Molecular Weight Distribution of Polystyrene by High Performance Size-Exclusion Chromatography) and having a melting point over the range of 170°C to 180°C.

[0103] As noted above, solid thermoplastic polyvinyl butyral resins may be used as a film former as well.

[0104] Polyvinyl butyral is a thermoplastic polymer prepared by hydrolysis of polyvinyl acetate and subsequent condensation with butyraldehyde. The polymer contains hydroxyl, acetyl and butyraldehyde functional groups and its generic chemical structure is depicted below:

[0105] Polyvinyl butyral is commercially available as different grades with varying molecular weight and different hydroxyl, acetyl and butyraldehyde contents i.e., different x, y, z values and which determine their physical and chemical properties. Commercially available solid thermoplastic polyvinyl butyral resins include those sold under the trade name BUTVAR by Eastman Chemical Company, or MOWITAL by Kuraray Europe GmbH. Suitable solid thermoplastic polyvinyl butyral resins include BUTVAR B-79, available from Eastman. BUTVAR B-79 is a solid thermoplastic polyvinyl butyral resin having a molecular weight of 50,000-80,000 g / mol (size exclusion chromatography with low angle laser light scattering standard)2024P00381 and a softening point in the range of 140-200°C. Other suitable commercial solid thermoplastic polyvinyl butyral resins may include BUTVAR B-72, BUTVAR B-74, BUTVAR B-76, BUTVAR B-90, and BUTVAR B-98, each also available from Eastman. Desirably, the solid thermoplastic polyvinyl butyral resin may be polyvinyl butyral resin having a molecular weight of 50,000-80,000 g / mol (size exclusion chromatography with low angle laser light scattering standard) and a softening point in the range of 140-200°C, which is available commercially under the trade name BUTVAR B-79.

[0106] Other suitable solid thermoplastic polyvinyl butyral resins include MOWITAL B30 HH, available from Kuraray. MOWITAL B30 HH is a solid thermoplastic polyvinyl butyral resin having a molecular weight of 50,000 -70,000 and a softening range of 140-180°C. Other suitable commercial solid thermoplastic polyvinyl butyral resins may include MOWITALB20 H, B30 T, B30 H, B45 H, B60 T, B60 H, and B60 HH, each also available from Kuraray.

[0107] The solid thermoplastic polyvinyl butyral resin may have a softening point in the range of from about 50°C to about 300°C, suitably from about 100°C to about 250°C, preferably from about 140°C to about 200°C. The solid thermoplastic polyvinyl butyral resin may act as a film former. The use of a solid thermoplastic polyvinyl butyral resin having a high softening point such as from about 140°C to about 200°C is believed to impart the resulting compositions with good thermal resistance, making them able to perform well at high temperatures. For example, solid curable composition of the invention in tape form are suitable for applications at elevated temperatures, such as at 100°C, 150°C, or even higher. Softening point may be determined by DSC or by ring and ball method, DIN ISO 4625.

[0108] The solid thermoplastic polyvinyl butyral resin may have a molecular weight Mw in the range of from about 40,000 g / mol to about 250,000 g / mol, suitably in the range of from about 40,000 g / mol to about 170,000 g / mol, such as about 40,000 g / mol to 120,000 g / mol, for example 50,000 g / mol to 80,000 g / mol, wherein the molecular weight Mw is as determined in accordance with ASTM D5296-052024P00381(Standard Test Method for Molecular Weight Averages and Molecular Weight Distribution of Polystyrene by High Performance Size-Exclusion Chromatography).

[0109] The solid thermoplastic polyvinyl butyral resin may be present in an amount of from about 10 percent by weight to about 50 percent by weight, based on the total weight of the curable composition, suitably in an amount of from about 15 percent by weight to about 40 percent by weight based on the total weight of the curable composition, such as from about 15 percent by weight to about 35 percent by weight, for example about 20 percent by weight based on the total weight of the curable composition.

[0110] Other film formers include those copolymers of polyethylene and polyvinyl acetate, available commercially under the trade name LEVAMELT from Arlanxeo. A range of LEVAMELT-branded copolymers are available and includes for example, LEVAMELT 400, LEVAMELT 600 and LEVAMELT 900. The LEVAMELT products differ in the amount of vinyl acetate present. For example, LEVAMELT 400 comprises an ethylene-vinyl acetate copolymer comprising 40 weight percent vinyl acetate. The LEVAMELT products are supplied in granular form. The granules are almost colourless and dusted with silica and talc. LEVAMELT consists of methylene units forming a saturated main chain with pendant acetate groups. The presence of a fully saturated main chain is an indication that LEVAMELT-branded copolymers are particularly stable; they do not contain any reactive double bonds which make conventional rubbers prone to aging reactions, ozone and UV light. The saturated backbone is reported to make the polymer robust.

[0111] LEVAPREN-branded copolymers may also be used. According to the manufacturer, Arlanxeo, LEVAPREN-branded copolymers consist of methylene units forming a saturated polymer backbone with pendant acetate groups. These rubberlike copolymers are designated as ethylene-vinyl acetate copolymers, or EVM. These ethylene-vinyl acetate copolymers are used as synthetic rubbers, or as modifiers in thermoplastics, specifically PVC. Multiple LEVAPREN-branded copolymers are available commercially with each one designated based on its vinyl acetate content in2024P00381 the copolymer. For instance, LEVAPREN 400 (40% vinyl acetate), 450 (45% vinyl acetate), 500 (50% vinyl acetate), 600 (60% vinyl acetate), 700 (70% vinyl acetate), 800 (80% vinyl acetate), and 900 (90% vinyl acetate), are now commercially available. Some of these grades are offered with different viscosities within the same grade.

[0112] VINNOL surface coating resins available commercially from Wacker Chemie AG, Munich, Germany represent a broad range of vinyl chloride-derived copolymers and terpolymers that are promoted for use in different industrial applications. The main constituents of these polymers are different compositions of vinyl chloride and vinyl acetate. The terpolymers of the VINNOL product line additionally contain carboxyl or hydroxyl groups.

[0113] VINNOL surface coating resins with carboxyl groups are terpolymers of vinyl chloride, vinyl acetate and dicarboxylic acids, varying in terms of their molar composition and degree and process of polymerization. These terpolymers are reported to show excellent adhesion, particularly on metallic substrates.

[0114] VINNOL surface coating resins with hydroxyl groups are copolymers and terpolymers of vinyl chloride, hydroxyacrylate and dicarboxylate, varying in terms of their composition and degree of polymerization.

[0115] VINNOL surface coating resins without functional groups are copolymers of vinyl chloride and vinyl acetate of variable molar composition and degree of polymerization.

[0116] VINNOL H 40 / 60, as an example, is reported by the manufacturer as 61 .0 ± 1 .0:39.0 ± 1 .0 vinyl chloride to vinyl acetate, with the following physical properties: K value of 60 ± 1 (by EN ISO 1628-2); molecular weight of 100 - 140 x 103 Mw by size exclusion chromatography (with THF as a solvent and polystyrene as a standard); viscosity of 180 ± 30; particle size of < 1 ; and a Tg of about 62 °C (by DSC).

[0117] The identity, characteristics, functionality, if any, and other specific properties of the film former may vary based on the particular processing conditions,2024P00381 and that the selection of the appropriate film former in any particular case is within the ability of one of ordinary skill in the art.

[0118] A variety of additives may be included in the (meth)acrylate matrix, such as the following materials in an amount of up to about 10 percent by weight of the total weight of the composition: surface active agents, surfactants, wetting agents, antioxidants, thixotropy agents, reinforcement fibers, silane functional perfluoroether, phosphate functional perfluoroether, titanates, waxes, phenol formaldehyde, air release agents, flow additives, adhesion promoters, rheology modifiers, spacer beads, toughening agents, fillers, plasticizers and the like, examples of all of which are known to those of skill in the art.

[0119] For instance, as regard toughening agents, a variety of materials may be useful, such as those available commercially under the tradename HYCAR.

[0120] Also, various commercially available rubber particles, such as core shell rubbers, may be used.

[0121] Rubber particles, especially rubber particles that have relatively small average particle size (e.q., less than about 500 nm or less than about 200 nm), may also be included. The rubber particles may or may not have a shell common to known core-shell structures.

[0122] In the case of rubber particles having a core-shell structure, such particles generally have a core comprised of a polymeric material having elastomeric or rubbery properties (i.e., a glass transition temperature less than about 0°C, e.q., less than about -30°C) surrounded by a shell comprised of a non-elastomeric polymeric material (i.e., a thermoplastic or thermoset / crosslinked polymer having a glass transition temperature greater than ambient temperatures, e.q., greater than about 50°C). For example, the core may be comprised of a diene homopolymer or copolymer (for example, a homopolymer of butadiene or isoprene, a copolymer of butadiene or isoprene with one or more ethy lenical ly unsaturated monomers such as vinyl aromatic monomers, (meth)acrylonitrile, (meth)acrylates, or the like) while the shell may be comprised of a polymer or copolymer of one or more monomers such as2024P00381(meth)acrylates (e.q., methyl methacrylate), vinyl aromatic monomers (e.q., styrene), vinyl cyanides (e.q., acrylonitrile), unsaturated acids and anhydrides (e.q., acrylic acid), (meth)acrylamides, and the like having a suitably high glass transition temperature. Other rubbery polymers may also suitably be used for the core, including polybutylacrylate or polysiloxane elastomer (e.q., polydimethylsiloxane, particularly crosslinked polydimethylsiloxane).

[0123] Typically, the core will comprise from about 50 to about 95 weight percent of the rubber particles while the shell will comprise from about 5 to about 50 weight percent of the rubber particles.

[0124] Preferably, the rubber particles are relatively small in size. For example, the average particle size may be from about 0.03 pm to about 2 pm or from about 0.05 pm to about 1 pm. The rubber particles may have an average diameter of less than about 500 nm, such as less than about 200 nm. For example, the core-shell rubber particles may have an average diameter within the range of from about 25 to about 200 nm.

[0125] When used, these core shell rubbers allow for toughening to occur in the composition and oftentimes in a predictable manner — in terms of temperature neutrality toward cure - because of the substantial uniform dispersion, which is ordinarily observed in the core shell rubbers as they are offered for sale commercially.

[0126] In the case of those rubber particles that do not have such a shell, the rubber particles may be based on the core of such structures.

[0127] Desirably, the rubber particles are relatively small in size. For example, the average particle size may be from about 0.03 pm to about 2 pm or from about 0.05 pm to about 1 pm. In certain embodiments of the invention, the rubber particles have an average diameter of less than about 500 nm. In other embodiments, the average particle size is less than about 200 nm. For example, the rubber particles may have an average diameter within the range of from about 25 to about 200 nm or from about 50 to about 150 nm.2024P00381

[0128] The rubber particles may be used in a dry form or may be dispersed in a matrix, as noted above.

[0129] Typically, the composition may contain from about 5 to about 35 weight percent rubber particles.

[0130] Combinations of different rubber particles may advantageously be used in the present invention. The rubber particles may differ, for example, in particle size, the glass transition temperatures of their respective materials, whether, to what extent and by what the materials are functionalized, and whether and how their surfaces are treated.

[0131] Rubber particles that are suitable for use in the present invention are available from commercial sources. For example, rubber particles supplied by Eliokem, Inc. may be used, such as NEP R0401 and NEP R401 S (both based on acrylonitrile / butadiene copolymer); NEP R0501 (based on carboxylated acrylonitrile / butadiene copolymer; CAS No. 9010-81-5); NEP R0601A (based on hydroxy-terminated polydimethylsiloxane; CAS No. 70131-67-8); and NEP R0701 and NEP 0701 S (based on butadiene / styrene / 2-vinylpyridine copolymer; CAS No. 25053- 48-9). Also those available under the PARALOID tradename, such as PARALOID 2314, PARALOID 2300, and PARALOID 2600, from Dow Chemical Co. (Philadelphia, PA), and those available under the STAPHYLOID tradename, such as STAPHYLOID AC-3832, from Ganz Chemical Co., Ltd. (Osaka, Japan).

[0132] Rubber particles that have been treated with a reactive gas or other reagent to modify the outer surfaces of the particles by, for instance, creating polar groups (e.q., hydroxyl groups, carboxylic acid groups) on the particle surface, are also suitable for use herein. Illustrative reactive gases include, for example, ozone, C , F2, O2, SO3, and oxidative gases. Methods of surface modifying rubber particles using such reagents are known in the art and are described, for example, in U.S. Patent Nos. 5,382,635; 5,506,283; 5,693,714; and 5,969,053, each of which being hereby expressly incorporated herein by reference in its entirety. Suitable surface2024P00381 modified rubber particles are also available from commercial sources, such as the rubbers sold under the tradename VISTAMER by Exousia Corporation.

[0133] Where the rubber particles are initially provided in dry form, it may be advantageous to ensure that such particles are well dispersed in the adhesive composition prior to curing the adhesive composition. That is, agglomerates of the rubber particles are preferably broken up so as to provide discrete individual rubber particles, which may be accomplished by intimate and thorough mixing of the dry rubber particles with other components of the adhesive composition.

[0134] Rubber particles in the form of core-shell impact modifier may be prepared by emulsion polymerization. For example, a suitable method is a two-stage polymerization technique in which the core and shell are produced in two sequential emulsion polymerization stages. If there are more shells another emulsion polymerization stage follows. A graft copolymer is obtained by graft-polymerizing a monomer or monomer mixture containing at least an aromatic vinyl, alkyl methacrylate or alkyl acrylate in the presence of a latex containing a butadiene-based rubber polymer. Commercially available examples of such core-shell impact modifiers are available commercially under the CLEARSTRENGTH tradename from Arkema Inc., Cary, NC. Arkema describes CLEARSTRENGTH XT100, for instance, as a methyl methacrylate-butadiene-styrene core-shell toughening agent, which is compatible with various monomers and easily dispersible in most liquid resin systems, and exhibits a limited impact on their viscosity while providing a toughening effect over a wide range of service temperatures.

[0135] The (meth)acrylate matrix should also include an appropriate cure system, whether that be a photoinitiator package or an anaerobic cure system, or in some instances a combination of the two cure approaches.

[0136] As a photoinitiator package, absorbance profile of radiation in the electromagnetic spectrum oftentimes together with thermal stability with respect to end-use and processing requirements which, like the film former, may vary depending on the particular application at hand.2024P00381

[0137] Suitable photoinitiators include free radical photoinitiators, many of which are readily available to those of ordinary skill in the art. For instance, any of benzoin ethers, dialkoxy acetophenones, benzoin, methylphenyl glyoxylate, benzyl dimethyl ketal, 1 -hydroxycyclohexyl phenyl ketone, or substituted benzophenones, such as 3,3',4,4'-tetra(t-butylperoxycarbonyl) benzophenone, may be used. Desirably, the photoinitiator may be 2,2’-dimethoxy-2-phenylacetophenone.

[0138] Light activation may come about with use of any suitable light source known to those skilled in the art; visible or UV wavelengths can be used, depending primarily on the absorption profile of the photoinitiator and the particular (meth)acrylate matrices employed. Other sources of radiation such as microwave and IR may also be used. Common light sources include Hg arc lamps, microwave UV / vis sources, and light emitting diode (“LED”) light sources.

[0139] The photoinitiator package should be used in an amount of about 0.1 percent by weight to about 10 percent by weight, such as about 0.5 percent by weight to about 5 percent by weight, of the total (meth)acrylate matrix.In the anaerobic cure system, one or more of saccharin, toluidines, such as N,N- diethyl-p-toluidine (“DE-p-T”) and N,N-dimethyl-o-toluidine (“DM-o-T”), and acetyl phenyl hydrazine (“APH”) with maleic acid should be included. See e.g. U.S. Patent No. 3,218,305 (Krieble), U.S. Patent No. 4,180,640 (Melody), U.S. Patent No. 4,287,330 (Rich) and U.S. Patent No. 4,321 ,349 (Rich). Also stabilizers such as quinone or hydroquinone may be included. And peroxides may be included too. Suitable peroxides include benzoyl peroxide (“BPO”), dicumyl peroxide (“DCP”), tert- butylperoxy(2-ethylhexyl)-carbonate (“TBPEHC”), 2-hydroxy-2 -methylpropiophenone (“2-H-2-MPPh”), cumene hydroperoxide (“CHP”) and mixtures thereof. The peroxide is desirably tert-Butyl peroxybenzoate.

[0140] The anaerobic cure system should be present in an amount from about 0.01 percent to about 5 percent by weight of the total of the composition, such as from about 0.03 percent to about 1 percent by weight of the total of the composition,2024P00381 more preferably from about 0.05 percent to about 0.7 percent by weight of the total of the composition.

[0141] Desirably, the (meth)acrylate matrix may comprise hydroxyethyl methacrylate, such as that sold under the trade name BISOMER, urethane methacrylate resin and acrylic acid (glacial) as the meth (acrylates); tert-Butyl peroxybenzoate as the peroxide; 2,2’-Dimethoxy-2-phenylacetophenone as the photoinitiator, solid thermoplastic polyvinyl butyral resin having a molecular weight of 50,000-80,000 g / mol (size exclusion chromatography with low angle laser light scattering standard) and a softening point in the range of 140-200°C, which is available commercially under the trade name BUTVAR B-79 as the film former; in combination with a chelator package and an anaerobic cure package.

[0142] The piezoelectric adhesive tape laminate according to the present invention can be used as an adhesive, sealant or coating, particularly a structural adhesive having good adhesion strength, while at the same time providing good piezoelectric response.

[0143] By the term structural adhesive is meant herein an adhesive, which is a relatively strong adhesive that is normally used below its glass transition temperature, such an adhesive can carry significant stresses, and lend itself to structural applications, wherein the adhesive plays as a part of the physical structure of joined surfaces.

[0144] In contrast to the application of the piezoelectric adhesive composition onto the surface of the conductive element according to International Patent Publication No. WO 2016 / 0977077 where these steps are followed:1) applying the piezoelectric adhesive composition according to the present invention onto the surface of conductive element;2) evaporating the solvent (if present);3) curing the adhesive composition;4) annealing; and5) poling; or2024P00381 these steps are followed:1) applying the piezoelectric adhesive composition according to the present invention onto the surface of conductive element;2) evaporating the solvent (if present);3) applying second conductive element top of the piezoelectric adhesive layer;4) curing the adhesive composition;5) annealing; and6) poling, practicing the present invention involves the formation and use of the inventive piezoelectric adhesive tape laminate.

[0145] The known methods set forth in International Patent Publication No. WO 2016 / 0977077 are useful in forming the comparative [0,3] composites, as described in the examples below. But those known methods are not useful in forming the inventive [2,2] composites.

[0146] In contrast to that which is described in International Patent Publication No. WO 2016 / 0977077, in constructing the inventive piezoelectric adhesive tape laminate poling is not conducted on the type of combination and annealing is not conducted either.

[0147] The curable adhesive laminate tape may comprise: a first release liner; a first adhesive composition; a piezoelectric polymer film or piezoelectric polymer composite film; a second adhesive composition; and a second release liner, wherein at least one of the first adhesive composition or the second adhesive composition comprises a (meth)acrylate matrix comprising BISOMER (hydroxyethyl methacrylate), Urethane Methacrylate Resin and acrylic acid (glacial) as the meth(acrylates); tert-Butyl peroxybenzoate as the peroxide, 2,2’-Dimethoxy-2-2024P00381 phenylacetophenone as the photoinitiator; solid thermoplastic polyvinyl butyral resin having a molecular weight of 50,000-80,000 g / mol (size exclusion chromatography with low angle laser light scattering standard) and a softening point in the range of 140-200°C, which is available commercially under the trade name BUTVAR B-79 as the film former; in combination with a chelator package and an anaerobic cure package. The first and / or the second release liner may be a PET release liner, preferably a coated PET release liner e.g. siliconised PET release liner. The piezoelectric polymer film or piezoelectric polymer composite film may desirably be constructed from polyvinylidene difluoride (PVDF) .

[0148] The PVDF in the (meth)acrylate adhesive composition may be 39 weight percent after solvent evaporation based on the total weight of the composition.

[0149] The (meth)acrylate adhesive composition layer may have a thickness of 50 pm and the piezoelectric polymer film or piezoelectric polymer composite film layer has a thickness of 30 pm. The (meth)acrylate adhesive composition layer may have a thickness of 50 pm and the piezoelectric polymer film or piezoelectric polymer composite film layer has a thickness of 50 pm. The (meth)acrylate adhesive composition layer may have a thickness of 50 pm and the piezoelectric polymer film or piezoelectric polymer composite film layer has a thickness of 80 pm. The (meth)acrylate adhesive composition layer may have a thickness of 50 pm and the piezoelectric polymer film or piezoelectric polymer composite film layer has a thickness of 110 pm.

[0150] The (meth)acrylate adhesive composition layer may have a thickness of 30 pm and the piezoelectric polymer film or piezoelectric polymer composite film layer has a thickness of 80 pm. The (meth)acrylate adhesive composition layer may have a thickness of 50 pm and the piezoelectric polymer film or piezoelectric polymer composite film layer has a thickness of 80 pm. The (meth)acrylate adhesive composition layer may have a thickness of 100 pm and the piezoelectric polymer film or piezoelectric polymer composite film layer has a thickness of 80 pm.2024P00381

[0151] Desirably, the (meth)acrylate adhesive composition layer comprises a solid (meth)acrylate as defined herein.

[0152] The inventive piezoelectric adhesive tape laminate can be used as a sensor, an emitter or as a generator in energy harvester.

[0153] Suitable sensors can be for example pressure sensors and suitable emitters can be for example acoustic transducers.

[0154] A device, such as an emitter, a sensor or a generator for an energy harvester can be provided, wherein the device comprises a piezoelectric adhesive composition according to the present invention between two conductive elements.

[0155] The device can be manufactured without separately adhering or attaching a piezoelectric component to a surface of conductive elements with an additional or separate adhesive.

[0156] Other uses of such piezoelectric adhesive laminate tapes include sensor materials for structural health monitoring of adhesively bonded structures, coatings for such structures and / or sealants used in such structures. Other uses of such piezoelectric adhesive laminate tapes include use in a monitoring system, such as for fluid flow pathways, for example for monitoring pipes. For instance, with reference to an English language machine translation of Chinese Patent Document No. CN 105765750B, a sandwich layer may be disposed between two piezoelectric layers, where each piezoelectric layer includes a polarized piezoelectric polymer. In the case of a touch sensor, according to the CN ‘750B document, a separately addressable electrode is arranged above a first piezoelectric layer or a second piezoelectric layer. A circuit is coupled to the first electrode and the second electrode, so that detection of a response to the touch surface being activated, telecommunications between the one electrode relative to second electrode may occur. The electrodes themselves can be directly deposited on the piezoelectric layer(s) and the deposition may occur in a random or non-random2024P00381 pattern. The electrodes can be transparent, examples of which include indium tin oxide (ITO) and antimony doped tin oxide (ATO), and silver nanowire.

[0157] With reference to commercial applications, effective maintenance of pipelines is essential in order to transport / distribute in many cases long distances fluids of many kinds. For instance, fuel is transported / distributed from production or storage facilities to consumers throughout the United States, through a vast network of existing fuel transmission and distribution pipelines which exists to ensure the ready availability of affordable fuel. But, with well over 1 million miles of pipeline, constant monitoring is not economically feasible or routinely performed.

[0158] Currently, pipeline inspection may use in-line-inspection tools, such as “pigs” (pipeline inspection gauges), which are inserted into a pipeline or pipeline segment, and then either self-propelled or pushed along the interior of the pipe via applied pressure. “Smart-pigs” may also collect data on the interior pipeline surface based on, for example, magnetic flux leakage, ultrasound testing, or visual inspection. While established and accepted methods for structural health monitoring for pipelines, pigging is only performed infrequently. For instance, certain older pipelines may suffer from limited access or low / no-flow conditions, making inspection via pigging a potentially risky operation. And use of such smart-pigs also involves periodic shutdown, or restriction of flow of the fluid in the pipes to permit introduction of the pig for inspection. Of course, once introduced the pig should then be removed.

[0159] If a fault is detected this will also then have to be monitored over time, which then also requires pipe fluid flow stoppages. In other words many of the current inspection methods do not allow continuous, online and remote monitoring. Such continuous, online and remote inspection is desirable as it allows the detection and location of a fault at the moment that it is formed. Such a fault can then be continuously monitored without interrupting fluid flow, allowing operators to plan repair of a particular section when the fault reaches a critical stage where it poses a danger to the integrity / structural safety of the greater pipeline.2024P00381

[0160] Therefore, many testing methods and systems at a minimum do not have the ability to remotely and continuously monitor the interior conditions of pipes and pipelines.

[0161] In addition, even where leaks are identified they are likely to be much smaller as they have been identified earlier. Such smaller leaks oftentimes go undetected and unrepaired for extended periods of time, during which loss of fluid has occurred, potential ground pollution has occurred and the small leaks have the chance to become larger leaks, exacerbating fluid loss and ground pollution.

[0162] Accordingly, there exists a need for a new way in which to monitor remotely, continuously if desired and non-invasively pipeline integrity. Meeting that need would allow for optimization of pipeline use and scheduled maintenance, such as by enabling accurate location detection of faults as they form and without the need for human intervention or manual handling. This correlates to less pipeline downtime and less unnecessary cleaning and replacement of pipelines. A significant public benefit would be realized, as fewer major pipeline leaks and blowouts would occur. And a much smaller expense would be involved instead of a full replacement of a pipeline or installation of fiber optic monitoring or sensing systems. As such, fast and widespread adoption may be realized, even by public entities, such as utilities, whose budgets are constrained by law or by appropriations.

[0163] The inventive laminate may be applied to one or more surface(s) of a pipe or pipeline, a flange, a pump, an elbow, a hopper or a chute (collectively, “fluid flow pathways”), for instance, to permit for remote detection, monitoring and / or reporting of a condition on the applied surface and how that condition may be impacting performance of the flow of fluid and / or the surrounding environment of the fluid flow pathway(s).

[0164] The system thus created for detection, monitoring and / or reporting of the condition and the performance of the fluid flow pathway(s) involves the placement of the inventive laminate tape about a surface of a portion of the fluid flow pathway(s). The inventive laminate tape may be applied as a wrap or a patch on the selected2024P00381 surface. Oftentimes but not necessarily the placement is on a portion of the fluid flow pathway(s) - e.g., a valve, joint, bend or junction -- that may be more susceptible to stress or stress related defects. Within the inventive laminate is a piezoelectric layer that is capable of generating an electrical signal and when a flaw occurs within the fluid flow pathway(s), a different electrical signal is generated.

[0165] The signals generated may be harvested by circuitry disposed in proximity to the fluid flow pathway(s) on which the inventive laminate tape is disposed. The harvested signals may then be transmitted as data which is then stored for evaluation purposes. The differentiation in the electrical signals provides information on the extent and even the nature of the fault, and whether a repair or replacement is needed then or in the future. See e.g. FIG 11 .

[0166] Accordingly, in another aspect, provided herein is a method for monitoring assets, such as in a fluid flow pathway(s), the method comprising: applying the inventive curable adhesive laminate tape of the invention to a surface of a portion of an asset such as a fluid flow pathway for example a pipe; providing monitoring equipment, such as a remote device, to receive signals generated by the piezoelectric layer of the laminate tape, and receiving generated signals for monitoring and reporting conditions in the fluid flow pathway(s). The laminate tape may be in the form of a wrap or a patch and comprises: a first release liner; a first adhesive composition (which may comprise a (meth)acrylate matrix); a piezoelectric polymer film or piezoelectric polymer composite film having: a film thickness of from about 1 pm to about 500 pm, a piezoelectric coefficient d33 value of from about 5 to about 40 picocoulombs / Newton (pC / N), from about 10 to about 35 pC / N, or from about 20 to about 30 pC / N, each when measured according to National Physical Laboratory Measurement Good Practice Guide No. 44: Measuring Piezoelectric d33 Coefficients Using Direct Method (2001),2024P00381 a modulus of from about 2,000 to about 2,700 Pascals (Pa), and a dielectric constant of from about 8 to about 50; a second adhesive composition (which may comprise a (meth)acrylate matrix); and a second release liner.

[0167] Prior to application of the inventive curable adhesive laminate tape, the first and / or second release liner must be removed. The inventive curable adhesive laminate tape of the invention may be applied to one or more surface(s) of a portion of an asset. Accordingly, the first and / or second release liner may be removed and the second and / or first release liner may remain on the inventive curable adhesive laminate tape where it is not adhered to the surface of a portion of an asset.

[0168] In another aspect, provided herein is a system for monitoring assets such as in a fluid flow pathway(s) for example in pipes. The system comprises the application of the inventive curable adhesive laminate tape, which comprises: a first release liner; a first adhesive composition (which may comprise a (meth)acrylate matrix); a piezoelectric polymer film or piezoelectric polymer composite film having: a film thickness of from about 1 pm to about 500 pm, a piezoelectric coefficient d33 value of from about 5 to about 40 picocoulombs / Newton (pC / N), from about 10 to about 35 pC / N, or from about 20 to about 30 pC / N, each when measured according to National Physical Laboratory Measurement Good Practice Guide No. 44: Measuring Piezoelectric d33 Coefficients Using Direct Method (2001), a modulus of from about 2,000 to about 2,700 Pascals (Pa), and a dielectric constant of from about 8 to about 50; a second adhesive composition (which may comprise a (meth)acrylate matrix); and a second release liner,2024P00381

[0169] to a surface of a portion of an asset such as a fluid flow pathway for example a pipe. Prior to application of the inventive curable adhesive laminate tape, the first and / or second release liner must be removed. The system may include monitoring equipment, such as a remote device, to receive signals generated by the piezoelectric layer of the laminate tape. The monitoring equipment will typically receive generated signals and utilise those for monitoring and reporting conditions in the asset such as a fluid pathway for example a pipe.

[0170] Conditions to be reported may include anomaly detection such as cracks or leaks, pressure and temperature abnormalities and failed adhesion bonds.Suitable monitoring equipment, e.g. signal harvesting circuitry, for use with the inventive piezoelectric adhesive laminate tape is depicted in FIG. 11. Three main stages of monitoring are described, including the signal generation, processing (involving data acquisition and processing) and data analysis.

[0171] The invention will be more fully described by the following examples which are presented solely for illustrative purposes.2024P00381EXAMPLES

[0172] The initial examples shown below involve the creation of [2,2] composites and [0,3] composites to show the respective piezoelectric capabilities together with the adhesive capabilities.(Meth)acrylate

[0173] An anaerobically curable product - based on (meth)acrylate chemistry -- used for gasketing, threadlocking and structural bonding, LOCTITE AA 3510 (available commercially from Henkel Ireland Ltd.), was used to make films by the addition of BUTVAR B-79, a polyvinyl butyral resin from Eastman Chemical, as a film former with ethyl acetate as solvent for solvent casting. Equal amounts of BUTVAR B-79 and ethyl acetate were used to make a solution for film casting.

[0174] The constituents and relative amounts in a weight percent basis of the (meth)acrylate matrix for the anaerobic adhesive layers is noted below in Table 1 .Table 1Component: Weight Percent:BISOMER (hydroxyethyl 25.91 methacrylate)Chelator package 0.08Urethane Methacrylate Resin124.40Anaerobic cure package 0.54 tert-Butyl peroxybenzoate 0.54Acrylic acid, glacial 1.322,2’-Dimethoxy-2- 1.08 phenylacetophenoneBUTVAR B-79 23.08Ethyl Acetate 23.081Made in sequential steps from the reaction of diols and dicarboxylic acids to form polyester diols, followed by reaction with toluene diisocyanate and finally capping with hydroxy propyl(meth)acrylate.2024P00381

[0175] To ethyl acetate in a HDPE wide-neck bottle was added the various listed constituents with mixing in a speed mixer at 3500 rpm for a period of time of about 5 minutes.

[0176] Using an Elcometer 4340 automatic film applicator, the (meth)acrylate formulation from Table 1 and the commercially available anaerobically curable products listed above together with BUTVAR B-79 and ethyl acetate were cast onto a 75 pm PET backing liner at a thickness of 30 pm, 50 pm or 100 pm, as desired. The ethyl acetate solvent from the constituents in Table 1 was allowed to evaporate at room temperature over a period of time of 2 hours to permit film formation of the first adhesive layer. A 50 pm film of PVDF (PVDF-P0050 from PolyK Technologies) of 30 x 300 x 0.05 mm width, length and thickness was placed on top of this first adhesive layer and a second adhesive layer was coated on top of the PVDF film. The ethyl acetate solvent was again allowed to evaporate at room temperature over a period of time of 2 hours. A 75 pm PET backing liner was placed over the so-formed second adhesive layer to provide the laminate tape assembly as shown in FIG. 1 . The so- formed piezoelectric anaerobic adhesive laminate tape assembly was then used to mate stainless steel substrates together.

[0177] Lapshear test specimens were prepared as follows in accordance with ASTM D100210(2019), using the laminate tape assembly as described above and shown in FIG. 1 :

[0178] The first siliconised PET release liner was removed to expose the first (meth)acrylate adhesive layer from the (meth)acrylate adhesive laminate tape. A stainless steel substrate was placed face down onto a surface. A section of (meth)acrylate adhesive laminate tape was cut in dimensions of at least about 25.4 mm x 12.7 mm and disposed on the stainless steel lapshear in a manner to ensure bondline coverage of 322.6 mm2.

[0179] The second siliconised PET release liner was then removed exposing the second adhesive layer. Another stainless steel lapshear was then brought into2024P00381 contact with the second adhesive layer to give a 322.6 mm2bonded area. The mated lapshear assembly was clamped in place for a period of time of about 24 hours.

[0180] The piezoelectric coefficient ‘dss’ was measured through the metal lapshear bondline using a PIEZOTEST d33 PiezoMeter System employing the Berlincourt Method, as above. Shear strength of the lapshear specimens was measured on a Zwick Tensile Testing machine, as above.

[0181] The (meth)acrylate matrix formed as above was used to make a (meth)acrylate [0,3] composite.

[0182] The PVDF in the (meth)acrylate [2,2] composite was determined to be 39 weight percent after solvent evaporation. In order to directly compare the (meth)acrylate [2,2] composite with the (meth)acrylate [0,3] composite, the weight percent of PVDF was calculated from the (meth)acrylate [2,2] composite and applied to the (meth)acrylate [0,3] composite.

[0183] Thus, a comparative (meth)acrylate formulation for the adhesive layers was prepared from the constituents and relative amounts noted below in Table 2.2024P00381Table 2Component: Weight Percent:BISOMER (hydroxyethyl 17.91 methacrylate)Chelator package 0.05Urethane Methacrylate Resin216.45Anaerobic cure package 0.36 tert-Butyl peroxybenzoate 0.36Acrylic acid, glacial 0.892,2’-Dimethoxy-2- 0.73 phenylacetophenoneBUTVAR B-79 15.56Ethyl Acetate 15.56PVDF Powder’ 32.57Available from abcr GmbH, product code AB211736

[0184] The comparative (meth)acrylate formulation made from the constituents in Table 2 was prepared by mixing the constituents in a speed mixer at 3500 rpm for a period of time of 5 minutes.

[0185] A layer of siliconised PET release liner was placed on the stage of an Elcometer 4340 Automatic Film Applicator, and this (meth)acrylate formulation was then bar-coated onto the release liner at the desired thickness, namely 30 pm, 50 pm or 100 pm.

[0186] The ethyl acetate solvent from the constituents in Table 2 was allowed to evaporate at room temperature over a period of time of 2 hours to permit film formation of the adhesive layer.

[0187] Lapshear specimens were prepared with this (meth)acrylate formulation as previously outlined above.

[0188] The remaining film was cut into small sections for contact poling.2Made in sequential steps from the reaction of diols and dicarboxylic acids to form polyester diols, followed by reaction with toluene diisocyanate and finally capping with hydroxy propyl(meth)acrylate.2024P00381

[0189] The piezoelectric coefficient 'dss' was measured using a PIEZOTEST d33PiezoMeter System employing the Berlincourt Method.

[0190] The physical properties measured and observed for the inventive (meth)acrylate [2,2] composite and the comparative (meth)acrylate [0,3] composite have been captured in Table 3 below.Table 3a39 wt.% PVDFb24 hour cure on Stainless SteelcPoling Conditions: Corona Poling was carried out using a Milman Corona Poling Unit with Pin Voltage= 40 kV, Grid Voltage = 20 kV, Pin Height = 60 mm, Grid Height = 30 mm, Time = 5 minutes* Electric Shortage occurred through sample

[0191] The physical properties measured and observed for the inventive (meth)acrylate [2,2] composite and the comparative (meth)acrylate [0,3] composite captured in Table 3 demonstrate lower (though still acceptable) bond strength for the (meth)acrylate [2,2] composite compared to the (meth)acrylate [0,3] composite on stainless steel lapshear specimens while the (meth)acrylate [2,2] composite demonstrated a d33value whereas the (meth)acrylate [0,3] composite showed none.2024P00381Piezoelectric Film Thickness in f2,21 Composites

[0192] The next series of examples involve the creation of [2,2] composites to show the respective piezoelectric capabilities depending on the thickness of the PVDF layer in the adhesive tape laminate.

[0193] The composites were made from (meth)acrylate adhesive layers at a thickness of 50 pm and a PVDF layer of 30 pm, 50 pm, 80 pm and 110 pm. Stainless steel lapshear substrates were used with (meth)acrylate adhesive layers.

[0194] Table 4 shows (meth)acrylate adhesive layers of 50 pm with a PVDF layer of 30 pm and the bond strengths and piezoelectric effect achieved over time. FIG. 2 depicts this data visually, where the bar charts show adhesive strength and the curve shows piezoelectric effect, each for the listed room temperature aging periods.Table 4

[0195] At a thickness of 30 pm for the piezoelectric layer, adhesive bond strength seems to improve over time in these assemblies, while the piezoelectric effect seems to at least remain somewhat constant over time (though each within experimental error according to the standard deviations).

[0196] Table 5 shows 50 pm (meth)acrylate adhesive layers with a PVDF layer of 50 pm and the bond strengths and piezoelectric effect achieved over time. FIG. 3 depicts this data visually, where the bar charts show adhesive strength and the curve shows piezoelectric effect, each for the listed time periods.2024P00381Table 5

[0197] At a thickness of 50 m for the piezoelectric layer, adhesive bond strength seems to improve over time in these assemblies, while the piezoelectric effect seems to at least remain somewhat constant and in some cases improves over time (though each within experimental error according to the standard deviations).

[0198] Table 6 shows 50 pm (meth)acrylate adhesive layers with a PVDF layer of 80 pm and the bond strengths and piezoelectric effect achieved over time. FIG. 4 depicts this data visually, where the bar charts show adhesive strength and the curve shows piezoelectric effect, each of the listed time periods.Table 6

[0199] At a thickness of 80 pm for the piezoelectric layer, adhesive bond strength seems to improve over time in these assemblies, while the piezoelectric2024P00381 effect seems to at least remain somewhat constant and in some cases improves over time (though each within experimental error according to the standard deviations).

[0200] Table 7 shows 50 pm (meth)acrylate adhesive layers with a PVDF layer of 110 pm and the bond strengths and piezoelectric effect achieved over time. FIG. 5 depicts this data visually, where the bar charts show adhesive strength and the curve shows piezoelectric effect, each of the listed time periods.Table 7

[0201] At a thickness of 110 pm for the piezoelectric layer, adhesive bond strength seems to improve over time in these assemblies, while the piezoelectric effect seems to at least remain somewhat constant and in some cases improves over time (though each within experimental error according to the standard deviations).

[0202] In general, from the data collected in Tables 4-7 it appears that as the thickness of the layer of the PVDF film increases within a (meth)acrylate adhesive layer at a constant thickness of 50 pm, the value of the corresponding d33 is retained within experimental error over the time periods evaluated for the room temperature aging evaluations. The d33 results here thus demonstrate excellent piezoelectric properties are achieved.2024P00381Adhesive Film Thickness in f2,21 Composites

[0203] The next series of examples involve the creation of [2,2] composites to show the respective piezoelectric capabilities depending on the thickness of the adhesive layers in the adhesive tape laminate and its impact on piezoelectric effect.

[0204] The composites were made from each of cyanoacrylate, epoxy and (meth)acrylate adhesive layers, each at a thickness of 30 pm, 50 pm and 100 pm, and a PVDF layer of 80 pm sandwiched in between.

[0205] Table 8 shows the various adhesive layers at a thickness of 30 pm with a PVDF layer of 80 pm and the bond strengths and piezoelectric effect achieved over time. FIG. 6 depicts this data visually, where the bar charts show adhesive strength and the curve shows piezoelectric effect, at each of the listed room temperature aging periods.Table 8

[0206] At a thickness of 80 pm for the piezoelectric layer and an adhesive layer thickness of 30 pm, adhesive bond strength seems to improve over time in these assemblies, while the piezoelectric effect seems to at least remain somewhat constant and in some cases improves over time.

[0207] Table 9 shows the various adhesive layers at a thickness of 50 pm with a PVDF layer of 80 pm and the bond strengths and piezoelectric effect achieved over time. FIG. 7 depicts this data visually, where the bar charts show adhesive strength2024P00381 and the curve shows piezoelectric effect, at each of the listed room temperature aging periods.Table 9

[0208] At a thickness of 80 pm for the piezoelectric layer and an adhesive layer thickness of 50 pm, adhesive bond strength seems to improve over time in these assemblies, while the piezoelectric effect seems to at least remain somewhat constant and in some cases improves over time.

[0209] Table 10 shows the various adhesive layers at a thickness of 100 pm with a PVDF layer of 80 pm and the bond strengths and piezoelectric effect achieved over time. FIG. 8 depict this data visually, where the bar charts show adhesive strength and the curve shows piezoelectric effect, at each of the listed room temperature aging periods.2024P00381Table 10

[0210] At a thickness of 80 m for the piezoelectric layer and an adhesive layer thickness of 100 pm, adhesive bond strength seems to improve over time in these assemblies, while the piezoelectric effect seems to at least remain somewhat constant and in some cases improves over time.

[0211] Table 11 shows the adhesive layers at a thickness of 30 pm with a PVDF layer of 80 pm and the bond strengths and piezoelectric effect achieved initially at room temperature for 24 hours and then over time when exposed to a temperature of 40°C and a relative humidity of 98%. FIG. 9 depicts this data visually, where the bar charts show adhesive strength and the curve shows piezoelectric effect, at each of the listed time periods under the noted accelerated aging conditions.2024P00381Table 11

[0212] Under these accelerated aging conditions, adhesive bond strength seems to improve over time in these assemblies, while the piezoelectric effect seems to at least remain somewhat constant and in some cases improves over time.

[0213] Table 12 shows the adhesive layers at a thickness of 30 pm with a PVDF layer of 80 pm and the bond strengths and piezoelectric effect achieved initially at room temperature for 24 hours and then over time when exposed to a temperature of 80°C. FIG. 10 depicts this data visually, where the bar charts show adhesive strength and the curve shows piezoelectric effect, each of the listed time periods under the noted accelerated aging conditions.Table 122024P00381

[0214] Under these accelerated aging conditions, adhesive bond strength seems to improve over time in these assemblies, while the piezoelectric effect seems to at least remain somewhat constant and in some cases improves over time.

Claims

2024P00381What is Claimed is:1 . A curable adhesive laminate tape comprising: a first release liner; a first adhesive composition; a piezoelectric polymer film or piezoelectric polymer composite film having: a film thickness of from about 1 pm to about 500 pm, a piezoelectric coefficient d33 value of from about 5 to about 40 picocoulombs / Newton (pC / N), from about 10 to about 35 pC / N, or from about 20 to about 30 pC / N, each when measured according to National Physical Laboratory Measurement Good Practice Guide No. 44: Measuring Piezoelectric d33 Coefficients Using Direct Method (2001), a modulus of from about 2,000 to about 2,700 Pascals (Pa), and a dielectric constant of from about 8 to about 50; a second adhesive composition; and a second release liner, wherein at least one of the first adhesive composition or the second adhesive composition comprises a (meth)acrylate matrix, and when cured the adhesive laminate tape demonstrates one or more of the following physical properties:• lap shear strength on stainless steel of from about 1 .0 to about 11 (N / mm2), when measured according to ASTM D1002,• after exposure to room temperature aging conditions for a period of time of up to 6 weeks, lap shear strength on stainless steel of from about 1 .0 to about 11 (N / mm2), when measured according to ASTM D1002,• after exposure to accelerated aging conditions of 80°C for a period of time of up to 6 weeks, lap shear strength on stainless steel of from about 3.5 to about 9 (N / mm2), when measured according to ASTM D1002,• after exposure to accelerated aging conditions of 40°C and 98% relative humidity for a period of time of up to 6 weeks, lap shear strength on stainless2024P00381 steel of from about 4.0 to about 8.0 (N / mm2), when measured according to ASTM D1002,• up to 180 percent adhesion retention on stainless steel after exposure to accelerated aging conditions of 80°C for a period of time of up to 6 weeks;• up to 71 percent d33 coefficient retention on stainless steel after exposure to accelerated aging conditions of 80°C for a period of time of up to 6 weeks;• up to 110 percent adhesion retention on stainless steel after exposure to accelerated aging conditions of 40°C and 98% relative humidity for a period of time of up to 6 weeks;• up to 173 percent d33 coefficient retention on stainless steel after exposure to accelerated aging conditions of 40°C and 98% relative humidity for a period of time of up to 6 weeks;• when disposed and cured between stainless steel substrates a d33 coefficient across the stainless steel substrates of from about 1 .5 to about 11 after exposure to room temperature aging conditions for a period of time of 2 weeks, when measured according to National Physical Laboratory Measurement Good Practice Guide No. 44: Measuring Piezoelectric d33 Coefficients Using Direct Method (2001).

2. The curable adhesive laminate tape according to claim 1 , wherein the (meth)acrylate matrix comprises a film former.

3. The curable adhesive laminate tape according to claim 1 , wherein the piezoelectric polymer film or piezoelectric polymer composite film has a film thickness of from about 1 pm to about 500 pm.

4. The curable adhesive laminate tape according to claim 1 , wherein the piezoelectric polymer film or piezoelectric polymer composite film has a film thickness of from about 10 pm to about 150 pm.

5. The curable adhesive laminate tape according to claim 1 , wherein the piezoelectric polymer film or piezoelectric polymer composite film has a film thickness of from about 20 pm to about 110 pm.2024P003816. The curable adhesive laminate tape according to claim 1 , wherein the piezoelectric polymer film or piezoelectric polymer composite film has a film thickness of from about 25 pm to about 75 pm.

7. The curable adhesive laminate tape according to claim 1 , wherein the piezoelectric polymer film or piezoelectric polymer composite film has a piezoelectric coefficient d33 value of from about 10 to about 35 pC / N, when measured according to National Physical Laboratory Measurement Good Practice Guide No. 44: Measuring Piezoelectric d33 Coefficients Using Direct Method (2001).

8. The curable adhesive laminate tape according to claim 1 , wherein the piezoelectric polymer film or piezoelectric polymer composite film has a piezoelectric coefficient d33 value of from about 20 to about 30 pC / N, when measured according to National Physical Laboratory Measurement Good Practice Guide No. 44: Measuring Piezoelectric d33 Coefficients Using Direct Method (2001).

9. The curable adhesive laminate tape according to claim 1 , wherein the piezoelectric polymer film or piezoelectric polymer composite film is constructed from a member selected from the group consisting of polyvinylidene difluoride (PVDF), polyvinylidene difluoride trifluoroethylene (P(VDF-TrFE)), polyvinylidene difluoride hexafluoropropylene (P(VDF-HFP)), polyvinylidene difluoride chlorofluoroethylene (P(VDF-CFE)), polyvinylidene fluoride-co-trifluoroethylene-co-hexafluoropropylene (PVDF-TrFE-HFP), and polyvinylidene fluoride-co-trifluoroethylene-co- chlorofluoroethylene (PVDF-TrFE-CFE).

10. The curable adhesive laminate tape according to claim 1 , wherein the first adhesive composition comprises a (meth)acrylate composition and the second adhesive composition comprises a cyanoacrylate composition or an epoxy composition.11 . The curable adhesive laminate tape according to claim 1 , wherein each of the first adhesive composition and the second adhesive composition comprises a (meth)acrylate composition.2024P0038112. Use of the curable adhesive laminate tape according to any preceding claim in a monitoring system, such as for fluid flow pathways, for example for monitoring pipes.

13. Use of the curable adhesive laminate tape according to claim 1 as a sensor to monitor structural health of adhesively bonded structures.

14. A device comprising the curable adhesive laminate tape according to any of claims 1 to 11 disposed between two conductive elements.

15. A method for monitoring assets, such as in a fluid flow pathway(s), the method comprising: applying the laminate tape of any of claims 1 to 11 to a surface of a portion of an asset such as a fluid flow pathway for example a pipe; providing monitoring equipment, such as a remote device, to receive signals generated by the piezoelectric layer of the laminate tape, and receiving generated signals for monitoring and reporting conditions in the fluid flow pathway (s).

16. The method of Claim 15, wherein the laminate tape is in the form of a wrap or a patch.

17. A system for monitoring assets, such as in a fluid flow pathway(s), the system comprising: the laminate tape of any of claims 1 to 11 bonded to a surface of a portion of an asset such as a fluid flow pathway for example a pipe; monitoring equipment, such as a remote device, to receive signals generated by the piezoelectric layer of the laminate tape.

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