MEMBRANES COMPRISING A THERMALLY CURED ADHESIVE

Abstract

Disclosed is an adhesive composition comprising an acrylic resin and an oligomeric resin having a reactive group and methods for making and using the adhesive composition in roofing membranes. The adhesive composition is thermally cured to form an adhesive layer. The adhesive composition may be applied to a membrane, such as a single-ply membrane, and then thermally cured. The single-ply membrane may then be adhered, via the adhesive layer, to a substrate, such as a roofing substrate.

Claims

1. An adhesive layer comprising an acrylic-based polymer crosslinked by thermal heating with an oligomer having a reactive group, wherein the adhesive layer has a (shear adhesion failure temperature test (SAFT) value from 80 to 110 C. and a Tg from 40 to 30 C.

2. The adhesive layer of claim 1, wherein the reactive group is an epoxy group, an acid group, a urethane group, or combinations thereof.

3. The adhesive layer of claim 1, wherein the adhesive composition has a thickness from 5 to 15 mils.

4. The adhesive layer of claim 1, wherein the adhesive layer has a SAFT value from 80 to 110 C.

5. The adhesive layer of claim 1, wherein the adhesive layer has a SAFT value from 80 to 110 C.

6. The adhesive layer of claim 1, wherein the adhesive layer has a glass transition temperature from 40 to 30 C.

7. The adhesive layer of claim 1, wherein the acrylic-based polymer is a polyacrylate.

8. The adhesive layer of claim 1, wherein the polyacrylate comprises one or more units defined by the formula: ##STR00003## where each R.sup.1 is individually hydrogen or a hydrocarbyl group and each R.sup.2 is individually a hydrocarbyl group.

9. The adhesive layer of claim 8, wherein the polyacrylate is a homopolymer and wherein each R.sup.1 and R.sup.2, respectively, throughout the polymer are the same in each unit.

10. The adhesive layer of claim 8, wherein the polyacrylate is a copolymer, and wherein at least two different R.sup.1 and/or two different R.sup.2 are present in the polymer chain.

11. The adhesive layer of claim 8, wherein the polyacrylate is a copolymer, and wherein at least two different R.sup.1 are present in the polymer chain.

12. The adhesive layer of claim 8, wherein the polyacrylate is a copolymer, and wherein two different R.sup.2 are present in the polymer chain.

13. The adhesive layer of claim 8, wherein the hydrocarbyl group in each of each R.sup.1 and R.sup.2 is independently selected from alkyl, cycloalkyl, substituted cycloalkyl, alkenyl, cycloalkenyl, substituted cycloalkenyl, aryl, substituted aryl, aralkyl, alkaryl, allyl, and alkynyl groups, with each group containing in the range of from 1 carbon atom up to 20 carbon atoms.

14. The adhesive layer of claim 1, wherein the acrylic-based polymer is poly (butylacrylate) or poly (2-ethylhexylacrylate).

15. The adhesive layer of claim 7, wherein the polyacrylate is formulated with at least one of a photoinitiator, solvent, plasticizer, resins, or combinations thereof.

16. A membrane comprising the adhesive layer of claim 1.

17. The membrane of claim 16, wherein the membrane is a single ply membrane.

18. The membrane of claim 16, wherein the membrane comprises thermoplastic polyolefin (TPO), ethylene propylene diene terpolymer (EPDM), polyvinyl chloride (PVC), or combinations thereof.

19. The membrane of claim 16, wherein the membrane has a thickness from 45 to 90 mils.

20. The membrane of claim 16, wherein the adhesive composition has a thickness from 5 to 15 mils.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] A further understanding of the nature and advantages of the present invention may be realized by reference to the remaining portions of the specification and the drawings.

[0017] FIG. 1 is graph showing the results of tear drop testing in accordance with embodiments of the present invention.

[0018] FIG. 2 is a graph showing complex viscosity in accordance with embodiments of the present invention.

[0019] FIG. 3 is a graph showing average loads over oriented straid board in accordance with embodiments of the present invention.

[0020] FIG. 4 is a graph showing average loads over insulation board in accordance with embodiments of the present invention.

[0021] FIG. 5 is a graph showing average loads over gypsum board in accordance with embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0022] Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limits of that range is also specifically disclosed. Each smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in that stated range is encompassed. The upper and lower limits of these smaller ranges may independently be included or excluded in the range, and each range where either, neither or both limits are included in the smaller ranges is also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included.

[0023] As used herein and in the appended claims, the singular forms a, an, and the include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a process includes a plurality of such processes, and so forth.

[0024] Also, the words comprise, comprising, include, including, and includes when used in this specification and in the following claims are intended to specify the presence of stated features, integers, components, or steps, but they do not preclude the presence or addition of one or more other features, integers, components, steps, acts, or groups.

Introduction

[0025] Methods for applying an adhesive layer to a membrane are disclosed herein. An adhesive composition is applied to a surface of the membrane and the adhesive composition is then thermally cured to form an adhesive layer on the membrane. The adhesive composition comprises an acrylic resin and an oligomeric resin having a reactive group. The adhesive composition is a curable adhesive, e.g., a curable hot-melt adhesive. When the adhesive composition is cured by heat, i.e., thermally cured, it has surprisingly and unexpectedly been found that the performance is greatly improved, as compared to UV cured adhesives. Without being bound by theory, it is believed that this improved performance is due to a full cure of the adhesive composition to the membrane. This and other advantages are described herein.

Acrylic Resin

[0026] As indicated above, the adhesive employed in the present invention is a curable hot-melt adhesive, which may also be referred to as a radiation-curable adhesive, a curable pressure-sensitive adhesive, or a pressure-sensitive adhesive. In one or more embodiments, the curable hot-melt adhesive may be an acrylic-based hot-melt adhesive. In one or more embodiments, the adhesive is a polyacrylate, such as a polyacrylate elastomer. In one or more embodiments, useful polyacrylates include one or more units defined by the formula:

##STR00001##

[0027] where each R.sup.1 is individually hydrogen or a hydrocarbyl group and each R.sup.2 is individually a hydrocarbyl group. In the case of a homopolymer, each R.sup.1 and R.sup.2, respectively, throughout the polymer are same in each unit. In the case of a copolymer, at least two different R.sup.1 and/or two different R.sup.2 are present in the polymer chain.

[0028] In one or more embodiments, hydrocarbyl groups include, for example, alkyl, cycloalkyl, substituted cycloalkyl, alkenyl, cycloalkenyl, substituted cycloalkenyl, aryl, substituted aryl, aralkyl, alkaryl, allyl, and alkynyl groups, with each group containing in the range of from 1 carbon atom, or the appropriate minimum number of carbon atoms to form the group, up to about 20 carbon atoms. These hydrocarbyl groups may contain heteroatoms including, but not limited to, nitrogen, oxygen, boron, silicon, sulfur, and phosphorus atoms. In particular embodiments, each R.sup.2 is an alkyl group having at least 4 carbon atoms. In particular embodiments, R.sup.1 is hydrogen and R.sup.2 is selected from the group consisting of butyl, 2-ethylhexyl, and mixtures thereof.

[0029] Specific examples of polyacrylate elastomers that are useful as adhesives in the practice of the present invention include poly (butylacrylate), and poly (2-ethylhexylacrylate). These polyacrylate elastomers may be formulated with photoinitiators, solvents, plasticizers, and resins such as natural and hydrocarbon resins, for example. The skilled person can readily formulate a desirable adhesive composition. Useful adhesive compositions are disclosed, for example, in U.S. Pat. Nos. 6,720,399, 6,753,079, 6,831,114, 6,881,442, and 6,887,917, which are incorporated herein by reference.

[0030] Useful adhesive compositions may be commercially available in the art, depending on the desired specific components. For example, useful adhesives include those available under the tradename acResin (BASF), those available under the tradename AroCure (Ashland Chemical), and NovaMeltRC (NovaMelt). Such compositions, however, are described as being UV curable and are not taught to be heat curable or otherwise curable in the absence of UV curing.

[0031] In one or more embodiments, the polyacrylate elastomers that are useful as a component of the adhesive in the practice of this disclosure may have a glass transition temperature (Tg) of less than 0 C., e.g., less than 5 C., less than 10 C., less than 15 C., less than 20 C., less than 25 C., or less than 30 C. In these or other embodiments, useful polyacrylates may be characterized by a Tg of from about 70 to 0 C., from 65 to 20 C., or from 40 to about 30 C. In some aspects, the polyacrylate resin is AC 250, sold by BASF. This resin has a viscosity from approximately 40-60 Pa's and a Tg of approximately 39 C.

[0032] In one or more embodiments, the polyacrylate elastomers that are useful as a component of the adhesive in the practice of this invention may be characterized by a weight average molecular weight of from about 100 to about 350 kg/mole, in other embodiments from about 150 to about 270 kg/mole, and in other embodiments from about 180 to about 250 kg/mole.

[0033] In one or more embodiments, the polyacrylate elastomers that are useful as a component of the adhesive the practice of this invention may be characterized by a Brookfield viscosity at 150 C. of from 20,000 to 70,000 cps, e.g., 30,000 to 60,000 cps, or from 40,000 to about 50,000 cps. In some aspects, the acrylic resin is a butyl acrylate resin, e.g., polybutyl acrylate.

[0034] In some aspects, the acrylic resin may also comprise a UV-curable oligomer. In accordance with the method described herein, however, since UV light is not applied to cure the resin, UV curing will not occur by itself. Accordingly, the acrylic resin is not purposefully UV cured to the membrane. Any UV curing that does occur is incidental, i.e., unintentional. In some aspects, the acrylic resin is not subjected to any UV curing.

Oligomeric Resin Having a Reactive Group

[0035] The adhesive composition described herein also comprises an oligomeric resin having a reactive group. The oligomeric resin having a reactive group is not particularly limited so long as it has a group that reacts with the acrylic resin when exposed to heat, e.g., thermal curing. Some exemplary reactive groups include epoxy group, an acid group, a urethane group, or combinations thereof. In some aspects, the oligomeric resin having a reactive group is an oligomeric resin having an epoxide group. An exemplary oligomeric resin is Joncryl ADR 4385, a liquid acrylic resin that contains epoxy groups. Without being bound by theory, it is believed that it is these reactive groups, e.g., epoxy groups, that allow for thermal curing of the adhesive composition rather than the application of UV light.

Adhesive Composition and Application Thereof

[0036] The adhesive composition comprises the acrylic resin and oligomeric resin having a reactive group, as described herein. Without being bound by theory, it is believed that when thermally cured, the acrylate resin reacts with the thermally reactive oligomer and the acrylate groups branch to form a network. This network increases the strength of the adhesive layer.

[0037] The adhesive composition may also include additional components, such as colorants and tackifiers. In some aspects, when a tackifier is included, the tackifier may be present in an amount from 0 to 7 wt. %, e.g., from 0.1 to 7 wt. %, from 0.25 to 6.5 wt. %, from 0.5 to 6 wt. %, from 0.75 to 5.5 wt. %, or from 1 to 5 wt. %. Without being bound by theory, the tackifier may be included to improve the initial adhesion of the adhesive composition, i.e., prior to heat curing. In some aspects, when a colorant is included, the colorant may be present in an amount from 0 to 1.5 wt. %, based on the total weight of the adhesive composition, e.g., from 0.1 to 1.5 wt. %, from 0.5 to 1.5 wt. %, from 0.75 to 1.5 wt. %, or from 1.0 to 1.5 wt. %. Without being bound by theory, the colorant may be included to aid in UV absorption. In some aspects, both a tackifier and a colorant are included.

[0038] The adhesive composition may be applied to a membrane by a variety of methods, including use a slit die, a transfer coater, or a release liner.

[0039] Suitable materials for forming a release liner that is a polymeric film or extrudate include polypropylene, polyester, high-density polyethylene, medium-density polyethylene, low-density polyethylene, polystyrene or high-impact polystyrene. The coating or layer applied to the film and/or cellulosic substrate may include a silicon-containing or fluorine-containing coating. For example, a silicone oil or polysiloxane may be applied as a coating. In other embodiments, hydrocarbon waxes may be applied as a coating. The liner, which may be referred to as a release liner, can be applied to an exposed surface adhesive layer.

[0040] The membrane may be a single-ply membrane. In some aspects, the membrane comprises thermoplastic polyolefin (TPO), ethylene propylene diene terpolymer (EPDM), polyvinyl chloride (PVC), or combinations thereof. The adhesive composition may be applied in a thickness from 5 to 15 mils, from 6 to 14 mils, from 6 to 13 mils, or from 7 to 11 mils. The thickness of the adhesive composition may be selected depending on the desired end use, e.g., the type of roofing substrate to which the membrane will be adhered.

Thermal Curing

[0041] Following application of the adhesive composition to the membrane, the adhesive composition is thermally cured. The heat for thermal curing may be applied by a convection heater, a heated die, a radiant heat oven, an infrared heater, radiant heat rollers, or combinations thereof. The heat may be applied at a temperature from 50 to 125 C., e.g., from 60 to 120 C., from 70 to 120 C., from 75 to 125 C., from 75 to 110 C., or any combination of ranges and endpoint thereof.

[0042] The thermal curing may be conducted so that from 85 to 100% of the acrylic resin is reacted with the oligomeric resin, e.g., from 87.5 to 100%, from 90 to 100%, from 92.5 to 100%, from 95 to 100%, from 97.5 to 100%, or from 99 to 100%. In some aspects, essentially 100% of the acrylic resin is reacted with the oligomeric resin. It is not desirable to go above 100%, referred to as over curing due to a sharp decrease in adhesion, i.e., from 60 to 70% decrease. This thermal curing step may be completed in a single step, or in multiple steps. In some aspects, the % of the reaction is based on the SAFT test using a one (1) kilogram weight.

[0043] Exemplary reactions between an acrylic resin and a thermally reactive epoxied group oligomer are shown below, wherein each R may independently be a hydrogen, substituted or unsubstitued C1-20 alkyl group, or other group as contemplated herein.

##STR00002##

[0044] Without being bound by theory, it is believed that by thermally curing the adhesive composition, rather than using ultraviolet curing, the acrylic resin is more completely reacted because the heat penetrates the adhesive composition more than ultraviolet energy could. Accordingly, the adhesive composition is more strongly adhered to the membrane and experiences less cohesive failure over time, i.e., stays attached to both the membrane and to the roofing substrate.

[0045] The molecular weight of the polymer may vary depending on the specific polymer. For polyacrylic acid polymers, the weight average molecular weight (Mw) optionally ranges from 2000 to 7000 amu, e.g., from 3000 to 5000 amu, or from 3500 to 4500 amu.

Adhesive Layer

[0046] The polymer compound may be a solution polymer that helps make a rigid thermoplastic binder when cured. In contrast, when the polymer compound is an emulsion polymer, the final binder compositions are usually less rigid (i.e., more flexible) at room temperature. The cured adhesive layer is formed on the membrane following heat curing. The adhesive layer may have a thickness from 5 to 15 mils, from 6 to 14 mils, from 6 to 13mils, or from 7 to 11 mils. The thickness of the adhesive layer, like the adhesive composition, may be selected depending on the desired end use, e.g., the type of roofing substrate to which the adhesive layer is adhered. In some aspects, the adhesive layer has a thickness from 5 to 50% relative to the thickness of the membrane, e.g., from 10 to 45%, from 15 to 40%, or from 20 to 35%.

[0047] The adhesive layer may have a shear adhesion failure temperature (SAFT) value from 80 to 110 C., e.g., from 85 to 110 C., from 90 to 105 C., or from 95 to 100 C. The adhesive layer may not flow or have movement at temperatures from 80 to 11 C. and may be tacky at 15 C.

[0048] The adhesive layer may have a glass transition temperature from 40 to 30 C., e.g., from 39 to 31 C., from 38 to 32 C., from 37 to 33 C., or from 36 to 34 C.

Membrane

[0049] The membrane to which the adhesive composition is applied may be a single ply membrane. In some aspects, the membrane may be a multi ply membrane, e.g., a membrane have more than a single ply. In some aspects, the membrane thermoplastic polyolefin (TPO), ethylene propylene diene terpolymer (EPDM), polyvinyl chloride (PVC), or combinations thereof.

[0050] In some aspects, following the formation of the adhesive layer on the membrane, the method may further comprise heat welding a seam of the membrane.

Roofing Substrate

[0051] In some aspects, the membrane is secured to a roofing substrate by the adhesive layer. The adhesive layer is exposed, e.g., by removing a release liner, and then pressed onto the roofing substrate. In some aspects, a roofing primer may be used. In these aspects, the primer is applied to the roofing substrate and allowed to dry until tacky to the touch. Then the adhesive layer is pressed onto the primer, securing the membrane to the roofing substrate.

[0052] The roofing substrate may comprise paper faced insulation board, isocyanate insulation board, gypsum board, plywood, oriented strand board (OSB), cement board, or combinations thereof.

[0053] Once assembled, the membrane, adhesive layer, and roofing substrate may be referred to as a three-layer material, though other combinations of the layers are also contemplated herein.

[0054] Once assembled, the maximum load strength between the roofing substrate and the adhesive layer may be from 2 to 20 force pounds, as measured using a tear drop test on an Instron Pull Tester, e.g., from 2.05 to 20 force pounds, from 2.5 to 20 force pounds, from 3 to 20 force pounds, from 3 to 17.5 force pounds, from 3.5 to 17.5 force pounds, from 4 to 15 force pounds, from 4.5 to 15 force pounds, from 5 to 15 force pounds, from 6 to 15 force pounds, from 7 to 15 force pounds, from 7.5 to 15 force pounds, from 4.2 to 14 force pounds, from 4.5 to 13 force pounds, from 5 to 10 force pounds, and all values in between.

EMBODIMENTS

[0055] Embodiment 1: A method of applying an adhesive layer to a membrane, the method comprising: a) providing a membrane; b) applying an adhesive composition to a surface of the membrane, wherein the adhesive composition comprises an acrylic resin and an oligomeric resin having a reactive group; and c) thermally curing the adhesive composition to form an adhesive layer on the membrane.

[0056] Embodiment 2: The method of Embodiment 1, wherein the reactive group is an epoxy group, an acid group, a urethane group, or combinations thereof.

[0057] Embodiment 3: The method of Embodiment 1 or 2, further comprising: d) applying a release liner to a surface of the adhesive layer opposite the surface of the membrane.

[0058] Embodiment 4: The method of any of the preceding Embodiments, wherein the membrane is a single ply membrane.

[0059] Embodiment 5: The method of any of the preceding Embodiments, wherein the membrane comprises thermoplastic polyolefin (TPO), ethylene propylene diene terpolymer (EPDM), polyvinyl chloride (PVC), or combinations thereof.

[0060] Embodiment 6: The method of any of the preceding Embodiments, wherein the adhesive composition has a thickness from 5 to 15 mils.

[0061] Embodiment 7: The method of any of the preceding Embodiments, wherein the membrane has a thickness from 45 to 90 mils.

[0062] Embodiment 8: The method of any of the preceding Embodiments, wherein the thermally curing comprises reacting Embodiment 85 to 100% of the acrylic resin with the oligomeric resin.

[0063] Embodiment 9: The method of any of the preceding Embodiments, wherein the adhesive layer has a SAFT value from 80 to 110 C. (ASTM D 4498).

[0064] Embodiment 10: The method of any of the preceding Embodiments, wherein the adhesive layer has a glass transition temperature from 40 to 30 C.

[0065] Embodiment 11: The method of any of the preceding Embodiments, wherein the thermally curing comprises applying heat at a temperature from 50 to 125 C.

[0066] Embodiment 12: The method of any of the preceding Embodiments, wherein the thermally curing comprises applying heat with a heated die, a radiant heat oven, an infrared heater, radiant heat rollers, or combinations thereof.

[0067] Embodiment 13: The method of any of the preceding Embodiments, wherein the method further comprises: d) heat welding a seam of the membrane.

[0068] Embodiment 14: A method of adhering a membrane to a roofing substrate, the method comprising: a) providing a membrane; b) applying an adhesive composition to a surface of the membrane, wherein the adhesive composition comprises an acrylic resin and an oligomeric resin having a reactive group; c) thermally curing the adhesive composition to form an adhesive layer on the membrane; and d) contacting the adhesive layer with a roofing substrate to adhere the membrane to the roofing substrate.

[0069] Embodiment 15: The method of Embodiment 14, wherein the acrylic resin is a hot-melt acrylic resin.

[0070] Embodiment 16: The method of Embodiment 14 or 15, wherein the reactive group is an epoxy group, an acid group, a urethane group, or combinations thereof.

[0071] Embodiment 17: The method of any of Embodiments 14-16, wherein the substrate comprises paper faced insulation board, isocyanate insulation board, gypsum board, plywood, oriented strand board (OSB), cement board, or combinations thereof.

[0072] Embodiment 18: A membrane comprising an adhesive layer prepared according to any of the preceding Embodiments.

[0073] Embodiment 19: A three-layer material, the material comprising: a membrane, an adhesive layer, and a roofing substrate, wherein the membrane and adhesive layer are prepared according to any of Embodiments 1-13.

[0074] Embodiment 20: An adhesive layer comprising an acrylic-based polymer crosslinked by thermal heating with an oligomer having a reactive group, wherein the adhesive layer has a (shear adhesion failure temperature test (SAFT) value from 80 to 110 C. and a Tg from 40 to 30 C.

EXPERIMENTAL

[0075] The following Examples are presented to provide specific representative embodiments of the present invention. The invention is not limited to the specific details as set forth in these Examples.

Example 1

[0076] Three single ply membranes (Comparative Sample A and Inventive Samples B and C) were secured to isocyanate insulation board with a hot melt adhesive layer. The hot melt adhesive layer was formed from a hot melt adhesive composition containing 97.5 wt. % polybutyl acrylate (AC Resin 250) and 2.5 wt. % liquid acrylic resin with epoxy functionality (Joncryl ADR 3585). The hot melt adhesive composition was applied in a thickness of 8 mils and heat cured. From 90 to 100% of the adhesive layer was cured, as measured by a modified ASTM D4498 (the test was conducted at 71.11 C. using a 3 inch by 8 inch (7.62 by 20.32 cm) stainless steel plate. The maximum load strength between the hot melt adhesive and the substrate was tested using a tear drop test. As shown in FIG. 1, for Comparative Sample A, an EPDM first single play membrane was secured to an isocyanate insulation board after an adhesive layer was UV-cured onto the EPDM membrane. The maximum load strength for Comparative Sample A was approximately 3.7 pounds force. For Sample C, which was prepared identically to Comparative Sample A except that it was heat cured rather than UV cured, the maximum load strength was approximately 4.4 pounds force. Thus, heat curing resulted in a 19% increase. For Sample B, where the membrane was TPO, the maximum load strength was approximately 7.7 pounds force, a 110% increase relative to Comparative Sample A due to heat curing rather than UV curing.

Example 2

[0077] Varying amounts of a liquid acrylic resin with epoxy functionality (Joncryl 4385 ADR) were mixed with polybutyl acrylate (AC 250 resin from BASF) and the complex viscosity was tested as a function of time as reported in FIG. 2. Each sample of AC 250 was weighed and heated to approximately 30 C. to soften the sample. The liquid acrylic resin (initiator) was then added and stirred with the AC 250. The stirred samples were then placed in a rheometer and held at 30 C. The adhesive composition was extruded onto a membrane. Next, the membrane comprising the extruded adhesive composition was sent through an infrared heater at a rate of 10 ft/min (3.048 m/min) and at a temperature of 165 C. to thermally cure the adhesive composition to form an adhesive layer on the membrane. Once the membrane comprising the adhesive layer was removed from the heater, a release liner was applied and the membrane was rolled up. Once it had cooled to room temperature, the membrane was unrolled. The release liner was removed and the membrane and adhesive layer were heated to a temperature of 100 C. The temperature of 100 C. was selected to mimic the temperature that the membrane may be exposed to on a hot roof.

[0078] Five samples were tested and the results are shown in FIG. 2. Sample E (top line) was tested with 2.5% liquid acrylic resin at 2% strain. Sample F (second line from the top) was tested with 2.5% liquid acrylic resin at 2% strain. Sample G (middle line) was tested with 2.5% liquid acrylic resin at 2% strain. Sample H (second line from the bottom) was tested with 2.5% liquid acrylic resin at 2% strain. Comparative Sample I (bottom line) was tested at 2% strain with 0% liquid acrylic resin. As expected, the Complex Viscosity of Comparative Sample I did not increase over time, indicating that no curing occurred. The bottom line indicates a 2% strain rheological test performed on a system heated to 100 C. and cured with 0% initiator. In this case, viscosity did not increase over time, due to the lack of initiator, leading to no crosslinking. On the other hand, in presence of 2.5% initiator, the complex viscosity does increase over time, as detected during a 2% strain rheological test performed at 35 C., 50 C., 75 C. and 100 C. (top line, second line from the top, middle line and second line from the bottom, respectively).

Example 3

[0079] An adhesive composition comprising 1 wt. % liquid acrylic resin with epoxy functionality (Joncryl 4385 ADR) and 99 wt. % polybutyl acrylate (AC 250 resin from BASF) was prepared and applied to EPDM and TPO membranes as reported below. The adhesive composition was cured and each membrane was secured to a roofing substrate. Each roofing substrate secured to a membrane via the heat cured adhesive layer was then tested at either 6.67 C., room temperature (approximately 20 C.) or at 71.1 C., in order to mimic temperatures to which a roofing substrate would be exposed on a structure. The average load for each sample was tested as reported in FIGS. 3-5, according to an Instron Tester. The samples showing each combination of membrane, roofing substrate, and temperature are shown in Table 1.

TABLE-US-00001 TABLE 1 Sample Membrane Roofing Substrate Temperature ( C.) J EPDM Straid Board 6.67 K EPDM Straid Board 71.1 L EPDM Straid Board ~20 (room temperature) M TPO Straid Board 6.67 N TPO Straid Board 71.1 O TPO Straid Board ~20 (room temperature) P EPDM Insulation Board 6.67 Q EPDM Insulation Board 71.1 R EPDM Insulation Board ~20 (room temperature) S TPO Insulation Board 6.67 T TPO Insulation Board 71.1 U TPO Insulation Board ~20 (room temperature) V EPDM Gypsum Board 6.67 W EPDM Gypsum Board 71.1 X EPDM Gypsum Board ~20 (room temperature) Y TPO Gypsum Board 6.67 Z TPO Gypsum Board 71.1 AA TPO Gypsum Board ~20 (room temperature)

[0080] The results indicate that heat curing has a superior average force pound value as compared to UV curing. UV curing typically results in an average from 0.5 to 2.0 force pounds while each reported result was above this value and in some cases, well above this value.

[0081] While the invention has been described in detail, modifications within the spirit and scope of the invention will be readily apparent to those of skill in the art. It should be understood that aspects of the invention and portions of various embodiments and various features recited herein and/or in the appended claims may be combined or interchanged 10 either in whole or in part. In the foregoing descriptions of the various embodiments, those embodiments which refer to other embodiments may be appropriately combined with other embodiments as will be appreciated by one of ordinary skill in the art. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only and is not intended to limit the invention.