METHOD AND ARRANGEMENT FOR PRE-CURING AN ADHESIVE LAYER

Abstract

The invention provides a method for pre-curing an adhesive layer bonding a first component to a second component. The adhesive layer is heated by treating an adhesive layer component as heating the first component with a pair of electrodes that are in electrical contact with a surface of the first component, the pair of electrodes applying a predetermined electrical current (I.sub.1, I.sub.2) to the first component. The invention further provides an arrangement for pre-curing a layer of adhesive.

Claims

1-15. (canceled)

16. An arrangement for pre-curing an adhesive layer, comprising: a bonded structure having a first component bonded to a second component by means of the adhesive layer; and a device comprising a pair of electrodes that is in electrical contact with a surface of the first component, the pair of electrodes being adapted to apply a predetermined electrical current (I.sub.1, I.sub.2) to the first component in order to heat the adhesive layer by treating an adhesive layer component.

17. The arrangement according to claim 16, wherein the pair of electrodes are adapted to apply a first electrical current (I.sub.1) to the first component for raising the temperature of the adhesive layer above an activation threshold (AT) and thereafter to apply a second electrical current (I.sub.2) to the first component for holding the temperature of the adhesive layer in a predetermined temperature range (TR) above the activation threshold (AT).

18. The arrangement according to claim 16, wherein the predetermined temperature range (TR) is less than a degradation temperature (DT) of the adhesive layer.

19. The arrangement according to claim 16, wherein the device comprises a means for applying a mechanical pressure (P) to the surface of the first component and a surface of the second component for a predetermined time duration (t3) during pre-curing the adhesive layer.

20. The arrangement according to claim 16, wherein the adhesive layer comprises by a thermosetting adhesive, the first component comprises a material having an electrical conductivity greater than about 100000 S/m and the second component comprises at least one of a fiber reinforced composite, a plastic, a ceramic, aluminum and magnesium.

21. A vehicle part that comprises an adhesive layer pre-cured by a method of claim 1.

22. A vehicle that comprises a vehicle part of claim 21.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The enclosed figures are to convey a further understanding of the embodiments of the invention. They illustrate embodiments and serve in connection with the description to explain principles and concepts of the invention.

[0039] Other embodiments and many of the stated advantages are evident with respect to the figures. The illustrated elements of the figures are not necessarily shown to scale with respect to each other.

[0040] FIG. 1A illustrates an exemplary arrangement for pre-curing an exemplary adhesive layer according to an exemplary embodiment of the invention;

[0041] FIG. 1B illustrates an exemplary arrangement for pre-curing an exemplary adhesive layer according to an exemplary embodiment of the invention;

[0042] FIG. 1C illustrates an exemplary arrangement for pre-curing an exemplary adhesive layer according to an exemplary embodiment of the invention;

[0043] FIG. 2 is a graph of an electrical current, a pressure and a temperature against time of an exemplary pre-curing method according to an exemplary embodiment of the invention;

[0044] FIG. 3 is a graph of temperature against time of heating an exemplary adhesive layer according to an exemplary embodiment of the invention; and

[0045] FIG. 4 is a flow diagram of an exemplary method for pre-curing an exemplary adhesive layer according to an exemplary embodiment of the invention.

[0046] Unless indicated otherwise, like reference numbers throughout the figures indicate like elements.

DETAILED DESCRIPTION

[0047] It is understood that the term vehicle or vehicular or other similar term as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g. fuels derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more sources of power, for example both gasoline-powered and electric-powered vehicles.

[0048] The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms a, an and the are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms comprises and/or comprising, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term and/or includes any and all combinations of one or more of the associated listed items.

[0049] Unless specifically stated or obvious from context, as used herein, the term about is understood as within a range of normal tolerance in the art, for example within 2 standard deviations of the mean. About can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear from the context, all numerical values provided herein are modified by the term about.

[0050] FIG. 1A illustrates an exemplary arrangement for pre-curing an exemplary adhesive layer according to an exemplary embodiment of the invention.

[0051] The arrangement 1 may comprise a bonded structure 5 having a first component 11 bonded to a second component 12 by means of the adhesive layer 10. A device (not shown in FIG. 1A) may comprise a pair of electrodes 13 that is in electrical contact with a surface 11a of the first component 11.

[0052] FIG. 1B illustrates another exemplary arrangement for pre-curing the adhesive layer according to an exemplary embodiment of the invention.

[0053] As being in electrical contact with the surface 11a of the first component 11, the pair of electrodes may apply a predetermined electrical current to the first component 11 in order to heat the adhesive layer 10 by treating the adhesive layer component as heating the first component 11.

[0054] Furthermore, the device further comprises a unit for applying a mechanical pressure P to the surface 11a of the first component 11 and a surface 12a of the second component 12 for a predetermined time duration during pre-curing the adhesive layer 10.

[0055] FIG. 1C illustrates an exemplary arrangement for pre-curing the adhesive layer according to an exemplary embodiment of the invention.

[0056] After pre-curing of the adhesive layer is completed, a mechanical pressure P may be applied to the surface 11a of the first component 11 and a surface 12a of the second component 12 is released and the pair of electrodes 13 may be retracted from the surface 11a of the first component 11.

[0057] FIG. 2 is a graph of an electrical current, a pressure and a temperature against time of an exemplary pre-curing method according to an exemplary embodiment of the invention.

[0058] A first electrical current I.sub.1 may be applied to the first component by means of the pair of electrodes for raising the temperature T of the adhesive layer above an activation threshold AT.

[0059] The adhesive layer may preferably comprise a one-component epoxy. Alternatively, the adhesive layer may comprise a two-component epoxy, a one-component polyurethane, a two-component polyurethane or a two-component acrylic.

[0060] The activation threshold of the adhesive layer may be about 180 C. for the one-component epoxy. Alternatively, the activation threshold of the adhesive layer may be 120 C. for the two-component epoxy, 100 C. for one-component polyurethane, 90 C. the two-component polyurethane and 60 C. for the two-component acrylic.

[0061] Thereafter, a second electrical current I.sub.2 may be applied to the first component by means of the pair of electrodes for holding the temperature T of the adhesive layer in a predetermined temperature range above the activation threshold. The predetermined temperature range selected for pre-curing the adhesive layer may be of about 180 C. to 240 C. for the one-component epoxy. A recommended curing temperature range may be of about 150 C. to 210 C. for the one-component epoxy.

[0062] Alternatively, the predetermined temperature range selected for pre-curing the adhesive layer may be of about 120 C. to 200 C. for the two-component epoxy. A recommended curing temperature range may be of about 25 C. to 180 C. for the two-component epoxy.

[0063] Alternatively, the predetermined temperature range selected for pre-curing the adhesive layer may be of about 100 C. to 160 C. for the one-component polyurethane. A recommended curing temperature range may be of about 70 C. to 130 C. for the one-component polyurethane.

[0064] Alternatively, the predetermined temperature range selected for pre-curing the adhesive layer may be of about 90 C. to 140 C. for the two-component polyurethane. A recommended curing temperature range may be of about 25 C. to 130 C. for the two-component polyurethane.

[0065] Alternatively, the predetermined temperature range selected for pre-curing the adhesive layer may be of about 60 C. to 120 C. for the two-component acrylic. A recommended curing temperature range may be of about 25 C. to 80 C. for the two-component acrylic.

[0066] The first electrical current I.sub.1 may be of about 3000 A. Alternatively, the first electrical current I.sub.1 may be in a range of about 500 A to 5500 A, or particularly of about 1750 A to 4250 A.

[0067] The first electrical current I.sub.1 may be applied to the first component for a time duration of about 4000 ms. Alternatively, the first current I.sub.1 may be applied to the first component within a time range of about 1000 ms to 7000 ms, or particularly of about 2500 ms to 5500 ms.

[0068] The second electrical current I.sub.2 may comprise a predetermined number of pulses of about 850 A. Alternatively, the predetermined number of pulses of the second electrical current I.sub.2 may be within a range of about 250 A to 1450 A, or particularly of about 650 A and 1050 A. The predetermined number of pulses may be applied to the first component for a time duration of about 500 ms. Alternatively, the predetermined number of pulses of the second electrical current I.sub.2 may be applied to the first component within a time range of about 300 ms to 700 ms, or particularly of about 400 ms to 600 ms.

[0069] After each of the pulses, there may be a pause of about 500 ms. Alternatively, after each of the pulses the pause may be within the range of about 100 ms to 900 ms, or particularly of about 300 ms to 700 ms.

[0070] The predetermined number of pulses may be of about 30 pulses. Alternatively, the predetermined number of pulses may be within a range of about 10 to 50 pulses, or particularly of about 20 to 40 pulses.

[0071] The total time duration, during which the first component and consequently the adhesive layer are heated to above the activation threshold and are held within the predetermined temperature range, may be greater than about 30 s.

[0072] Before the first electrical current is applied by the pair of electrodes to the first component, the mechanical pressure P may be applied to the surface of the first component and the surface of the second component for the predetermined time duration during pre-curing the adhesive layer.

[0073] Furthermore, as shown in FIG. 2, the temperature of the adhesive layer usually may rise at a substantially constant rate during application of the first electrical current I.sub.1 and may be subsequently held at a substantially constant level during application of the second electrical current I.sub.2. When the application of the second electrical current I.sub.2 ends, the temperature T of the adhesive layer may begin to fall.

[0074] FIG. 3 is a graph of temperature against time of heating the adhesive layer according to an exemplary embodiment of the invention.

[0075] The predetermined temperature range TR may be selected for pre-curing the adhesive layer. The predetermined temperature range TR may be greater than the activation threshold AT and less than a degradation temperature DT of the adhesive layer. As indicated in FIG. 3, the activation threshold of the adhesive layer may be 180 C. for the one-component epoxy. Alternatively, depending on a choice of adhesive, the activation threshold and/or the degradation temperature and consequently the predetermined temperature range may be different.

[0076] The degradation temperature DT of the adhesive layer may be greater than about 240 C. for the one-component epoxy. Alternatively, the degradation temperature DT of the adhesive layer may be greater than about 200 C. for the two-component epoxy, greater than about 160 C. for one-component polyurethane, greater than about 140 C. the two-component polyurethane and greater than about 120 C. for the two-component acrylic.

[0077] Initially, the temperature of the adhesive layer may increase greater than the activation threshold, for example, in about 3 to 5 s. Thereafter, the temperature of the adhesive layer may be maintained at a substantially constant temperature within the predetermined temperature range TR for a time duration of about 30 s. Upon completing the heating of the adhesive layer, the temperature may begin to fall.

[0078] The arrangement for pre-curing an adhesive layer may have a lap shear strength of greater than about 1.0 MPa for a pre-curing time of about 40 seconds.

[0079] The adhesive layer may comprise a thermosetting adhesive. However, any material generally used in the related arts may be suitably used. For example, the first component may comprise steel. Alternatively, the first component may comprise aluminium or magnesium. Further, the first component may comprise any material having an electrical conductivity greater than about 100000 S/m.

[0080] The second component may comprise a fibre reinforced composite. Alternatively, the second component may comprise one of a plastic, a ceramic, aluminium, magnesium.

[0081] FIG. 4 is a flow diagram of the method for pre-curing the adhesive layer according to an exemplary embodiment of the invention.

[0082] In step S1, the first electrical current may be applied to the first component by means of the pair of electrodes for raising the temperature of the adhesive layer above the activation threshold. In step S2, the second electrical current may be applied to the first component by means of the pair of electrodes for maintaining the temperature of the adhesive layer in a predetermined temperature range that is greater than the activation threshold and less than the degradation temperature of the adhesive layer. In step S3, a mechanical pressure may be applied to the surface of the first component and a surface of the second component for a predetermined time duration during pre-curing the adhesive layer.

[0083] Even though the present invention was described with respect to preferred embodiments, it is not limited thereto, but may be modified in numerous ways. Particularly, the invention may be adapted or modified in numerous ways without deviating from the gist of the invention.

[0084] The shape of the first and second component may for instance be any desired shape. Furthermore, the pair of electrodes may be placed at any desired position on the surface of the first component. Moreover, the second electrical current may be constant or pulsed, depending on specific requirements. Alternatively, other methods for pre-curing of adhesives such as by induction or infrared heating may be employed.