Tangential joining method

Abstract

The invention relates to a joining method wherein a first surface (2) of a first adherend (1) and a second surface (8) of a second adherend (6) are bonded to one another by provision of an adhesive tape (3) having a first side (4) and a second side (7), there being disposed on the first side (4) a first activatable adhesive and on the second side (7) a second activatable adhesive, the latter being an activatable pressure-sensitive adhesive, the first side (4) of the adhesive tape (3) is contacted with the first surface (2) of the first adherend (1) to produce a preliminary assembly, the second surface (8) of the second adherend (6) is joined in a joining movement to the second side (7) of the adhesive tape (3), the joining movement having a tangential component and a perpendicular component relative to the second side (7) of the adhesive tape (3), with a ratio between tangential and perpendicular components of greater than 0.5, where a region of contact between second surface (8) of the second adherend (6) and second side (7) of the adhesive tape (3) is provided with a nonaqueous lubricant.

Claims

1. A method comprising: providing an adhesive tape comprising a first side and a second side, wherein: an activatable adhesive is disposed on the first side; an activatable pressure-sensitive adhesive is disposed on the second side; the first side is in contact with a first surface of a first adherend; a nonaqueous lubricant is disposed between the second side and a second surface of a second adherend; bonding the first surface and the second surface with the adhesive tape; and joining in a joining movement the second surface to the second side, wherein: the joining movement comprises a tangential component relative to the second side and a perpendicular component relative to the second side; a ratio between the tangential component and the perpendicular component is greater than 0.5:1; the nonaqueous lubricant is in fluid form at room temperature; the nonaqueous lubricant has a dynamic viscosity of at least 5 mPa s measured according to DIN 53019-1 at a measuring temperature of 25° C. and a shear rate of 1 s.sup.−1; and the activatable pressure-sensitive adhesive, when applied to the second side of the adhesive tape in a thickness of 200 μm, exhibits a peel adhesion, on a steel substrate coated with 1 g/m.sup.2 of the nonaqueous lubricant at a removal speed of 300 mm/min after one hour of storage at 23° C. and a relative atmospheric humidity of 50%, of less than 50% of the peel adhesion after 24 h of storage.

2. The method as claimed in claim 1, wherein the nonaqueous lubricant comprises a grease, a petrolatum, a hotmelt nonaqueous lubricant, a plasticizer, a liquid resin, a reactive resin, a polyol, a fatty acid, an ester of a fatty acid, a mineral oil, a paraffinic oil, a naphthenic oil, a synthetic oil, or a silicone oil.

3. The method as claimed in claim 1, wherein the ratio between the tangential component and the perpendicular component is greater than 1:1.

4. The method as claimed in claim 1, wherein the activatable pressure-sensitive adhesive comprises an activated pressure-sensitive adhesive.

5. The method as claimed in claim 1, wherein the activatable adhesive bonds more quickly to an oil-coated surface than the activatable pressure-sensitive adhesive.

6. The method as claimed in claim 1, further comprising, before bonding, coating the first surface and the second surface with the nonaqueous lubricant.

7. The method as claimed in claim 1, wherein the activatable pressure-sensitive adhesive comprises a base polymer and a reactive resin.

8. The method as claimed in claim 7, wherein the base polymer comprises an acrylate, a methacrylate, a polyurethane, a natural rubber, a synthetic rubber, a styrene block copolymer comprising an unsaturated polydiene block, a partly-hydrogenated polydiene block, a fully-hydrogenated polydiene block, a styrene block copolymer comprising a polybutadiene, a styrene block copolymer comprising a polyisoprene, a styrene block copolymer comprising a poly(iso)butylene, a styrene block copolymer comprising a copolymer of at least two of a polyisoprene, a poly(iso)butylene, and a poly(iso)butylene, a polyolefin, a fluoropolymer, a silicone, a polyamide, or a polyhydroxyether comprising a phenoxy resin.

9. The method as claimed in claim 7, wherein the reactive resin further comprises: a constituent for a polymer comprising a polyepoxide, a polyester, a polyether, a polyurethane, a polysulfide, a polysiloxane, or an acrylic polymer; and a polymer based on a phenolic resin, on cresol, or on a novolac.

10. The method as claimed in claim 1, wherein the adhesive tape comprises a carrier layer comprising a polyethylene, a polypropylene, a cyclic olefin copolymer (COC), a polyvinyl chloride (PVC), a polyester, a polyethylene naphthalate (PEN), an ethylene-vinyl alcohol (EVOH), a polyvinylidene chloride (PVDC), a polyvinylidene fluoride (PVDF), a polyacrylonitrile (PAN), a polycarbonate (PC), a polyamide (PA), a polyethersulfone (PES), or a polyimide (P1).

11. The method as claimed in claim 1, wherein: at least one of the activatable adhesive and the activatable pressure-sensitive adhesive comprises an oil absorber; the oil absorber comprises a phyllosilicate, a zeolite, silica, a graphite, lime, cellulose and derivatives thereof, an aerogel, a polyurethane, a polyolefin, an acrylate-nitrile-alcohol polymer, an urethane-isocyanate-alcohol polymer, a perlite, silk, peat, straw, or rubber.

12. The method as claimed in claim 1, further comprising: applying the nonaqueous lubricant to the second side and thereafter contacting the second side with the second surface; applying the nonaqueous lubricant to the second surface and thereafter contacting the nonaqueous lubricant with the second side; the nonaqueous lubricant has a boiling temperature under ambient pressure of more than 120° C.; the nonaqueous lubricant has a dynamic viscosity of more than 100 mPa sat a measuring temperature of 25° C. and a shear rate of 1 s.sup.−1; the nonaqueous lubricant has a static contact angle relative to the activatable pressure-adhesive of less than or equal to 60° measured at 23° C. and 50% relative atmospheric humidity; and/or the nonaqueous lubricant has a dynamic viscosity of less than or equal to 10 Pa s measured according to DIN 53019-1 at a measuring temperature of 25° C. and a shear rate of 1 s.sup.−1.

13. The method as claimed in claim 1, wherein: a contact angle of the nonaqueous lubricant relative to the activatable adhesive is greater than 30°; a contact angle of the nonaqueous lubricant relative to the activatable pressure-sensitive adhesive is less than 30°; or a contact angle of the nonaqueous lubricant relative to the activatable adhesive is greater than 30° and a contact angle of the nonaqueous lubricant relative to the activatable pressure-sensitive adhesive is less than 30°.

14. The method as claimed in claim 1, wherein the nonaqueous lubricant comprises a mineral oil, a paraffinic oil, a naphthenic oil, a synthetic oil, a silicone oil, an anticorrosion oil, a forming oil, a liquid tackifier resin, or a reactive resin.

15. The method as claimed in claim 14, wherein the anticorrosion oil is present and comprises a prelube anticorrosion oil, a hotmelt anticorrosion oil, or a spot lubricant anticorrosion oil.

16. The method as claimed in claim 1, wherein: the nonaqueous lubricant comprises a first component; the activatable pressure-sensitive adhesive comprises a second component; and the first component is from the same chemical group as the second component.

17. The method as claimed in claim 1, wherein the nonaqueous lubricant is present in an amount of between 0.1 and 10 g/m.sup.2.

18. The method as claimed in claim 1, wherein: the nonaqueous lubricant is disposed in a drop on the activatable pressure-sensitive adhesive; and a contact angle of the drop relative to the activatable pressure-sensitive adhesive differs from a contact angle of a drop of the non-aqueous lubricant relative to the activatable adhesive by at least 10°.

19. A method comprising: providing an adhesive tape comprising a first side and a second side, wherein: an activatable adhesive is disposed on the first side; an activatable pressure-sensitive adhesive is disposed on the second side; the first side is in contact with a first surface of a first adherend; a nonaqueous lubricant is disposed between the second side and a second surface of a second adherend; bonding the first surface and the second surface with the adhesive tape; and joining in a joining movement the second surface to the second side, wherein: the joining movement comprises a tangential component relative to the second side and a perpendicular component relative to the second side; a ratio between the tangential component and the perpendicular component is greater than 0.5:1; the nonaqueous nonaqueous lubricant comprises a grease, a petrolatum, a hotmelt nonaqueous lubricant, a plasticizer, a reactive resin, a polyol, a fatty acid, or an ester of a fatty acid; and the activatable pressure-sensitive adhesive, when applied to the second side of the adhesive tape in a thickness of 200 μm, exhibits a peel adhesion, on a steel substrate coated with 1 g/m.sup.2 of the nonaqueous lubricant at a removal speed of 300 mm/min after one hour of storage at 23° C. and a relative atmospheric humidity of 50%, of less than 50% of the peel adhesion after 24 h of storage.

20. A method of joining a first adherent to a second adherent, said method comprising: (a) providing an adhesive tape comprising a first side and a second side; an activatable adhesive disposed on the first side; and an activatable pressure-sensitive adhesive disposed on the second side; (b) bonding the first side of said adhesive tape to a first surface of said first adherent; (c) bonding the second side of said adhesive tape to a second surface of said second adherent in a joining movement; wherein a nonaqueous lubricant is disposed between the second side and said second surface of said second adherent and is present during the joining movement; the joining movement comprises a tangential component relative to the second side and a perpendicular component relative to the second side; a ratio between the tangential component and the perpendicular component is greater than 0.5:1; the nonaqueous lubricant is in fluid form at room temperature; the nonaqueous lubricant has a dynamic viscosity of at least 5 m Pa s measured according to DIN 53019-1 at a measuring temperature of 25° C. and a shear rate of 1 s.sup.−1; and the activatable pressure-sensitive adhesive absorbs the nonaqueous lubricant slowly such that the activatable pressure-sensitive adhesive, when applied to the second side of the adhesive tape in a thickness of 200 μm, exhibits a peel adhesion, on a steel substrate coated with 1 g/m.sup.2 of the nonaqueous lubricant at a removal speed of 300 mm/min after one hour of storage at 23° C. and a relative atmospheric humidity of 50%, of less than 50% of the peel adhesion after 24 h of storage.

Description

(1) FIG. 1 shows a preliminary assembly with an adhesive tape applied to a first surface of a first adherend,

(2) FIG. 2 shows the preliminary assembly produced in FIG. 1, which is applied in at least partially tangential movement to a second surface of a second adherend,

(3) FIG. 3 shows first and second adherends bonded with the adhesive tape of the invention,

(4) FIG. 4a shows a vectorial division of the joining movement into a tangential component and a perpendicular component with respect to a second surface of the adhesive tape,

(5) FIG. 4b shows first and second adherends assembled by joining.

(6) The figures are not to scale. FIG. 1 shows a first adherend 1. This is an oil-coated metal panel of the kind used in bodywork construction for automobiles. An adhesive tape 3 is stuck to a first surface 2 of the first adherend 1. The adhesive tape 3 is stuck to the first adherend 1 in a first method step. The adhesive tape 3 has a first side 4 which is bonded on the first surface 2 of the first adherend. The first side of the adhesive tape is coated with a first activatable PSA. The association of adhesive tape 3 and first adherend 1 according to FIG. 1 is also referred to here as the preliminary assembly. The composition of the first PSA is preferably such that the oil present on the metal panel is absorbed quickly or displaced during application and therefore establishes an adhesive bond with the first adherend 1.

(7) FIG. 2 shows a second method step. A second adherend 6 is joined to the first adherend 1 in a joining movement which includes a tangential movement component relative to the first adherend 1. With regard to at least a region 5 of a second adhesive tape side 7 which is opposite the first adhesive tape side 4, the joining movement includes a tangential movement component in the sense that a second surface 8 of the second adherend 6 moves, as a result of the joining movement with a tangential movement component, to the second side 7 of the adhesive tape in the region 5.

(8) The tangential component of the joining movement, and a component thereof perpendicular to the second side 7 of the adhesive tape 3 in the region 5, have a ratio of 0.5, preferably 1.0, more preferably of more than 4.

(9) The second side 7 of the adhesive tape 3 is formed by a second activatable PSA. The second surface 8 of the second adherend 6 is coated in accordance with the invention with a nonaqueous lubricant. As a result of the effect of the lubricant, the second surface 8 of the second adherend 6 slides along on the second side 7 of the adhesive tape 3, without the adhesive tape 3 slipping. The second side 7 of the adhesive tape 3 therefore does not attach immediately on first contact to the second surface 8 of the second adherend 6.

(10) FIG. 3 shows a third method step, in which the first and second adherends 1, 6 and the adhesive tape 3 have reached their final position relative to one another. In the position shown in FIG. 3, the two PSAs are activated and produce a strong adhesive bond of the first surface 2 of the first adherend 1 to the second surface 8 of the second adhered 6. The composition of the second PSA is preferably such that it absorbs the lubricant applied to the second surface 8 of the second adherend 6, allowing a firm bonded connection to be produced between the adherends 1 and 6 following activation of the PSAs.

(11) FIG. 4 shows in part a) two adherends 1 and 6, the adherend 1 having two adhesive tapes 3 stuck to it so as to produce a preliminary assembly. The second surface 7 of the adhesive tapes 3 is furnished with a lubricant. The second adherend 6 is guided toward the first adherend 1 with the joining movement 9. The joining movement 9 may be broken down into a component 10 tangential to the second surface of an adhesive tape, and a component 11 perpendicular thereto. The angle between the tangential and vertical components 10 and 11 is 90°. The ratio between tangential and perpendicular components is greater than 0.5 and here in particular greater than 4. As a result of the joining movement and the subsequent adhesive bonding with activation of the activatable PSA, the two profiles 1 and 6 are nested, as shown in part b) of FIG. 4.

(12) Table 1 shows initially preferred combinations of a first activatable PSA and a second activatable PSA. The idea behind the table is that of designing the first activatable PSA in such a way that it adheres as quickly as possible to the oil-coated metal sheet forming the first surface 2 of the first adherend 1; the first activatable PSA is based, for example, on a polymer that is based on synthetic rubber or polyolefins, while the reactive resin selected is an epoxide.

(13) The second activatable PSA is selected such that it attaches only with a delay to the second surface 8 of the second adherend 6, which is likewise an oil-coated metal sheet; the second PSA is based preferably, for example, on a polyurethane or acrylate, while the activatable part selected in turn is an epoxide. Every PSA is based on a viscoelastic part and an activatable part, with the viscoelastic part based on one of the abovementioned polymers and the activatable part on a reactive resin in the sense of the definition given at the outset for “based”. Preference is given to combining viscoelastic parts with viscoelastic parts, reactive parts with reactive parts, or reactive parts with viscoelastic parts in accordance with table 1.

(14) This means that provided the reactive part of the first adhesive comprises epoxy resin, the elastomer of the second adhesive is selected preferably freely from the group indicated in table 1, and also any resin from the stated group, with the exception of epoxide, is preferred as a reactive resin of the second adhesive,

(15) or that

(16) first adhesives based in the viscoelastic part on a polyolefin or synthetic rubber are preferably combined with second adhesives based on a polyurethane or acrylic polymer,

(17) or that

(18) first adhesives based in the viscoelastic part on a polyolefin or synthetic rubber are preferably combined with second adhesives whose reactive part is based on epoxy resin.

(19) In experiments, activatable PSAs K1 to K4 were produced. The activatable PSAs are based on the following raw materials:

(20) Raw Materials Used

(21) Base Polymers

(22) TABLE-US-00002 Breon Nitrile butadiene rubber with an acrylonitrile N41H80 fraction of 41% from Zeon Chemicals (London, UK) Desmomelt Largely linear hydroxyl polyurethane. Desmomelt 530 is 530 a highly crystalline, elastic polyurethane of very low thermoplasticity from Bayer MaterialScience. The enthalpy of fusion as measured by DSC is 54.7 J/g. Poly bd R Hydroxyl-terminated polybutadiene from Cray 45 HTLO Valley with a molecular weight Mw of about 2800 g/mol and a hydroxyl functionality of about 2.5 Polyvest Maleic anhydride-functionalized polybutadiene MA 75 from Evonik with a molecular weight Mw of about 3000 g/mol and an acid number of about 80 mg KOH/g Azalt Bitumen 50/70 (B65) from Total 50/70

(23) Reactive Resins

(24) TABLE-US-00003 Epikote Difunctional bisphenol A/epichlorohydrin liquid 828 epoxide with a weight per epoxide of about 190 g/eq from Momentive. Viscosity at 25° C. of about 13 Pa s. PolyDis Nitrile rubber-modified epoxy resin based on PD3611 bisphenol F diglycidyl ether with an elastomer content of 40% and a weight per epoxide of 550 g/eq from Schill + Seilacher “Struktol”. Viscosity at 25° C. of 10 000 Pa s. PolyDis Nitrile rubber-modified epoxy resin based on PD3691 bisphenol A diglycidyl ether with an elastomer content of 5% and a weight per epoxide of 205 g/eq from Schill + Seilacher “Struktol”. Viscosity at 25° C. of 300 Pa s. Tactix Dicyclopentadiene-epoxy-novolac resin with a weight 556 per epoxide of 215-235 g/eq and a softening point of 53° C. from Huntsman.

(25) Curing Agents

(26) TABLE-US-00004 Dyhard Latent curing agent from AlzChem for epoxy 100S systems, consisting of micronized dicyandiamide in which 98% of the particles are smaller than 10 μm. Dyhard Latent uron accelerator for epoxy systems, in which UR500 98% of the particles are smaller than 10 μm. Mahlschwefel Twice-refined soluble elemental sulfur with a 80/90° purity of at least 99.9% from Avokal MBTS 2,2′-Dibenzothiazyl disulfide from Weber&Schaer TEDA Triethylenediamine crystal from Trigon (1,4-diazabicyclo[2.2.2]octane)

(27) Fillers

(28) TABLE-US-00005 Weiβfeinkalk Calcium oxide CL 90 - Q -90 from Rheinkalk Talkum Pharma M Talc from Scheruhn, BET surface area about 4.6 m.sup.2/g Printex 60 Furnace black, oil absorption No. 118, BET surface area about 115 m.sup.2/g

(29) The table below shows the composition in parts by weight of adhesives K1 to K4 on the basis of the raw materials identified above:

(30) Adhesives:

(31) TABLE-US-00006 TABLE 2 Example: K1 K2 K3 K4 Parts Parts Parts Parts by wt by wt by wt by wt Breon N41H80 20 20 Desmomelt 530 20 Epikote 828 80 PolyDis PD3611 65 30 PolyDis PD3691 15 10 Tactix 556 40 Dyhard 100S 5.56 2.49 3.51 Dyhard UR500 0.56 0.25 0.35 Poly bd R 45 HTLO 28 Polyvest MA 75 15.1 Azalt 50/70 15 Mahlschwefel 80/90° 16 MBTS 1.5 Weiβfeinkalk 3 Talkum 15 Printex 60 6.1 TEDA 3

(32) The activatable PSAs K1 to K4 were prepared in the laboratory by dissolving the polymer in butanone at 23° C. Next the reactive resins were added. Subsequently the curing agent was added with vigorous shearing by stirring.

(33) To produce layers of adhesive, the various adhesives were applied from a solution to a conventional liner (siliconized polyester film) by means of a laboratory coating apparatus, and were dried. The layer thickness of adhesive after drying was 200±10 μm. Drying took place in each case initially at RT for ten minutes and for ten minutes at 105° C. in a laboratory drying cabinet. The dried layers of adhesive were each lined, immediately after drying, with a second liner (siliconized polyester film with lower release force) on the open side.

(34) For K5, first of all two components were prepared: the A component was prepared by mixing the raw materials indicated, apart from the Polyvest MA75, in a planetary mixer or dissolver for two hours. To obtain a bubble-free product, the mixture was degassed during the final ten minutes of the mixing process by application of a reduced pressure of less than 0.02 bar (15 torr). The result in each case was a paste which can be processed further at room temperature. The B component was the Polyvest MA75.

(35) A and B components were mixed together on a 2-component mixing system and immediately coated out on a customary coating unit, onto a double-sided release paper, to give a pasty film 200 μm in thickness. On subsequent passage through a heating tunnel, crosslinking took place at 70° C. to form the pressure-sensitive adhesive layer.

(36) Lubricants:

(37) G1: Ferrocoat 6130 from Quaker, a paraffinic oil (CAS 64742-65-0) having a viscosity of about 150 mPa s

(38) G2: Anticorit PL 3802-39S, prelube oil from Fuchs, based on naphthenic oil (CAS 265-156-6) with a viscosity of about 300 mPa s

(39) G3: Wingtack 10 from Cary Valley, an aliphatic hydrocarbon resin having a viscosity of about 30 Pa s

(40) G4: Epikote 828 from Momentive, an epoxy resin based on the diglycidyl ether of bisphenol A and having an epoxy equivalent of about 190 g with a viscosity of about 13 Pa s.

(41) G5: Uvacure 1500 from Cytec, a cycloaliphatic diepoxide (3,4-epoxycyclohexane or methyl 3,4-epoxycyclohexylcarboxylate) with a viscosity of about 275 mPa s.

(42) G6: Demineralized water, viscosity about 1 mPa s

(43) Lubricants G1 and G2 are oils typically used in the production of automobiles, whereas lubricants G3, G4 and G5 are composed primarily of constituents which are constituents of (activatable) PSAs and are therefore easier for the PSA to absorb. G3 is a nonreactive resin, whereas lubricants G4 and G5 comprise reactive resins. As a comparative substance from the prior art, water (G6) was selected.

(44) Measurement Values:

(45) TABLE-US-00007 TABLE 3 Example: K1 K2 K3 K4 Peel adhesion instantaneous, 5.0 12.1 6.7 2.6 uncured (steel)/N cm.sup.−1 Peel adhesion after 24 h, 4.2 4.5 2.8 2.1 uncured (steel with lubricant G1)/N cm.sup.−1 Peel adhesion after 1 h, uncured 2.2 1.3 0.1 1.8 (steel with G1)/N cm.sup.−1 Dynamic shear test (steel)/MPa 13 12 31 12 Dynamic shear test (steel with 11 11 28 11 G1)/MPa Wetting angle/° G1 7 33 G2 13 30 G4 55 76 G5 41 51 G6 93 103

(46) The peel adhesions shown in table 3 for the uncured adhesive tapes were determined in analogy to ISO 29862 (method 3) at 23° C. and 50% relative atmospheric humidity with a removal speed of 300 mm/min and a peel angle of 180°. The thickness of the layer of adhesive was 200 μm in each case. An etched PET film 50 μm thick was used as reinforcing film, and is obtainable from Coveme (Italy).

(47) The substrate used comprises steel plates in accordance with the standard. In some cases these plates were coated with lubricant in an amount of about 1 g/m.sup.2. The measuring strip was bonded using a roll-on machine at a temperature of 23° C. The adhesive tapes were removed immediately after application or after a storage time of one or 24 h, respectively. The measurement value (in N/cm) was obtained as the mean value from three individual measurements.

(48) In the determination of the peel adhesion on oiled steel substrates, a paraffinic oil with a viscosity of about 300 mPa s was used (Ferrocoat 6130).

(49) The dynamic shear value shown in table 3 was determined in a tensile shear test. The parameter for the quality of the bonding achieved was the bond strength determined for the various adhesive tapes and lubricants on an assembly produced by the method of the invention. For this purpose, the bond strength was determined quantitatively in each case in a dynamic tensile shear test based on DIN-EN 1465 at 23° C. and 50% rh for a test speed of 1 mm/min (results in N/mm.sup.2=MPa).

(50) The test rods used were made of steel and were cleaned with acetone prior to bonding. The lubricant, where used, was applied by immersion of the test rod into a solution of the lubricant to transfer it to one of the test elements. The solutions were adjusted so as to deposit a layer of about 1 g/m.sup.2 of the lubricant. The layer thicknesses of the adhesive tapes were about 200 μm in each case. After joining had taken place, the bonded test elements were stored at 23° C. for 24 hours and then cured at 180° C. for 30 minutes. The figure reported is the mean value from three measurements.

(51) The wetting angle shown in table 3 was determined by means of another common test method. The static contact angle of the lubricant was measured in a method based on DIN EN 828, the drop volume selected here being about 4 μl. The measurement was undertaken at a temperature of 23° C. The angle reported here is the mean wetting angle from three measurements.

(52) In accordance with the standard, the contact angle was measured about 10 s after the end of metering.

(53) Table 3 shows that the peel adhesion resulting from use of the lubricant G1, for which the experiments were carried out, after 24 hours and after one hour, is consistently lower, but the decrease is heavily dependent on the particular adhesive used. The adhesives K1 and K4 absorb the oil comparatively quickly, and so after an hour of storage the peel adhesion is higher than 50% of the peel adhesion after 24 h of storage, whereas the adhesives K2 and K3 absorb the oil more slowly, so that the peel adhesion after an hour of storage is not higher than 30% of the peel adhesion after 24 h of storage. Preferably, therefore, the adhesives K1 or K4 would be selected for the first side 4 of an adhesive tape 3 for the bonding of two oiled metal sheets 1 and 6, whereas the adhesives K2 or K3 would be selected for the second side 7 of the adhesive tape 3. In spite of the slower development of the peel adhesion in the case of the adhesives K2 and K3, the shear strength achieved after activation, as in the case of the adhesives K1 and K4, is only slightly affected by the lubricant, and in particular the shear strength is reduced by not more than 15%, and even, in the case of K2, K3 and K4, by less than 10%.

(54) It is important to assess the lubricity of the various lubricants G1 to G6 applied to the adhesives K1 to K4. In this case, the experimental design selected was as follows:

(55) To simulate the sliding in a tangential joining method, sections of the layers of adhesive produced, measuring 25×25 mm.sup.2, were laminated by their first side to a clean steel plate in the laboratory, at 23° C. and 50% relative atmospheric humidity. Immediately thereafter a second steel plate, coated with about 2 g/m.sup.2 of the lubricant, was applied vertically to the second side of the adhesive tape section, and pressed on with a force of about 10 N for about 1 s. Immediately thereafter the steel plates were moved manually in a tangential movement relative to one another, in order to determine the lubricity. Sliding with little application of force was assessed as very good (++); sliding with little application of force but a breakaway torque was assessed as good (+); sliding with moderate application of force and a higher breakaway torque was evaluated as satisfactory (o); sliding with a high application of force was assessed as adequate (−); and sticking was assessed as very poor (−−). Since lubricant G6 could not be coated homogeneously onto the steel plate even with addition of surfactant, a drop of the lubricant measuring about 0.1 ml was applied to the second side of the adhesive. Through the pressing of the second steel plate, which here is untreated, the lubricant drop was distributed on the second adhesive tape surface.

(56) The following table summarizes the result:

(57) TABLE-US-00008 TABLE 4 G1 G2 G3 G4 G5 G6 K1 ++ ++ 0 + ++ −− K2 ++ ++ 0 + ++ −− K3 ++ ++ 0 + ++ −− K4 + + 0 + ++ −− (Lubricity: ++ very easy, no breakaway torque, + easy, low breakaway torque, 0 moderate, higher breakaway torque, − high, −− sticking, no sliding possible)

(58) First of all it became clear as early as during sample preparation that water is an unsuitable lubricant here, since it cannot be distributed evenly either over the substrate or over the second adhesive tape surface. Lubricants here advantageously were those having a contact angle on the adhesive of less than 60°, since with these lubricants it was easier to produce a homogeneous film. Likewise advantageous is the effect of a viscosity above that of water (>5 mPa s), more particularly a viscosity of above 100 mPa s. In the case of the experiment carried out in the variant described, the water showed no lubricating effects; it was pressed out of the bonded joint, and the adhesion faces stuck to one another.

(59) It is clear that the low-viscosity nonaqueous lubricants G1, G2 and G5 exhibit outstanding lubricating properties. The lubricants G3 and G4, with a viscosity of more than 10 Pa s, exhibit good lubricating properties, but these properties set in only after a breakaway torque, so placing them within the framework of the invention. At the same time, using the example of G1, it was demonstrated that the lubricant is very well tolerated by the adhesives K1, K2 and K4 and that peel adhesions are developed after just a short time. The lubricant is resorbed more quickly by the adhesive K4, leading to relatively high peel adhesions after an hour. However, this still has no adverse effect on the lubricity. The lubricant is resorbed more slowly by the adhesive K3, but likewise leads to only a slight loss of shear strength.

(60) The difference in the resorption rate was utilized in the bonding of a two-ply adhesive tape consisting of a layer of K3 and a layer of K4. In analogy to the lubricity test, the first side of the adhesive tape with the adhesive K4 was laminated onto a steel plate, here furnished with 2 g/m.sup.2 of the lubricant G1, and the laminated assembly was stored for a minute under aforementioned laboratory conditions. The lubricity test was then carried on as described above with the lubricant G1. In the case of the tangential movement, there was very good sliding on the surface of the adhesive K3, whereas the adhesive K4 already exhibited sufficient sticking on the likewise oiled surface of the first substrate, meaning that there was no shifting of the adhesive tape section there.

LIST OF REFERENCE NUMERALS

(61) 1 first adherend 2 first surface of the first adherend 3 adhesive tape 4 first side of the adhesive tape 5 region 6 second adherend 7 second side of the adhesive tape 8 second surface of the second adherend 9 joining movement 10 component of the joining movement tangential to the second side of the adhesive tape 11 component of the joining movement perpendicular to the second side of the adhesive tape