METHOD FOR ADHERING PROFILES TO SUBSTRATE SURFACES

Abstract

Provided are methods for adhesively bonding profiles to substrate surface. An example method includes plasma-treating each of a profile surface and a first adhesive side of a layer of pressure sensitive adhesive. The pressure sensitive adhesive includes a) 40 to 70 wt %, based on the total weight of the pressure sensitive adhesive, of at least one poly(meth)acrylate; b) 15 to 50 wt %, based on the total weight of the pressure sensitive adhesive, of at least one synthetic rubber; and c) at least one tackifier compatible with the poly(meth)acrylate(s). The method further includes bonding the profile surface and the first adhesive side to one another, plasma-treating a second adhesive side of the layer of the pressure sensitive adhesive, and bonding the plasma-treated second adhesive side to the substrate surface.

Claims

1. A method for adhesively bonding profiles to substrate surfaces, the method comprising: plasma-treating each of a profile surface and a first adhesive side of a layer of pressure sensitive adhesive, the pressure sensitive adhesive comprising: a) 40 to 70 wt %, based on the total weight of the pressure sensitive adhesive, of at least one poly(meth)acrylate; b) 15 to 50 wt %, based on the total weight of the pressure sensitive adhesive, of at least one synthetic rubber; and c) at least one tackifier compatible with the poly(meth)acrylate(s) bonding the profile surface and the first adhesive side to one another, plasma-treating a second adhesive side of the layer of the pressure sensitive adhesive, and bonding the plasma-treated second adhesive side to the substrate surface.

2. The method of claim 1, wherein the substrate surface is a low surface energy (LSE) substrate surface and the plasma-treated second adhesive side is adhered to the LSE substrate surface; wherein a low energy surface substrate has a surface energy of 38 mN/m or less.

3. The method of claim 1, wherein an adhesive tape is used as the layer of pressure sensitive adhesive.

4. The method of claim 1, wherein the profile surface and the first adhesive side are plasma-treated simultaneously.

5. The method of claim 1, wherein the substrate surface is not plasma-treated and the plasma-treated second adhesive side is bonded to the non-plasma-treated substrate surface.

6. The method of claim 1, wherein the profile surface comprises a material selected from the group consisting of polypropylene, polyethylene, a blend of acrylonitrile-butadiene-styrene and polyvinyl chloride, a thermoplastic vulcanizate, a styrenic block copolymer, and any combination thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0174] The invention is described by means of three exemplary embodiments, in which:

[0175] FIG. 1 shows a heat flow/temperature graph for determining the glass transition temperature,

[0176] FIG. 2 shows a schematic product construction made up of profile, ACX.sup.plus7812 adhesive tape and LSE substrate surface,

[0177] FIGS. 3a, 3b show a PP/EPDM profile surface with LMWOMs after a plasma overtreatment, and

[0178] FIG. 4 shows the results of a comparative experiment between untreated and treated samples.

DETAILED DESCRIPTION

[0179] With reference to FIG. 2, Tesa® ACXplus 7812 is an acrylate foam adhesive tape for bonding of exterior mounted components.

[0180] The composition of Tesa® ACXplus 7812 is typically as follows:

TABLE-US-00001 Polymethacylate 49 wt % Kraton D 1118* 29 wt % Microballons 920 DU40 4 wt % Dertophene DT 105** 18 wt % *Kraton D 1118 styrene-butadiene-styrene 76 wt % diblock, block polystyrene content: 31 wt %, Kraton polymers (molecular weight Mw of the 3-block fraction of 150 000 g/mol) **Dertophene DT 105 terpene-phenolic resin

[0181] A profile surface 2 of a profile 1, and also first and second adhesive sides 3, 4 of an adhesive tape 6, were plasma-treated using a plasma apparatus from the manufacturer Plasmatreat with the designation “Openair-plasma”.

[0182] Using the plasma apparatus, in a simultaneous plasma treatment of the profile surface 2 of PP and EPDM and the first adhesive side 3 of the ACX.sup.plus7812 adhesive tape 6, four tests were carried out to show the increase in peel adhesion on simultaneous treatment of both interfaces, by comparison with nontreatment or, respectively, with treatment of only one of the two interfaces. The results of the measurements are set out in FIG. 4, the peel adhesion being determined in each case after 20 minutes and 24 hours.

[0183] It is clearly apparent that there is an increase in peel adhesion between the profile surface 2 and the first adhesive side 3 of the ACX.sup.plus7812 adhesive tape 6, relative to the reference bond, when both interfaces are plasma-treated. In the case of the reference bond, neither of the two reference faces is plasma-treated.

[0184] An increase in peel adhesion in fact occurs not only with PP and EPDM profiles, but instead with virtually all plastics profiles, relative to the ACX.sup.plus7812 adhesive tape 6, when both interfaces have been plasma-treated.

[0185] In addition, the tests were undertaken to verify manufacturer recommendations for the plasma activation of the PP/EPDM profile surfaces 2; here it emerged that the plasma parameters frequently delivered by the manufacturers to the user are not suitable, since almost universally the maximum possible surface tension on the profiles 1 is desired, since it is associated with the anticipated improvement in peel adhesion. This, however, did not prove to be correct.

[0186] The fabrication trial described below was carried out using an OPENAIR plasma rotation unit (system: RD1004, FG5001) from Plasmatreat, Steinhagen/Germany. The nozzle attachment used possesses a diameter of 10 mm and an exit angle of 5° (Art. PTF 2646).

[0187] In the trial, a treatment speed of 6 m/min was chosen, and the nozzle distance was reduced in four steps from 20 to 14 mm (see tab. 1). After the treatment, the surface tension was measured using test inks.

TABLE-US-00002 TABLE 1 Measurement of the surface tension with different plasma parameters Treatment speed Treatment distance Surface tension Trial [m/min] [mm] [mN/m] 1 6 20 44 2 6 18 50 3 6 16 56 4 6 14 66

[0188] The profiles 1 produced were cut into test units 150 mm in size, and their peel strength (90°-T-peel) was determined on a Zwick tensile testing machine.

[0189] The PP/PDM (Moplen EP1006, LyondellBasell) profiles furnished with ACX.sup.PUS adhesive tape 6 and pretreated were investigated for their fracture mode (see tab. 2) in accordance with the Volkswagen group standard TL 52018-F “foam adhesive tape double-sided”. after [0190] as-supplied state (.fwdarw.3d RT), [0191] hot storage (.fwdarw.storage for 240 h at +90° C.; 24 h acclimatization under standard conditions), and [0192] heat-plus-humidity storage (.fwdarw.storage for 240 h at +40° C. and 10000 relative humidity; storage is followed by drying at +70° C. in a forced air drying cabinet with fresh air supply—duration 8 h; 24 h acclimatization under standard conditions).

TABLE-US-00003 TABLE 2 Fracture modes after storage (VW TL 52018) Fracture aspect after . . . Heat-plus-humidity Surface As-supplied Hot storage storage 240 h +40° C. tension state 240 h +90° C., 100% rel. hum., [mN/m] (3d RT) acclimatization acclimatization 44 Adhesive cohesive (some mixed cohesive (some mixed fracture) fracture) 50 adhesive cohesive (primarily) cohesive (some mixed fracture) 56 adhesive cohesive (some mixed adhesive (primarily) fracture) 66 adhesive adhesive adhesive

[0193] This result scenario shows that in the case of the high surface tensions, a deterioration is found in the fracture aspect after hot storage and particularly after hot-and-humid storage.

[0194] The known phenomena is attributable to an overtreatment of the PP/EPDM profile surface 2. The highly oxidized “polymer debris” LMWOM, produced as a result of unfavorable parameters, lies on the polymer surface and is no longer joined covalently to the bulk of the polymer matrix. LMWOM is highly water-soluble and so promotes the rearward migration of moisture into the interfaces.

[0195] As shown by the fracture aspect according to table 2, overtreated profile surfaces 2 can dramatically impair the resistance to heat plus humidity. The heat resistance in the combination of materials described above may be influenced by overtreatment, and heat/humidity storage may even cause bonds which, under standard conditions, undergo adhesive fracture to suffer cohesive fracture.

[0196] Even after the above-stated reconditioning, the damage to the adhesive bond can no longer be “healed”.

[0197] The LMWOMs have a particularly strong effect on the hydrophilic test liquids, thereby distorting the measurement of the surface tension. Functional groups which are covalently bonded on the pretreated polymer matrix are not brought into solution and, moreover, produce different contact angles relative to overtreated surfaces. In analytical terms, the functionalization on the profile surface 2 with the functionalized LMWOMs is identical (see FIGS. 3a, 3b). Differentiation is possible only with difficulty.

[0198] It has now emerged that in the plasma treatment of the opposite, second adhesive side 4 of the adhesive tape 6 in the form of a pressure-sensitive adhesive tape, there is a marked increase in peel adhesion on LSE substrates as LSE substrate surfaces 7, even when only the second adhesive side 4 of the adhesive tape 6 is plasma-treated and not the LSE substrate surface 7. This, of course, leads to a considerable facilitation of the bonding process, since the bulky LSE substrate surface 7, for example the LSE substrate surface 7 of a substrate 8 such as a vehicle door, for example, of a part of a vehicle panel, etc. need no longer be pretreated with a plasma apparatus. With regard to the adhesive bonding of plasma-treated PSA layers, such as ACX.sup.plus7812, for example, and an LSE substrate surface 7, reference is also made to DE 10 2016 224 684 A1, in which corresponding series of experiments were carried out. In accordance with the invention, however, it has now emerged that through the use of the ACX.sup.plus7812 adhesive tape 6, in other words of an acrylate adhesive tape, the adhesive bonding of virtually all profiles 1 to LSE substrate surfaces 7 is possible, and the LSE substrate surface 7 does not need to be plasma-treated, but instead only the second adhesive layer 4 of the ACX.sup.plus7812 adhesive tape 6, which, however, functions as a mediator, as a kind of adhesive promoter, between the LSE substrate surface 7 and the profile surface 2.

LIST OF REFERENCE NUMERALS

[0199] 1 Profile [0200] 2 Profile surface [0201] 3 First adhesive side [0202] 4 Second adhesive side [0203] 6 Adhesive tape [0204] 7 LSE substrate surface [0205] 8 Substrate