Method for producing an adhesive sealing tape

Abstract

The aim is to provide an efficient method for producing a multi-layer adhesive tape having a heat-sealing layer and a pressure sensitive adhesive that results in effective composite adhesion of the individual layers to one another. This is accomplished with a method for producing an adhesive sealing tape covered with a release liner, said method comprising a) heating a pressure-sensitive adhesive in such a way that the pressure-sensitive adhesive is present as a melt; and b) producing a composite in a roll nip in such a way that a hotmelt adhesive layer is lying on one roll, a release liner is lying on the other roll, the release liner having an outer release layer, and this outer release layer pointing away from the roll surface, the pressure-sensitive adhesive melt is introduced into the roll nip and by rotation of the rolls, contacting of the layers and cooling, a composite is obtained with the sequence of hotmelt adhesive layerpressure-sensitive adhesiverelease liner, the release liner remaining on the pressure-sensitive adhesive until the adhesive tape is applied.

Claims

1. A method for producing an adhesive sealing tape covered with a release liner, comprising a) heating a pressure-sensitive adhesive to obtain the pressure-sensitive adhesive present in melt form; b) producing a composite in a roll nip so that (i) a hotmelt adhesive layer is lying on one roll, (ii) a release liner is lying on another roll, the release liner having an outer release layer, said outer release layer pointing away from a roll surface, (iii) the pressure-sensitive adhesive melt is introduced into the roll nip and (iv) by rotation of the rolls, contacting of the layers and cooling, a composite is obtained with the following sequence: the hotmelt adhesive layer, the pressure-sensitive adhesive, then the release liner, wherein the release liner remains on the pressure-sensitive adhesive until the adhesive sealing tape is applied.

2. The method according to claim 1, wherein the hotmelt adhesive layer is a polyolefin layer.

3. The method according to claim 1, wherein the pressure-sensitive adhesive in step b) is a foamed pressure-sensitive adhesive.

4. The method according to claim 1, wherein the pressure-sensitive adhesive comprises at least 30 wt % poly(meth)acrylate, based on the total weight of the pressure-sensitive adhesive.

5. The method according to claim 1, wherein the outer release layer of the release liner is a silicone layer or a polycarbamate layer.

6. The method according to claim 1, wherein the release liner comprises a polyolefin carrier layer.

7. A method of producing a seal in a vehicle comprising a step of applying the adhesive sealing tape produced by the method according to claim 1 to a substrate.

Description

EXAMPLE

[0169] 1. Preparing the Pressure-Sensitive Adhesive

[0170] Preparing Polyacrylate Base Polymer:

[0171] A reactor conventional for radical polymerizations was filled with 72.0 kg of 2-ethylhexyl acrylate, 20.0 kg of methyl acrylate, 8.0 kg of acrylic acid and 66.6 kg of acetone/isopropanol (94:6). After nitrogen gas had been passed through the reactor for 45 minutes with stirring, the reactor was heated up to 58 C. and 50 g of AIBN, in solution in 500 g of acetone, were added. The external heating bath was then heated to 75 C. and the reaction was carried out constantly at this external temperature. After 1 hour a further 50 g of AIBN, in solution in 500 g of acetone, were added, and after 4 hours the batch was diluted with 10 kg of acetone/isopropanol mixture (94:6).

[0172] After 5 hours and again after 7 hours, initiation was repeated in each case with 150 g of bis(4-tert-butylcyclohexyl) peroxydicarbonate, in each case in solution in 500 g of acetone. After a reaction time of 22 hours, the polymerization was discontinued and the batch was cooled to room temperature. The product had a solids content of 55.8% and was dried. The resulting polyacrylate had a K value of 58.9, an average molecular weight Mw of 748 000 g/mol, a polydispersity D (Mw/Mn) of 8.9 and a static glass transition temperature Tg of 35.2 C.

[0173] Preparation of the PSA:

[0174] In a planetary roller extruder, the synthetic rubber Kraton D1118 in pellet form was melted via a solids metering facility. A microballoon paste (50% Expancel 051DU40 in Ethomeen C25) was added. Via a side feeder, the polyacrylate base polymer, having undergone preliminary melting in a single-screw extruder, was introduced and a terpene-phenolic resin (Dertophen DT105) was metered in. Added to the mixture were a crosslinker solution (Polypox R16 15% in Rheofos RDP) a an accelerator solution (15% Epicure 925 in Rheofos RDP). The melt was thoroughly mixed, and the microballoons expanded in the process. This gave a foamed PSA having a density of 550 kg/m.sup.3. The composition was 48% polyacrylate, 25% Kraton D1118, 18% Dertophen DT105, 4% crosslinker/accelerator solution (crosslinker: accelerator=1:1), 5% microballoon paste (figures in wt %).

[0175] 2. Production of the Adhesive Sealing Tape

[0176] 2.1 Release Liner Used

[0177] The release liner used was a double-sidedly siliconized (solvent-free, addition-crosslinked silicone system with platinum catalyst) PET film 75 m thick.

[0178] 2.2 Hotmelt Adhesive Used

[0179] A blown polypropylene film 40 m thick, Borealis BA110CF (heterophasic copolymer with an MFI of 0.85 g/10 min), was used, and had been subjected by the manufacturer to off-line corona pretreatment.

[0180] 2.3 Laminating Operation

[0181] The PSA was guided via a nozzle into a calender nip, the temperature of the adhesive being 140-150 C. In the calender nip, the PSA was coated out between the release liner, supplied from above, and the hotmelt adhesive layer, supplied from below. The width of the calender nip was 800 m. The two calender rolls were each heated to 90 C., and the web speed was 5 m/min.

[0182] The shaped web with the layer sequence of hotmelt sealing filmpressure-sensitive adhesive layerrelease liner was subsequently passed via a chill roll (temperature 8 C.) and further through a cooling channel (room temperature), and was then wound up in the form of a completed adhesive sealing tape. The temperature of the product during winding corresponded to the ambient temperature.

[0183] 3. Test/Results

[0184] The adhesive sealing tape for testing was slit to a width of 8.5 mm.

[0185] The hotmelt adhesive layer of the adhesive sealing tape and an EPDM profile were superficially melted by IR radiation and in this state were assembled by means of laminating rolls in a laminating nip. The resultant assembly was cooled for a number of minutes to room temperature.

[0186] The release liner was then removed from the PSA layer of the adhesive sealing tape; it was removable from the PSA with an expenditure of force customary for this operation. Immediately thereafter, an etched aluminium foil (127 m in thickness) was applied to the layer of PSA, by pressing the film down five times back and forth using a 2 kg roller.

[0187] After a resting time of 24 hours, the resulting adhesive assembly was pulled apart by hand vertically with respect to the plane of the bond; without exception, cohesive fracture within the foamed PSA layer was observed.