FOAMED ADHESIVE MASS LAYER AND ADHESIVE TAPE COMPRISING THE FOAMED ADHESIVE MASS LAYER

Abstract

The invention relates to a foamed adhesive mass layer comprising a) 41.7 to 62.0 wt. % of an elastomer component, b) 37.7 to 58.0 wt. % of an adhesive resin component, c) 0 to 15 wt. % of a soft resin component, d) 0 to 18 wt. % further additives, and e) microballoons with a proportion of preferably 0.3 to 2.5 wt. %, preferably 0.5 to 2.0 wt. % and particularly preferably 0.7 to 1.7 wt. %, wherein the microballoons are at least partially expanded, wherein the elastomer component (a) consists of up to at least 90 wt. % polyvinyl aromatic compound polydine block copolymer, wherein the adhesive resin component (b) contains up to 4 to 100 wt. % of at least one type K1 if a rosin oligomer with a softening temperature (Ring & Ball, Test VI) of at least 90° C., and wherein the density (Text IX) of the foamed adhesive mass layer is at least 600 kg/m.sup.3 and max. 920 kg/m.sup.3.

Claims

1. A foamable pressure-sensitive adhesive, especially for double-sided self-adhesive tapes, comprising a) 41.7 wt % to 62.0 wt % of an elastomer component, b) 37.7 wt % to 58.0 wt % of a tackifier resin component, c) 0 wt % to 15 wt % of a plasticizer resin component, d) 0 wt % to 18 wt % of further additives and e) expandable microballoons having a fraction of preferably 0.3 wt % to 2.5 wt %, more preferably 0.5 wt % to 2.0 wt % and very preferably 0.7 wt % to 1.7 wt %, where the elastomer component (a) consists at least 90 wt % of polyvinylaromatic-polydiene block copolymer, and where the tackifier resin component (b) comprises 4 wt % to 100 wt % (based on the tackifier resin component) of at least one variety K1 of a rosin oligomer having a softening temperature (ring & ball, test VI) of at least 90° C.

2. A foamed pressure-sensitive adhesive layer, especially for double-sided self-adhesive tapes, comprising a) 41.7 wt % to 62.0 wt % of an elastomer component, b) 37.7 wt % to 58.0 wt % of a tackifier resin component, c) 0 wt % to 15 wt % of a plasticizer resin component, d) 0 wt % to 18 wt % of further additives and e) microballoons having a fraction of preferably 0.3 wt % to 2.5 wt %, more preferably 0.5 wt % to 2.0 wt % and very preferably 0.7 wt % to 1.7 wt %, where the microballoons are in an at least partially expanded state, where the elastomer component (a) consists at least 90 wt % of polyvinylaromatic-polydiene block copolymer, where the tackifier resin component (b) comprises 4 wt % to 100 wt % (based on the tackifier resin component) of at least one variety K1 of a rosin oligomer having a softening temperature (ring & ball, test VI) of at least 90° C., and where the density (test IX) of the foamed pressure-sensitive adhesive layer is at least 600 kg/m.sup.3 and at most 920 kg/m.sup.3.

3. The pressure-sensitive adhesive (layer) as claimed in claim 1, characterized in that the pressure-sensitive adhesive (layer) comprises 45 to 55 wt % of an elastomer component.

4. The pressure-sensitive adhesive (layer) as claimed in claim 1, characterized in that the pressure-sensitive adhesive (layer) comprises 45 to 55 wt % of a tackifier resin component.

5. The pressure-sensitive adhesive (layer) as claimed in claim 1, characterized in that the tackifier resin component (b) contains 5 wt % to 70 wt %, preferably 10 wt % to 50 wt %, more preferably 15 wt % to 40 wt %, such as for example 20 wt % to 30 wt %, of at least one variety K1 of a rosin oligomer having a softening temperature (ring & ball, test VI) of at least 90° C.

6. The pressure-sensitive adhesive (layer) as claimed in claim 1, characterized in that the tackifier resin component (b) further comprises at least one variety K2 of a tackifier resin which possesses a DACP (diacetone alcohol cloud point, test VII) of greater than −20° C., preferably greater than 0° C., and a softening temperature (ring & ball, test VI) of greater than or equal to 70° C., preferably greater than or equal to 100° C. and at most +140° C., where the tackifier resin component (b) typically contains at most 96 wt %, preferably at least 30 wt % and not more than 95 wt %, more preferably 50 to 90 wt %, more preferably still 60 to 85 wt % and more particularly 70 to 80 wt %, of this tackifier resin variety K2.

7. The pressure-sensitive adhesive (layer) as claimed in claim 1, characterized in that the pressure-sensitive adhesive (layer) comprises 2 to 10.0 wt % of a plasticizer resin component.

8. The pressure-sensitive adhesive (layer) as claimed in claim 1, characterized in that the plasticizer resin component (c) is a plasticizer resin or plasticizer resin mixture having a softening temperature (ring & ball, test VI) of <30° C., preferably having a melt viscosity at 25° C. and 1 Hz (test VIII) of at least 20 Pa*s, preferably of at least 50 Pa*s.

9. The pressure-sensitive adhesive (layer) as claimed in claim 1, characterized in that the pressure-sensitive adhesive (layer) comprises up to 10 wt % of further additives.

10. The pressure-sensitive adhesive layer as claimed in claim 2, characterized in that the density of the pressure-sensitive adhesive layer, as determined by means of test IX, is at least about 650 kg/m.sup.3 and at most about 870 kg/m.sup.3 and preferably at least 700 kg/m.sup.3 and at most 820 kg/m.sup.3.

11. An adhesive tape which comprises at least one pressure-sensitive adhesive layer as claimed in claim 2, where the adhesive tape is preferably a double-sided adhesive tape such as especially a transfer tape.

12. The adhesive tape as claimed in claim 11, which is redetachable without residue or destruction by extensive stretching substantially in the bond plane.

13. An assembly wherein two substrates are bonded by means of a double-sided adhesive tape as claimed in claim 11, where the two substrates are preferably components of a mobile device.

14. The use of an adhesive tape as claimed in claim 11 for bonding components of mobile devices, such as rechargeable batteries.

15. The pressure-sensitive adhesive (layer) as claimed in claim 2, characterized in that the pressure-sensitive adhesive (layer) comprises 45 to 55 wt % of an elastomer component.

16. The pressure-sensitive adhesive (layer) as claimed in claim 2, characterized in that the pressure-sensitive adhesive (layer) comprises 45 to 55 wt % of a tackifier resin component.

17. The pressure-sensitive adhesive (layer) as claimed in claim 3, characterized in that the pressure-sensitive adhesive (layer) comprises 45 to 55 wt % of a tackifier resin component.

18. The pressure-sensitive adhesive (layer) as claimed in claim 2, characterized in that the tackifier resin component (b) contains 5 wt % to 70 wt %, preferably 10 wt % to 50 wt %, more preferably 15 wt % to 40 wt %, such as for example 20 wt % to 30 wt %, of at least one variety K1 of a rosin oligomer having a softening temperature (ring & ball, test VI) of at least 90° C.

19. The pressure-sensitive adhesive (layer) as claimed in claim 3, characterized in that the tackifier resin component (b) contains 5 wt % to 70 wt %, preferably 10 wt % to 50 wt %, more preferably 15 wt % to 40 wt %, such as for example 20 wt % to 30 wt %, of at least one variety K1 of a rosin oligomer having a softening temperature (ring & ball, test VI) of at least 90° C.

20. The pressure-sensitive adhesive (layer) as claimed in claim 4, characterized in that the tackifier resin component (b) contains 5 wt % to 70 wt %, preferably 10 wt % to 50 wt %, more preferably 15 wt % to 40 wt %, such as for example 20 wt % to 30 wt %, of at least one variety K1 of a rosin oligomer having a softening temperature (ring & ball, test VI) of at least 90° C.

Description

EXAMPLES

[0204] The PSA (layer) of the invention is described below in preferred embodiment on the basis of a number of examples, without thereby wishing to impose any instruction whatsoever on the invention.

[0205] Also given are comparative examples, which represent unsuitable adhesive (layer)s.

[0206] The constituents of the pressure-sensitive adhesives (PSAs) were dissolved in this case at 40% in special-boiling-point benzene/toluene/acetone, admixed with the microballoons suspended in mineral spirit, and coated out in the desired layer thickness, using a coating bar, onto a PET film furnished with a silicone release. The solvent was then evaporated off at 100° C. for 15 min to dry the layer of composition. This is possible in the examples given, since microballoons are utilized here which have an expansion temperature above 100° C. If utilizing other microballoons, the skilled person selects, correspondingly, suitable production temperatures, without departing from the scope of the present invention.

[0207] After drying had taken place, the adhesive layer was lined with a second ply of PET liner as defined above, free from any air inclusions, and was foamed for 30 s at 170° C. between the two liners, while suspended in a circulation drying cabinet.

[0208] Table 2 shows the raw materials used. Tables 3a to 3f show the formulas of the inventive examples and comparative examples (% figures in the compositions are wt %) and also their characteristics.

TABLE-US-00002 TABLE 2 raw materials used. Elastomer component Calprene C4302 Polystyrene- Linear SBS* (a) (Dynasol polybutadiene block PS content 31%* Elastomeros) copolymer Calprene C7318 Polystyrene- Linear SBS* (Dynasol polybutadiene block PS content 32%* Elastomeros) copolymer Calprene C411 Polystyrene- Radial SBS* (Dynasol polybutadiene block PS content 30%* Elastomeros) copolymer Europrene Sol T190 Polystyrene- Linear SIS** (Versalis) polyisoprene block PS content 16%** copolymer Tackifier resin Dymerex (K1) Dimerized rosin Softening point component (b) (Eastman Chemical) resin 144° C. Foral 105-E (K1) Hydrogenated Softening point (Eastman Chemical) rosin pentaerythritol 101° C. ester Foral 85-E Hydrogenated rosin Softening point 85° C. (Eastman Chemical) glycerol ester Hydrogral P (K1)partially Softening point 97° C. (DRT) hydrogenated rosin pentaerythritol ester Dertophene T160 Terpene phenolic resin Softening point (DRT) 160° C. Dertophene T105 Terpene phenolic resin Softening point (DRT) 105° C. Regalite R1125 (K2) Fully Softening point 125° C. (Eastman Chemical) hydrogenated C9 DACP = +55° C. hydrocarbon resin Dercolyte A115 (K2) Alpha-pinene Softening point 115° C. (DRT) resin DACP = +35° C. Plasticizer resin Wingtack 10 Aliphatic C5 liquid Softening point 10° C.; component (c) (Cray Valley) resin melt viscosity 22 Pa s Additives (d) Irganox 1010 Primary aging inhibitor (BASF) (sterically hindered phenol derivative) Irgafos 168 Secondaryaging (BASF) inhibitor (Phosphoric ester) Microballoons Expancel 920 DU20 (Nouryon) *Manufacturer data, Dynasol Elastomers; **manufacturer data, Versalis SpA

[0209] All examples (C: comparative example; E: inventive example) contained, unless specified otherwise, 1 wt % microballoons (Expancel 920 DU20), based on the total weight of the PSA without solvent. Foamed adhesive transfer tapes were produced in 100 μm thickness. By die-cutting or cutting of strips, pressure-sensitive adhesive strips with desired dimensions were obtained.

TABLE-US-00003 TABLE 3a Formulas and their characteristics. Example Example Example Example Raw materials C1 E2 E3 E4 (a) Elastomer Calprene 20.0 20.0 20.0 20.0 [%] C411 Calprene 29.0 29.0 29.0 29.0 C7318 (b) Tackifier resin Dymerex — 2.5 5.5 10.0 K1 [%] (b) Tackifier resin Dercolyte 49 46.5 43.5 39.0 K2 A115 [%] (c) Plasticizer — — — — resin [%] (d) Additives [%] Irganox 0.5 0.5 0.5 0.5 1010 Irgafos 0.5 0.5 0.5 0.5 168 Shock resistance 603 618 647 809 [mJ] Shock resistance 0.0 +2.3 +7.3 +34.2 improvement [%] Peel adhesion to 6.7 9.2 8.9 11.9 steel 180° [N/cm] SAFT 124 125 125 123 [° C.] Density 743 750 743 736 [kg/m.sup.3]

TABLE-US-00004 TABLE 3b Further formulas and their characteristics. Ex- Ex- Ex- Ex- Ex- Raw ample ample ample ample ample materials C5 E6 E7 E8 E9 (a) Elastomer Calprene 10.0 10.0 10.0 10.6 10.0 [%] C411 Calprene 37.0 37.0 37.0 37.0 37.0 C4302 (b) Tackifier Foral — 5.0 10.0 18.0 30.0 resin K1 105-E [%] (b) Tackifier Dercolyte 47.0 42.0 37.0 29.0 17.0 resin K2 A115 [%] (c) Plasticizer Wingtack 4.0 4.0 4.0 4.0 4.0 resin 10 [%] (d) Additives Irganox 0.5 0.5 0.5 0.5 0.5 [%] 1010 Irgafos 0.5 0.5 0.5 0.5 0.5 168 Shock 677 883 912 721 706 resistance [mJ] Shock 0.0 +30.4 +34.7 +6.5 +4.2 resistance improvement [%] Peel adhesion 6.0 7.8 7.2 5.8 5.8 to steel 180° [N/cm] SAFT 118 115 117 112 110 [° C.] Density 761 812 823 820 820 [kg/m.sup.3]

TABLE-US-00005 TABLE 3c Further formulas and their characteristics. Example Example Example Example Raw materials C10 E11 C1 E12 (a) Elastomer Europrene 50.0 50.0 — — [%] Sol T190 Calprene — — 20.0 20.0 C411 Calprene — — 29.0 29.0 C7318 Hydrogral P — — — 10.0 (b) Tackifier Foral 105-E resin K1 [%] (b) Tackifier Regalite 45.0 35.0 — — resin K2 R1125 [%] Dercolyte — — 49.0 39.0 A115 (c) Plasticizer Wingtack 10 3.0 3.0 — — resin [%] (d) Additives [%] Irganox 0.5 0.5 0.5 0.5 1010 Irgafos 0.5 0.5 0.5 0.5 168 Shock 706 1015 603 686 resistance [mJ] Shock 0.0 +44 0.0 13.8 resistance improvement [%] Peel adhesion to 7.8 11.5 6.7 6.0 steel 180° [N/cm] SAFT 112 107 124 126 [° C.] Density 784 813 743 784 [kg/m.sup.3]

TABLE-US-00006 TABLE 3d Further formulas and their characteristics. Ex- Ex- Ex- Ex- Ex- Raw ample ample ample ample ample materials C5 E13 C14 C15 C16 (a) Elastomer Calprene 10.0 10.0 10.0 10.0 10.0 [%] C411 Calprene 37.0 37.0 37.0 37.0 37.0 C4302 (b) Tackifier Hydrogral P — 10.0 — — — resin K1 [%] (b) Tackifier Dertophene — — — 10.0 — resin T160 [%] Dertophene — — — — 10.0 T105 Foral 85-E —   10.0 — — (b) Tackifier Dercolyte 47.0 37.0 37.0 37.0 37.0 resin A115 K2 [%] (c) Wingtack 4.0 4.0 4.0 4.0 4.0 Plasticizer 10 resin [%] (d) Additives Irganox 0.5 0.5 0.5 0.5 0.5 [%] 1010 Irgafosi 0.5 0.5 0.5 0.5 0.5 168 Shock 677 883 633 544 574 resistance [mJ] Shock 0.0 +30.4 −6.5 −19.6 −15.2 resistance improvement [%] Peel 6.0 8.2 6.0 10.5 6.1 adhesion to steel 180° [N/cm] SAFT 118 115 111 115 125 [° C.] Density 761 820 805 780 792 [kg/m.sup.3]

TABLE-US-00007 TABLE 3e Further formulas and their characteristics. Example Example Raw materials C17 E18 (a) Elastomer Europrene 40.0 60.0 [%] Sol T190 (b) Tackifier Hydrogral P 20.0 10.0 resin K1 Foral 105-E — — [%] (b) Tackifier Regalite 35.0 25.0 resin K2 R1125 [%] Dercolyte — — A115 (c) Plasticizer Wingtack 10 3.0 3.0 resin [%] (d) Additives [%] Irganox 0.5 0.5 1010 Irgafos 0.5 0.5 168 Shock 162 603 resistance [mJ] Shock −/−*** −/−*** resistance improvement [%] Peel adhesion to 17.4 7.0 steel 180° [N/cm] SAFT 102 113 [° C.] Density 840 809 [kg/m.sup.3] ***Improvement in shock resistance by comparison with a reference formulation not determined.

TABLE-US-00008 TABLE 3f Further formulas and their characteristics. Raw Ex. Ex. Ex. Ex. Ex. Ex. Ex. materials C19 C20 E21 E11 E22 C23 C24 (a) Elastomer Europrene 50.0 49.9 49.7 50.0 49.1 48.5 47.5 [%] Sol T190 (b) Tackifier Hydrogral 10.0 10.0 10.0 10.0 9.8 19.7 9.5 resin K1 P [%] (b) Tackifier Regalite 36.0 35.9 35.8 35.0 35.2 34.9 34.2 resin K2 R1125 [%] (c) Plasticizer Wingtack 3.0 3.0 3.0 3.0 2.9 2.9 2.8 resin 10 [%] (d) Additives Irganox 0.5 0.5 0.5 0.5 0.5 0.5 0.5 [%] 1010 Irgafos 0.5 0.5 0.5 0.5 0.5 0.5 0.5 168 (e) Micro- Expancel 0.0 0.2 0.5 11.0 2.0 3.0 5.0 balloons [%] 920 DU20 Shock 162 412 780 1015 736 515 368 resistance [mJ] Shock −/−*** −/−*** −/−*** +44 −/−*** −/−*** −/−*** resistance improvement [%] Peel adhesion 16.4 14.3 13.1 11.5 9.7 8.5 5.1 to steel 180° [N/cm] SAFT 97 106 112 107 115 116 123 [° C.] Density 984 926 909 813 706 595 477 [kg/m.sup.3] ***Improvement in shock resistance by comparison witha reference formulation determined.

[0210] A comparison of examples C1, E2, E3 and E4 shows in particular the positive effect of the fraction of the variety K1 of a rosin oligomer having a softening temperature (ring & ball, test VI) of at least 90° C. on the shock resistance and the peel adhesion, for comparable thermal shear strength.

[0211] A comparison of examples C5 and E6 to E9, in which a different tackifier resin variety K1 is used, again shows in particular the positive effect of the fraction of the variety K1 on the shock resistance and the peel adhesion, for comparable thermal shear strength. Especially interesting in this case is that the shock resistance and the peel adhesion pass through a maximum, depending on the proportion of the variety K1.

[0212] C10 and E11 show the depicted relationships when using a different elastomer or tackifier resin K1, respectively.

[0213] C1 and E12 show the depicted relationships when using a modified elastomer composition.

[0214] A comparison of examples C5 and E13 shows that the proportional replacement of non-polar tackifier resin K2 with tackifier resin K1 leads to an improvement in the shock resistance and peel adhesion, for comparable thermal shear strength.

[0215] A comparison of examples C5 and C14 to C16 shows that the proportional replacement of non-polar tackifier resin K2 with rosin oligomer having too low a softening temperature, or with other varieties of polar tackifier resins such as terpene phenolic resin, may in fact lead to a deterioration in the profile of properties, such as the shock resistance in particular.

[0216] Example C17 shows in particular that too low an elastomer fraction is detrimental to the shock resistance.

[0217] Table 3f indicates that the selection of the amount of microballoons used is also essential for obtaining the desired improvement in performance, particularly in the shock resistance.