PRESSURE-SENSITIVE ADHESIVE COMPOUNDS, AND SELF-ADHESIVE PRODUCTS AND COMPOSITES COMPRISING THE LATTER

Abstract

The present invention relates to a foamed pressure-sensitive adhesive compound on the basis of aromatic polyvinyl-polydiene block copolymers, in particular for double-sided self-adhesive strips, containing a) 39.8 wt. % to 51.8 wt. % of an elastomer component, b) 35.0 wt. % to 58.0 wt % of an adhesive resin component, c) 2.0 wt. % to 15.0 wt. % of a plasticizer component, d) 0.0 wt. % to 18.0 wt. % of further additives and e) microballoons, the microballoons being at least partly expanded.

Claims

1. A foamed pressure-sensitive adhesive layer based on polyvinylaromatic-polydiene block copolymers, especially for double-sided self-adhesive tapes, comprising a) 39.8 wt % to 51.8 wt % of an elastomer component, b) 35.0 wt % to 58.0 wt % of a tackifier resin component, c) 2.0 wt % to 15.0 wt % of a plasticizer component, d) 0.0 wt % to 18.0 wt % of further additives and e) microballoons, preferably in an amount of 0.2 wt % to 2.5 wt %, where the microballoons are in an at least partly expanded state, where the elastomer component (a) consists at least 90 wt % of one or more polyvinylaromatic-polydiene block copolymers, where the mean diblock fraction, based on the total polyvinylaromatic-polydiene block copolymers, is at most 35 wt %, where the polydiene blocks of the polyvinylaromatic-polydiene block copolymers have a mean vinyl fraction (test IX) of less than 20 wt %, based on the total polydiene blocks, and where, based on the total polyvinylaromatic-polydiene block copolymers, at least one polyvinylaromatic-polydiene block copolymer with a peak molar mass (test Ia) of at least 125 000 g/mol is present at at least 15 wt %, preferably at least 25 wt %, and up to 100 wt %, preferably at most 90 wt %, where the tackifier resin component (b) comprises at least 75 wt %, based on the tackifier resin component, of at least one tackifier resin having a DACP (test II) of at least −20° C. and a softening temperature of at least 85° C. and at most 140° C. (test IIIa), where the plasticizer component (c) comprises at least one plasticizer resin and/or mineral oil each having a softening temperature (ring & ball, test VI) of <30° C., where the sum of tackifier resin component (b) and plasticizer component (c) is at least 48 wt % and at most 60 wt % and the harmonic mean of the softening temperature (test IIIb) of tackifier resin component and plasticizer component is at least 95° C. and at most 125° C., and where the density (test XI) of the foamed pressure-sensitive adhesive layer is at least 600 kg/m.sup.3 and at most 950 kg/m.sup.3.

2. The pressure-sensitive adhesive layer as claimed in claim 1, characterized in that the mean diblock fraction, based on the total polyvinylaromatic-polydiene block copolymers, is at most 25 wt %, preferably at most 15 wt %.

3. The pressure-sensitive adhesive layer as claimed in claim 1, characterized in that the polydiene blocks of the polyvinylaromatic-polydiene block copolymers have a mean vinyl fraction (test IX) of less than 17 wt %, preferably less than 13 wt %, based on the total polydiene blocks.

4. The pressure-sensitive adhesive layer as claimed in claim 1, characterized in that based on the total polyvinylaromatic-polydiene block copolymers, at least one polyvinylaromatic-polydiene block copolymer with a peak molar mass (test Ia) of at least 200 000 g/mol, very preferably at least 250 000 g/mol, is present at at least 15 wt %, preferably at least 25 wt %, and up to 100 wt %, preferably at most 90 wt %.

5. The pressure-sensitive adhesive layer as claimed in claim 1, characterized in that the pressure-sensitive adhesive layer comprises 47.0 wt % to 55.0 wt % of a tackifier resin component.

6. The pressure-sensitive adhesive layer as claimed in claim 1, characterized in that the tackifier resin component (b) comprises at least 75 wt %, based on the tackifier resin component, of at least one tackifier resin having a DACP (test II) of at least 0° C. and a softening temperature of at least 100° C. (test IIIa).

7. The pressure-sensitive adhesive layer as claimed in claim 1, characterized in that the pressure-sensitive adhesive layer comprises 3.0 wt % to 10.0 wt % of a plasticizer component.

8. The pressure-sensitive adhesive layer as claimed in claim 1, characterized in that the plasticizer component (c) is a plasticizer resin or plasticizer resin mixture having a softening temperature (ring & ball, test IIIa) of <30° C., preferably having a melt viscosity at 25° C. and 1 Hz (test IV) 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 sum of tackifier resin component (b) and plasticizer component (c) is at least 50 wt % and at most 58 wt %.

10. The pressure-sensitive adhesive layer as claimed in claim 1, characterized in that the harmonic mean of the softening temperature (test IIIb) of tackifier resin component (b) and plasticizer component (c) is at most 125° C.

11. The pressure-sensitive adhesive layer as claimed in claim 1, characterized in that the pressure-sensitive adhesive layer comprises up to 10.0 wt % of further additives.

12. The pressure-sensitive adhesive layer as claimed in claim 1, characterized in that the fraction of microballoons is 0.5 wt % to 2.0 wt %, preferably 0.7 wt % to 1.7 wt %.

13. The pressure-sensitive adhesive layer as claimed in claim 1, characterized in that the density (test XI) of the pressure-sensitive adhesive layer is at least 650 kg/m.sup.3 and at most 900 kg/m.sup.3 and preferably at least 700 kg/m.sup.3 and at most 850 kg/m.sup.3.

14. An adhesive tape which comprises at least one pressure-sensitive adhesive layer as claimed in claim 1, where the adhesive tape is preferably a double-sided adhesive tape and more particularly a transfer tape.

15. The adhesive tape as claimed in claim 14, which is redetachable without residue or destruction by extensive stretching substantially in the bond plane.

16. An assembly wherein two substrates are bonded by means of a double-sided adhesive tape as claimed in claim 14, where the two substrates are preferably components of a mobile device.

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

18. The pressure-sensitive adhesive layer as claimed in claim 2, characterized in that the polydiene blocks of the polyvinylaromatic-polydiene block copolymers have a mean vinyl fraction (test IX) of less than 17 wt %, preferably less than 13 wt %, based on the total polydiene blocks.

19. The pressure-sensitive adhesive layer as claimed in claim 2, characterized in that based on the total polyvinylaromatic-polydiene block copolymers, at least one polyvinylaromatic-polydiene block copolymer with a peak molar mass (test Ia) of at least 200 000 g/mol, very preferably at least 250 000 g/mol, is present at at least 15 wt %, preferably at least 25 wt %, and up to 100 wt %, preferably at most 90 wt %.

20. The pressure-sensitive adhesive layer as claimed in claim 3, characterized in that based on the total polyvinylaromatic-polydiene block copolymers, at least one polyvinylaromatic-polydiene block copolymer with a peak molar mass (test Ia) of at least 200 000 g/mol, very preferably at least 250 000 g/mol, is present at at least 15 wt %, preferably at least 25 wt %, and up to 100 wt %, preferably at most 90 wt %.

Description

EXAMPLES

[0217] 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 (E: example in accordance with the invention).

[0218] Also given are comparative examples, which represent unsuitable adhesive layers (C: comparative example).

[0219] 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, and then the solvent was 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.

[0220] After drying had taken place, the adhesive layer was lined with a second ply PET liner, free from any air inclusions, and was foamed for 30 s at 170° C. between the two liners, while suspended in a forced-air drying cabinet.

[0221] Table 2 shows the raw materials used. Tables 3a to 3g show the formulas of the inventive examples (E) and comparative examples (C) (% figures in the compositions are wt % unless otherwise indicated; “BC” denotes block copolymer) and also their characteristics.

Raw Materials Used:

[0222]

TABLE-US-00002 TABLE 1 raw materials used. Elastomer Calprene C4302 Polystyrene- Linear SBS* component (a) (Dynasol polybutadiene block PS content 31%* Elastomeros) copolymer Diblock content 24%*** Peak M.W. (Triblock) 110 000 g/mol*** Vinyl content 12%**** Calprene C7318 Polystyrene- Linear SBS* (Dynasol polybutadiene block PS content 32%* Elastomeros) copolymer Diblock content 76%*** Peak M.W. (Triblock) 160 000 g/mol*** Vinyl content 11%**** Calprene C411 Polystyrene- Radial SBS* (Dynasol polybutadiene block PS content 30%* Elastomeros) copolymer Diblock content <16%*** Peak M.W. (radial BC) 320 000 g/mol*** Vinyl content 12%**** Europrene Sol T190 Polystyrene- Linear SIS** (Versalis) polyisoprene block PS content 16%** copolymer Diblock content 25%** Peak M.W. (Triblock) 179 000 g/mol Vinyl content 10%**** Europrene Sol T9113 Polystyrene- Linear SIS** (Versalis) polyisoprene block PS content 18%** copolymer Diblock content 8%** Peak M.W. (Triblock) 148 000 g/mol Vinyl content 9%**** Tackifier resin Regalite R1125 Fully hydrogenated C9 Softening point 125° C. component (b) (Eastman Chemical) hydrocarbon resin DACP = +55° C. Dercolyte A115 Alpha-pinene resin Softening point 115° C. (DRT) DACP = +35° C. Piccolyte A135 Alpha-pinene resin Softening point 135° C. (Pinova) DACP = +30° C. Plasticizer Wingtack 10 Aliphatic C5 liquid Softening point 10° C. component (c) (Cray Valley) resin Piccolyte A25 Polyterpene-based Softening point 25° C. (Pinova) liquid resin Pionier 2070P White oil Glass transition temperature −73° C., estimated softening point −23° C. (softening point = glass transition temperature + 50° C.) Additives (d) Irganox 1010 Primary aging inhibitor (BASF) (sterically hindered phenol derivative) Irgafos 168 Secondary aging (BASF) inhibitor (Phosphoric ester) Microballoons Expancel 920 DU20 (Nouryon) *Manufacturer data, Dynasol Elastomers; **manufacturer data, Versalis; ***estimation from GPC measurements; ****according to test IX.

[0223] 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. C1 C2 C3 C4 Calprene C7318  0% 48% 25% 25% Calprene C4302 48%  0% 25%  0% Calprene C411  0%  0%  0% 25% Dercolyte A115 48% 48% 48% 48% Wingtack 10  2%  2%  2%  2% Irganox 1010 0.5%  0.5%  0.5%  0.5%  Irgafos 168 0.5%  0.5%  0.5%  0.5%  Expancel 920 DU20 1.0%  1.0%  1.0%  1.0%  Diblock 24% 76% 50% <46%  Fraction of high  0% 24% 12% 54% molecular mass BC Sum of b) + c) 50% 50% 50% 50% Harmonic mean 109° C. 109° C. 109° C. 109° C. of b) and c) DuPont PC/PC 611 mJ 493 mJ 567 mJ 579 mJ Peel 5.7 N/cm 9.2 N/cm 7.1 N/cm 6.5 N/cm SAFT 115° C. 122° C. 119° C. 130° C. Density 785 kg/m.sup.3 773 kg/m.sup.3 795 kg/m.sup.3 804 kg/m.sup.3

TABLE-US-00004 TABLE 3b further formulas and their characteristics. E5 E6 E7 E8 Calprene C4302  0% 24% 10% 12% Calprene C411 48% 24% 35% 36% Dercolyte A115 48% 48% 49% 48% Wingtack 10  2%  2%  4%  2% Irganox 1010 0.5%  0.5%  0.5%  0.5%  Irgafos 168 0.5%  0.5%  0.5%  0.5%  Expancel 920 DU 20 1.0%  1.0%  1.0%  1.0%  Diblock <16%  <20%  <18%  <18%  Fraction of high 84% 42% 65% 57% molecular mass BC Sum of b) + c) 50% 50% 53% 50% Harmonic mean 109° C. 109° C. 105° C. 109° C. of b) and c) DuPont PC/PC 653 mJ 675 mJ 734 mJ 673 mJ Peel steel 3.8 N/cm 4.4 N/cm 4.9 N/cm 4.0 N/cm SAFT 137° C. 126° C. 129° C. 131° C. Density 813 kg/m.sup.3 794 kg/m.sup.3 779 kg/m.sup.3 813 kg/m.sup.3

TABLE-US-00005 TABLE 3c further formulas and their characteristics. E9 E10 E11 Calprene C411 .sup. 0% .sup. 0% 43% Europrene Sol T190 .sup. 0%  50%  0% Europrene Sol T9113  50% .sup. 0%  0% Dercolyte A115 .sup. 0% .sup. 0% 49% Regalite R1125 45.5%  45.5%   0% Wingtack 10 2.5% 2.5%  6% Irganox 1010 0.5% 0.5% 0.5%  Irgafos 168 0.5% 0.5% 0.5%  Expancel 920 DU20 1.0% 1.0% 1.0%  Diblock 8.0% 25.0%  <16.0% .sup.   Fraction of high  92%  75% 84% molecular mass BC Sum of b) + c)  48%  48% 55% Harmonic mean 117° C. 117° C. 100° C. of b) and c) DuPont PC/PC 706 mJ 706 mJ 725 mJ Peel steel 10.5 N/cm 7.8 N/cm 5.1 N/cm SAFT 116° C. 112° C. 132° C. Density 786 kg/m.sup.3 738 kg/m.sup.3 784 kg/m.sup.3

TABLE-US-00006 TABLE 3d further formulas and their characteristics. E12 E13 C14 C15 Calprene C7318  0%  0% 12%  0% Calprene C4302 20% 20%  0% 31% Calprene C411 27% 27% 37% 20% Dercolyte A115  0%  0% 39% 37% Piccolyte A135 37% 43%  0%  0% Wingtack 10  0%  0% 10% 10% Piccolyte A25 14%  8%  0%  0% Irganox 1010 0.5%  0.5%  0.5%  0.5%  Irgafos 168 0.5%  0.5%  0.5%  0.5%  Expancel 920 DU20 1.0%  1.0%  1.0%  1.0%  Diblock <19.4% .sup.   <19.4% .sup.   <30.7% .sup.   <20.9% .sup.   Fraction of high 48.2%.sup.  48.2%.sup.  69.3%.sup.  32.9%.sup.  molecular mass BC Sum of b) + c) 51% 51% 49% 47% Harmonic mean 97° C. 113° C. 88° C. 87° C. of b) and c) DuPont PC/PC 839 mJ 868 mJ 544 mJ 500 mJ Peel 6.8 N/cm 9.7 N/cm 3.8 N/cm 2.6 N/cm SAFT 128° C. 131° C. 132° C. 118° C. Density 803 kg/m.sup.3 779 kg/m.sup.3 753 kg/m.sup.3 753 kg/m.sup.3

TABLE-US-00007 TABLE 3e further formulas and their characteristics. E16 E10 E17 C18 C19 Calprene C4302 30%  .sup. 0% 0% 0% 0% Calprene C411 11%  .sup. 0% 0% 0% 0% Europrene Sol T190 0%  50% 49%  48.5%   47.5%   Dercolyte A115 53%  .sup. 0% 0% 0% 0% Piccolyte A135 0% .sup. 0% 0% 0% 0% Regalite R1125 0% 45.5%  45.5%   45%  44%  Wingtack 10 4% 2.5% 2.5%.sup.  2.5%.sup.  2.5%.sup.  Irganox 1010 0.5%.sup.  0.5% 0.5%.sup.  0.5%.sup.  0.5%.sup.  Irgafos 168 0.5%.sup.  0.5% 0.5%.sup.  0.5%.sup.  0.5%.sup.  Microballoons 1% 1.0% 2% 3% 5% Diblock <21.9%     25.0%  25.0%   25.0%   25.0%   Fraction of high 22.5%    75% 75%  75%  75%  molecular mass BC Sum of b) + c) 57.0%    48% 48.0%   47.5%   46.5%   Harmonic mean 101° C. 117° C. 117° C. 117° C. 117° C. of b) and c) DuPont PC/PC 706 mJ 706 mJ 721 mJ 515 mJ 368 mJ Peel 11.1 N/cm 7.8 N/cm 8.3 N/cm 7.7 N/cm 6.9 N/cm SAFT 114° C. 112° C. 118° C. 125° C. 131° C. Density 790 kg/m.sup.3 771 kg/m.sup.3 651 kg/m.sup.3 550 kg/m.sup.3 447 kg/m.sup.3

TABLE-US-00008 TABLE 3f further formulas and their characteristics. C20 E21 E22 E24 E25 Calprene C4302 31%  31% 29% 27% 27% Calprene C411 20%  20% 19% 17% 17% Dercolyte A115 47%   0%  0%  0%  0% Piccolyte A135 0% 37% 38% 39% 39% Wingtack 10 0% 10% 12% 15%  0% Piccolyte A25 0%  0%  0%  0% 15% Irganox 1010 0.5%.sup.  0.5%  0.5%  0.5%  0.5%  Irgafos 168 0.5%.sup.  0.5%  0.5%  0.5%  0.5%  Microballoons 1%  1%  1%  1%  1% Diblock <20.9%     <20.9% .sup.   <20.8% .sup.   <20.9% .sup.   <20.9% .sup.   Fraction of high 32.9%   32.9%.sup.  33.3%.sup.  32.4%.sup.  32.4%.sup.  molecular mass BC Sum of b) + c) 47.0%   47.0%.sup.  50.0%.sup.  54.0%.sup.  54.0%.sup.  Harmonic mean 115° C. 100° C. 96° C. 90° C. 97° C. of b) and c) DuPont PC/PC 519 mJ 706 mJ 736 mJ 780 mJ 780 mJ Peel 3.5 N/cm 5.2 N/cm 6.7 N/cm 7.9 N/cm 9.2 N/cm SAFT 126° C. 124° C. 116° C. 114° C. 118° C. Density 791 kg/m.sup.3 787 kg/m.sup.3 817 kg/m.sup.3 799 kg/m.sup.3 814 kg/m.sup.3

TABLE-US-00009 TABLE 3g further formulas and their characteristics. E26 E27 E28 C29 Calprene C7318 12%  0% 0% 0% Calprene C4302 0% 0% 0% 10%  Calprene C411 38%  0% 0% 33%  Europrene Sol T190 0% 50.0%   50.0%   0% Dercolyte A115 0% 0% 0% 0% Piccolyte A135 38.0%   0% 0% 53.0%   Regalite R1125 0% 45.5%   43.0%   0% Wingtack 10 10.0%   0% 0% 2.0%.sup.  Pionier 2070P 0% 2.5%.sup.  5.0%.sup.  0% Irganox 1010 0.5%.sup.  0.5%.sup.  0.5%.sup.  0.5%.sup.  Irgafos 168 0.5%.sup.  0.5%.sup.  0.5%.sup.  0.5%.sup.  Microballoons 1% 1% 1% 1% Diblock <28.5%     25%  25%  <17.9%     Fraction of high 75%  75%  75%  64.4%   molecular mass BC Sum of b) + c) 48%  48%  48%  55%  Harmonic mean 101° C. 113° C. 102° C. 129° C. of b) and c) DuPont PC/PC 736 mJ 824 mJ 853 mJ 162 mJ Peel 6.0 N/cm 9.1 N/cm 7.9 N/cm 14.2 N/cm SAFT 140° C. 113° C. 112° C. 129° C. Density 814 kg/m.sup.3 738 kg/m.sup.3 774 kg/m.sup.2 761 kg/m.sup.3

[0224] Foamed adhesive transfer tapes 100 μm thick were investigated.

[0225] The comparative examples C1 to C4 from table 3a show that if the peak molar mass is too low or the diblock fraction too high, respectively, in the polyvinylaromatic-polydiene block copolymer, the shock resistance recorded is deserving of improvement.

[0226] By increasing the peak molar mass or reducing the diblock fraction, respectively, it is possible, as shown by examples E5 to E11 from table 3b or 3c, to improve the shock resistance, so that it corresponds to the preferred profile of requirements from table 1. The bond strength and thermal shear strength also each correspond to said profile of requirements.

[0227] Inventive examples E12 and E13 and comparative examples C14 and C15 from table 3d show, moreover, that the harmonic mean of the softening temperature of the tackifier resin component and of the plasticizer component, of at least 95° C., is essential for achieving the object on which the invention is based, particularly for obtaining a satisfactory shock resistance and bond strength, respectively.

[0228] Inventive examples E16 and E17 and comparative examples C18 and C19 from table 3e show, moreover, that the selection of a suitable microballoon fraction is likewise essential for achieving the object on which the invention is based, especially for obtaining a satisfactory shock resistance.

[0229] The same is true, as shown by comparative example C20 from table 3f, with regard to the presence of plasticizer, such as plasticizer resin in particular.