Acrylate Structural Adhesive

Abstract

The invention relates to a two-component structural adhesive, i.e. to a two-component system of a first component and a second component spatially separated from one another, wherein the reaction of the first component and the second component after mixing results in a structural adhesive. The first component comprises at least four of a (meth)acrylic acid, a C.sub.1-6-alkyl (meth)acrylate, a cycloalkyl (meth)acrylate, a hydroxy-C.sub.1-6-alkyl (meth)acrylate, and/or a glycolether (meth)acrylate. The second component comprises a peroxide polymerization initiator. Additionally, the first component and/or the second component comprises at least two toughening agents (a first toughening agent and a second toughening agent); the second toughening agent differing from the first toughening agent; a first impact modifier; and optionally a second impact modifier differing from the first impact modifier.

Claims

1: A two-component system of a (i) first component comprising a (meth)acrylic acid, a C.sub.1-6-alkyl (meth)acrylate, a hydroxy-C.sub.1-6-alkyl (meth)acrylate, and additionally a cycloalkyl (meth)acrylate, and/or a glycolether (meth)acrylate according to general formula (I),
CH.sub.2═CR—C(═O)—O—[CH.sub.2CH.sub.2—O].sub.n—C.sub.mH.sub.2m+1,   (I), wherein R is —H or —CH.sub.3; index n is an integer within the range of from 1 to 12; and index m is an integer within the range of from 1 to 8; and (ii) a second component comprising a peroxide polymerization initiator; wherein the first component and/or the second component additionally comprise a first toughening agent; a second toughening agent differing from the first toughening agent; a first impact modifier; and optionally, a second impact modifier differing from the first impact modifier; wherein the first component and the second component are spatially separated from one another; and wherein the reaction of the first component and the second component after mixing results in a structural adhesive.

2: The two-component system according to claim 1, wherein the (meth)acrylic acid is methacrylic acid or acrylic acid; the C.sub.1-6-alkyl (meth)acrylate is methyl (meth)acrylate or ethyl (meth)acrylate; and the hydroxy-C.sub.1-6-alkyl (meth)acrylate is hydroxyethyl (meth)acrylate or hydroxypropyl (meth)acrylate.

3: The two-component system according to claim 1, wherein the cycloalkyl (meth)acrylate is isobornyl acrylate or isobornyl methacrylate.

4: The two-component system according to claim 1, wherein the (meth)acrylic acid is methacrylic acid.

5: The two-component system according to claim 2, wherein the content of the (meth)acrylic acid is within the range of 5.0±4.0 wt.-%, relative to the total weight of the two-component system.

6: The two-component system according to claim 1, wherein the C.sub.1-6-alkyl (meth)acrylate is selected from the group consisting of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate and butyl methacrylate.

7: The two-component system according to claim 1, wherein the two-component system comprises essentially no C.sub.1-6-alkyl (meth)acrylate other than methyl methacrylate.

8: The two-component system according to claim 6, wherein the content of the C.sub.1-6-alkyl (meth)acrylate is at most 50 wt.-%, relative to the total weight of the two-component system.

9: The two-component system according to claim 6, wherein the content of the C.sub.1-6-alkyl (meth)acrylate is at most 40 wt.-%, relative to the total weight of the two-component system.

10: The two-component system according to claim 6, wherein the content of the C.sub.1-6-alkyl (meth)acrylate is at most 30 wt.-%, relative to the total weight of the two-component system.

11: The two-component system according to claim 6, wherein the content of the C.sub.1-6-alkyl (meth)acrylate is within the range of 25±10 wt.-%, relative to the total weight of the two-component system.

12: The two-component system according to claim 1, wherein the cycloalkyl (meth)acrylate is selected from the group consisting of isobornyl acrylate, isobornyl methacrylate, 1-adamantyl acrylate, 1-adamantyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, methylcyclohexyl acrylate, methylcyclohexyl methacrylate, trimethylcyclohexyl acrylate, trimethylcyclohexyl methacrylate, butylcyclohexyl acrylate, butylcyclohexyl methacrylate, furfuryl acrylate, and furfuryl methacrylate.

13: The two-component system according to claim 12, wherein the content of the cycloalkyl (meth)acrylate is less than 5.5 wt.-%, at most 5.0 wt.-%, at most 4.8 wt.-%, at most 4.6 wt.-%, at most 4.4 wt.-%, at most 4.2 wt.-%, or at most 4.0 wt.-%, relative to the total weight of the two-component system.

14: The two-component system according to claim 12, wherein the content of the cycloalkyl (meth)acrylate is within the range of 5.0±4.0 wt.-%, 5.0±3.0 wt.-%, or 5.0±2.0 wt.-%, relative to the total weight of the two-component system.

15: The two-component system according to claim 12, wherein the hydroxy-C.sub.1-6-alkyl (meth)acrylate is selected from the group consisting of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate.

16: The two-component system according to claim 12, wherein the content of the hydroxy-C.sub.1-6-alkyl (meth)acrylate, is more than 6.0 wt.-%, at least 6.5 wt.-%, at least 7.0 wt.-%, 7.5 wt.-%, at least 8.0 wt.-%, at least 8.5 wt.-%, or at least 9.0 wt.-%, relative to the total weight of the two-component system.

17: The two-component system according to claim 1, wherein the content of the hydroxy-C.sub.1-6-alkyl (meth)acrylate is within the range of 10±8.0 wt.-%, 10±6.0 wt.-%, or 10±4.0 wt.-%, relative to the total weight of the two-component system.

18-23. (canceled)

24: The two-component system according to claim 1, wherein the first toughening agent is a liquid (meth)acrylate terminated butadiene-acrylonitrile copolymer.

25. (canceled)

26: The two-component system according to claim 1, wherein the second toughening agent is a solid styrene-butadiene-styrene block-copolymer (SBS).

27-28. (canceled)

29: The two-component system according to claim 1, wherein the first impact modifier is a a core shell impact modifier having an all-acrylic core shell based on butyl-acrylate rubber.

30-59. (canceled)

Description

EXAMPLES 1 TO 7 (PROPHETIC)

[0223]

TABLE-US-00001 ingredient [wt-%.sup.1] Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 first component (10 parts per weight): acrylic acid 2.85 — 3.63 4.06 4.16 4.32 5.00 methacrylic acid — 2.93 — — — — — methyl methacrylate 48.59  — 43.05  45.02  45.13  — 36.58  methyl acrylate — 41.98  — — — 36.46  — hydroxypropyl acrylate 4.32 — — — — — 13.63  hydroxypropyl methacrylate — 6.38 6.42 7.32 7.54 12.45  — isobornyl acrylate 0.13 3.34 3.45 3.52 4.83 5.00 5.32 first liquid toughening agent 6.00 6.00 6.00 4.00 4.00 4.00 2.00 second solid toughening agent 8.00 7.00 6.00 5.00 4.00 3.00 2.00 first core shell impact modifier 5.33 6.23 6.33 7.02 8.54 8.63 8.90 second core shell impact modifier 4.32 6.38 6.42 7.32 7.54 12.45  13.63  adhesion promoter A 5.32 5.00 — 2.64 — 1.31 1.20 adhesion promoter B — — 4.32 — 1.50 — — accelerator 3.02 2.83 2.64 2.50 1.83 1.64 1.32 curative 3.02 2.83 2.64 2.50 1.83 1.64 1.32 stabilizer 0.02 0.02 0.02 0.02 0.02 0.02 0.02 TOTAL 90.92  90.92  90.92  90.92  90.92  90.92  90.92  second component (1 part per weight): peroxide polymerization initiator 3.00 3.27 3.38 3.54 3.83 4.00 4.13 first core shell impact modifier 4.88 4.49 4.27 4.06 3.69 3.41 3.23 inorganic filler 1.20 1.32 1.43 1.48 1.56 1.67 1.72 TOTAL 9.08 9.08 9.08 9.08 9.08 9.08 9.08 .sup.1relative to the total weight of the two-component system, i.e. after the first component and the second component have been mixed with one another

EXAMPLE 8

[0224]

TABLE-US-00002 ingredient function [wt.-%.sup.2] first component (10 parts): methacrylic acid (meth)acrylic acid 4.40 methyl methacrylate C.sub.1-6-alkyl (meth)acrylate 29.98 hydroxyethyl methacrylate hydroxy-C.sub.1-6-alkyl (meth)acrylate 11.50 isobornyl methacrylate cycloalkyl (meth)acrylate 3.90 (meth)acrylate terminated butadiene-acrylonitrile copolymer first toughening agent 9.00 styrene-butadiene-styrene block-copolymer second toughening agent 7.20 all-acrylic core shell based on butyl-acrylate rubber first core shell impact modifier 3.70 methacrylate butadiene styrene copolymer second core shell impact modifier 25.00 toluidine derivative curative 1.20 Zn dimethacrylate accelerator 1.15 Leuco violet cure indicator 0.05 hydroquinone derivative stabilizer 0.02 phosphate methacrylate adhesion promoter 2.90 TOTAL 100.00 second component (1 part): dibenzyol peroxide peroxide polymerization initiator 57.00 core-shell poly(butadiene) rubber dispersion third core shell impact modifier 36.00 amorphous precipitated silica filler 7.00 TOTAL 100.00 .sup.2relative to the total weight of the single components

EXAMPLES 9 TO 13

[0225]

TABLE-US-00003 ingredient [wt.-%.sup.3] function Ex. 9 Ex. 10 Ex. 11 Ex. 12 Ex. 13 first component (10 parts): methacrylic acid (meth)acrylic acid 4.40 4.74 4.84 5.13 5.46 methyl methacrylate C.sub.1-6-alkyl 30.03 30.23 30.82 32.67 35.10 (meth)acrylate 2-hydroxyethyl hydroxy-C.sub.1-6-alkyl 11.50 12.39 12.64 13.40 16.89 methacrylate (meth)-acrylate isobornyl methacrylate isobornyl 3.90 4.20 4.29 4.54 4.83 methacrylate (meth)acrylate terminated first toughening 9.00 9.70 — 10.48 — butadiene-acrylonitrile agent copolymer styrene - butadiene - second toughening 7.20 — 7.91 8.39 — styrene block-copolymer agent all-acrylic core shell based first core shell 3.70 3.99 4.07 16.95 3.88 on butyl-acrylate rubber impact modifier methacrylate butadiene second core shell 25.00 26.94 27.47 — 26.23 styrene (MBS) copolymer impact modifier toluidine derivative curative 1.20 1.29 1.32 1.40 1.26 Zn dimethacrylate accelerator 1.15 1.24 1.26 1.34 1.21 hydroquinone derivative stabilizer 0.02 2.16 2.20 2.33 2.10 phosphate methacrylate adhesion promoter 2.90 3.13 3.19 3.38 3.04 TOTAL 100.00 100.00 100.00 100.00 100.00 second component (1 part): peroxide polymerization initiator 35.48 35.48 35.48 35.48 35.48 bisphenol-F type epoxy resin 30.55 30.55 30.55 30.55 30.55 all-acrylic core shell based first core shell 10.2 10.2 10.2 10.2 10.2 on butyl-acrylate rubber impact modifier anhydrous aluminum inorganic filler 20.44 20.44 20.44 20.44 20.44 silicate black epoxy resin 3.33 3.33 3.33 3.33 3.33 TOTAL 100.00 100.00 100.00 100.00 100.00 .sup.3relative to the total weight of the single components

EXAMPLES 14 TO 17

[0226]

TABLE-US-00004 ingredient [wt.-%.sup.4] Ex. 14 Ex. 15 Ex. 16 Ex. 17 first component (10 parts): methacrylic acid (meth)acrylic acid 7.73 7.72 7.98 7.65 methyl methacrylate C.sub.1-6-alkyl (meth)acrylate 32.91 32.87 33.99 32.57 2-hydroxyethyl methacrylate hydroxy-C.sub.1-6-alkyl (meth)-acrylate 20.21 20.19 15.65 15.92 isobornyl methacrylate isobornyl methacrylate — butyldiglycol methacrylate glycolether (meth)acrylate 5.00 (meth)acrylate terminated butadiene- first toughening agent — acrylonitrile copolymer styrene-butadiene-styrene block- second toughening agent 7.31 — copolymer all-acrylic core shell based on butyl- first core shell impact modifier 6.58 6.57 6.80 6.51 acrylate rubber methacrylate butadiene styrene (MBS) second core shell impact modifier 25.52 25.50 20.87 25.26 copolymer toluidine derivative curative 1.73 1.21 1.25 1.20 Zn dimethacrylate accelerator 0.61 0.63 0.60 hydroquinone derivative stabilizer 2.22 2.22 2.30 2.20 phosphate methacrylate adhesion promoter 3.12 3.11 3.22 3.09 TOTAL 100.00 100.00 100.00 100.00 second component (1 part): peroxide polymerization initiator 35.48 35.48 35.48 35.48 bisphenol-F type epoxy resin 30.55 30.55 30.55 30.55 all-acrylic core shell based on butyl- first core shell impact modifier 10.2 10.2 10.2 10.2 acrylate rubber anhydrous aluminum silicate inorganic filler 20.44 20.44 20.44 20.44 coloring paste 3.33 3.33 3.33 3.33 TOTAL 100.00 100.00 100.00 100.00 .sup.4relative to the total weight of the single components

Characterization:

[0227]

TABLE-US-00005 Ex. 10 Ex. 11 Ex. 13 Ex. 8 Ex. 9 comparative comparative Ex. 12 comparative first toughening agent + + + − + − second toughening agent + + − + + − first impact modifier + + + + + + second impact modifier + + + + − + Lap shear Alu 5754 abraded 18.0 15.4 15.7 15.7 15.7 22.1 (MPa) - 1 mm bondline 55% cf 100% cf 95% CF 100% CF 100% CF 100% CSF Lap shear Alu 5754 abraded 25 N/A N/A N/A N/A N/A (MPa) - 0.3 mm bondline 100% cf Lap shear Stainless steel N/A N/A N/A N/A N/A N/A (MPa) - 0.3 mm gap Youngs modulus E [MPa] 649 700 1143 1102 1181 1375 Tensile strength s [MPa] 17.9   17.7 20.3 20.3 20.3 26 Elongation at break [%] 110 107 62.3 19 8.4 5 T-peel strength (N/mm - 9.3  15 N/A N/A N/A N/A facies) 80% cf Shrinkage [%] 16.6 N/A N/A N/A N/A N/A Max gap fill [mm] >100 N/A N/A N/A N/A N/A Sag 0 mm OK OK OK OK OK OK Wedge impact 26.6 N/mm N/A N/A N/A N/A N/A 12.1 J Open time [min] 4-6  4 4 2.5 4 8.5 Fixture time [min] 8 N/A N/A N/A N/A N/A Exothermic time [min] (10 g) N/A 10 11 17 15 11 (105.5° C.) (104.5° C.) (90.1° C.) (99.7° C.) (117° C.) Ex. 14 Ex. 15 Ex. 16 Ex. 17 comparative comparative comparative comparative first toughening agent − − − − second toughening agent − − + − first impact modifier + + + + second impact modifier + + + + Lap shear Alu 5754 abraded N/A N/A N/A N/A (MPa) - 1 mm bondline Lap shear Alu 5754 abraded 21.1 20.8 21.4 19.9 (MPa) - 0.3 mm bondline 100% SCF 100% SCF 100% CF 100% SCF Lap shear Stainless steel 26.5 25.6 22.8 26.2 (MPa) - 0.3 mm gap 100% SCF 100% SCF 100% SCF 100% SCF Youngs modulus E [MPa] 1071 1265 1036 N/A Tensile strength s [MPa] 23.1 26.2 19.4 N/A Elongation at break [%] 6.3 10 10.6 N/A T-peel strength (N/mm - 5.5 4.65 9.81 4.96 facies) 100% CF 100% CF 100% CF 100% CF Shrinkage [%] N/A N/A N/A N/A Max gap fill [mm] N/A N/A N/A N/A Sag N/A N/A N/A N/A Wedge impact N/A N/A N/A N/A Open time [min] 18-22 (at 12 (at 8 (at 14-15 (at 24° C.) 27.2° C.) 26° C.) 26° C.) Fixture time [min] RT = 24° C. RT = 27.2° C. RT = 26° C. RT = 26° C. MT = 22.4° C. MT = 25.5° C. MT = 24.4° C. MT = 23.9° C. 41 min/97.9° C. 23 min/129° C. 23 min/120.3° C. 27 min/118.2° C. Exothermic time [min] (10 g) N/A N/A N/A N/A RT = room temperature; MT = material temperature

[0228] As demonstrated by the above data, the inventive two-component system comprising first and second toughening agent as well as first and second impact modifier provides improved Lap shear (at alu 5754 abraded 0.3 mm bondline; Ex. 8 vs. Ex. 14-17).

[0229] Further, as demonstrated by the above data, the inventive two-component system comprising first and second toughening agent as well as first and second impact modifier provides improved elongation at break (Ex. 8-9 vs. Ex. 10-16).

[0230] Still further, as demonstrated by the above data, the inventive two-component system comprising first and second toughening agent as well as first and second impact modifier provides improved T-peel strength (N/mm—facies; Ex. 8-9 vs. Ex. 14-17).