Cold curing epoxy resin primer or adhesive

Abstract

The invention relates to the use of an epoxy resin composition, containing at least one reaction product from the reaction of at least one amine of formula (I) with at least one carbonyl compound of formula (II) and hydrogen, as a cold curing primer or adhesive. Primers or adhesives of this type cure rapidly and trouble-free at ambient temperature, even at cold temperatures such as 10 or 5 C., suffer remarkably little yellowing and are free from toxic phenol compounds such as phenol, tert-butylphenol or nonylphenol. The primer has a particularly low viscosity and is particularly suitable for priming porous mineral substrates.

Claims

1. An epoxy resin composition comprising at least one reaction product from the reaction of at least one amine of the formula (I) with at least one carbonyl compound of the formula (II) and hydrogen, ##STR00004## where A is a phenylene radical or cyclohexylene radical, R is a hydrogen radical or alkyl radical having 1 to 8 carbon atoms, m is 0 or 1, and X is a hydroxyl radical or methyl radical or methoxy radical, wherein: the molar ratio between the amine of the formula (I) and the carbonyl compound of the formula (II) is in the range from 1/0.7 to 1/1.2, the reaction product contains an amount of amine of the formula (III) in the range from 30 to 80 weight % of the reaction product, ##STR00005## and the epoxy resin composition is a cold-curing primer or adhesive.

2. The epoxy resin composition as claimed in claim 1, wherein the amine of the formula (I) is selected from the group consisting of 1,3-bis(aminomethyl)benzene and 1,3-bis(aminomethyl)cyclohexane.

3. The epoxy resin composition as claimed in claim 1, wherein the carbonyl compound of the formula (II) is selected from the group consisting of salicylaldehyde and 2-hydroxyacetophenone.

4. A primer for pretreating porous mineral substrates, comprising: a resin component comprising at least one epoxy resin and a hardener component comprising the at least one reaction product as claimed in claim 1.

5. The primer as claimed in claim 4, wherein it has a viscosity at 20 C. of not more than 5 Pa.Math.s, determined as specified in the description.

6. The primer as claimed in claim 4, wherein it comprises at least one diluent selected from the group consisting of benzyl alcohol, styrenized phenol, ethoxylated phenol, aromatic hydrocarbon resins containing phenol groups, and cardanol.

7. The primer as claimed in claim 4, wherein the hardener component comprises less than 0.1 weight % of phenol compounds selected from the group consisting of phenol, cresol, resorcinol, tert-butylphenol, nonylphenol and dodecylphenol.

8. An adhesive comprising a resin component comprising at least one epoxy resin and a hardener component comprising the at least one reaction product as claimed in claim 1.

9. A layer structure comprising at least one layer of the primer as claimed in claim 4, at least one layer of a curable polymer composition, optionally an outer layer and/or sealing.

10. The layer structure as claimed in claim 9, wherein it represents a coating system, where the curable polymer composition is a plastics coating.

11. The layer structure as claimed in claim 10, wherein it represents a floor or a protective coating or a water seal.

12. A method for coating or bonding a porous mineral substrate, comprising (i) applying the primer as claimed in claim 4 to the porous mineral substrate, in an amount sufficient to close the pores, (ii) curing the applied primer at a temperature of 5 C. to 35 C. at least to capacity to accept foot traffic, (iii) applying at least one layer of a curable polymer composition to the applied and at least partly cured primer.

13. The method as claimed in claim 12, wherein the primer is applied and/or cured at a temperature of 5 C. to below 20 C.

14. A reaction product containing an amine compound of the formula (III) from the reaction of at least one amine of the formula (I) with at least one carbonyl compound of the formula (II) and hydrogen, ##STR00006## where A is a phenylene radical or cyclohexylene radical, R is a hydrogen radical or alkyl radical having 1 to 8 carbon atoms, m is 0 or 1, and X is a hydroxyl radical or methyl radical or methoxy radical, where the amine and the carbonyl compound in a molar ratio in the range from 1/0.8 to 1/1.1 are subjected to catalytic hydrogenation with molecular hydrogen in a solvent, without isolation of the imine intermediate formed and without removal of the water liberated, and wherein the reaction product contains an amount of amine of the formula (III) in the range from 30 to 80 weight% of the reaction product, ##STR00007##

Description

EXAMPLES

(1) Set out below are working examples which are intended to elucidate in more detail the invention described. The invention is of course not confined to these working examples described. AHEW stands for the amine hydrogen equivalent weight. EEW stands for the epoxide equivalent weight. Standard conditions refer to a temperature of 231 C. and a relative atmospheric humidity of 505%. SC stands for standard conditions.
Description of Measurement Methods:

(2) Infrared spectra (FT-IR) were measured as undiluted films on an FT-IR instrument 1600 from Perkin-Elmer equipped with a horizontal ATR measurement unit with ZnSe crystal; the absorption bands are reported in wavenumbers (cm.sup.1); (measuring window: 4000-650 cm.sup.1).

(3) The viscosity was measured on a thermostated cone/plate viscometer, Rheotec RC30 (cone diameter 50 mm, cone angle 1, cone tip/plate distance 0.05 mm) at a shear rate of 10 s.sup.1.

(4) The amine number was determined by titration (with 0.1N HClO.sub.4 in acetic acid against crystal violet).

(5) Commercial Substances Used:

(6) Araldite GY 250: bisphenol A diglycidyl ether, EEW about 187.5 g/eq (from Huntsman) Araldite DY-E: monoglycidyl ether of C.sub.12 to C.sub.14 alcohols, EEW about 290 g/eq (from Huntsman) SR-Dur 2750: Mannich base based on 4-tert-butylphenol, 1,3-bis(aminomethyl)benzene and trimethyl-1,6-hexanediamine, containing 10 to 25 weight % of 4-tert-butylphenol, AHEW 75.0 g/eq (from SRS Meeder)
Preparation of Inventive Reaction Products:
Reaction Product A1: Reaction Product Comprising N-(2-hydroxybenzyl)-1,3-bis(aminomethyl)benzene

(7) A round-bottomed flask was charged at room temperature with 27.24 g (0.20 mol) of 1,3-bis(aminomethyl)benzene (MXDA, from Mitsubishi Gas Chemicals) under a nitrogen atmosphere. With thorough stirring, a solution of 24.42 g (0.20 mol) of salicylaldehyde in 250 ml of isopropanol was added slowly dropwise, followed by stirring for 2 hours. Thereafter the reaction mixture was hydrogenated under a hydrogen pressure of 80 bar, at a temperature of 90 C. and with a flow rate of 5 ml/min, on a continuous hydrogenation apparatus with Pd/C fixed-bed catalyst. To monitor the reaction, IR spectroscopy was used to verify whether the imine band at about 1665 cm.sup.1 had disappeared. At that point the hydrogenated solution was concentrated under reduced pressure at 65 C. This gave a yellowish liquid having a viscosity of 22.1 Pa.Math.s at 20 C. and an amine number of 458 mg KOH/g.

(8) FT-IR: 3022, 2846, 2721, 2613, 1587, 1454, 1254, 1082, 843, 747, 699.

(9) Reaction Product A2: Reaction Product Comprising N-(2-hydroxybenzyl)-1,3-bis(aminomethyl)cyclohexane

(10) A round-bottomed flask was charged at room temperature with 14.22 g (0.10 mol) of 1,3-bis(aminomethyl)cyclohexane (1,3-BAC, from Mitsubishi Gas Chemicals) under a nitrogen atmosphere. With thorough stirring, a solution of 12.21 g (0.10 mol) of salicylaldehyde in 350 ml of isopropanol was added slowly dropwise, followed by stirring for 2 hours. Thereafter the reaction mixture was hydrogenated under a hydrogen pressure of 90 bar, at a temperature of 90 C. and with a flow rate of 4 ml/min, on a continuous hydrogenation apparatus with Pd/C fixed-bed catalyst. To monitor the reaction, IR spectroscopy was used to verify whether the imine band at about 1665 cm.sup.1 had disappeared. At that point the hydrogenated solution was concentrated under reduced pressure at 65 C. This gave a yellowish liquid having a viscosity of 124 Pa.Math.s at 20 C. and an amine number of 445 mg KOH/g.

(11) FT-IR: 2915, 2846, 2726, 1589, 1455, 1413, 1257, 1151, 1102, 1036, 953, 931, 842, 793, 720.

(12) Preparation of Noninventive Reaction Products as a Comparison:

(13) Reaction Product R1: Reaction Product Comprising N-(2-hydroxybenzyl)-4-methyl-1,5-pentanediamine

(14) A round-bottomed flask was charged at room temperature with 23.24 g (0.20 mol) of 1,5-diamino-2-methylpentane (Dytek A, from Invista) under a nitrogen atmosphere. With thorough stirring, a solution of 24.42 g (0.20 mol) of salicylaldehyde in 250 ml of isopropanol was added slowly dropwise, followed by stirring for 2 hours. Thereafter the reaction mixture was hydrogenated under a hydrogen pressure of 80 bar, at a temperature of 90 C. and with a flow rate of 5 ml/min, on a continuous hydrogenation apparatus with Pd/C fixed-bed catalyst. To monitor the reaction, IR spectroscopy was used to verify whether the imine band at about 1665 cm.sup.1 had disappeared. At that point the hydrogenated solution was concentrated under reduced pressure at 65 C. This gave a yellowish liquid having a viscosity of 2.3 Pa.Math.s at 20 C. and an amine number of 506 mg KOH/g.

(15) Reaction Product R2: Reaction Product Comprising N-(2-hydroxybenzyl)-3,3(5),5-trimethyl-1,6-hexanediamine

(16) A round-bottomed flask was charged at room temperature with 15.82 g (0.10 mol) of 2,2(4),4-trimethylhexamethylenediamine (Vestamin TMD, from Evonik) under a nitrogen atmosphere. With thorough stirring, a solution of 12.21 g (0.10 mol) of salicylaldehyde in 250 ml of isopropanol was added slowly dropwise, followed by stirring for 2 hours. Thereafter the reaction mixture was hydrogenated under a hydrogen pressure of 80 bar, at a temperature of 90 C. and with a flow rate of 4 ml/min, on a continuous hydrogenation apparatus with Pd/C fixed-bed catalyst. To monitor the reaction, IR spectroscopy was used to verify whether the imine band at about 1665 cm.sup.1 had disappeared. At that point the hydrogenated solution was concentrated under reduced pressure at 65 C. This gave a dark yellow liquid having a viscosity of 4.4 Pa.Math.s at 20 C. and an amine number of 414 mg KOH/g.

(17) Reaction Product R3: Reaction Product Comprising N-(2-hydroxybenzyl)-4,7-diaza-1,10-decanediamine

(18) A round-bottomed flask was charged at room temperature with 34.85 g (0.20 mol) of N,N-bis(3-aminopropyl)ethylenediamine (N4-amine, from BASF) under a nitrogen atmosphere. With thorough stirring, a solution of 24.42 g (0.20 mol) of salicylaldehyde in 400 ml of isopropanol was added slowly dropwise, followed by stirring for 2 hours. Thereafter the reaction mixture was hydrogenated under a hydrogen pressure of 85 bar, at a temperature of 90 C. and with a flow rate of 4 ml/min, on a continuous hydrogenation apparatus with Pd/C fixed-bed catalyst. To monitor the reaction, IR spectroscopy was used to verify whether the imine band at about 1665 cm.sup.1 had disappeared. At that point the hydrogenated solution was concentrated under reduced pressure at 65 C. This gave a yellowish liquid having a viscosity of 2.5 Pa.Math.s at 20 C. and an amine number of 794 mg KOH/g.

(19) Reaction Product R4: Reaction Product Comprising N-benzyl-1,3-bis(amino-methyl)benzene

(20) A round-bottomed flask was charged at room temperature with 27.24 g (0.20 mol) of 1,3-bis(aminomethyl)benzene (MXDA, from Mitsubishi Gas Chemicals) under a nitrogen atmosphere. With thorough stirring, a solution of 26.53 g (0.25 mol) of benzaldehyde in 250 ml of isopropanol was added slowly dropwise, followed by stirring for 2 hours. Thereafter the reaction mixture was hydrogenated under a hydrogen pressure of 80 bar, at a temperature of 90 C. and with a flow rate of 5 ml/min, on a continuous hydrogenation apparatus with Pd/C fixed-bed catalyst. To monitor the reaction, IR spectroscopy was used to verify whether the imine band at about 1665 cm.sup.1 had disappeared. At that point the hydrogenated solution was concentrated under reduced pressure at 65 C. This gave a yellowish liquid having a viscosity of 0.1 Pa.Math.s at 20 C. and an amine number of 438 mg KOH/g.

(21) Reaction Product R5: Reaction Product Comprising N-(4-hydroxybenzyl)-1,3-bis(aminomethyl)benzene

(22) A round-bottomed flask was charged at room temperature with 27.24 g (0.20 mol) of 1,3-bis(aminomethyl)benzene (MXDA, from Mitsubishi Gas Chemicals) under a nitrogen atmosphere. With thorough stirring, a solution of 24.42 g (0.20 mol) of 4-hydroxybenzaldehyde in 250 ml of isopropanol was added slowly dropwise, followed by stirring for 2 hours. Thereafter the reaction mixture was hydrogenated under a hydrogen pressure of 80 bar, at a temperature of 90 C. and with a flow rate of 5 ml/min, on a continuous hydrogenation apparatus with Pd/C fixed-bed catalyst. To monitor the reaction, IR spectroscopy was used to verify whether the imine band at about 1665 cm.sup.1 had disappeared. At that point the hydrogenated solution was concentrated under reduced pressure at 65 C. This gave a highly viscous yellowish liquid having a viscosity of >200 Pa.Math.s at 20 C. and 8 Pa.Math.s at 60 C.

(23) Reaction Product R6: Reaction Product Comprising N-(4-hydroxy-2-methoxy-benzyl)-1,3-bis(aminomethyl)benzene

(24) A round-bottomed flask was charged at room temperature with 27.24 g (0.20 mol) of 1,3-bis(aminomethyl)benzene (MXDA, from Mitsubishi Gas Chemicals) under a nitrogen atmosphere. With thorough stirring, a solution of 30.43 g (0.20 mol) of vanillin in 250 ml of isopropanol was added slowly dropwise, followed by stirring for 2 hours. Thereafter the reaction mixture was hydrogenated under a hydrogen pressure of 80 bar, at a temperature of 90 C. and with a flow rate of 5 ml/min, on a continuous hydrogenation apparatus with Pd/C fixed-bed catalyst. To monitor the reaction, IR spectroscopy was used to verify whether the imine band at about 1665 cm.sup.1 had disappeared. At that point the hydrogenated solution was concentrated under reduced pressure at 65 C. This gave a highly viscous orange-colored liquid having a viscosity of >200 Pa.Math.s at 20 C. and 15 Pa.Math.s at 60 C.

(25) Reaction Product R7: N,N-bis(2-hydroxybenzyl)-1,3-bis(aminomethyl)-benzene

(26) In a round-bottomed flask, 13.62 g (0.10 mol) of 1,3-bis(aminomethyl)benzene (MXDA, from Mitsubishi Gas Chemicals), 24.42 g (0.20 mol) of salicylaldehyde and 400 ml of isopropanol were mixed under a nitrogen atmosphere and stirred at room temperature for 2 hours. Thereafter the reaction mixture was hydrogenated under a hydrogen pressure of 85 bar, at a temperature of 90 C. and with a flow rate of 4 ml/min, on a continuous hydrogenation apparatus with Pd/C fixed-bed catalyst. To monitor the reaction, IR spectroscopy was used to verify whether the imine band at about 1665 cm.sup.1 had disappeared. At that point the hydrogenated solution was concentrated under reduced pressure at 65 C. This gave a highly viscous yellowish liquid having a viscosity of >200 Pa.Math.s at 20 C. and 2.9 Pa.Math.s at 60 C. and an amine number of 303 mg KOH/g.

(27) Production of Epoxy Resin Compositions:

Examples 1 to 7

(28) For each example, the ingredients specified in table 1 were mixed in the stated quantities (in parts by weight) of the resin component using a centrifugal mixer (SpeedMixer DAC 150, FlackTek Inc.) and the mixtures were stored in the absence of moisture.

(29) The reaction product specified in table 1, in the stated quantity, was subsequently mixed with the resin component using the centrifugal mixer, processed to a homogeneous liquid, and immediately used and tested as follows:

(30) 5 minutes after mixing, the viscosity at 20 C. was ascertained (Viscosity (5)). A first film was drawn down in a film thickness of 500 m onto a glass plate, which was stored and cured under standard conditions. This film was used for determination of the Knig hardness (pendulum hardness according to Knig, as per DIN EN ISO 1522, Knig hardness (SC)) after 1 day (1 d), 2 days (2 d), 4 days (4 d) and 7 days (7 d). Furthermore, the appearance of the cured film was assessed (denoted appearance (SC) in table 1). A film identified as attractive there was clear and had a glossy and non-tacky surface without structure. Structure here refers to any kind of marking or pattern on the surface.

(31) A second film was drawn down onto a glass plate in a film thickness of 500 m, and this film, immediately after application, was stored and cured for 7 days at 8 C. and 80% relative humidity and subsequently under standard conditions. Here, again, a determination was made of the Knig hardness, in each case after 1 day (1 d 8/80%), 2 days (2 d 8/80%), 7 days (7 d 8/80%) and 8 days (+1 d SC). The appearance of this film was then assessed (denoted in table 1 by appearance (8/80%)), in the same way as described for the appearance (SC).

(32) The measure used for the yellowing, moreover, was the color change after exposure in a weathering tester. For this purpose, a further film was drawn down in a film thickness of 500 m onto a glass plate and was stored, or cured, under standard conditions for 2 weeks and subsequently exposed in a Q-Sun Xenon Xe-1 weathering tester with Q-SUN Daylight-Q optical filter and with a xenon lamp, with a luminous intensity of 0.51 W/m.sup.2 at 340 nm and at a temperature of 65 C. for 72 hours (Q-Sun (72 h)). Thereafter the color difference E of the film thus exposed was determined in comparison to the corresponding unexposed film, using an NH310 colorimeter from Shenzen 3NH Technology Co. LTD, equipped with Silicon Photoelectric Diode Detector, Light Source A, Color Space Measurement Interface CIE L*a*b*C*H*. A high E value here represents a large color difference, and severe yellowing.

(33) The results are reported in table 1.

(34) These epoxy resin compositions are suitable as primers or adhesives. The viscosity after the two components have been mixed is a measure of the workability as a primer. The development of the Knig hardness is a measure of the cure rate and of the ultimate hardness under the respective conditions.

(35) The examples labeled with (Ref.) are comparative examples.

(36) TABLE-US-00001 TABLE 1 Composition and properties of examples 1 to 7. Example 3 4 5 6 7 1 2 (Ref.) (Ref.) (Ref.) (Ref.) (Ref.) Resin comp.: Araldite GY-250 167.2 167.2 167.2 167.2 167.2 167.2 167.2 Araldite DY-E 31.8 31.8 31.8 31.8 31.8 31.8 31.8 Hardener comp.: Reaction product A1 A2 R1 R2 R3 R4 81.0 82.8 74.1 88.1 56.1 95.0 SR-Dur 2750 75.0 Viscosity (5) [Pa .Math. s] 3.5 5.1 3.3 1.7 2.4 2.6 0.51 Knig (1 d SC) 165 171 168 60 31 74 56 hardness (2 d SC) 197 198 182 108 71 87 140 [s] (4 d SC) 202 204 203 138 110 87 183 (7 d SC) 207 210 205 155 153 95 204 Appearance (SC) slightly attractive attractive slight attractive tacky, slightly matt structure matt matt Q-Sun (72 h) E 5.8 5.9 23.0 12.3 5.7 6.1 n.d. Knig (1 d 8/80%) 14 24 27 n.d. n.d. n.d. n.d. hardness (2 d 8/80%) 74 83 70 n.d. n.d. n.d. n.d. [s] (7 d 8/80%) 140 155 120 27 33 52 63 (+1 d SC) 190 182 148 42 84 92 121 Appearance (8/80%) slightly matt, slight matt, slightly cloudy, cloudy, matt slight structure slight matt tacky, structure structure structure structure n.d. stands for not determined
Production of Primers:

Examples 8 to 18

(37) For each example, the ingredients specified in tables 2 to 3 were mixed in the stated quantities (in parts by weight) of the hardener component using a centrifugal mixer (SpeedMixer DAC 150, FlackTek Inc.) and the mixtures were stored in the absence of moisture.

(38) Similarly, the resin component ingredients specified in tables 2 to 3 were processed and stored.

(39) The two components of each primer were subsequently processed at room temperature, using the centrifugal mixer, to give a homogeneous liquid, which was immediately used and tested as follows:

(40) 5 minutes after mixing, the viscosity at 20 C. was ascertained (Viscosity (5)). Each primer was applied by brush to three concrete garden slabs so that the primer fully covered the surface of the slabs and the pores were closed by the primer. Then one garden slab was stored under standard conditions, and two garden slabs at 8 C. and 80% relative humidity. For determining the time required to regain amenability to accept foot traffic, a determination was then made of the time, under standard conditions (SC) and 8 C. and 80% relative humidity (8/80%), respectively, that was required until a metal cylinder 24 mm in diameter with a weight of 1 kg, standing on the surface for 60 seconds, no longer experienced sticking and did not leave any mark.

(41) The results are reported in tables 2 to 3.

(42) The examples labeled with (Ref.) are not inventive and they serve as a comparison.

(43) TABLE-US-00002 TABLE 2 Composition (in parts by weight) and properties of the primers of examples 8 to 16. Example 10 11 12 13 14 15 16 8 9 (Ref.) (Ref.) (Ref.) (Ref.) (Ref.) (Ref.) (Ref.) Resin component: Araldite GY-250 167.2 167.2 167.2 167.2 167.2 167.2 167.2 167.2 167.2 Araldite DY-E 31.8 31.8 31.8 31.8 31.8 31.8 31.8 31.8 31.8 Hardener component: Reaction product A1 A2 R1 R2 R4 R5 R6 R7 81.0 82.8 74.1 88.1 95.0 81.0 90.8 174.0 SR-Dur 2750 75.0 Benzyl alcohol 34.0 35.5 32.0 31.8 31.8 34.0 34.0 34.0 40.0 Viscosity (5) [Pa .Math. s] 1.5 2.5 2.2 1.1 1.3 0.41 8.1.sup.1 12.3.sup.1 5.1 Amenable to foot traffic under SC 6.5 h 6 h 4.5 h 8 h 8 h 12 h n.d. n.d. 12 h at 8/80% 22 h 20 h 22 h 30 h 48 h 48 h n.d. n.d. 55 h n.d. stands for not determined .sup.1viscosity too high

(44) TABLE-US-00003 TABLE 3 Composition (in parts by weight) and properties of the primers of examples 17 and 18. Example 18 17 (Ref.) Resin component: Araldite GY-250 167.2 167.2 Araldite DY-E 31.8 31.8 Hardener component: Reaction product A1 81.0 SR-Dur 2750 75.0 Cardanol.sup.1 34.6 32.0 Viscosity (5) [Pa .Math. s] 3.8 4.9 Amenable to foot traffic under SC 5 h 4 h at 8/80% 18 h 15 h .sup.1Cardolite NX-2026 from Cardolite Corp.
Production of Coatings:

Examples 19 to 24

(45) The garden slabs of examples 8, 9 and 17, primed with inventive primers, were each coated, after 24 hours of curing at 8 C. and 80% relative humidity, with a commercial floor coating, as specified in table 4. In one case, Sikafloor-264 pebble grey (2-component epoxy resin coating from Sika Schweiz AG) was applied in a layer thickness of 1.5 mm, by pouring the freshly mixed coating onto the garden slab primed with the respective primer and spreading it using a doctor blade. Alternatively, Sikafloor-400 N Elastic pebble grey (flexible 1-component polyurethane coating form Sika Schweiz AG) was applied in a layer thickness of 1.5 mm, by pouring it onto the garden slab primed with a respective primer and spreading it using a doctor blade.

(46) After a cure time of 7 days under standard conditions, each garden slab bore a high-quality, multi-coat floor covering with defect-free surface and outstanding adhesion between the coats.

(47) TABLE-US-00004 TABLE 4 Structure of the coatings of examples 19 to 24. Example 19 20 21 22 23 24 Primer from example 8 8 9 9 17 17 Sikafloor type 264 400N 264 400N 264 400N
Production of Adhesives:

Examples 25 and 26

(48) For example 25, the ingredients specified in table 5, in the quantities stated (in parts by weight), of the hardener component were mixed using a centrifugal mixer (SpeedMixer DAC 150, FlackTek Inc.) and stored in the absence of moisture.

(49) For example 26 (comparison), the hardener component used was Sikadur 31 CF normal component B (from Sika Schweiz AG) in the quantity indicated in table 5.

(50) The resin component used in each case was Sikadur 31 CF normal component A (from Sika Schweiz AG) with an EEW of about 838 g, in the quantity specified in table 5.

(51) The two components were subsequently processed at room temperature, using the centrifugal mixer, to form a homogeneous paste, which was immediately used and tested as follows:

(52) A number of adhesive bonds were produced, by applying in each case several grams of adhesive to a concrete slab, which had been cleaned with a steel brush, and then adhering to the slab a cylinder of acetone-cleaned steel having a diameter of 20 mm over its base area, the thickness of the bondline being 2 mm. The bonds were stored under standard conditions. After 2 days, they were pulled apart to fracture in a method based on DIN EN 4624 with a testing speed of 2 mm/min, in order to determine the strength of the bond at the maximum force (tensile adhesion, concrete/steel).

(53) Furthermore, a number of bonds were produced by bonding pairs of cylinders made from acetone-cleaned steel, and having a diameter of 20 mm, together at the round base area, using the adhesive, in such a way that the thickness of the bondline was 2 mm. The bonds were stored under standard conditions. After 2 days, they were pulled apart to fracture in a method based on DIN EN ISO 4624 with a testing speed of 2 mm/min, in order to determine the strength of the bond at the maximum force (tensile adhesion, steel/steel).

(54) In addition, the compressive strength was ascertained, by curing and storing the adhesive in the form of blocks with dimensions of 12.712.725.4 mm under standard conditions. After 2 days and after 7 days, a number of such blocks were compressed according to ASTM D695 at a testing speed of 1.3 mm/min until destruction, with the value of the compressive strength being read off in each case at the maximum force.

(55) The results are reported in table 5.

(56) Example 26, labeled with (Ref.), is not inventive and it serves as a comparison.

(57) TABLE-US-00005 TABLE 5 Composition (in parts by weight) and properties of the adhesives of examples 25 and 26. Example 26 25 (Ref.) Resin component Sikadur 31 component A 200.0 200.0 Hardener component Sikadur 31 component B 100 Reaction product A1 21.0 Black iron oxide pigment 0.1 Finely ground quartz 0-75 m 36.0 Silica sand 0.1-0.3 mm 27.9 Precipitated, stearate-coated chalk 15.0 Tensile adhesion concrete/ 2 days SC 3.7 MPa.sup.1 4.4 MPa.sup.1 steel Tensile adhesion steel/ 2 days SC 15.2 MPa 24.5 MPa steel Compressive strength 2 days SC 77.6 MPa 56.2 MPa 7 days SC 86.8 MPa 64.9 MPa .sup.1Fraction within the concrete