ADDUCT OF ALKYLATED DIAMINE AND NOVOLAK EPOXY RESIN

Abstract

An amine-functional adduct from the reaction of at least one amine of the formula (I) with at least one novolak epoxy resin having an average functionality in the range from 2.5 to 4. The adduct is liquid at room temperature without thinners and without a large excess of amine. It is suitable as a curing agent for epoxy resin compositions, in which it permits good workability, rapid curing, high hydrophobicity, and a high crosslinking density. It is particularly suitable for coatings, in which it permits nice surfaces, good intercoat adhesion, high thermal shock resistance, and good protection against steel corrosion.

Claims

1. An amine-functional adduct from the reaction of at least one amine of the formula (I),
Z—NH-A-NH—CH.sub.2—Y  (I) where A is a divalent alkylene, cycloalkylene or arylalkylene radical having 2 to 15 carbon atoms, Z is H or —CH.sub.2—Y, and Y is H or an alkyl, cycloalkyl, aralkyl or aryl radical having 1 to 11 carbon atoms, wherein the two nitrogen atoms to which the A radical is attached are separated from one another by at least two carbon atoms and the amine of the formula (I) contains a total of at least 8 carbon atoms, with at least one novolak epoxy resin having an average functionality in the range from 2.5 to 4.

2. The adduct as claimed in claim 1, wherein A is selected from the group consisting of 1,2-ethylene, 1,2-propylene, 1,3-propylene, 1,4-butylene, 1,3-butylene, 2-methyl-1,2-propylene, 1,3-pentylene, 1,5-pentylene, 2,2-dimethyl-1,3-propylene, 1,6-hexylene, 2-methyl-1,5-pentylene, 1,7-heptylene, 1,8-octylene, 2,5-dimethyl-1,6-hexylene, 1,2-cyclohexylene, 1,3-cyclohexylene, 1,4-cyclohexylene, 4(2)-methyl-1,3-cyclohexylene, 1,3-cyclohexylene bis(methylene), and 1,4-cyclohexylenebis(methylene).

3. The adduct as claimed in claim 1, wherein Y is selected from the group consisting of H, methyl, ethyl, propyl, isopropyl, butyl, pentyl, heptyl, hept-2-yl, phenyl, 4-methylphenyl, 1-naphthyl, and cyclohexyl.

4. The adduct as claimed in claim 1, wherein Z is H or that the amine of the formula (I) is a mixture comprising an amine of the formula (I) where Z═H and an amine of the formula (I) where Z═—CH.sub.2—Y.

5. The adduct as claimed in claim 1, wherein A is 1,2-ethylene and Y is phenyl.

6. The adduct as claimed in claim 1, wherein the novolak epoxy resin is a phenol-formaldehyde novolak glycidyl ether.

7. The adduct as claimed in claim 1, wherein the reaction takes place in a stoichiometric ratio of less than 3 mol of amine of the formula (I) to 1 molar equivalent of epoxy groups of amine of the formula (I) to 1 molar equivalent of epoxy groups.

8. The adduct as claimed in claim 1, wherein it contains oligomeric compounds of the formula (III), ##STR00003## where n on average has a value in the range from 0.5 to 3, and G.sup.1 and G.sup.2 are Z, with the proviso that at least one of the two is —CH.sub.2—Y.

9. The adduct as claimed in claim 1, wherein it has a viscosity at 20° C. in the range from 5 to 500 Pa.Math.s, measured using a cone-plate viscometer at a shear rate of 10 s.sup.−1.

10. A curing agent for epoxy resins comprising at least one adduct as claimed in claim 1 and at least one further constituent selected from the group consisting of further amines, accelerators, and thinners.

11. The curing agent as claimed in claim 10, wherein at least one further amine selected from the group consisting of N-benzylethane-1,2-diamine, N,N′-dibenzylethane-1,2-diamine, 1,5-diamino-2-methylpentane, 2,2(4),4-trimethylhexane-1,6-diamine, 1,2-diaminocyclohexane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, bis(4-aminocyclohexyl)methane, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, 2(4)-methyl-1,3-diaminocyclohexane, 1,3-bis(aminomethyl)benzene, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, N-(2-aminoethyl)propane-1,3-diamine, N,N′-bis(3-aminopropyl)ethylenediamine, dipropylenetriamine, bis(hexamethylene)triamine, polyoxypropylene diamines having an average molecular weight M.sub.n in the range from 200 to 500 g/mol, and polyoxypropylene triamines having an average molecular weight M.sub.n in the range from 300 to 500 g/mol is present.

12. The curing agent as claimed in claim 10, wherein 5 to 70% of all amine hydrogens present originate from the adduct.

13. An epoxy resin composition comprising a resin component comprising at least one epoxy resin and a curing agent component comprising at least one adduct as claimed in claim 1 or a curing agent for epoxy resins comprising at least one adduct as claimed in claim 1 and at least one further constituent selected from the group consisting of further amines, accelerators, and thinners.

14. A coating, primer, adhesive, sealant, potting compound, casting resin, impregnating resin or matrix for fiber composites, comprising the epoxy resin composition as claimed in claim 13.

15. An article comprising the coating, primer, adhesive, sealant, potting compound, casting resin, impregnating resin or matrix for fiber composites as claimed in claim 14.

Description

EXAMPLES

[0187] Working examples are presented hereinbelow, the purpose of which is to further elucidate the described invention. The invention is of course not limited to these described working examples.

[0188] “AHEW” stands for amine hydrogen equivalent weight.

[0189] “EEW” stands for epoxy equivalent weight.

[0190] “Standard climatic conditions” (“SCC”) refer to a temperature of 23±10° C. and a relative humidity of 50±5%.

[0191] The chemicals used were unless otherwise stated from Sigma-Aldrich Chemie GmbH.

[0192] Description of the Measurement Methods:

[0193] Viscosity was measured on a thermostated Rheotec RC30 cone-plate viscometer (cone diameter 50 mm, cone angle 1°, cone tip-plate distance 0.05 mm, shear rate 10 s.sup.−1).

[0194] Amine value was determined by titration (with 0.1 N HClO.sub.4 in acetic acid against crystal violet).

[0195] Substances and Abbreviations Used: [0196] D.E.N.® 431: Phenol-formaldehyde novolak glycidyl ether, EEW approx. 175 g/eq, average functionality approx. 2.8 (from Olin) [0197] D.E.N.® 438: Phenol-formaldehyde novolak glycidyl ether, EEW approx. 180 g/eq, average functionality approx. 3.6 (from Olin) [0198] Epilox® N 18-10 Phenol-formaldehyde novolak glycidyl ether, EEW approx. 175 g/eq, average functionality approx. 2.6 (from Leuna Harze) [0199] Araldite® GY 250: Bisphenol A diglycidyl ether, EEW approx. 187 g/eq (from Huntsman) [0200] Araldite® DY-E: Monoglycidyl ethers of C.sub.12 to C.sub.14 alcohols, EEW approx. 290 g/eq (from Huntsman) [0201] B-EDA N-Benzylethane-1,2-diamine, prepared as described below, 150.2 g/mol, AHEW 50.1 g/eq [0202] IPDA 3-Aminomethyl-3,5,5-trimethylcyclohexylamine, AHEW 42.6 g/eq (Vestamin® IPD from Evonik)

N-Benzylethane-1,2-diamine (B-EDA)

[0203] An initial charge of 180.3 g (3 mol) of ethane-1,2-diamine at room temperature was mixed with a solution of 106.0 g (1 mol) of benzaldehyde in 1200 ml of isopropanol and stirred for 2 hours, then hydrogenated at 80° C., 80 bar hydrogen pressure, and a flow rate of 5 ml/min in a continuous hydrogenation apparatus with a Pd/C fixed-bed catalyst, and the hydrogenated solution was concentrated on a rotary evaporator at 65° C., resulting in the removal of unreacted ethane-1,2-diamine, water, and isopropanol. The resulting reaction mixture was purified by distillation at 80° C. under reduced pressure. This gave a colorless liquid having an N-benzylethane-1,2-diamine content determined by GC of >97%.

[0204] Preparation of Adducts:

[0205] Adduct A1:

[0206] 55.0 g of N-benzylethane-1,2-diamine (B-EDA, 0.366 mol) were heated to 80° C. and 33.0 g of D.E.N.® 438 (0.183 mol EP groups) heated to a temperature of 60° C. were added gradually with thorough stirring, maintaining the temperature of the reaction mixture between 70 and 90° C. The reaction mixture was held within this temperature range for one hour and then cooled. A clear, slightly yellowish liquid having a viscosity at 20° C. of 24.1 Pa.Math.s, an amine value of 460 mg KOH/g, and a calculated AHEW of 96.2 g/eq was obtained.

[0207] Adduct A2:

[0208] 55.0 g of N-benzylethane-1,2-diamine (B-EDA, 0.366 mol) was heated to 80° C. and 32.0 g of D.E.N.® 431 (0.183 mol EP groups) heated to a temperature of 60° C. was added gradually with thorough stirring, maintaining the temperature of the reaction mixture between 70 and 90° C. The reaction mixture was held within this temperature range for one hour and then cooled. A clear, slightly yellowish liquid having a viscosity at 20° C. of 8.4 Pa.Math.s, an amine value of 464 mg KOH/g, and a calculated AHEW of 95.1 g/eq was obtained.

[0209] Adduct A3:

[0210] 55.0 g of N-benzylethane-1,2-diamine (B-EDA, 0.366 mol) were heated to 80° C. and 42.7 g of D.E.N.® 431 (0.244 mol EP groups) heated to a temperature of 60° C. were added gradually with thorough stirring, maintaining the temperature of the reaction mixture between 70 and 90° C. The reaction mixture was held within this temperature range for one hour and then cooled. A clear, slightly yellowish liquid having a viscosity at 20° C. of 256 Pa.Math.s, an amine value of 404 mg KOH/g, and a calculated AHEW of 114.4 g/eq was obtained.

[0211] Adduct A4 (Ref.):

[0212] 55.0 g of N-benzylethane-1,2-diamine (B-EDA, 0.366 mol) were heated to 80° C. and 45.0 g of Araldite® GY 250 (0.241 mol EP groups) were added gradually with thorough stirring, maintaining the temperature of the reaction mixture between 70 and 90° C. The reaction mixture was held within this temperature range for one hour and then cooled. A clear, slightly yellowish liquid having a viscosity at 20° C. of 262 Pa.Math.s, an amine value of 408 mg KOH/g, and a calculated AHEW of 116.3 g/eq was obtained.

[0213] Adduct A5 (Ref.):

[0214] An initial charge of 47.7 g of 1,2-diaminocyclohexane (Dytek® DCH-99, from Invista, 0.42 mol) was heated to 60° C. To this were slowly added with thorough stirring 37.6 g of D.E.N.® 438 (0.21 mol EP groups) preheated to 60° C., maintaining the temperature of the reaction mixture between 70 and 90° C. The reaction mixture was held within this temperature range for one hour and then cooled. A clear, slightly yellowish, highly viscous liquid having a viscosity at 50° C. of 98 Pa.Math.s, an amine value of 532 mg KOH/g, and a calculated AHEW of 58.3 g/eq was obtained.

[0215] Adduct A6 (Ref.):

[0216] An initial charge of 90.0 g of bis(6-aminohexyl)amine (Dytek® BHMT-HP, from Invista, 0.42 mol) was heated to 60° C. To this was slowly added with thorough stirring 37.6 g of DEN® 438 (0.21 mol EP groups) preheated to 60° C., maintaining the temperature of the reaction mixture between 70 and 90° C. The reaction mixture was held within this temperature range for one hour and then cooled. A clear, slightly yellowish liquid having a viscosity at 20° C. of 22.5 Pa.Math.s, an amine value of 529 mg KOH/g, and a calculated AHEW of 67.9 g/eq was obtained.

[0217] Production of Epoxy Resin Coatings:

Examples 1 to 11

[0218] For each example, the ingredients of the resin component specified in Tables 1 and 2 were mixed in the specified amounts (in parts by weight) using a centrifugal mixer (SpeedMixer™ DAC 150, FlackTek Inc.) and stored with the exclusion of moisture.

[0219] The ingredients of the curing agent component specified in Tables 1 and 2 were likewise processed and stored.

[0220] The two components of each composition were then processed using the centrifugal mixer into a homogeneous liquid and this was tested immediately as follows:

[0221] Viscosity was measured in the described manner at a temperature of 20° C. 5 min after mixing the resin component and curing agent component.

[0222] Gel time was determined by moving a freshly mixed amount of about 3 g under standard climatic conditions with a spatula at regular intervals until the mass underwent gelation.

[0223] Shore D hardness was determined in accordance with DIN 53505 on two cylindrical test specimens (diameter 20 mm, thickness 5 mm), one of which was stored under standard climatic conditions and the other at 8° C. and 80% relative humidity, and the hardness measured in each case after 1 day and after 2 days.

[0224] Appearance (SCC) was determined on a film applied to a glass plate in a layer thickness of 500 μm and stored under standard climatic conditions for 14 days. A film was described as “nice” if it had a glossy and nontacky surface with no structure. “Structure” refers to any kind of marking or pattern on the surface.

[0225] Appearance (8°/80%) was determined on a film applied to a glass plate in a layer thickness of 500 μm and stored for 7 days at 8° C. and 80% humidity and then for 7 days under standard climatic conditions. 24 hours after application, a polypropylene bottle top beneath which a damp sponge had been positioned was placed on the film. After a further 24 hours, the sponge and the bottle top were removed and positioned at a new point on the film, from which it was in turn removed and repositioned after 24 hours, this being done a total of 4 times. The appearance of this film was then assessed in the same way as described for Appearance (SCC). “Blushing” was reported as the number of white-colored spots that had formed as a result of the damp sponge. A faint, white-colored spot was designated as “(1)”.

[0226] The König hardness (König pendulum hardness, measured in accordance with DIN EN ISO 1522) was in addition determined on some films. For this, a first film having a layer thickness of 500 μm was applied to a glass plate, stored under standard climate conditions and the König hardness determined after 1 day (“König hardness (1d SCC)”), after 2 days (“König hardness (2d SCC)”), after 7 days (“König hardness (7d SCC)”), and after 14 days (“König hardness (14d SCC)”). In addition, a second film having a layer thickness of 500 μm was applied to a glass plate and this was immediately after application stored for 7 days at 8° C. and 80% relative humidity and then for 2 weeks under standard climate conditions, with the König hardness determined after 7 days at 8° C. and 80% relative humidity (“König hardness (7d 8°/80%)”) and then after a further 2 days under SCC (“König hardness (+2d SCC)”), after a further 7 days under SCC (“König hardness (+7d SCC)”), and after a further 14 days under SCC (“König hardness (+14d SCC)”). As a measure of yellowing, the change in color after stressing in a weathering tester was additionally determined (Q-Sun (72 h)). For this, a further film in a layer thickness of 500 μm was applied to a glass plate and stored under standard climatic conditions for 14 days and then subjected to stress in a Q-Sun Xenon Xe-1 weathering tester with a Q-SUN Daylight-Q optical filter and a xenon lamp having a light intensity of 0.51 W/m.sup.2 at 340 nm at a temperature of 65° C. for 72 hours. The color difference ΔE of the film thus stressed versus a corresponding unstressed film was then determined 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*.

[0227] The results are reported in Tables 1 and 2.

[0228] The examples designated “(Ref.)” are comparative examples.

TABLE-US-00001 TABLE 1 Composition and properties of examples 1 to 6. 4 5 6 Example 1 2 3 (Ref.) (Ref.) (Ref.) Resin component: Araldite ® GY 250: 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 Curing agent component: Adduct A1 96.2 — — — — — Adduct A2 —   95.1 — — — — Adduct A3 — —  114.4 — — — Adduct A4 — — —  116.3 — — Adduct A5 — — — — 58.3 — Adduct A6 — — — — — 67.9 Viscosity (5′) [Pa .Math. s] 5.9   4.2   19.4   15.0 n.d..sup.1 2.0 Gel time (h:min) 2:30 2:40 2:20 2:40 n.d..sup.1 3:30 Shore D (1 d SCC) 82 81 82 78 n.m..sup.2 67 (2 d SCC) 82 82 82 78 45 72 Shore D (1 d 8°/80%) 74 74 74 74 n.m..sup.2 16 (2 d 8°/80%) 78 78 78 75 n.m..sup.2 44 Appearance (SCC) nice nice nice nice structure haze Appearance (8°/80%) nice nice nice nice tacky, haze, liquid uneven Blushing 0  (1)  (1)  (1) n.m..sup.3 n.m..sup.3 Q-Sun (72 h) ΔE 2.5 3.0   3.5   2.1 n.d. n.d. .sup.1not determined (very high viscosity) .sup.2not measurable (too soft) .sup.3not measurable (surface too inhomogeneous for assessment) “n.d.” stands for “not determined”

TABLE-US-00002 TABLE 2 Composition and properties of examples 7 to 11. Example 9 10 11 7 8 (Ref.) (Ref.) (Ref.) Resin component: Araldite ® GY 250:  167.2  167.2  167.2 167.2 167.2 Araldite ® DY-E:   31.8   31.8   31.8 31.8 31.8 Curing agent component: Adduct A1   38.5 — — — — Adduct A3 —   38.0 — — — Adduct A4 — —   46.5 — — Adduct A5 — — — 23.3 — Adduct A6 — — — — 27.2 IPDA   25.8   25.8   25.8 25.8 25.8 Benzyl alcohol   25.0   25.0   25.0 25.0 25.0 Viscosity (5′) [Pa .Math. s]    1.12    1.45    1.46 1.07 0.91 Gel time (h:min) 3:25 3:20 3:30 4:15 3:20 Shore D (1 d SCC) 66 67 65 68 68 (2 d SCC) 78 78 78 78 76 Shore D (1 d 8°/80%) 16 18 15 n.m..sup.2 22 (2 d 8°/80%) 65 67 63 39 65 König h. (1 d SCC) 52 51 45 36 36 [s] (2 d SCC) 99 93 95 115 99 (7 d SCC) 153  151  155  164 148 (14 d SCC) 161  158  160  176 151 König h. (7 d 8°/80%) 31 38 22 28 18 [s] (+2 d SCC) 115  122  115  87 52 (+7 d SCC) 152  153  151  105 97 (+14 d SCC) 163  164  161  110 123 Appearance (SCC) nice nice nice nice (structure) Appearance (8°/80%) nice nice nice structure structure Blushing  (1)  (1)  (1) 4 4 Q-Sun (72 h) ΔE   2.1   1.7   2.5 n.d. n.d. .sup.2not measurable (too soft); “n.d.” stands for “not determined”

Examples 12 to 13

[0229] For each example, the ingredients of the resin component specified in Table 3 were mixed in the specified amounts (in parts by weight) using a centrifugal mixer (SpeedMixer™ DAC 150, FlackTek Inc.) and stored with exclusion of moisture. The ingredients of the curing agent component indicated in Table 3 were processed and stored in a similar manner.

[0230] The two components of each composition were then processed using the centrifugal mixer into a homogeneous liquid and this was tested immediately as follows: [0231] To assess the appearance and the intercoat adhesion, a test specimen of each coating was produced by spraying a wet film layer of 180 μm onto a 150×100×3 mm steel sheet using a gravity spray gun, storing this for 24 hours under standard climate conditions and then applying a second wet film layer of 180 μm using a gravity spray gun. After storage for a period of 14 days under standard climate conditions, the surface of the coating was assessed (=Appearance). An even, nontacky, glossy surface without structure, deposits or other defects was rated as “nice”. As a measure of intercoat adhesion, a pull-off adhesion test in accordance with ISO 4624 was then carried out at a test speed of 1 MPa/s, in which a dolly glued onto the coating was pulled off vertically in an upward direction. Intercoat adhesion was here rated as “poor” if the pull-off adhesion value was less than 5 MPa and an adhesive break pattern had occurred between the two layers of the test specimen. Otherwise, the intercoat adhesion was rated as “good”.

[0232] As a measure of the thermal shock resistance, a steel sheet (blasted steel SA 2%, surface roughness 60-80 μm) 150×100×3 mm was coated by twice spraying a 220 μm wet film (=2×approx. 150 μm dry film, approx. 300 μm dry film overall) using a gravity spray gun, with a wait time of 24 hours observed between the layers. The test specimens thus produced were stored for 7 days under standard climate conditions and then underwent 20 cycles in accordance with DIN EN ISO 19277 between an air-circulation oven at 204° C. and ice-water, in which the test specimens were stored in the air-circulation oven at 204° C. and once every 24 hours taken out of the oven and immediately immersed in a bucket of ice-water for 1 minute and then immediately returned to the air-circulation oven (=1 cycle). The test specimens were stored in the air-circulation oven over the weekend. After 20 cycles, the test specimens were cooled to room temperature and visually examined with a loupe to determine whether the coating was intact or had been destroyed, and whether cracks or flaking in the coating or corrosion on the steel sheet had occurred.

[0233] As a measure of the corrosion resistance, a test specimen produced in the same way as for the test for intercoat adhesion was stressed with condensation water in accordance with ISO 6270-1 for 720 h and then a pull-off adhesion test in accordance with ISO 4624 carried out at a test speed of 1 MPa/s. If the test specimen showed no signs of corrosion and the pull-off adhesion value was more than 6 MPa, the test was rated “very good”. A further identically produced test specimen was stressed for 1440 h with neutral salt spray in accordance with ISO 9227 and then a pull-off adhesion test in accordance with ISO 4624 carried out at a test speed of 1 MPa/s, with the test rating evaluated as described for stressing with condensation water.

[0234] The results are reported in Table 3.

TABLE-US-00003 TABLE 3 Composition and properties of examples 12 to 13. Example 12 13 Resin component: Epilox ® N 18-10 21.0 21.0 Xylene 10.0 10.0 Zinc pigment 10.0 10.0 Talc 39.0 39.0 Pigment paste 10.0 10.0 n-Butanol 10.0 10.0 Curing agent component: Adduct A1 11.5 — Adduct A2 — 11.5 Appearance nice nice Intercoat adhesion good good Thermal shock resistance: passed passed Corrosion resistance: Condensation water: very good very good Salt spray: very good very good