Patent Application
20170362443
This disclosure relates to aqueous primer compositions and methods of their use, in some embodiments as adhesive primers on metal surfaces.
Briefly, the present disclosure provides a primer composition comprising an aqueous dispersion of a) a thermosetting resin, b) an organosilane containing no hydrolyzable group, and c) a curing agent. In some embodiments, the primer composition additionally comprises d) a rare earth metal containing corrosion inhibitor. In some embodiments, the primer composition comprises no chromium. In some embodiments, the organosilane containing no hydrolyzable group is an aminosilanol. In some embodiments, the organosilane containing no hydrolyzable group is an aminosilanol according to formula I:
R2—NH—R1—Si(OH)3 [I].
wherein R1 is a branched or linear alkylene group containing 1 to 20 carbon atoms, and wherein R2 is selected from the group consisting of H and R2NH—R1—, wherein when R2 is R2—NH—R1—, each R1 and each R2 are selected independently of any others and the molecular weight of no R2 is more than 1500. In some embodiments, the organosilane containing no hydrolyzable group is an aminosilanol according to formula I:
R2—NH—R1—Si(OH)3 [I].
wherein R1 is a branched or linear alkylene group containing 1 to 20 carbon atoms, and wherein R2 is selected from the group consisting of H and H2N—R1—, wherein each R1 is selected independently. In some embodiments, the organosilane containing no hydrolyzable group is an aminosilanol according to formula II:
H2N—R1—Si(OH)3 [II].
wherein R1 is a branched or linear alkylene group containing 1 to 20 carbon atoms. In some embodiments of the preceding formulas, R1 is a linear alkylene group. In some embodiments of the preceding formulas, R1 contains at least 2 carbon atoms. In some embodiments of the preceding formulas, no more than 10 carbon atoms; in some no more than 6 carbon atoms; in some no more than 4 carbon atoms; and in some no more than 3 carbon atoms. In some embodiments of the primer composition, the thermosetting resin is an epoxy resin. In some embodiments of the primer composition, the curing agent is an epoxy curing agent. In some embodiments, the curing agent is 2,2-bis-[4-(4-aminophenoxy)-phenyl]propane. In some embodiments of the primer composition, the rare earth metal containing corrosion inhibitor is a cerium containing corrosion inhibitor.
All scientific and technical terms used herein have meanings commonly used in the art unless otherwise specified.
As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” encompass embodiments having plural referents, unless the content clearly dictates otherwise.
As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.
As used herein, “have”, “having”, “include”, “including”, “comprise”, “comprising” or the like are used in their open ended sense, and generally mean “including, but not limited to.” It will be understood that the terms “consisting of” and “consisting essentially of” are subsumed in the term “comprising,” and the like.
The present disclosure provides aqueous primer compositions. In some embodiments the compositions are chromium-free. In some embodiments the compositions perform well as adhesive primers on metal surfaces. In some embodiments the compositions perform well as adhesive primers on sol-gel treated metal surfaces. In some embodiments the compositions perform well as adhesive primers on non-sol-gel treated metal surfaces. In some embodiments the compositions perform well as adhesive primers both on sol-gel treated metal surfaces and on non-sol-gel treated metal surfaces.
The following numbered embodiments are intended to illustrate the present disclosure but should not be construed to unduly limit this disclosure.
a) a thermosetting resin,
b) an organosilane containing no hydrolyzable group,
c) a curing agent.
d) a rare earth metal containing corrosion inhibitor.
R2—NH—R1—Si(OH)3 [I].
wherein R1 is a branched or linear alkylene group containing 1 to 20 carbon atoms, and wherein R2 is selected from the group consisting of H and R2—NH—R1—, wherein when R2 is R2—NH—R1—, each R1 and each R2 are selected independently of any others and the molecular weight of no R2 is more than 1500.
R2—NH—R1—Si(OH)3 [I].
wherein R1 is a branched or linear alkylene group containing 1 to 20 carbon atoms, and wherein R2 is selected from the group consisting of H and H2N—R1—, wherein each R1 is selected independently.
H2N—R1—Si(OH)3 [II].
wherein R1 is a branched or linear alkylene group containing 1 to 20 carbon atoms.
Objects and advantages of this disclosure are further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this disclosure.
The following abbreviations are used to describe the examples:
° C.: degrees Centigrade
° C./min: degrees Centigrade per minute
° F.: degrees Fahrenheit
° F./min: degrees Fahrenheit per minute
cm: centimeter
g/cm3 grams per cubic centimeter
ipfi: inch.pound-ft per inch
kgcw: kilograms per centimeter width
mg: milligram
mil: 10-3 inch
mm: millimeter
μm: micrometer
nm: nanometer
N.cm−1: Newtons per centimeter
MPa: megaPascals
piw: pounds per inch width
Unless stated otherwise, all other reagents were obtained, or are available from fine chemical vendors such as Sigma-Aldrich Company, St. Louis, Mo., or may be synthesized by known methods. Unless otherwise reported, all ratios are by weight.
Abbreviations for reagents used in the examples are as follows:
0.92 grams M5 was homogeneously dispersed in 14.45 grams PZ-323 by means of a high speed mixer operating at between 1,000-2,000 rpm for approximately 2-4 minutes at 25° C. With the mixer continuing to run at 300-500 rpm, 55.76 grams EPZ-3546 and 5.66 grams EPZ-5108 were blended into the dispersion, followed by 3.65 grams TDI. 9.11 grams IPA, 2.48 grams acetone, 0.74 grams ARCOSOLV, 113.4 grams of a 10% aqueous dispersion of BAPP, and 28.7 grams of a 30% aqueous dispersion of ETF inhibitor were slowly added, in 3-5 minute intervals. After 5 minutes, 2.46 grams APST organosilane was added and mixing continued for another 15 minutes. Deionized water was then added to adjust the resulting homogeneous aqueous sol gel primer dispersion to between 25-30 wt. %.
The procedure generally described in Example 1 was repeated, according to the compositions listed in Table 1. The components are reported as weight ratios.
Grade 2024T bare aluminum panels were obtained from Erickson Metals of Minnesota, Inc., Coon Rapids, Minn. Prior to bonding with structural adhesive, the panels were subjected to one of the following surface preparation processes:
The bare aluminum panel was soaked in OAKITE 165 caustic wash solution for 10 minutes at 85° C. The panel was then immersed in tap water for 10 minutes at 21° C., followed by a continuous spray rinsing with tap water for approximately 3 more minutes. The panel was then immersed in an FPL etch solution for 10 minutes at 66° C., after which the panel was spray rinsed with water for approximately 3 minutes at 21° C., allowed to drip dry for another 10 minutes, then dried in an oven for 30 minutes at 54° C. The etched panel was then anodized in a bath of 85% percent phosphoric acid at 72° F. (22.2° C.) for approximately 25 minutes at a voltage of 15 volts and a maximum current of 100 amps, rinsed with water for approximately 3 minutes at 21° C., allowed to drip dry for another 10 minutes, then dried in an oven for 10 minutes at 66° C. Within 24 hours of being anodized, the aluminum panel was sprayed with one of the sol-gel primer compositions described above, dried at 70° F. (21.1° C.) for 30 minutes, then cured in an oven set at 250° F. (121.1° C.) for 60 minutes. The resulting cured primer thickness was approximately 0.1-0.2 mils (2.5 to 5.1 μm).
The bare aluminum panel was abraded by grit-blasting with 180-mesh (approximately 78 μm) alumina mineral in a closed cabinet until all of the oxide layer was removed, about 1-3 minutes. Residual grit was removed by means of compressed air, rinsing with solvent and allowing to dry for10 minutes at approximately 25° C. The aluminum panel was then pre-treated with AC-130-2 and dried at 75° F. (23.9° C.) for 60 minutes, after which it was sprayed with one of the sol-gel primer compositions described above, dried at 70° F. (21.1° C.) for 30 minutes, then cured in an oven set at 250° F. (121.1° C.) for 60 minutes. The resulting cured primer thickness was approximately 0.1-0.2 mils (2.5 to 5.1 μm).
The bare aluminum panel was subjected to the FPL etch and AC-130-2 surface pre-treatment as described above, after which it was sprayed with one of the sol-gel primer compositions described above, dried at 70° F. (21.1° C.) for 30 minutes, then cured in an oven set at 250° F. (121.1° C.) for 60 minutes. The resulting cured primer thickness was approximately 0.1-0.2 mils (2.5 to 5.1 μm).
Sol-gel primers of the present invention, along with Comparatives A and B, were evaluated according to one or more of the following tests. With respect to the bonding tests, the samples were subjected to one of the following cure cycles:
The sample was vacuum bagged to a pressure of approximately 28 inches mercury (94.8 kPa) in an autoclave, model number “ECONOCLAVE 3×5”, from ASC Process Systems, Sylmar, Calif. Autoclave pressure was increased to 45 psi (310.3 kPa), during which the vacuum bag was vented to the atmosphere once the autoclave pressure surpassed 15 psi (103.4 kPa). Autoclave temperature was then increased at a rate of 4.5° F. (2.5° C.) per minute to one of the following set points:
One liner was removed from a 1-inch (25.4 mm) by ⅝-inch (15.9 mm) wide strip of structural adhesive film and the exposed adhesive manually pressed along the longer edge of a 63 mil (1.60 mm) thick, 4-inch by 7-inch (10.16 cm by 17.78 cm) aluminum test panel. After removing any trapped air bubbles by means of a rubber roller, the opposing liner was removed and another test panel was pressed onto the exposed adhesive, at an overlap of 0.5 inches (12.7 mm). The assembly was then taped together and autoclaved according to one of the cure cycles described above, after which the co-joined panels were cut into seven strips, each measuring 1-inch by 7.5 inches (2.54 by 19.05 cm). The strips were then evaluated for overlap shear strength according to ASTM D-1002, using a tensile strength tester, model “SINTECH 30” from MTS Corporation, Eden Prairie, Minn., at 70° F. (21.1° C.) and a grip separation rate of 0.05 inches/min. (1.27 mm/min.). Six overlap shear test panels were prepared and evaluated per each example. Results are listed in Tables 2-4 represent sol-gel primer evaluations with three different structural adhesive films and cure cycles.
Two test panels, one measuring 63 mils by 8-inches by 3-inches (1.60 mm by 20.32 cm by 7.62 cm), the other measuring 25 mils by 10-inches by 3-inches (0.635 mm by 25.4 cm by 7.62 cm), were bonded together with a structural adhesive and cured in the autoclave, as described in the Overlap Shear Test method. Test strips, 0.5 inches (12.7 mm) wide were cut from the bonded panel assembly and evaluated for floating roller peel strength of the thinner substrate, according to ASTM D-3167-76, using the tensile strength tester. Separation rate was 6 inches/minute (15.24 cm/min) at 70° F. (21.1° C.). Results were normalized for 1-inch (2.54 cm) wide test strips. Five test panels were prepared and evaluated per each example. Results are listed in Tables 5-7 represent sol-gel primer evaluations with three different structural adhesive films.
Two test panels, one measuring 40 mils by 16-inches by 8-inches (1.16 mm by 40.64 cm by 20.32 cm), the other measuring 20 mils by 16-inches by 8-inches (0.508 mm by 40.64 cm by 20.32 cm), were bonded together with a structural adhesive and cured in the autoclave as described in the Overlap Shear Test method Test strips, 1 inches (25.4 mm) wide were cut from the bonded panel assembly and evaluated for climbing drum peel strength of the thinner substrate, according to ASTM D-1781, using the tensile strength tester. Separation rate was 3 inches/minute (7.62 cm/min) at 70° F. (21.1° C.). Results listed in Table 8 were normalized for 1-inch (2.54 cm) wide test strips. Five test panels were prepared and evaluated per each example.
Two test panels, measuring 125 mils by 6-inches by 6-inches (3.2 mm by 15.24 cm by 15.24 cm), were bonded together with a structural adhesive and cured in the autoclave as described in the Overlap Shear Test method. Test strips, 1 inches (25.4 mm) wide were cut from the bonded panel assembly and open the end of the test specimen that contains the separation film, and insert the wedge. The test coupon was evaluated for wedge crack test, according to ASTM 3762-03, after which they were placed in a controlled humidity chamber at 140° F. (60° C.) and 95% relative humidity. The crack growth and failure mode were subsequently evaluated after one week. Results are listed in Tables 9-11.
A primed, Augustm Grade 2024T bare aluminum, thickness 0.25-0.35 mil, was tested in Salt Spray Exposures Chamber in accordance with ASTM B-117. The results showed the sol-gel primers in the invention gave good corrosion resistance performance using different surface preparation (with sol-gel or without sol-gel surface treatment) after salt spray exposure, which is comparable to chromate based primers.
Various modifications and alterations of this disclosure will become apparent to those skilled in the art without departing from the scope and principles of this disclosure, and it should be understood that this disclosure is not to be unduly limited to the illustrative embodiments set forth hereinabove.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2015/067439 | 12/22/2015 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62095141 | Dec 2014 | US |
