Thermoset adhesive, automotive component using thermoset adhesive, and method of manufacturing same

Abstract

A thermoset adhesive for bonding two materials having different linear expansion coefficients with reduced warping and without spaces being formed therebetween. The thermoset adhesive of the present invention comprises an epoxy resin, a core-shell rubber, thermally expansive microparticles, and a curing agent. The thermally expansive microparticles can have at least one or any combination of an average particle size of from 9 to 19 μm, an expansion initiation temperature of from 70 to 100° C., and a maximum expansion temperature of from 110 to 135° C.

Claims

1. A component comprising: a first plate-shaped member, a second plate-shaped member, and a cured thermoset adhesive disposed between the first plate-shaped member and the second plate-shaped member and bonding together the first plate-shaped member and the second plate-shaped member, wherein the first plate-shaped member has a linear expansion coefficient different from a linear expansion coefficient of the second plate-shaped member, and the thermoset adhesive comprises an epoxy resin, a core-shell rubber, thermally expansive microparticles, and a hardening agent, with the thermally expansive microparticles having an average particle size of from 9 to 19 μm, an expansion initiation temperature of from 70 to 100° C., and a maximum expansion temperature of from 110 to 135° C.

2. The component according to claim 1, wherein the thermoset adhesive has a heat generation initiation temperature of 150° C. or less, and a maximum heat generation temperature of 155° C. or less, when differential scanning calorimetry is performed at a temperature gradient of 10° C./minute.

3. The component according to claim 2, wherein the first plate-shaped member contains aluminum.

4. The component according to claim 3, wherein the second plate-shaped member contains iron.

5. The component according to claim 2, wherein the second plate-shaped member contains iron.

6. The component according to claim 1, wherein the thermoset adhesive comprises an amount of thermally expansive microparticles equivalent to about 0.3 mass % or more of the thermoset adhesive.

7. The component according to claim 6, wherein the thermoset adhesive comprises an amount of thermally expansive microparticles equivalent to about 20 mass % or less of the thermoset adhesive.

8. The component according to claim 6, wherein the thermoset adhesive comprises an amount of thermally expansive microparticles equivalent to about 15 mass % or less of the thermoset adhesive.

9. The component according to claim 6, wherein the thermoset adhesive comprises an amount of thermally expansive microparticles equivalent to about 12 mass % or less of the thermoset adhesive.

10. The component according to claim 1, wherein the thermally expansive microparticles of the thermoset adhesive exhibit a volumetric expansion factor of about 2× or more.

11. The component according to claim 10, wherein the thermally expansive microparticles of the thermoset adhesive exhibit a volumetric expansion factor of about 20× or less.

12. The component according to claim 10, wherein the thermally expansive microparticles of the thermoset adhesive exhibit a volumetric expansion factor of about 15× or less.

13. The component according to claim 10, wherein the thermally expansive microparticles of the thermoset adhesive exhibit a volumetric expansion factor of about 10× or less.

14. The component according to claim 1, wherein the thermoset adhesive has a viscosity, measured at 25° C. and a shear rate of 15.5 s.sup.−1 using a rotational viscometer, in the range of from about generally roughly 10 Pa.Math.s up to about 1,000 Pa s.

15. The component according to claim 1, wherein the first plate-shaped member contains aluminum.

16. The component according to claim 15, wherein the second plate-shaped member contains iron.

17. The component according to claim 1, wherein the second plate-shaped member contains iron.

18. The component according to claim 1, wherein said component is an automotive component.

Description

EXAMPLES

(1) In the following working examples, specific embodiments of the present disclosure are exemplified, but the present invention is not restricted thereto. All parts and percentages are in terms of mass unless otherwise indicated.

(2) The reagents, raw materials, and the like used in these working examples are shown below in Table 1.

(3) TABLE-US-00001 TABLE 1 Trade name Description Supplier <Epoxy resin> YD128 DGEBA (bisphenol A Nippon Steel & Sumikin diglycidyl ether) Chemical Co., Ltd. Epoxy equivalent weight: 189 Araldite ® Polypropylene glycol glycidyl Huntsman Corporation DY3601 ether PO units: 11-12 Epoxy equivalent weight: 385-405 Cardura ® Glycidyl neodecanoate Hexion Specialty E10P Reactive plasticizer Chemicals Inc. Epoxy equivalent weight: 248 <Core-shell rubber> KaneAce ® Polybutadiene- Kaneka Corp. B-564 poly(methyl methacrylate) core- shell rubber particles <Filler> M. QUARTZ Y74 Silica filler Marukama Ltd. Shieldex ® Ca ion-modified silica gel Grace Davison AC3 Anti-corrosive filler <Rheology modifier> CAB-O-SIL ® Hydrophobic fumed silica Cabot Corporation TS720 Aerosil ® Hydrophobic fumed silica Nippon Aerosil Co., Ltd. RX-200 (trimethylsilyl group-modified) Average particle size: 12 nm <Curing agent> Amicure ® Dicyandiamide Air products CG-1200 Omicure ® 4,4′-methylene- CVC Specialty Chemicals U-52 bis(phenyldimethyl urea) Inc. Fujicure ® Modified polyamine latent T&K TOKA Corp. FXR-1020 curing agent Fujicure ® Modified polyamine latent T&K TOKA Corp. FXR-1081 curing agent Aradur ® N-(2-methylphenyl)- Huntsman Corporation 2844 imidedicarbonimidic diamide Curezol ® 2,4-diamino-6-[2′-methyl Shikoku Chemicals Corp. 2MA-OK imidazolyl-(1′)]-ethyl-s-triazine isocyanuric acid adduct Curezol ® 2-phenyl-4,5-dihydroxymethyl Shikoku Chemicals Corp. 2PHZ-PW imidazole <Thermally expansive microparticles> F-36LVD Polyacrylonitrile-based shell Matsumoto Yushi Average particle size: 13-19 μm Seiyaku Co., Ltd. Expansion initiation temperature: 75-85° C. Maximum expansion temperature: 110-120° C. F-36D Polyacrylonitrile-based shell Matsumoto Yushi Average particle size: 10-16 μm Seiyaku Co., Ltd. Expansion initiation temperature: 70-80° C. Maximum expansion temperature: 110-120° C. F-48D Polyacrylonitrile-based shell Matsumoto Yushi Average particle size: 9-15 μm Seiyaku Co., Ltd. Expansion initiation temperature: 90-100° C. Maximum expansion temperature: 125-135° C. F-100MD Polyacrylonitrile-based shell Matsumoto Yushi Average particle size: 17-23 μm Seiyaku Co., Ltd. Expansion initiation temperature: 115-125° C. Maximum expansion temperature: 155-165° C. FN-100SD Polyacrylonitrile-based shell Matsumoto Yushi Average particle size: 10-20 μm Seiyaku Co., Ltd. Expansion initiation temperature: 125-135° C. Maximum expansion temperature: 150-160° C. FN-105D Polyacrylonitrile-based shell Matsumoto Yushi Average particle size: 35-45 μm Seiyaku Co., Ltd. Expansion initiation temperature: 120-135° C. Maximum expansion temperature: 175-185° C. <Other> Preton ® Lubricating anti-rust agent Sugimura Chemical R303-PX2 Industrial Co., Ltd.

(4) A thermoset adhesive was prepared as follows according to the formulation shown in Table 2. First, KaneAce® B-564 (core-shell rubber) was mixed with YD128 and either Araldite® DY3601 or Cardura® E10P (epoxy resin) in a wide-mouthed flask, which was placed in an oven and heated to 95° C. The contents of the wide-mouthed flask were mixed in a mixer at 95° C. to prepare a homogeneous dispersion. After the dispersion was cooled to room temperature, the remaining ingredients shown in table 2 apart from the CAB-O-SIL® TS720 or Aerosil® RX-200 (rheology modifier) were added and stirred in a mixer. After the dispersion reached a homogeneous consistency, the CAB-O-SIL® TS720 or Aerosil® RX-200 (rheology modifier) was added and the dispersion was stirred again. Afterwards, the dispersion was degassed for thirty minutes in a vacuum to obtain a thermoset adhesive. The obtained thermoset adhesive was used to perform the following performance evaluation tests.

(5) TABLE-US-00002 TABLE 2 Working Working Working Working Working Working Working Working Working Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 YD128 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 Araldite DY3601 0 0 0 0 0 0 0 0 0 Cardura 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 E10P KaneAce B-564 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 M. QUARTZ Y74 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 Shieldex AC3 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 CAB-O-SIL TS720 0.3 0 0 0.3 0.3 0 0 0 0 Aerosil RX-200 0 0.3 0.3 0 0 0.3 0.3 0.3 0.3 Amicure CG-1200 0 0 0 0 0 0 0 1.0 1.0 Omicure U-52 0 0 0 0 0 0 0 0.1 0.1 Fujicure FXR-1020 1.0 1.0 0 1.0 0 1.0 0 0 0 Fujicure FXR-1081 0 0 0 0 0 0 0 0 0 Aradur 0 0 0 0 0 0 0 0 0 2844 Curezol 0 0 1.0 0 1.0 0 1.0 0 0 2MA-OK Curezol 2PHZ-PW 0 0 0 0 0 0 0 0 0 F-36LVD 0.43 0 0 0.26 0.86 0 0 0 0 F-36D 0 0.43 0 0 0 0 0.86 2.0 0 F-48D 0 0 1.29 0 0 0.86 0 0 3.0 F-100MD 0 0 0 0 0 0 0 0 0 FN-100SD 0 0 0 0 0 0 0 0 0 FN-105D 0 0 0 0 0 0 0 0 0 Total 26.3 26.3 27.2 26.2 26.8 26.8 26.8 28.0 29.0 Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 Ex. 11 Ex. 12 YD128 5.0 5.0 5.0 5.0 5.0 7.5 7.5 5.0 7.5 7.5 7.5 7.5 Araldite 5.0 5.0 5.0 5.0 5.0 0 0 5.0 0 0 0 0 DY3601 Cardura 0 0 0 0 0 2.5 2.5 0 2.5 2.5 2.5 2.5 E10P KaneAce 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 B-564 M. 14.0 14.0 14.0 14.0 14.0 12.0 12.0 14.0 12.0 12.0 12.0 12.0 QUARTZ Y74 Shieldex 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 AC3 CAB-O- 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0 0 0 0 SIL TS720 Aerosil 0 0 0 0 0 0 0 0 0.3 0.3 0.3 0.3 RX-200 Amicure 0 0 0 0 0 0 0 0 0 0 0 1.0 CG-1200 Omicure 0 0 0 0 0 0 0 0 0 0 0 0.1 U-52 Fujicure 1.0 0 0 0 0 1.0 0 0 0 0 0 0 FXR- 1020 Fujicure 0 1.0 0 0 0 0 0 0 0 0 0 0 FXR- 1081 Aradur 0 0 1.0 0 0 0 0 0 0 0 0 0 2844 Curezol 0 0 0 1.0 0 0 1.0 1.0 1.0 1.0 1.0 0 2MA- OK Curezol 0 0 0 0 1.0 0 0 0 0 0 0 0 2PHZ- PW F- 0 0 0 0 0 0 0 0 0 0 0 0 36LVD F-36D 0 0 0 0 0 0 0 0 0 0 0 0 F-48D 0 0 0 0 0 0 0 0 0 0 0 0 F- 0 0 0 0 0 0 0 0 0.86 0 1.72 0 100MD FN- 0 0 0 0 0 0 0 0 0 0.86 0 0 100SD FN-105D 0 0 0 0 0 0 0 2.8 0 0 0 1.0 Total 27.9 27.9 27.9 27.9 27.9 25.9 25.9 30.7 26.8 26.8 27.6 27.0 (“Comp. Ex.” = Comparative Example)
Performance Evaluation Tests

(6) The performance of the thermoset adhesive of the present disclosure was evaluated according to the following methods.

(7) 1. Panel Warping and Adhesive Layer Uniformity

(8) An aluminum (Al) test panel (A6061P-T6; Nippon Light Metal Co., Ltd.; thickness 1.0 mm×width 25 mm×length 150 mm) having two nut/bolt fastening holes spaced 100 mm apart and a galvannealed steel (GA) test panel (JFE Steel Corp.; thickness 0.8 mm×width 25 mm×length 150 mm) having two similar holes were wiped using methyl ethyl ketone (MEK), then submerged in Preton® R303-PX2 and left standing for 24 hours in a perpendicular position as an anti-rust treatment. The thermoset adhesive was applied to the Al test panel using a spatula to form an adhesive layer, after which the GA test panel was placed upon the adhesive layer, and the Al test panel and GA test panel were fixed in place at two locations using nuts and bolts. In the present embodiment, a separate spacer was not used for the adhesive layer; thus, the thickness of the adhesive layer was 0.1 mm (corresponding to the maximum particle size of the added filler).

(9) The test piece prepared as described above was heated in an over under “fast bake” and “slow bake” conditions. In “fast bake” heating, the test piece was heated from 30° C. to 190° C. at a rate of 6.4° C./minute over 25 minutes, then allowed to cool after being kept at 190° C. for 15 minutes. In “slow bake” heating, the test piece was heated from 30° C. to 70° C. over 10 minutes, kept at from 75 to 78° C. for 10 minutes, heated to 185° C. over 20 minutes at a rate of 5.4° C./minute, kept at 185° C. for 10 minutes, and allowed to cool. Both of these heating methods model electrodeposition drying conditions (temperature profiles) used in automobile manufacturing. After the adhesive layer had cured, the maximum gap between the Al test panel and the GA test panel was measured for each test piece. The maximum gap was observed roughly halfway between the two nut/bolt fastenings. The GA test panel was then pulled off the Al test panel, and the uniformity of the adhesive layer was visually observed and rated according to one of three grades: A indicating the gap between the test panels being completely filled, with no spaces therebetween; B indicating the presence of partially unfilled sections within permissible limits; and C indicating an unusable product.

(10) 2. Overlap Shear (OLS) Test

(11) The tip (10 mm from the end) of an aluminum (Al) test panel (A6061P-T6; Nippon Light Metal Co., Ltd.; thickness 1.0 mm×width 25 mm×length 150 mm) was wiped with methyl ethyl ketone (MEK), submerged in Preton® R303-PX2, and left standing for 24 hours in a perpendicular position as an anti-rust treatment. The thermoset adhesive was applied to the Al test panel using a spatula to form an adhesive layer, and a separate Al test panel subjected to an anti-rust treatment using Preton® R303-PX2 was placed upon the adhesive layer with an overlap of 10 mm and clamped in place using a clip. In the present embodiment, a separate spacer was not used for the adhesive layer; thus, the thickness of the adhesive layer was 0.1 mm (corresponding to the maximum particle size of the added filler). The test piece prepared as described above was heated in an over under “fast bake” and “slow bake” conditions. After the adhesive layer had cured, a test was performed using a Tensilon testing apparatus in tensile mode at a crosshead speed of 5 mm/minute.

(12) 3. T-Peel Test

(13) An aluminum (Al) test panel (A6061P-T6; Nippon Light Metal Co., Ltd.; thickness 1.0 mm×width 25 mm×length 150 mm) was wiped with methyl ethyl ketone (MEK), submerged in Preton® R303-PX2, and left standing for 24 hours in a perpendicular position as an anti-rust treatment. The thermoset adhesive was applied to the Al test panel using a spatula to form an adhesive layer, and a separate Al test panel subjected to an anti-rust treatment using Preton® R303-PX2 was placed upon the adhesive layer and clamped in place using a clip. In the present embodiment, a separate spacer was not used for the adhesive layer; thus, the thickness of the adhesive layer was 0.1 mm (corresponding to the maximum particle size of the added filler). The test piece prepared as described above was heated in an over under “fast bake” and “slow bake” conditions. After the adhesive layer had cured, a test was performed using a Tensilon testing apparatus in T-peel mode at a peel rate of 200 mm/minute.

(14) 4. DSC (Differential Scanning Calorimetry)

(15) Roughly from 2 to 10 mg of a thermoset adhesive specimen was introduced into an aluminum pan and analyzed using a Perkin Elmer Pyris 1 differential scanning calorimeter to determine heat generation initiation temperature and maximum heat generation temperature.

(16) Test results are summarized in table 3.

(17) TABLE-US-00003 TABLE 3 Working Working Working Working Working Working Working Working Working Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Fast bake Max. gap (mm) 0.4 0.6 0.7 0.5 0.6 0.5 0.7 0.7 0.7 Filling of gap by A A A B A A A A A adhesive post curing OLS [MPa] 14.1 9.5 12.0 21.0 14.0 7.9 10.1 13.2 15.4 (CF) (CF) (CF) (CF) (CF) (CF) (CF) (CF) (CF) T peel [N/25 mm] 32.8 21.8 33.6 47.1 41.4 21.3 29.0 13.1 25.3 (CF) (CF) (CF) (CF) (CF) (CF) (CF) (CF) (CF) Slow bake Max. gap [mm] 0.3 0.4 0.7 0.6 0.6 0.9 1.0 0.9 Filling of gap by A A A C C C C C adhesive post curing OLS [MPa]*.sup.) 14.0 9.0 10.9 12.8 8.3 9.5 10.8 11.3 (CF) (CF) (CF) (CF) (CF) (CF) (CF) (CF) T peel [N/25 mm] 52.7 27.4 40.2 29.4 20.3 21.9 22.8 18.4 (CF) (CF) (CF) (CF) (CF) (CF) (CF) (CF) DSC Heat generation 100 100 149 100 146 100 148 155 155 initiation temperature (° C.) Maximum heat 125 124 152 130 150 119 152 179 176 generation temperature (° C.) *.sup.)In the table, CF signifies cohesive failure, and TCF signifies thin-layer failure. (“Comp. Ex.” = Comparative Example) Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 Ex. 11 Ex. 12 Fast bake Max. gap (mm) 0.4 0.4 0.8 0.6 0.8 0.4 0.5 1.5 0.62 0.9 0.9 1.1 Filling of gap by C C C C C C C C C C C C adhesive post curing OLS [MPa] T peel (N/25 mm) Slow bake Max. gap (mm) Filling of gap by adhesive post curing OLS [MPa]*.sup.) T peel (N/25 mm) DSC Heat generation 96 94 133 150 176 97 147 152 149 148 147 156 initiation temperature (° C.) Maximum heat 121 117 169 155 179 123 151 156 151 151 151 171 generation temperature (° C.) *.sup.)In the table, CF signifies cohesive failure, and TCF signifies thin-layer cohesive failure.