Curable resin composition and adhesive for bonding structural material using composition

Abstract

To show a curable resin composition suitable as an adhesive for bonding a structural material having good adhesiveness to aluminum in particular. A curable resin composition containing (A1) phosphoric acid-modified epoxy resin obtained by reacting a phosphoric acid (a1) and an epoxy compound (a2) (excluding a urethane-modified epoxy resin and a urethane-modified chelate epoxy resin); and (A2) an epoxy resin (excluding component (A1)); (B) a block urethane; and (C) a latent curing agent, in which a phosphorus content in a total mass of component (A1) and component (A2) is 0.01 to 2.0% by mass.

Claims

1. A curable resin composition comprising: (A1) a phosphoric acid-modified epoxy resin obtained by reacting a phosphoric acid (a1) and an epoxy compound (a2) excluding a urethane-modified epoxy resin and a urethane-modified chelate epoxy resin; and (A2) an epoxy resin excluding component (A1); (B) a blocked urethane, which is a compound obtained by further reacting a blocking agent (b4) with a polyurethane resin (b3) obtained by reacting a polyol (b1) and a polyisocyanate (b2), wherein the blocking agent (b4) is at least one compound selected from the group consisting of active methylene compounds, oxime compounds, monohydric alcohols, glycol derivatives, amine compounds, phenols and ε-caprolactams; and (C) a latent curing agent, wherein the latent curing agent (C) is at least one compound selected from the group consisting of dicyandiamide, hydrazides, 4,4′-diaminodiphenylsulfone, boron trifluoride amine complex salt and ureas, wherein a phosphorus content in a total mass of component (A1) and component (A2) is 0.01 to 2.0% by mass.

2. The curable resin composition according to claim 1, wherein the epoxy compound (a2) is a bisphenol epoxy resin.

3. An adhesive for bonding a structural material, which uses the curable resin composition according to claim 1.

4. The adhesive for bonding a structural material according to claim 3, which is used for bonding aluminum materials.

Description

EXAMPLES

(1) The present invention will be specifically described with reference to Examples. Note that the “%” below is based on mass unless otherwise specified.

(2) [Production Example 1: Production of Composition 1 including Phosphoric acid-Modified Epoxy Resin (A1) and Epoxy Resin (A2)]

(3) In a 2 L 5-neck separable round bottom flask equipped with a Dimroth condenser, a stirring blade, and a nitrogen line, 890.6 g of “Adeka resin EP-4100E” (bisphenol A type epoxy resin, epoxy equivalent: 190 g/eq., manufactured by Adeka Corp.) as the epoxy compound (a2) and 142.4 g of methyl ethyl ketone were mixed. The temperature of the obtained mixture was set at 40° C., and 11.1 g of an 85% by mass phosphoric acid aqueous solution as a phosphoric acid (a1) was gradually added thereto while maintaining the temperature in the system at 60° C. or lower. After completion of the addition, the mixture was heated to 70° C. and stirred for 30 minutes to complete the reaction of phosphoric acid with EP-4100E. After completion of the reaction, the inside of the system was further heated and methyl ethyl ketone and water in the system were removed under conditions of 140° C. and 30 mmHg. At this point, there is a reaction product of phosphoric acid and EP-4100E as well as unreacted EP-4100E in the reaction system. The reaction product of phosphoric acid and EP-4100E corresponds to the phosphoric acid-modified epoxy resin (A1) of the present invention. The unreacted EP-4100E corresponds to the epoxy resin (A2) of the present invention. Theoretically, 64 g of phosphoric acid-modified epoxy resin (A1) and 836 g of epoxy resin (A2) will be present.

(4) Thereafter, 120 g of “Adeka Glycirol ED-523T” (neopentyl glycol glycidyl ether, epoxy equivalent: 140 g/eq., manufactured by Adeka Corp.) which is an epoxy compound not further modified by a phosphoric acid was added to the system as an additional epoxy resin (A2). In this manner, 1020 g of composition 1 including a phosphoric acid-modified epoxy resin (A1) and an epoxy resin (A2) was obtained. The phosphorus content of composition 1 is a theoretical value of 0.29% by mass.

(5) [Production Example 2 Production of Composition 2 including Phosphoric Acid-Modified Epoxy Resin (A1) and Epoxy Resin (A2)]

(6) In a 2 L 5-neck separable round bottom flask equipped with a Dimroth condenser, a stirring blade, and a nitrogen line, 1009.3 g of “Adeka resin EP-4100E” as the epoxy compound (a2) and 151.4 g of methyl ethyl ketone were mixed. The temperature of the obtained mixture was set at 40° C., and 12.6 g of an 85% by mass phosphoric acid aqueous solution as a phosphoric acid (a1) was gradually added thereto while maintaining the temperature in the system at 60° C. or lower. After completion of the addition, the mixture was heated to 70° C. and stirred for 30 minutes to complete the reaction of phosphoric acid with “EP-4100E”. After completion of the reaction, the inside of the system was further heated and methyl ethyl ketone and water in the system were removed under conditions of 140° C. and 30 mmHg. At this point, there is a reaction product of phosphoric acid and EP-4100E as well as unreacted EP-4100E in the reaction system. The reaction product of phosphoric acid and EP-4100E corresponds to the phosphoric acid-modified epoxy resin (A1) of the present invention. The unreacted EP-4100E corresponds to the epoxy resin (A2) of the present invention. Theoretically, 72.7 g of phosphoric acid-modified epoxy resin (A1) and 944.3 g of epoxy resin (A2) will be present. In this manner, 1020 g of composition 2 including phosphoric acid-modified epoxy resin (A1) and epoxy resin (A2) was obtained. The phosphorus content of composition 2 is a theoretical value of 0.33% by mass.

(7) [Production Example 3 Production of Composition 3 including Phosphoric Acid-Modified Epoxy Resin (A1) and Epoxy Resin (A2)]

(8) In a 2 L 5-neck separable round bottom flask equipped with a Dimroth condenser, a stirring blade, and a nitrogen line, 1003.4 g of “Adeka resin EP-4100E” as the epoxy compound (a2) and 181.3 g of methyl ethyl ketone were mixed. The temperature of the obtained mixture was set at 40° C., and 18.3 g of an 85% by mass phosphoric acid aqueous solution as a phosphoric acid (a1) was gradually added thereto while maintaining the temperature in the system at 60° C. or lower. After completion of the addition, the mixture was heated to 70° C. and stirred for 30 minutes to complete the reaction of phosphoric acid with EP-4100E. After completion of the reaction, the inside of the system was further heated and methyl ethyl ketone and water in the system were removed under conditions of 140° C. and 30 mmHg.

(9) At this point, there is a reaction product of phosphoric acid and EP-4100E as well as unreacted EP-4100E in the reaction system. The reaction product of phosphoric acid and EP-4100E corresponds to the phosphoric acid-modified epoxy resin (A1) of the present invention. The unreacted EP-4100E corresponds to the epoxy resin (A2) of the present invention. In this manner, 1020 g of composition 3 including phosphoric acid-modified epoxy resin (A1) and epoxy resin (A2) was obtained. The phosphorus content of composition 3 is a theoretical value of 0.48% by mass.

(10) [Production Example 4 Production of Composition 4 including Urethane-Modified Chelate Epoxy Resin and Epoxy Resin (A2)]

(11) 1000 g of Adeka polyether G-3000B (polypropylene glycol glyceryl ether having a number average molecular weight of 3000, manufactured by Adeka Corp.) was added to a 2 L 5-neck separable round bottom flask equipped with a Dimroth condenser, a stirring blade, and a nitrogen line and degassed under reduced pressure at 100 to 110° C. and 30 mmHg or less for 1 hour. The inside of the reaction system was cooled to 60° C., 174 g of tolylene diisocyanate was added thereto and reacted at 90 to 100° C. for 3 hours under a nitrogen stream, and, when it was confirmed that the NCO % was 3.6% by mass or less, the reaction was finished. In this manner, a urethane prepolymer was obtained.

(12) 2800 g of Adeka resin EP-4100E as an epoxy resin was added to a 5 L 5-neck separable round bottom flask equipped with a Dimroth condenser, a stirring blade, and a nitrogen line and then, at 40° C., 17.6 g of an 85% by mass phosphoric acid aqueous solution was gradually added thereto such that the temperature inside the system did not exceed 60° C. After completion of the addition, the mixture was heated to 70° C. and then stirred for 30 minutes to complete the reaction of phosphoric acid and EP-4100E. At this point, phosphoric acid-modified epoxy resin is formed.

(13) After completion of the reaction, the inside of the system was further heated and water in the system was removed under conditions of 140° C. and 30 mmHg, then 580 g of the urethane prepolymer and 0.075 g of dioctyltin dilaurate were added thereto, and the hydroxyl group in the phosphoric acid-modified epoxy resin and the isocyanate group in the urethane prepolymer were made to react. After confirming that the absorption of NCO disappeared in the IR absorption spectrum, the reaction was finished, and 3395 g of composition 4 including a urethane-modified chelate epoxy resin was obtained. Composition 4 theoretically includes 682.2 g of urethane-modified chelate epoxy resin and 2713.8 g of EP-4100E which is an unreacted epoxy resin. In addition, the phosphorus content of composition 4 is a theoretical value of 0.14% by mass.

(14) Composition 4 does not include the phosphoric acid-modified epoxy compound used in the present invention.

(15) [Production Example 5: Production of Composition 5 including Urethane-Modified Epoxy Resin]

(16) 240 g of Adeka polyether G-3000B (propylene oxide addition polymer of glycerin having a number average molecular weight of 3000, manufactured by Adeka Corp.) was added to a 5 L 5-neck separable round bottom flask equipped with a Dimroth condenser, a stirring blade, and a nitrogen line and degassed under reduced pressure for 1 hour under conditions of 100 to 110° C. and 30 mmHg or less. The inside of the reaction system was cooled to 60° C., 42 g of tolylene diisocyanate was added thereto, and the reaction was carried out at 90 to 100° C. for 3 hours under a nitrogen stream. The reaction was finished after confirming that the NCO % was 3.6% by mass or less. Thereafter, 791 g of Adeka Resin EP-4901 (bisphenol F type epoxy resin manufactured by Adeka Corp., epoxy equivalent: 170 g/eq.), 70 g of Adeka Glycirol ED-503 (1,6-hexanediol diglycidyl ether manufactured by Adeka Corp., epoxy equivalent: 165 g/eq.), and 0.08 g of dibutyltin dilaurate as a catalyst for a urethane reaction were added and reacted at 80 to 90° C. The reaction was finished by confirming that the absorption of NCO disappeared in the IR absorption spectrum. In this manner, 1140 g of composition 5 including a urethane modified epoxy resin was obtained. Composition 5 does not include the phosphoric acid-modified epoxy compound used in the present invention.

(17) [Production Example 6: Production of Blocked urethane (B)] 500 g of “Adeka Polyether G-1500” as the polyol (b1) (polypropylene glycol glyceryl ether having a number average molecular weight of 1,500, manufactured by Adeka Corp.) was added to a 1 L 5-neck separable round bottom flask equipped with a Dimroth condenser, a stirring blade, and a nitrogen line and the mixture was degassed under reduced pressure at 100 to 110° C. and 30 mmHg or less for 1 hour. The inside of the reaction system was cooled to 60° C., 221 g of isophorone diisocyanate as the polyisocyanate (b2) and 0.075 g of dioctyltin dilaurate as a catalyst were added thereto and reacted at 90 to 100° C. for 3 hours under a nitrogen stream. When the isocyanate group content (NCO %) in the reaction system was confirmed to be 5.9% by mass, the reaction was finished. In this manner, a polyurethane resin (b3) was obtained. Next, 781 g of polyurethane resin (b3), 150 g of p-tert-butylphenol as a blocking agent (b4), and 0.025 g of dioctyl tin dilaurate as a catalyst were added to a 1 L 5-neck separable round bottom flask equipped with a Dimroth condenser, a stirring blade, and a nitrogen line and reacted at 90 to 100° C. for 3 hours. When it was confirmed that absorption of NCO disappeared in the IR absorption spectrum, the reaction was finished. In this manner, the blocked urethane (B) was obtained.

(18) [Example 1] Production of Curable Resin Composition 1

(19) 70 g of composition 1, 30 g of the blocked urethane (B), 7 g of dicyandiamide (DICY) as a latent curing agent (C), 1 g of N,N-dimethyl-N′-phenylurea (Fenuron), and 25 g of calcium carbonate were added into a 500 mL disposable cup, and stirred with a spatula at 25° C. for 5 minutes. Thereafter, the mixture was further stirred using a planetary stirrer to obtain a curable resin composition 1 of the present invention. The adhesive strength of the obtained curable resin composition 1 is shown in Table 1. The adhesive strength (KN/mm) is a value measured by a T-type peeling test performed in accordance with JIS K6854-3, using aluminum and iron as adherends and with a peel rate of 100 mm/min at 23° C.

(20) [Examples 2 to 5, Comparative Examples 1 to 3] Production of Curable Resin Compositions 2 to 5 and Control Curable Resin Compositions 1 to 3

(21) Curable resin compositions of the present invention and control curable resin compositions were prepared by changing the blends as shown in Table 1. The adhesive strength of the obtained curable resin composition was measured in the same manner as in Example 1. The results are shown in Table 1. In Table 1, “EH-5011S” is an imidazole type latent curing agent manufactured by Adeka Corp.

(22) TABLE-US-00001 TABLE 1 Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 1 Example 2 Example 3 Example 4 Example 5 Control Control Control Curable Curable Curable Curable Curable curable curable curable resin resin resin resin resin resin resin resin compo- compo- compo- compo- compo- compo- compo- compo- sition 1 sition 2 sition 3 sition 4 sition 5 sition 1 sition 2 sition 3 Composition Composition 1 70 35 7 Composition 2 70 Composition 3 70 Epoxy resin (A2) EP- 35 63 100 4100E Composition 4 70 Composition 5 70 Blocked urethane (B) 30 30 30 30 30 30 30 Latent curing agent 7 7 7 7 7 7 7 7 DICY Fenuron 1 1 1 1 1 1 Latent curing agent 3 3 EH-5011S Calcium carbonate 25 25 25 25 25 25 25 25 T-type Average Base 4.2 4.5 5.1 3.9 3.0 0.6 1.1 0.7 peeling test stress material: Al at 23° C. Base 13.3 13.8 14.1 13.2 10.5 0.8 13.7 5.4 (KN/m) material: Fe

(23) As shown in Table 1, the curable resin compositions 1 to 5 of the present invention containing all of the phosphoric acid-modified epoxy resin (A1), epoxy resin (A2) (not (A1)), the blocked urethane (B), and the latent curing agent (C) exhibit high adhesive force to both aluminum and iron members. On the other hand, the control curable resin compositions 1 to 3 are inferior in adhesiveness to aluminum. That is, the control curable resin composition 1 not including the phosphoric acid-modified epoxy resin (A1) and the blocked urethane (B) has low adhesive force to both aluminum and iron. The control curable resin composition 2 including the urethane-modified chelate epoxy resin in place of the phosphoric acid-modified epoxy resin (A1) of the present invention has a good adhesive strength to iron but poor adhesive strength to aluminum. The control curable resin composition 3 including a urethane modified epoxy resin in place of the phosphoric acid-modified epoxy resin (A1) of the present invention has low adhesive force to both aluminum and iron.

INDUSTRIAL APPLICABILITY

(24) The resin composition of the present invention has high adhesive strength to aluminum and iron, and, in particular, is a suitable material for producing an adhesive for bonding a structural material for automobiles, vehicles (bullet trains, trains, and the like), civil engineering, construction, ships, airplanes, the space industry, and the like. As the development of automobiles using materials instead of iron accelerates along with recent changes in the automobile industry, it is considered that the adhesives for bonding structural materials using the resin composition of the present invention are suitable as adhesives for bonding structural materials for the automobiles incorporating these material changes, and the present invention is extremely useful industrially.