Metal alkoxide, and aqueous resin crosslinking composition and aqueous resin composition which use same

Abstract

The present invention provides a novel metal alkoxide having excellent hydrolysis resistance, and a crosslinking agent composition for aqueous resin and an aqueous resin composition each using the same. A metal alkoxide represented by the following formula (1-1), (1-2), or (1-3) and having a mass average molecular weight of 800 to 8,500 is used:
Ti(OA).sub.4  (1-1)
Zr(OA).sub.4  (1-2)
Al(OA).sub.3  (1-3) wherein A's are each independently a residue resulting from removal of a hydroxy group from a polyalkylene glycol monohydrocarbyl ether represented by the following general formula (1a):
R.sup.11(OCHR.sup.12CH.sub.2).sub.nOH  (1a) wherein R.sup.11 is an alkyl group having 1 to 4 carbon atoms or a phenyl group; R.sup.12 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; and n is an integer of 4 to 45.

Claims

1. A crosslinking agent composition for aqueous resin, comprising a metal alkoxide represented by the following formula (1-1), (1-2), or (1-3) and having a mass average molecular weight of 800 to 8,500:
Ti(OA).sub.4  (1-1)
Zr(OA).sub.4  (1-2)
Al(OA).sub.3  (1-3) wherein A's are each independently a residue resulting from removal of a hydroxy group from a polyalkylene glycol monohydrocarbyl ether represented by the following general formula (1a):
R.sup.11(OCHR.sup.12CH.sub.2).sub.nOH  (1a) wherein R.sup.11 is an alkyl group having 1 to 4 carbon atoms or a phenyl group; R.sup.12 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; and n is an integer of 4 to 45, OR a metal alkoxide represented by the following formula (2-1), (2-2), or (2-3) and having a mass average molecular weight of 600 to 6,000:
Ti(OA).sub.p(OR).sub.4-p  (2-1)
Zr(OA).sub.q(OR).sub.4-q  (2-2)
Al(OA).sub.r(OR).sub.3-r  (2-3) wherein A's are each independently a residue resulting from removal of a hydroxy group from a polyalkylene glycol monohydrocarbyl ether represented by the following general formula (1a); R's are each independently an alkyl group having 1 to 20 carbon atoms; p and q are each a number of 2 or more and less than 4; and r is a number pf 2 or more and less than 3:
R.sup.11(OCHR.sup.12CH.sub.2).sub.nOH  (1a) wherein R.sup.11 is an alkyl group having 1 to 4 carbon atoms or a phenyl group: R.sup.12 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; and n is an integer of 4 to 45; and at least one compound selected from a polycarbodiimide and a polyoxazoline.

2. An aqueous resin composition comprising at least one aqueous resin containing at least any one of an alcoholic hydroxy group and a carboxy group, at least one compound selected from a polycarbodiimide and a polyoxazoline, and a metal alkoxide represented by the following formula (1-1), (1-2), or (1-3) and having a mass average molecular weight of 800 to 8,500:
Ti(OA).sub.4  (1-1)
Zr(OA).sub.4  (1-2)
Al(OA).sub.3  (1-3) wherein A's are each independently a residue resulting from removal of a hydroxy group from a polyalkylene glycol monohydrocarbyl ether represented by the following general formula (1a):
R.sup.11(OCHR.sup.12CH.sub.2).sub.nOH  (1a) wherein R.sup.11 is an alkyl group having 1 to 4 carbon atoms or a phenyl group; R.sup.12 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; and n is an integer of 4 to 45, OR a metal alkoxide represented by the following formula (2-1), (2-2), or (2-3) and having a mass average molecular weight of 600 to 6,000:
Ti(OA).sub.p(OR).sub.4-p  (2-1)
Zr(OA).sub.q(OR).sub.4-q  (2-2)
Al(OA).sub.r(OR).sub.3-r  (2-3) wherein A's are each independently a residue resulting from removal of a hydroxy group from a polyalkylene glycol monohydrocarbyl ether represented by the following general formula (1a); R's are each independently an alkyl group having 1 to 20 carbon atoms; p and a are each a number of 2 or more and less than 4; and r is a number of 2 or more and less than 3;
R.sup.11(OCHR.sup.12CH.sub.2).sub.nOH  (1a) wherein R.sup.11 is an alkyl group having 1 to 4 carbon atoms or a phenyl group; R.sup.12 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; and n is an integer of 4 to 45.

Description

EXAMPLES

(1) The present invention is hereunder described in detail by reference to Examples, but it should be construed that the present invention is not limited by these Examples.

(2) Details of blending raw materials in production of each of aqueous resin compositions of the following Examples, Comparative Examples, and Synthesis Examples are as follows. In the following aqueous resins, it was considered that the hydroxyl value is a value based on an alcoholic hydroxy group, and the acid value is a value based on a carboxy group.

(3) <Aqueous Resin>

(4) Acrylic resin A (emulsion): “NeoCryl (registered trademark) XK-103”, manufactured by DSM Coating Resins B.V., solid component (resin component): 45% by mass, dispersion medium: water, hydroxyl value (expressed in terms of a solid component): 47.2 mgKOH/g, acid value (expressed in terms of a solid component): 3.2 mgKOH/g

(5) Acrylic resin B (emulsion): “BURNOCK (registered trademark) WE-304”, manufactured by DIC Corporation, solid component (resin component): 45% by mass, dispersion medium: water, hydroxyl value (expressed in terms of a solid component): 43 mgKOH/g

(6) Polyurethane resin dispersion: “SANCURE (registered trademark) 777”, manufactured by The Lubrizol Corporation, solid component (resin component): 35% by mass, acid value (dispersion): 21.4 mgKOH/g, aqueous dispersion

(7) <Compound (Z)>

(8) Polycarbodiimide (Z1): One produced by the following Synthesis Example P, solid component (component concentration): 40% by mass, polymerization degree: 6.5, solvent: water

(9) Polyoxazoline (Z2): “EPOCROS (registered trademark) WS500”, manufactured by Nippon Shokubai Co., Ltd., oxazoline group-containing polymer, polymer main chain: acrylic, solid component (component concentration): 39% by mass, oxazoline equivalent: 220 (calculated value as expressed in terms of a solid component), solvent: water and 1-methoxy-2-propanol

(10) <Metal Alkoxide>

(11) Titanium alkoxide (X1): One produced in the following Synthesis Example 1

(12) Titanium alkoxide (Y1-1): One produced in the following Synthesis Example 2

(13) Titanium alkoxide (Y1-2): One produced in the following Synthesis Example 3

(14) Titanium alkoxide (Y1-3): One produced in the following Synthesis Example 4

(15) Zirconium alkoxide (X2): One produced in the following Synthesis Example 5

(16) Zirconium alkoxide (Y2-1): One produced in the following Synthesis Example 6

(17) Zirconium alkoxide (Y2-2): One produced in the following Synthesis Example 7

(18) Zirconium alkoxide (Y2-3): One produced in the following Synthesis Example 8

(19) Aluminum alkoxide (X3): One produced in the following Synthesis Example 9

(20) Aluminum alkoxide (Y3-1): One produced in the following Synthesis Example 10

(21) Aluminum alkoxide (Y3-2): One produced in the following Synthesis Example 11

(22) Titanium tetra-n-butoxide: “ORGATIX TA-21”, manufactured by Matsumoto Fine Chemical Co., Ltd., molecular weight: 340.32

(Synthesis Example P) Synthesis of Polycarbodiimide

(23) 1,572 g of dicyclohexylmethane 4,4′-diisocyanate and 7.86 g of 3-methyl-1-phenyl-2-phospholene-1-oxide as a carbodiimidization catalyst were charged in a 3,000-mL reaction vessel equipped with a reflux tube and a stirrer and stirred under a nitrogen gas stream at 185° C. for 10 hours, to obtain an isocyanate-terminated polycarbodiimide that is a polymer of the dicyclohexylmethane 4,4′-diisocyanate.

(24) This isocyanate-terminated polycarbodiimide was mixed with a toluene solution of di-n-butylamine having an already-known concentration, thereby allowing the terminal isocyanate group and the di-n-butylamine to react with each other. The residual di-n-butylamine was subjected to neutral titration with a hydrochloric acid standard solution, and the residual amount [% by mass] of the isocyanate group (terminal isocyanate group amount) was calculated by the potentiometric titration method (used device: automated titration device “COM-900”, manufactured by Hiranuma Sangyo Co., Ltd.) and found to be 5.00% by mass. That is, a polymerization degree of this isocyanate-terminated polycarbodiimide (average content number of the carbodiimide group in one molecule) was 6.5.

(25) 51.8 g of the obtained isocyanate-terminated polycarbodiimide was dissolved at 120° C., to which was then added 24.7 g of polyethylene glycol monomethyl ether (“BLAUNON MP-400”, manufactured by Aoki Oil Industrial Co., Ltd., molecular weight: 400 (catalogue value), hereinafter the same), and the contents were heated to 140° C. and allowed to react with each other for 5 hours while stirring. With respect to the reaction product, it was confirmed through infrared absorption spectrum measurement that the absorption of the isocyanate group at a wavelength of 2,200 to 2,300 cm.sup.−1 vanished. Thereafter, the resultant was cooled to 80° C., to which was added 115 g of ion-exchanged water, followed by stirring for 1 hour, to obtain a polycarbodiimide aqueous solution having a solid component of 40% by mass.

(Synthesis Example 1) Synthesis of Titanium Alkoxide (X1)

(26) 50 g of titanium tetraisopropoxide (“TA-8”, manufactured by Matsumoto Fine Chemical Co., Ltd., titanium content: 16.9% by mass) and 282 g of polyethylene glycol monomethyl ether (“BLAUNON MP-400”) were charged in a reaction vessel equipped with a stirrer and stirred under a nitrogen gas stream at 90° C. for 24 hours, and isopropyl alcohol was discharged out the reaction vessel, to obtain a reaction product.

(27) After 2.00 g of the obtained reaction product was weighed in an alumina-made crucible and heated at 600° C. for 3 hours, the amount of the residue (titanium oxide) was found to be 0.0969 g (titanium content in the reaction product: 2.91% by mass). In view of the fact that this titanium content was coincident with the titanium content in the alkoxide (mass average molecular weight: 1,644) in which four polyethylene glycol monomethyl ethers (molecular weight: 400) were bonded to one titanium atom, it was confirmed that the targeted titanium alkoxide (X1) was obtained.

(Synthesis Example 2) Synthesis of Titanium Alkoxide (Y1-1)

(28) A reaction product was obtained in the same manner as in Synthesis Example 1, except that in Synthesis Example 1, the addition amount of the polyethylene glycol monomethyl ether was changed to 212 g.

(29) After 2.00 g of the obtained reaction product was weighed in an alumina-made crucible and heated at 600° C. for 3 hours, the amount of the residue (titanium oxide) was found to be 0.122 g (titanium content in the reaction product: 3.66% by mass). From this fact, it was confirmed that the targeted titanium alkoxide (Y1-1) (mass average molecular weight: 1,304) in which three in average of four isopropoxy groups in one molecule of the titanium tetraisopropoxide were substituted with polyethylene glycol monomethyl ether (molecular weight: 400) was obtained.

(Synthesis Example 3) Synthesis of Titanium Alkoxide (Y1-2)

(30) A reaction product was obtained in the same manner as in Synthesis Example 1, except that in Synthesis Example 1, the addition amount of the polyethylene glycol monomethyl ether was changed to 141 g.

(31) After 2.00 g of the obtained reaction product was weighed in an alumina-made crucible and heated at 600° C. for 3 hours, the amount of the residue (titanium oxide) was found to be 0.165 g (titanium content in the reaction product: 4.95% by mass). From this fact, it was confirmed that the targeted titanium alkoxide (Y1-2) (mass average molecular weight: 968) in which two in average of four isopropoxy groups in one molecule of the titanium tetraisopropoxide were substituted with polyethylene glycol monomethyl ether (molecular weight: 400) was obtained.

(Synthesis Example 4) Synthesis of Titanium Alkoxide (Y1-3)

(32) A reaction product was obtained in the same manner as in Synthesis Example 1, except that in Synthesis Example 1, the addition amount of the polyethylene glycol monomethyl ether was changed to 71 g.

(33) After 2.00 g of the obtained reaction product was weighed in an alumina-made crucible and heated at 600° C. for 3 hours, the amount of the residue (titanium oxide) was found to be 0.254 g (titanium content in the reaction product: 7.63% by mass). From this fact, it was confirmed that the targeted titanium alkoxide (Y1-3) (mass average molecular weight: 628) in which one in average of four isopropoxy groups in one molecule of the titanium tetraisopropoxide was substituted with polyethylene glycol monomethyl ether (molecular weight: 400) was obtained.

(Synthesis Example 5) Synthesis of Zirconium Alkoxide (X2)

(34) 50 g of zirconium tetra-n-propoxide (“ZA-45”, manufactured by Matsumoto Fine Chemical Co., Ltd., zirconium content: 21.0% by mass) and 184 g of polyethylene glycol monomethyl ether (“BLAUNON MP-400”) were charged in a reaction vessel equipped with a stirrer and stirred under a nitrogen gas stream at 90° C. for 24 hours, and n-propyl alcohol was discharged out the reaction vessel, to obtain a reaction product.

(35) After 2.00 g of the obtained reaction product was weighed in an alumina-made crucible and heated at 600° C. for 3 hours, the amount of the residue (zirconium oxide) was found to be 0.146 g (zirconium content in the reaction product: 5.40% by mass). In view of the fact that this zirconium content was coincident with the zirconium content in the alkoxide (mass average molecular weight: 1,687) in which four polyethylene glycol monomethyl ethers (molecular weight: 400) were bonded to one zirconium atom, it was confirmed that the targeted zirconium alkoxide (X2) was obtained.

(Synthesis Example 6) Synthesis of Zirconium Alkoxide (Y2-1)

(36) A reaction product was obtained in the same manner as in Synthesis Example 5, except that in Synthesis Example 5, the addition amount of the polyethylene glycol monomethyl ether was changed to 138 g.

(37) After 2.00 g of the obtained reaction product was weighed in an alumina-made crucible and heated at 600° C. for 3 hours, the amount of the residue (zirconium oxide) was found to be 0.182 g (zirconium content in the reaction product: 6.74% by mass). From this fact, it was confirmed that the targeted zirconium alkoxide (Y2-1) (mass average molecular weight: 1,347) in which three in average of four isopropoxy groups in one molecule of the zirconium tetraisopropoxide were substituted with polyethylene glycol monomethyl ether (molecular weight: 400) was obtained.

(Synthesis Example 7) Synthesis of Zirconium Alkoxide (Y2-2)

(38) A reaction product was obtained in the same manner as in Synthesis Example 5, except that in Synthesis Example 5, the addition amount of the polyethylene glycol monomethyl ether was changed to 92 g.

(39) After 2.00 g of the obtained reaction product was weighed in an alumina-made crucible and heated at 600° C. for 3 hours, the amount of the residue (zirconium oxide) was found to be 0.244 g (zirconium content in the reaction product: 9.02% by mass). From this fact, it was confirmed that the targeted zirconium alkoxide (Y2-2) (mass average molecular weight: 1,011) in which two in average of four isopropoxy groups in one molecule of the zirconium tetraisopropoxide were substituted with polyethylene glycol monomethyl ether (molecular weight: 400) was obtained.

(Synthesis Example 8) Synthesis of Zirconium Alkoxide (Y2-3)

(40) A reaction product was obtained in the same manner as in Synthesis Example 5, except that in Synthesis Example 5, the addition amount of the polyethylene glycol monomethyl ether was changed to 46 g.

(41) After 2.00 g of the obtained reaction product was weighed in an alumina-made crucible and heated at 600° C. for 3 hours, the amount of the residue (zirconium oxide) was found to be 0.367 g (zirconium content in the reaction product: 6.74% by mass). From this fact, it was confirmed that the targeted zirconium alkoxide (Y2-3) (mass average molecular weight: 671) in which one in average of four isopropoxy groups in one molecule of the zirconium tetraisopropoxide was substituted with polyethylene glycol monomethyl ether (molecular weight: 400) was obtained.

(Synthesis Example 9) Synthesis of Aluminum Alkoxide (X3)

(42) 50 g of aluminum trisecondary butoxide (“AL-3001”, manufactured by Matsumoto Fine Chemical Co., Ltd., aluminum content: 10.7% by mass) and 238 g of polyethylene glycol monomethyl ether (“BLAUNON MP-400”) were charged in a reaction vessel equipped with a stirrer and stirred under a nitrogen gas stream at 90° C. for 24 hours, and isopropyl alcohol was discharged out the reaction vessel, to obtain a reaction product.

(43) After 2.00 g of the obtained reaction product was weighed in an alumina-made crucible and heated at 600° C. for 3 hours, the amount of the residue (aluminum oxide) was found to be 0.0831 g (aluminum content in the reaction product: 2.20% by mass). In view of the fact that this aluminum content was coincident with the aluminum content in the alkoxide (mass average molecular weight: 1,224) in which three polyethylene glycol monomethyl ethers (molecular weight: 400) were coordinated with one aluminum atom, it was confirmed that the targeted aluminum alkoxide (X3) was obtained.

(Synthesis Example 10) Synthesis of Aluminum Alkoxide (Y3-1)

(44) A reaction product was obtained in the same manner as in Synthesis Example 9, except that in Synthesis Example 9, the addition amount of the polyethylene glycol monomethyl ether was changed to 159 g.

(45) After 2.00 g of the obtained reaction product was weighed in an alumina-made crucible and heated at 600° C. for 3 hours, the amount of the residue (aluminum oxide) was found to be 0.113 g (aluminum content in the reaction product: 3.00% by mass). From this fact, it was confirmed that the targeted aluminum alkoxide (Y3-1) (mass average molecular weight: 898) in which two in average of three secondary butoxy groups in one molecule of the aluminum trisecondary butoxide were substituted with polyethylene glycol monomethyl ether (molecular weight: 400) was obtained.

(Synthesis Example 11) Synthesis of Aluminum Alkoxide (Y3-2)

(46) A reaction product was obtained in the same manner as in Synthesis Example 9, except that in Synthesis Example 9, the addition amount of the polyethylene glycol monomethyl ether was changed to 79 g.

(47) After 2.00 g of the obtained reaction product was weighed in an alumina-made crucible and heated at 600° C. for 3 hours, the amount of the residue (aluminum oxide) was found to be 0.178 g (aluminum content in the reaction product: 4.71% by mass). From this fact, it was confirmed that the targeted aluminum alkoxide (Y3-2) (mass average molecular weight: 573) in which one in average of three secondary butoxy groups in one molecule of the aluminum trisecondary butoxide was substituted with polyethylene glycol monomethyl ether (molecular weight: 400) was obtained.

(48) [Production of Aqueous Acrylic Resin Composition]

Example 1

(49) In a 200-mL plastic container, 100 g of the acrylic resin A (emulsion) as an aqueous resin, 18 g of the polycarbodiimide (Z1) (carbodiimide group: 0.5 mol per mol of the alcoholic hydroxy group of the aqueous resin), and 2.0 g of the titanium alkoxide (X1) (0.13 parts by mass based on 100 parts by mass of the aqueous resin (solid component) as expressed in terms of a metal element amount) were weighed and mixed and stirred for 1 hour, to obtain an aqueous acrylic resin composition.

Examples 2 to 19

(50) Each of aqueous acrylic resin compositions was obtained in the same manner as in Example 1, except for using a blending composition as shown in the following Table 1.

Comparative Examples 1 to 9

(51) Each of aqueous acrylic resin compositions was obtained in the same manner as in Example 1, except for using a blending composition as shown in the following Table 2.

(52) [Solvent Resistance Evaluation (1) of Coating Film]

(53) Using each of the aqueous acrylic resin compositions obtained the aforementioned Examples and Comparative Examples, a coating film sample was prepared in the following manner, and a solvent resistance test of the coating film sample was performed. For reference, a coating film sample prepared using only the acrylic resin A was designated as Comparative Example 10, and this was subjected to the same test.

(54) (Preparation of Coating Film Sample)

(55) The aqueous acrylic resin composition immediately after preparation through stirring with a stirrer in a beaker for 1 hour was coated in a thickness of about 60 μm on an aluminum plate substrate by using a bar coater and dried for 10 minutes in a drying machine at a setting temperature of 130° C. Thereafter, the resultant was aged in a room at 25° C. for 1 day, to obtain a coating film sample.

(56) In addition, the above-prepared aqueous acrylic resin composition was stored in a room at 25° C. for 1 week, and using this aqueous acrylic resin composition, a coating film sample was prepared in the same manner.

(57) (Solvent Resistance Test)

(58) Each of the above-prepared coating film samples was subjected to a solvent resistance test by performing reciprocal double rubbing of 50 times with cotton wool impregnated with a 95% by volume ethanol aqueous solution as a solvent (load: 900 g/cm.sup.2) using a friction tester (“Model FR-1B”, manufactured by Suga Test Instruments Co., Ltd.). The solvent resistance of the coating film is an index of the crosslinking degree of a cured coating film of the aqueous resin composition, and it is expressed that the higher the crosslinking degree, the more excellent the solvent resistance is.

(59) The state of the coating film sample after the test was visually observed and evaluated according to the following evaluation criteria.

(60) <Evaluation Criteria>

(61) A: The coating film was not changed (colorless and transparent) or had thin rubbing marks.

(62) B: The coating film was partially whitened.

(63) C: The coating film was entirely whitened.

(64) D: A part of the coating film was dissolved, and a part of the substrate at the rubbed place was exposed.

(65) E: The coating film was dissolved, and the whole of the substrate at the rubbed place was exposed.

(66) The coating film graded as “Evaluation A” has sufficient solvent resistance, and it may be said that the cured coating film of the aqueous resin composition has a sufficiently high crosslinking degree. The coating film graded as “Evaluation B” is inferior to one graded as “Evaluation A”, but it may be said that the cured coating film has solvent resistance and has a high crosslinking degree. The coating films graded as “Evaluation C” and “Evaluation D” are not said to be sufficient in terms of the solvent resistance and are insufficient in terms of the crosslinking degree; and it may be considered that the coating film graded as “Evaluation C” is low in terms of the crosslinking degree, and the coating film graded as “Evaluation D” is very low in terms of the crosslinking degree or is not substantially crosslinked. The coating film graded as “Evaluation E” can be considered to be not crosslinked. These evaluation results are shown in the following Tables 1 and 2.

(67) TABLE-US-00001 TABLE 1 Example Blending composition [g] 1 2 3 4 5 6 7 8 9 10 Aqueous resin Acrylic resin A (emulsion) 100 100 100 100 100 100 100 100 100 100 (solid component: 45% by mass) Acrylic resin B (emulsion) (solid component: 45% by mass) Compound (Z) Polycarbodiimide (Z1) (solid 18 18 18 18 18 18 18 18 18 18 component: 40% by mass) Polyoxazoline (Z2) (solid component: 39% by mass) (Carbodiimide group or (0.5) (0.5) (0.5) (0.5) (0.5) (0.5) (0.5) (0.5) (0.5) (0.5) oxazoline group [mol] (vs. alcoholic hydroxy group or carboxy group of aqueous resin: total: 1 mol)) Metal alkoxide Titanium alkoxide (X1) 2.0 0.33 0.67 17.3 34.5 Titanium alkoxide (Y1-1) 1.6 Titanium alkoxide (Y1-2) 1.2 Zirconium alkoxide (X2) 1.1 Zirconium alkoxide (Y2-1) 0.89 Zirconium alkoxide (Y2-2) 0.7 Aluminum alkoxide (X3) Aluminum alkoxide (Y3-1) (Expressed in terms of a (0.13) (0.02) (0.04) (2.1) (2.2) (0.13) (0.13) (0.13) (0.13) (0.13) metal element amount [parts by mass] (vs. 100 parts by mass of aqueous resin)) Solvent resistance evaluation of coating film Immediately after B B B B B B B B B B preparation Stored for 1 week A B A B B A A A A A Example Blending composition [g] 11 12 13 14 15 16 17 18 19 Aqueous resin Acrylic resin A (emulsion) 100 100 100 100 100 100 100 100 (solid component: 45% by mass) Acrylic resin B (emulsion) 100 (solid component: 45% by mass) Compound (Z) Polycarbodiimide (Z1) (solid 18 18 3.6 7.2 72 90 18 component: 40% by mass) Polyoxazoline (Z2) (solid 10 10 component: 39% by mass) (Carbodiimide group or (0.5) (0.5) (0.1) (0.2) (0.2) (2.5) (0.5) (0.5) (0.5) oxazoline group [mol] (vs. alcoholic hydroxy group or carboxy group of aqueous resin: total: 1 mol)) Metal alkoxide Titanium alkoxide (X1) 2.0 2.0 2.0 2.0 2.0 2.0 Titanium alkoxide (Y1-1) 1.6 Titanium alkoxide (Y1-2) Zirconium alkoxide (X2) Zirconium alkoxide (Y2-1) Zirconium alkoxide (Y2-2) Aluminum alkoxide (X3) 2.7 Aluminum alkoxide (Y3-1) 2.9 (Expressed in terms of a metal (0.13) (0.13) (0.13) (0.13) (0.13) (0.13) (0.13) (0.13) (0.13) element amount [parts by mass] (vs. 100 parts by mass of aqueous resin)) Solvent resistance evaluation of coating film Immediately after B B B B B B B A A preparation Stored for 1 week A A B A A B A A A

(68) TABLE-US-00002 TABLE 2 Comparative Example Blending composition [g] 1 2 3 4 5 6 7 8 9 10 Aqueous resin Acrylic resin A (emulsion) 100 100 100 100 100 100 100 100 100 (solid component: 45% by mass) Acrylic resin B (emulsion) 100 (solid component: 45% by mass) Compound (Z) Polycarbodiimide (Z1) 18 18 18 18 18 18 (solid component: 40% by mass) Polyoxazoline (Z2) 10 (solid component: 39% by mass) (Carbodiimide group or oxazoline group (0.5) (0.5) (0.5) (0.5) (0.5) (0.5) (0.5) [mol] (vs. alcoholic hydroxy group or carboxy group of aqueous resin: total: 1 mol)) Metal alkoxide Titanium alkoxide (X1) 2.0 Titanium alkoxide (Y1-1) 1.6 Titanium alkoxide (Y1-3) 0.77 Zirconium alkoxide (Y2-3) 0.4 Aluminum alkoxide (Y3-2) 1.24 Titanium tetra-n-butoxide 0.43 (Expressed in terms of a metal (0.13) (0.13) (0.13) (0.13) (0.13) (0.13) element amount [parts by mass] (vs. 100 parts by mass of aqueous resin)) Solvent resistance evaluation of coating film Immediately after preparation C C C C C E C D D E Stored for 1 week C C C C C E C D D E
[Production of Aqueous Polyurethane Resin Composition]

Example 20

(69) In a 200-mL plastic container, 100 g of the polyurethane resin dispersion as an aqueous resin, 7.00 g of the polycarbodiimide compound (Z1) (carbodiimide group: 0.66 mol per mol of the carboxy group of the aqueous resin), and 2.0 g of the titanium alkoxide compound (X1) (0.17 parts by mass based in 100 parts by mass of the aqueous resin (solid component) as expressed in terms of a metal element amount) were weighed and mixed and stirred for 1 hour, to obtain an aqueous polyurethane resin composition.

Examples 21 to 27 and Comparative Examples 11 to 14

(70) Each of aqueous polyurethane resin compositions was obtained in the same manner as in Example 20, except for using a blending composition as shown in the following Table 3.

(71) [Solvent Resistance Evaluation (2) of Coating Film]

(72) Using each of the aqueous polyurethane resin compositions obtained the aforementioned Examples and Comparative Examples, a coating film sample was prepared in the following manner, and a solvent resistance test of the coating film sample was performed.

(73) (Preparation of Coating Film Sample)

(74) The aqueous polyurethane resin composition immediately after preparation through stirring with a stirrer in a beaker for 1 hour was coated in a thickness of about 60 μm on an aluminum plate substrate by using a bar coater and dried for 5 hours in a room at a setting temperature of 25° C., to obtain a coating film sample.

(75) (Solvent Resistance Test)

(76) Each of the above-prepared coating film samples was subjected to a solvent resistance test by performing reciprocal double rubbing of 100 times with cotton wool impregnated with a 95% by volume ethanol aqueous solution as a solvent (load: 900 g/cm.sup.2) using a friction tester (“Model FR-1B”, manufactured by Suga Test Instruments Co., Ltd.). The solvent resistance of the coating film is an index of the crosslinking degree of a cured coating film of the aqueous resin composition, and it is expressed that the higher the crosslinking degree, the more excellent the solvent resistance is.

(77) The state of the coating film sample after the test was visually observed and evaluated according to the following evaluation criteria.

(78) <Evaluation Criteria>

(79) A: The coating film was not changed.

(80) B: The coating film was whitened and scratched.

(81) C: The coating film was pierced, and a part of the substrate at the rubbed place was exposed.

(82) D: The coating film was dissolved, and the whole of the substrate at the rubbed place was exposed.

(83) The coating film graded as “Evaluation A” has sufficient solvent resistance, and it may be said that the cured coating film of the aqueous resin composition has a sufficiently high crosslinking degree. The coating film graded as “Evaluation B” is inferior to one graded as “Evaluation A”, but it may be said that the cured coating film has solvent resistance and has a high crosslinking degree. The coating films graded as “Evaluation C” and “Evaluation D” are not said to be sufficient in terms of the solvent resistance and are insufficient in terms of the crosslinking degree; and it may be considered that the coating film graded as “Evaluation C” is low in terms of the crosslinking degree, and the coating film graded as “Evaluation D” is very low in terms of the crosslinking degree or is not substantially crosslinked.

(84) These evaluation results are shown in the following Table 3.

(85) TABLE-US-00003 TABLE 3 Example Blending composition [g] 20 21 22 23 24 25 26 Aqueous resin Polyurethane resin dispersion 100 100 100 100 100 100 100 (solid component: 35% by mass) Compound (Z) Polycarbodiimide (Z1) 7.0 7.0 7.0 7.0 7.0 7.0 7.0 (solid component: 40% by mass) (Carbodiimide group [mol] (0.66) (0.66) (0.66) (0.66) (0.66) (0.66) (0.66) (vs. carboxy group of aqueous resin: total: 1 mol)) Metal alkoxide Titanium alkoxide (X1) 2.0 Titanium alkoxide (Y1-1) 1.6 Titanium alkoxide (Y1-2) 1.2 Zirconium alkoxide (X2) 1.1 Zirconium alkoxide (Y2-1) 0.89 Zirconium alkoxide (Y2-2) 0.7 Aluminum alkoxide (X3) 2.7 Aluminum alkoxide (Y3-1) (Expressed in terms of a metal (0.17) (0.17) (0.17) (0.17) (0.17) (0.17) (0.17) element amount [parts by mass] (vs. 100 parts by mass of aqueous resin)) Solvent resistance evaluation of A A A A A A A coating film Example Comparative Example Blending composition [g] 27 11 12 13 14 Aqueous resin Polyurethane resin dispersion 100 100 100 100 100 (solid component: 35% by mass) Compound (Z) Polycarbodiimide (Z1) 7.0 7.0 (solid component: 40% by mass) (Carbodiimide group [mol] (0.66) (0.66) (vs. carboxy group of aqueous resin: total: 1 mol)) Metal alkoxide Titanium alkoxide (X1) 2.0 Titanium alkoxide (Y1-1) Titanium alkoxide (Y1-2) Zirconium alkoxide (X2) 1.1 Zirconium alkoxide (Y2-1) Zirconium alkoxide (Y2-2) Aluminum alkoxide (X3) 2.7 Aluminum alkoxide (Y3-1) 2.9 (Expressed in terms of a metal (0.17) (0.17) (0.17) (0.17) element amount [parts by mass] (vs. 100 parts by mass of aqueous resin)) Solvent resistance evaluation of A D D D C coating film

(86) As noted from the evaluation results shown in Tables 1 to 3, it was perceived that the coating film formed using the aqueous resin composition of the present invention has a sufficiently high crosslinking degree. That is, it was perceived that by jointly using the compound (Z) and the metal alkoxide (X) or (Y), the crosslinking reactivity relative to the hydrophilic crosslinking group of the aqueous resin can be improved.