ADHESIVE AND SYNTHETIC LEATHER

Abstract

The present invention provides an adhesive characterized by containing an anionic urethane resin (A) having a flow-starting temperature of 100 C. or lower, a neutralizing agent (B), a carbodiimide crosslinking agent (C), and an aqueous medium (D). The present invention also provides a synthetic leather characterized by including at least a substrate (i), an adhesive layer (ii) formed of the adhesive, and a surface layer (iii). The carbodiimide crosslinking agent (C) is preferably produced from a starting material containing one or more polyisocyanates selected from the group consisting of 1,3-bis(1-methyl-1-isocyanatoethyl)benzene, 1,4-bis(1-methyl-1-isocyanatoethyl)benzene, and dicyclohexylmethane diisocyanate.

Claims

1. An adhesive comprising an anionic urethane resin (A) having a flow-starting temperature of 100 C. or lower, a neutralizing agent (B), a carbodiimide crosslinking agent (C), and an aqueous medium (D).

2. An adhesive according to claim 1, wherein the anionic urethane resin (A) has an acid value in the range of 1 to 35 mgKOH/g.

3. The adhesive according to claim 1 [[or 2]], wherein the neutralizing agent (B) has a boiling point of 200 C. or lower.

4. The adhesive according to claim 1, wherein the carbodiimide crosslinking agent (C) is produced from a starting material comprising one or more polyisocyanates selected from the group consisting of 1,3-bis(1-methyl-1-isocyanatoethyl)benzene, 1,4-bis(1-methyl-1-isocyanatoethyl)benzene, and dicyclohexylmethane diisocyanate.

5. The adhesive according to claim 1, wherein the carbodiimide crosslinking agent (C) is contained in an amount in the range of 0.5 to 25 parts by mass relative to 100 parts by mass of the anionic urethane resin (A).

6. A synthetic leather comprising at least a substrate (i), an adhesive layer (ii) formed of the adhesive according to claim 1, and a surface layer (iii).

7. The adhesive according to claim 2, wherein the neutralizing agent (B) has a boiling point of 200 C. or lower.

8. The adhesive according to claim 2, wherein the carbodiimide crosslinking agent (C) is produced from a starting material comprising one or more polyisocyanates selected from the group consisting of 1,3-bis(1-methyl-1-isocyanatoethyl)benzene, 1,4-bis(1-methyl-1-isocyanatoethyl)benzene, and dicyclohexylmethane diisocyanate.

9. The adhesive according to claim 3, wherein the carbodiimide crosslinking agent (C) is produced from a starting material comprising one or more polyisocyanates selected from the group consisting of 1,3-bis(1-methyl-1-isocyanatoethyl)benzene, 1,4-bis(1-methyl-1-isocyanatoethyl)benzene, and dicyclohexylmethane diisocyanate.

10. The adhesive according to claim 7, wherein the carbodiimide crosslinking agent (C) is produced from a starting material comprising one or more polyisocyanates selected from the group consisting of 1,3-bis(1-methyl-1-isocyanatoethyl)benzene, 1,4-bis(1-methyl-1-isocyanatoethyl)benzene, and dicyclohexylmethane diisocyanate.

11. The adhesive according to claim 2, wherein the carbodiimide crosslinking agent (C) is contained in an amount in the range of 0.5 to 25 parts by mass relative to 100 parts by mass of the anionic urethane resin (A).

12. The adhesive according to claim 3, wherein the carbodiimide crosslinking agent (C) is contained in an amount in the range of 0.5 to 25 parts by mass relative to 100 parts by mass of the anionic urethane resin (A).

13. The adhesive according to claim 4, wherein the carbodiimide crosslinking agent (C) is contained in an amount in the range of 0.5 to 25 parts by mass relative to 100 parts by mass of the anionic urethane resin (A).

14. The adhesive according to claim 7, wherein the carbodiimide crosslinking agent (C) is contained in an amount in the range of 0.5 to 25 parts by mass relative to 100 parts by mass of the anionic urethane resin (A).

15. The adhesive according to claim 8, wherein the carbodiimide crosslinking agent (C) is contained in an amount in the range of 0.5 to 25 parts by mass relative to 100 parts by mass of the anionic urethane resin (A).

16. The adhesive according to claim 9, wherein the carbodiimide crosslinking agent (C) is contained in an amount in the range of 0.5 to 25 parts by mass relative to 100 parts by mass of the anionic urethane resin (A).

17. A synthetic leather comprising at least a substrate (i), an adhesive layer (ii) formed of the adhesive according to claim 2, and a surface layer (iii).

18. A synthetic leather comprising at least a substrate (i), an adhesive layer (ii) formed of the adhesive according to claim 3, and a surface layer (iii).

19. A synthetic leather comprising at least a substrate (i), an adhesive layer (ii) formed of the adhesive according to claim 4, and a surface layer (iii).

20. A synthetic leather comprising at least a substrate (i), an adhesive layer (ii) formed of the adhesive according to claim 5, and a surface layer (iii).

Description

EXAMPLES

[0054] The present invention will be described in detail below with reference to examples.

Example 1

[0055] In the presence of 1,374 parts by mass of methyl ethyl ketone and 0.1 parts by mass of stannous octanoate, 1,000 parts by mass of a polyether polyol (PTMG 1000 manufactured by Mitsubishi Chemical Corporation, number average molecular weight; 1,000), 57 parts by mass of 2,2-dimethylolpropionic acid, and 317 parts by mass of isophorone diisocyanate were reacted at 70 C. until the viscosity of the solution reached 20,000 mPa.Math.s. Subsequently, 3 parts by mass of methanol was added to terminate the reaction, thereby obtaining a solution of an anionic urethane resin in methyl ethyl ketone. Into the urethane resin solution, 69 parts by mass of polyoxyethylene distyrenated phenyl ether (hydrophile-lipophile balance (hereinafter abbreviated as HLB) : 13) and 38 parts by mass of triethylamine (neutralizing agent; boiling point: 89.5 C.) were mixed, and then 2,748 parts by mass of ion exchange water was added to effect phase-transfer emulsification, thereby obtaining an emulsion in which the anionic urethane resin was dispersed in water.

[0056] Then, methyl ethyl ketone was distilled from the emulsion to thereby obtain a urethane resin composition having a nonvolatile content of 35% by mass. Note that the anionic urethane resin had a flow-starting temperature of 40 C. or lower and an acid value of 17.4 mgKOH/g.

[0057] Into 100 parts by mass of the obtained urethane resin composition, 1 part by mass of a thickening agent (Borchi Gel 0620 manufactured by Borchers) and 9 parts by mass of a carbodiimide crosslinking agent (produced from a starting material containing 1,3-bis(1-methyl-1-isocyanatoethyl)benzene and polyalkylene glycol monomethyl ether, solid content: 40% by mass, hereinafter abbreviated as crosslinking agent (1)) were put, and the mixture was stirred with a mechanical mixer at 2,000 rpm for 2 minutes, and was deaerated with a vacuum deaerator, thereby obtaining an adhesive.

[Method for Measuring Flow-starting Temperature of Anionic Urethane Resin (A)]

[0058] The urethane resin composition before blending a crosslinking agent was applied on a release paper (application thickness: 150 m), and was dried with a hot air drier at 70 C. for 2 minutes and then at 120 C. for 2 minutes, thereby obtaining a dried product. The dried product was measured for the flow-starting temperature using a flow tester CFT-500A manufactured by Shimadzu Corporation (a dice with a caliber of 1 mm and a length of 1 mm was used, load: 98 N, temperature rising rate: 3 C./minute).

[Method for Measuring Acid Value of Anionic Urethane Resin (A)]

[0059] The urethane resin composition before blending a crosslinking agent was dried and 0.05 g to 0.5 g of the dry solidified resin particles were weighed into a 300 mL Erlenmeyer flask, and then, about 80 mL of a mixed solvent of tetrahydrofuran and ion exchange water having a mass ratio [tetrahydrofuran/ion exchange water] of 80/20 was added to obtain a mixture liquid thereof.

[0060] Then, after addition of phenol phthalein indicator to the mixture liquid, the mixture liquid was titrated with an 0.1 mol/L aqueous potassium hydroxide solution whose concentration was precisely determined in advance, and the acid value (mgKOH/g) of the aqueous urethane resin (A) was determined according the following calculation formula (1) based on the amount of the aqueous potassium hydroxide solution used in the titration.

Calculation formula: A=(Bf5.611)/S (1)

In the formula, A is the acid value (mgKOH/g) of the resin solid component, B is the amount of the 0.1 mol/L aqueous potassium hydroxide solution (mL) used in the titration, f is the factor of the 0.1 mol/L aqueous potassium hydroxide solution, S is the mass of the resin particles (g) , and 5.611 is the formula weight of potassium hydroxide (56.11/10).

EXAMPLE 2

[0061] An adhesive was obtained in the same manner as in Example 1 except for changing the polyether polyol to a polyester polyol (ETERNACOLL UH-100 manufactured by Ube Industries, Ltd., number average molecular weight: 1,000). Note that the anionic urethane resin had a flow-starting temperature of 40 C. or lower and an acid value of 17.2 mgKOH/g.

EXAMPLE 3

[0062] An adhesive was obtained in the same manner as in Example 1 except for changing the polyether polyol to a polyester polyol (PLACCEL 210 manufactured by Daicel Corporation, number average molecular weight: 1,000). Note that the anionic urethane resin had a flow-starting temperature of 40 C. or lower and an acid value of 17.2 mgKOH/g.

EXAMPLE 4

[0063] In the presence of 1,374 parts by mass of methyl ethyl ketone and 0.1 parts by mass of stannous octanoate, 1,000 parts by mass of a polyether polyol (PTMG 1000 manufactured by Mitsubishi Chemical Corporation, number average molecular weight: 1,000), 57 parts by mass of 2,2-dimethylolpropionic acid, and 317 parts by mass of isophorone diisocyanate were reacted at 70 C. until the viscosity of the solution reached 20,000 mPa.Math.s, and then 3 parts by mass of methanol was added to terminate the reaction, thereby obtaining a solution of an anionic urethane resin in methyl ethyl ketone. Into the urethane resin solution, 69 parts by mass of polyoxyethylene distyrenated phenyl ether (hydrophile-lipophile balance (hereinafter abbreviated as HLB) : 13) and 61 parts by mass of tripropylamine (neutralizing agent; boiling point: 156 C.) were mixed, and then 2,748 parts by mass of ion exchange water was added to effect phase-transfer emulsification, thereby obtaining an emulsion in which the anionic urethane resin was dispersed in water.

[0064] Then, methyl ethyl ketone was distilled from the emulsion to thereby obtain a urethane resin composition having a nonvolatile content of 35% by mass. Note that the anionic urethane resin had a flow-starting temperature of 40 C. or lower and an acid value of 17.4 mgKOH/g.

EXAMPLE 5

[0065] In the presence of 1,374 parts by mass of methyl ethyl ketone and 0.1 parts by mass of stannous octanoate, 1,000 parts by mass of a polyether polyol (PTMG 1000 manufactured by Mitsubishi Chemical Corporation, number average molecular weight: 1,000), 57 parts by mass of 2,2-dimethylolpropionic acid, and 317 parts by mass of isophorone diisocyanate were reacted at 70 C. until the viscosity of the solution reached 40,000 mPa.Math.s, and then 3 parts by mass of methanol was added to terminate the reaction, thereby obtaining a solution of an anionic urethane resin in methyl ethyl ketone. Into the urethane resin solution, 69 parts by mass of polyoxyethylene distyrenated phenyl ether (hydrophile-lipophile balance (hereinafter abbreviated as HLB) : 13) and 38 parts by mass of triethylamine (neutralizing agent; boiling point: 89.5 C.). were mixed, and then 2,748 parts by mass of ion exchange water was added to effect phase-transfer emulsification, thereby obtaining an emulsion in which the anionic urethane resin was dispersed in water.

[0066] Then, methyl ethyl ketone was distilled from the emulsion to thereby obtain a urethane resin composition having a nonvolatile content of 35% by mass. Note that the anionic urethane resin had a flow-starting temperature of 52 C. and an acid value of 17.4 mgKOH/g.

[0067] Into 100 parts by mass of the obtained urethane resin composition, 1 part by mass of a thickening agent (Borchi Gel 0620 manufactured by Borchers) and 9 parts by mass of a carbodiimide crosslinking agent (1) were put, and the mixture was stirred with a mechanical mixer at 2,000 rpm for 2 minutes, and was deaerated with a vacuum deaerator, thereby obtaining an adhesive.

EXAMPLE 6

[0068] In the presence of 1,418 parts by mass of methyl ethyl ketone and 0.1 parts by mass of stannous octanoate, 1,000 parts by mass of a polyether polyol (PTMG1000 manufactured by Mitsubishi Chemical Corporation, number average molecular weight: 1,000), 74 parts by mass of 2,2-dimethylolpropionic acid, and 345 parts by mass of isophorone diisocyanate were reacted at 70 C. until the viscosity of the solution reached 20,000 mPa.Math.s, and then 3 parts by mass of methanol was added to terminate the reaction, thereby obtaining a solution of an anionic urethane resin in methyl ethyl ketone. Into the urethane resin solution, 69 parts by mass of polyoxyethylene distyrenated phenyl ether (hydrophile-lipophile balance (hereinafter abbreviated as HLB) : 13) and 38 parts by mass of triethylamine (neutralizing agent; boiling point: 89.5 C.). were mixed, then 2,836 parts by mass of ion exchange water was added to effect phase-transfer emulsification, thereby obtaining an emulsion in which the anionic urethane resin was dispersed in water.

[0069] Then, methyl ethyl ketone was distilled from the emulsion to thereby obtain a urethane resin composition having a nonvolatile content of 35% by mass. Note that the anionic urethane resin had a flow-starting temperature of 40 C. or lower and an acid value of 21.8 mgKOH/g.

[0070] Into 100 parts by mass of the obtained urethane resin composition, 1 part by mass of a thickening agent (Borchi Gel 0620 manufactured by Borchers) and 12 parts by mass of a crosslinking agent (1) were put, and the mixture was stirred with a mechanical mixer at 2,000 rpm for 2 minutes, and was deaerated with the vacuum deaerator, thereby obtaining an adhesive.

COMPARATIVE EXAMPLE 1

[0071] An adhesive was obtained in the same manner as in Example 1 except that the carbodiimide crosslinking agent was not used in Example 1.

COMPARATIVE EXAMPLE 2

[0072] An adhesive was obtained in the same manner as in Example 1 except that an oxazoline crosslinking agent (EPOCROS WS-700 manufactured by Nippon Shokubai Co., Ltd., solid content: 25% by mass) was used in place of the carbodiimide crosslinking agent in Example 1.

COMPARATIVE EXAMPLE 3

[0073] In the presence of 4,121 parts by mass of methyl ethyl ketone and 0.1 parts by mass of stannous octanoate, 1,000 parts by mass of a polyether polyol (PTMG1000 manufactured by Mitsubishi Chemical Corporation, number average molecular weight: 1,000), 57 parts by mass of 2,2-dimethylolpropionic acid, and 317 parts by mass of isophorone diisocyanate were reacted at 70 C. until the viscosity of the solution reached 100,000 mPa.Math.s, and then 3 parts by mass of methanol was added to terminate the reaction, thereby obtaining a solution of an anionic urethane resin in methyl ethyl ketone. Into the urethane resin solution, 69 parts by mass of polyoxyethylene distyrenated phenyl ether (hydrophile-lipophile balance (hereinafter abbreviated as HLB) : 13) and 38 parts by mass of triethylamine (neutralizing agent; boiling point: 89.5 C.) were mixed, and then 5,495 parts by mass of ion exchange water was added to effect phase-transfer emulsification, thereby obtaining an emulsion in which the anionic urethane resin was dispersed in water.

[0074] Then, methyl ethyl ketone was distilled from the emulsion to thereby obtain a urethane resin composition having a nonvolatile content of 35% by mass. Note that the anionic urethane resin had a flow-starting temperature of 110 C. and an acid value of 17.4 mgKOH/g.

[0075] Into 100 parts by mass of the obtained urethane resin composition, 1 part by mass of a thickening agent (Borchi Gel 0620 manufactured by Borchers) and 9 parts by mass of a crosslinking agent (1) were put, and the mixture was stirred with a mechanical mixer at 2,000 rpm for 2 minutes and was deaerated with a vacuum deaerator, thereby obtaining an adhesive.

PREPARATION EXAMPLE 1

Preparation of Formulation Liquid for Surface Layer

[0076] 100 parts by mass of an ether-based urethane dispersion (HYDRAN WLS-120AR manufactured by DIC Corporation, 2 parts by mass of a thickening agent (Borch Gel ALA manufactured by Borcher), 0.2 parts by mass of a leveling agent (TEGO Flow 425 manufactured by Evonik), 0.2 parts by mass of a defoaming agent (TEGO Twin 4000 manufactured by Evonik), and 5 parts by mass of a black pigment (DILAC HS-9550 manufactured by DIC Corporation) were stirred with a mechanical mixer at 2,000 rpm for 2 minutes, and was then deaerated using a vacuum deaerator to thereby obtain a formulation liquid for a surface layer.

[Method of Producing Synthetic Leather]

[0077] On a release paper (EK-100D manufactured by Lintec Corporation), the formulation liquid for a surface layer was applied with a knife coater (application thickness: 150 m), and then was dried using a hot air drier at 70 C. for 2 minutes and then at 120 C. for 2 minutes, thereby obtaining a surface layer. The adhesives obtained in Examples and Comparative Examples were each further applied on the surface layer with a knife coater (application thickness: 150 m), and then was dried using a hot air drier at 70 C. for 6 minutes. Finally, the nonwoven fabric substrate was superimposed on the dried product, and this assembly was then heat bonded by hot roll press (roll temperature: 100 C., press line pressure: 3 MPa/m.sup.2, feed rate: 1 m/min) and was further subjected to aging with a hot air drier at 70 C. for 2 days, thereby obtaining a synthetic leather.

[Method for Measuring Number Average Molecular Weight]

[0078] As the number average molecular weights of polyols and the like used in Examples and Comparative Examples, values measured by gel permeation chromatography (GPC) under the following conditions are shown.

Measurement Apparatus: High Speed GPC Apparatus (HLC-8220GPC manufactured by TOSOH Corporation) [0079] Column: the following columns manufactured by TOSOH Corporation were directly connected and used.

[0080] TSKgel G5000 (7.8 mm I.D.30 cm)1

[0081] TSKgel G4000 (7.8 mm I.D.30 cm)1

[0082] TSKgel G3000 (7.8 mm I.D.30 cm)1

[0083] TSKgel G2000 (7.8 mm I.D.30 cm)1 [0084] Detector: RI (refractive index detector) [0085] Column temperature: 40 C. [0086] Eluent: tetrahydrofuran (THF) [0087] Flow rate: 1.0 mL/minute [0088] Injection: 100 pL (tetrahydrofuran solution having sample concentration of 0.4% by mass) [0089] Standard samples: the following standard polystyrenes were used to create a calibration curve.
(Standard polystyrenes)

[0090] TSKgel standard polystyrene A-500 manufactured by TOSOH Corporation

[0091] TSKgel standard polystyrene A-1000 manufactured by TOSOH Corporation

[0092] TSKgel standard polystyrene A-2500 manufactured by TOSOH Corporation

[0093] TSKgel standard polystyrene A-5000 manufactured by TOSOH Corporation

[0094] TSKgel standard polystyrene F-1 manufactured by TOSOH Corporation

[0095] TSKgel standard polystyrene F-2 manufactured by TOSOH Corporation

[0096] TSKgel standard polystyrene F-4 manufactured by TOSOH Corporation

[0097] TSKgel standard polystyrene F-10 manufactured by TOSOH Corporation

[0098] TSKgel standard polystyrene F-20 manufactured by TOSOH Corporation

[0099] TSKgel standard polystyrene F-40 manufactured by TOSOH Corporation

[0100] TSKgel standard polystyrene F-80 manufactured by TOSOH Corporation

[0101] TSKgel standard polystyrene F-128 manufactured by TOSOH Corporation

[0102] TSKgel standard polystyrene F-288 manufactured by TOSOH Corporation

[0103] TSKgel standard polystyrene F-550 manufactured by TOSOH Corporation

[Method for Evaluating Pot Life]

[0104] In Examples and Comparative Examples, the viscosities of the adhesive at 10 minutes and at 3 days after blending the crosslinking agent were measured (Brookfield Viscometer, 10P corn, rotor revolution; 50 rpm). The case where the increasing rate of the viscosity after 3 days to the viscosity after 10 minutes was 0.5 to 2 times the increasing rate before blending the crosslinking agent was evaluated as 0, and the case where the former was less than 0.5 times or more than 2 times the latter was evaluated as .

[Method for Evaluating Peeling Strength]

[0105] A hot melt tape (BW-2 manufactured by Sun Chemical, Ltd.) having a width of 2.5 cm was placed on a surface of the synthetic leather and was heated at 150 C. for 30 seconds to bond the hot melt tape. Then, the sample was cut along the width of the hot melt tape. The sample was partially peeled, and the substrate and the hot melt tape were clipped with a chuck, and the peeling strength was measured using a tensile tester Autograph AG-I (manufactured by Shimadzu Corporation) (hereinafter abbreviated as initial peeling strength). The average of the obtained data (n=3) was determined and was converted based on 1 cm width (unit: kgf/cm).

[0106] In addition, in Examples and Comparative Examples, a synthetic leather which was produced at 6 hours after blending the crosslinking agent was evaluated in the same manner, and the obtained peeling strength was taken as a peeling strength at 6 hours after blending.

TABLE-US-00001 TABLE 1 Anionic urethane resin (A) Example 1 Example 2 Example 3 Example 4 Example 5 Flow-starting temperature ( C.) 40 C. or lower 40 C. or lower 40 C. or lower 40 C. or lower 52 C. Acid value (mgKOH/g) 17.4 17.4 17.4 17.4 17.4 Neutralizing agent (B) Triethylamine Triethylamine Triethylamine Tripropylamine Triethylamine Carbodiimide crosslinking agent (C) Crosslinking Crosslinking Crosslinking Crosslinking Crosslinking agent (1) agent (1) agent (1) agent (1) agent (1) Evaluation of pot life Evaluation of Initial 3.2 3.6 3.4 3.1 2.9 peeling strength 6 Hours after 3.5 3.9 3.6 3.3 3.1 blending

TABLE-US-00002 TABLE 2 Comparative Comparative Comparative Anionic urethane resin (A) Example 6 Example 1 Example 2 Example 3 Flow-starting temperature ( C.) 40 C. or lower 40 C. or lower 40 C. or lower 110 Acid value (mgKOH/g) 21.8 17.2 17.2 17.4 Neutralizing agent (B) Triethylamine Triethylamine Triethylamine Triethylamine Carbodiimide crosslinking agent (C) Crosslinking Oxazoline Crosslinking agent (1) crosslinking agent (1) agent Evaluation of pot life Evaluation of Initial 3.4 0.1 2 0.2 peeling strength 6 Hours after 3.5 0 1.8 0.1 blending

[0107] The adhesives of the present invention had a long available time (pot life) and were able to impart superior peeling strength.

[0108] On the other hand, Comparative Example 1, which was embodiment of containing no carbodiimide crosslinking agent (C), was insufficient in the peeling strength.

[0109] Comparative Example 2, which was an embodiment of using an oxazoline crosslinking agent in place of the carbodiimide crosslinking agent (C), was insufficient in the peeling strength.

[0110] Comparative Example 3, which was an embodiment of using an anionic urethane resin having a flow-starting temperature beyond the range defined in the present invention, was insufficient in the peeling strength.