ADHESIVE COMPOSITION AND LAMINATE

Abstract

Provided is an adhesive which, in a metal foil-containing laminated composite film used in a high temperature sterilization treatment, is resistant to the effects of moisture in the air during curing, has good workability when used as a solvent-free adhesive, and exhibits excellent adhesive strength and acid resistance. Provided is a method for producing an adhesive composition, the method including: a step of obtaining an alcohol-added isocyanate (E) by reacting a trifunctional or higher isocyanate compound (C2) and a monofunctional alcohol (D) at an equivalence ratio of isocyanate groups in the trifunctional or higher isocyanate compound (C2):monofunctional alcohol (D)=100 mol %:25 to 65 mol %, and a step of mixing a polyisocyanate (A) containing a trifunctional or higher isocyanate compound (C1) and the alcohol-added isocyanate (E), and an alcohol (B) having an acid value of 0.5 to 30 mgKOH/g, so that the equivalence ratio between isocyanate groups in the polyisocyanate (A) and hydroxyl groups in the alcohol (B) (isocyanate groups/hydroxyl groups) is within a range from 0.7 to 2.5.

Claims

1. A method for producing an adhesive composition, the method comprising: a step of obtaining an alcohol-added isocyanate (E) by reacting a trifunctional or higher isocyanate compound (C2) and a monofunctional alcohol (D) at an equivalence ratio of isocyanate groups in the trifunctional or higher isocyanate compound (C2):monofunctional alcohol (D)=100 mol %:25 to 65 mol %, and a step of mixing a polyisocyanate (A) comprising a trifunctional or higher isocyanate compound (C1) and the alcohol-added isocyanate (E), and an alcohol (B) having an acid value of 0.5 to 30 mgKOH/g, so that an equivalence ratio between isocyanate groups in the polyisocyanate (A) and hydroxyl groups in the alcohol (B) (isocyanate groups/hydroxyl groups) is within a range from 0.7 to 2.5.

2. The method for producing an adhesive composition according to claim 1, wherein the alcohol-added isocyanate (E) is included in an amount of 20 to 80% by weight out of 100% by weight of the polyisocyanate (A).

3. The method for producing an adhesive composition according to claim 1, wherein the trifunctional or higher isocyanate compound (C1) is a trimer of at least one diisocyanate compound selected from the group consisting of aliphatic diisocyanates, araliphatic diisocyanates and alicyclic diisocyanates.

4. The method for producing an adhesive composition according to claim 1, wherein the trifunctional or higher isocyanate compound (C2) is a trimer of at least one diisocyanate compound selected from the group consisting of aliphatic diisocyanates, araliphatic diisocyanates and alicyclic diisocyanates.

5. The method for producing an adhesive composition according to claim 1, wherein the monofunctional alcohol (D) is an alicyclic alcohol (D1).

6. The method for producing an adhesive composition according to claim 1, wherein the alcohol (B) comprises a polyol (B1) having an acid value of 1 to 15 mgKOH/g.

7. The method for producing an adhesive composition according to claim 6, wherein at least 70 mol % among 100 mol % of all hydroxyl groups within the polyol (B1) are primary hydroxyl groups.

8. The method for producing an adhesive composition according to claim 1, wherein the alcohol (B) comprises a polyol (B1) having an acid value of 15 to 40 mgKOH/g and a monofunctional alcohol (B2), wherein an amount of the monofunctional alcohol (B2) within 100% by weight of the alcohol (B) is not more than 50% by weight.

9. The method for producing an adhesive composition according to claim 8, wherein the adhesive composition satisfies a relationship of formula 1 shown below:
Xa/56.1×Xc−Yh/56.1×Yc≦0.26  (1) wherein Xa represents an acid value (mgKOH/g) of the polyol (B1), Xc represents a weight ratio of the polyol (B1) within a total weight of the polyol (B1) and the monofunctional alcohol (B2), Yh represents a hydroxyl value (mgKOH/g) of the monofunctional alcohol (B2), and Yc represents a weight ratio of the monofunctional alcohol (B2) within a total weight of the polyol (B1) and the monofunctional alcohol (B2).

10. The method for producing an adhesive composition according to claim 8, wherein a molecular weight of the monofunctional alcohol (B2) is at least 100 but not more than 6,000.

11. The method for producing an adhesive composition according to claim 1, wherein the adhesive composition is solvent-free.

12. The method for producing an adhesive composition according to claim 1, wherein the adhesive composition is for use in a laminated composite film containing a metal foil.

13. A method for producing a laminate, the method comprising a step of bonding at least two sheet-like substrates using an adhesive composition produced using the method for producing an adhesive composition according to claim 1.

Description

EXAMPLES

[0123] The present invention is described below in further detail using a series of examples, but the scope of the present invention is in no way limited by the following examples. In the examples, “parts” represents “parts by weight”, and “%” represents “% by weight”.

[0124] In the examples, the methods used for measuring the “viscosity”, “number average molecular weight”, “hydroxyl value”, “acid value” and “isocyanate equivalence” were as follows.

[0125] Viscosity: measured using a B-type viscometer (manufactured by Tokyo Keiki Inc., model number: BL).

[0126] Number average molecular weight: the polystyrene-equivalent molecular weight was used, and was measured using a Shodex GPC LF-604 column (manufactured by Shodex Inc.) and a GPC apparatus (GPC-104, manufactured by Shodex Inc.) fitted with an RI detector, and using THF as the developing solvent.

[0127] Hydroxyl value: measured in accordance with JIS K1557-1.

[0128] Acid value: measured in accordance with JIS K0070.

[0129] Isocyanate equivalence: measured in accordance with JIS K1603-1.

<Isocyanate Compound (C1)>

[0130] The following compounds were used as isocyanate compounds (C1-1) to (C1-3). [0131] C1-1: HDI biuret (product name: Basonat HB-100, manufactured by BASF Corporation) [0132] C1-2: HDI nurate (product name: TAKENATE D177N, manufactured by Mitsui Chemicals, Inc.) [0133] C1-3: IPDI nurate (product name: VESTANT 11890/100, manufactured by Evonik Industries AG)

(Synthesis Example 11) Isocyanate Compound (C1-4)

[0134] A reaction container was charged with 166.2 parts of a polyoxypropylene glyceryl ether having a number average molecular weight of 1,000 and an average number of hydroxyl groups of 3, and 83.8 parts of hexamethylene diisocyanate (200 mol % of isocyanate groups relative to 100 mol % of hydroxyl groups), and the mixture was reacted for 4 hours at 110° C. under constant stirring and under a stream of nitrogen gas, yielding an isocyanate compound (C1-4) with a number average molecular weight of 1,500. The isocyanate equivalence was 8.4%.

(Synthesis Example 12) Isocyanate Compound (C1-5)

[0135] A reaction container was charged with 87.2 parts of a polyoxypropylene glycol having a number average molecular weight of 600 and an average number of hydroxyl groups of 2, and 162.8 parts of hexamethylene diisocyanate biuret (300 mol % of isocyanate groups relative to 100 mol % of hydroxyl groups), and the mixture was reacted for 4 hours at 110° C. under constant stirring and under a stream of nitrogen gas, yielding an isocyanate compound (C1-5) with a number average molecular weight of 1,600. The isocyanate equivalence was 9.8%.

<Reaction Products (Alcohol-Added Isocyanates) (E) and (F)>

(Synthesis Example 1) Alcohol-Added Isocyanate (E-1)

[0136] A reaction container was charged with 219.9 parts of hexamethylene diisocyanate biuret and 30.1 parts of cyclohexanol (equivalent to 25 mol % relative to 100 mol % of isocyanate groups), and the mixture was reacted for 4 hours at 110° C. under constant stirring and under a stream of nitrogen gas, yielding an alcohol-added isocyanate (E-1).

(Synthesis Example 2) Alcohol-Added Isocyanate (E-2)

[0137] A reaction container was charged with 209.8 parts of hexamethylene diisocyanate biuret and 40.2 parts of cyclohexanol (equivalent to 35 mol % relative to 100 mol % of isocyanate groups), and the mixture was reacted for 4 hours at 110° C. under constant stirring and under a stream of nitrogen gas, yielding an alcohol-added isocyanate (E-2).

(Synthesis Example 3) Alcohol-Added Isocyanate (E-3)

[0138] A reaction container was charged with 184.4 parts of hexamethylene diisocyanate biuret and 65.6 parts of cyclohexanol (equivalent to 65 mol % relative to 100 mol % of isocyanate groups), and the mixture was reacted for 4 hours at 110° C. under constant stirring and under a stream of nitrogen gas, yielding an alcohol-added isocyanate (E-3).

(Synthesis Example 4) Alcohol-Added Isocyanate (E-4)

[0139] A reaction container was charged with 209.8 parts of hexamethylene diisocyanate biuret and 40.2 parts of hexanol (equivalent to 35 mol % relative to 100 mol % of isocyanate groups), and the mixture was reacted for 4 hours at 90° C. under constant stirring and under a stream of nitrogen gas, yielding an alcohol-added isocyanate (E-4).

(Synthesis Example 5) Alcohol-Added Isocyanate (E-5)

[0140] A reaction container was charged with 193.9 parts of hexamethylene diisocyanate biuret and 56.1 parts of borneol (equivalent to 35 mol % relative to 100 mol % of isocyanate groups), and the mixture was reacted for 4 hours at 110° C. under constant stirring and under a stream of nitrogen gas, yielding an alcohol-added isocyanate (E-5).

(Synthesis Example 6) Alcohol-Added Isocyanate (E-6)

[0141] A reaction container was charged with 193.3 parts of hexamethylene diisocyanate biuret and 56.7 parts of 1-menthol (equivalent to 35 mol % relative to 100 mol % of isocyanate groups), and the mixture was reacted for 4 hours at 110° C. under constant stirring and under a stream of nitrogen gas, yielding an alcohol-added isocyanate (E-6).

(Synthesis Example 7) Alcohol-Added Isocyanate (E-7)

[0142] A reaction container was charged with 213.6 parts of hexamethylene diisocyanate nurate and 36.4 parts of cyclohexanol (equivalent to 35 mol % relative to 100 mol % of isocyanate groups), and the mixture was reacted for 4 hours at 110° C. under constant stirring and under a stream of nitrogen gas, yielding an alcohol-added isocyanate (E-7).

(Synthesis Example 13) Alcohol-Added Isocyanate (E-8)

[0143] A reaction container was charged with 237.9 parts of the isocyanate compound (C1-4) and 12.1 parts of cyclohexanol (equivalent to 25 mol % relative to 100 mol % of isocyanate groups), and the mixture was reacted for 4 hours at 110° C. under constant stirring and under a stream of nitrogen gas, yielding an alcohol-added isocyanate (E-8) with a number average molecular weight of 1,580.

(Synthesis Example 14) Alcohol-Added Isocyanate (E-9)

[0144] A reaction container was charged with 236.0 parts of the isocyanate compound (C1-5) and 14.0 parts of cyclohexanol (equivalent to 25 mol % relative to 100 mol % of isocyanate groups), and the mixture was reacted for 4 hours at 110° C. under constant stirring and under a stream of nitrogen gas, yielding an alcohol-added isocyanate (E-9) with a number average molecular weight of 1,700.

(Synthesis Example 8) Alcohol-Added Isocyanate (F)

[0145] A reaction container was charged with 231.0 parts of hexamethylene diisocyanate biuret and 19.0 parts of cyclohexanol (equivalent to 15 mol % relative to 100 mol % of isocyanate groups), and the mixture was reacted for 4 hours at 110° C. under constant stirring and under a stream of nitrogen gas, yielding an alcohol-added isocyanate (F).

<Polyol (B1)>

(Synthesis Example 9) Polyol (B1-1)

[0146] A reaction container was charged with 175 parts of isophthalic acid, 320 parts of adipic acid, 49 parts of benzoic acid, 76 parts of ethylene glycol and 380 parts of neopentyl glycol, and an esterification was performed by heating at 150° C. to 240° C. under constant stirring and under a stream of nitrogen gas. When the acid value reached 2.1 (mgKOH/g), the reaction temperature was adjusted to 200° C., the pressure inside the reaction container was gradually reduced, and following the reaction for 30 minutes at a pressure of 1.3 kPa or lower, the reaction mixture was cooled to 110° C. Subsequently, 5.0 parts of trimellitic anhydride was added and an acid modification was performed at 110° C., yielding a polyol (B1-1). All of the hydroxyl groups of the obtained polyol (B1-1) were primary hydroxyl groups, the number average molecular weight was 750, the acid value was 3.6, and the hydroxyl value was 104.

(SYNTHESIS EXAMPLE 10) POLYOL (B1-2)

[0147] A reaction container was charged with 438 parts of isophthalic acid, 106 parts of ethylene glycol and 200 parts of neopentyl glycol, and an esterification was performed by heating at 150° C. to 240° C. under constant stirring and under a stream of nitrogen gas. When the acid value reached 1.5 (mgKOH/g), the reaction temperature was adjusted to 200° C., the pressure inside the reaction container was gradually reduced, and following the reaction for 30 minutes at a pressure of 1.3 kPa or lower, the reaction mixture was cooled to 110° C. Subsequently, 5.0 parts of trimellitic anhydride was added and an acid modification was performed at 110° C., yielding a polyol (B1-2). All of the hydroxyl groups of the obtained polyol (B1-2) were primary hydroxyl groups, the number average molecular weight was 850, the acid value was 5.1, and the hydroxyl value was 93.

(Synthesis Example 15) Polyol (B1-3)

[0148] A reaction container was charged with 175 parts of isophthalic acid, 320 parts of adipic acid, 49 parts of benzoic acid, 76 parts of ethylene glycol and 380 parts of neopentyl glycol, and an esterification was performed by heating at 150° C. to 240° C. under constant stirring and under a stream of nitrogen gas. When the acid value reached 2.1 (mgKOH/g), the reaction temperature was adjusted to 200° C., the pressure inside the reaction container was gradually reduced, and following the reaction for 30 minutes at a pressure of 1.3 kPa or lower, the reaction mixture was cooled to 110° C. Subsequently, 28 parts of trimellitic anhydride was added and an acid modification was performed at 110° C., yielding a polyol (B1-3). All of the hydroxyl groups of the obtained polyol (B1-3) were primary hydroxyl groups, the number average molecular weight was 750, the acid value was 20.1, and the hydroxyl value was 97.

(Synthesis Example 16) Polyol (B1-4)

[0149] A reaction container was charged with 175 parts of isophthalic acid, 320 parts of adipic acid, 49 parts of benzoic acid, 76 parts of ethylene glycol and 380 parts of neopentyl glycol, and an esterification was performed by heating at 150° C. to 240° C. under constant stirring and under a stream of nitrogen gas. When the acid value reached 2.1 (mgKOH/g), the reaction temperature was adjusted to 200° C., the pressure inside the reaction container was gradually reduced, and following the reaction for 30 minutes at a pressure of 1.3 kPa or lower, the reaction mixture was cooled to 110° C. Subsequently, 21 parts of trimellitic anhydride was added and an acid modification was performed at 110° C., yielding a polyol (B1-4). All of the hydroxyl groups of the obtained polyol (B1-4) were primary hydroxyl groups, the number average molecular weight was 750, the acid value was 15.0, and the hydroxyl value was 99.

(Synthesis Example 17) Polyol (B1-5)

[0150] A reaction container was charged with 175 parts of isophthalic acid, 320 parts of adipic acid, 49 parts of benzoic acid, 76 parts of ethylene glycol and 380 parts of neopentyl glycol, and an esterification was performed by heating at 150° C. to 240° C. under constant stirring and under a stream of nitrogen gas. When the acid value reached 2.1 (mgKOH/g), the reaction temperature was adjusted to 200° C., the pressure inside the reaction container was gradually reduced, and following the reaction for 30 minutes at a pressure of 1.3 kPa or lower, the reaction mixture was cooled to 110° C. Subsequently, 14 parts of trimellitic anhydride was added and an acid modification was performed at 110° C., yielding a polyol (B1-5). All of the hydroxyl groups of the obtained polyol (B1-5) were primary hydroxyl groups, the number average molecular weight was 750, the acid value was 10.2, and the hydroxyl value was 101.

<Monofunctional Alcohol (B2)>

[0151] The following compounds were used as monofunctional alcohols (B2-1) to (B2-4). [0152] B2-1: a polyoxypropylene alkyl ether (product name: Unilube MB-38, manufactured by NOF Corporation, theoretical hydroxyl value: 28 mgKOH/g) [0153] B2-2: a castor oil-based monofunctional alcohol (product name: URIC H-31, manufactured by Itoh Oil Chemicals Co., Ltd., theoretical hydroxyl value: 187 mgKOH/g) [0154] B2-3: a polyoxyalkylene alkyl ether (product name: Unilube 50 MB-72, manufactured by NOF Corporation, theoretical hydroxyl value: 18 mgKOH/g) [0155] B2-4: hexyldecanol (product name: Risonol 16SP, manufactured by Kokyu Alcohol Kogyo Co., Ltd., theoretical hydroxyl value: 231 mgKOH/g)

<Preparation of Adhesive Compositions>

[0156] Formulations of various adhesive compositions are shown in Table 1 and Table 2.

[0157] The trifunctional or higher isocyanate compounds (C1-1) to (C1-5), the alcohol-added isocyanates (E-1) to (E-9) or (F), the polyols (B1-1) to (B1-5), and the optional monofunctional alcohols (B2-1) to (B2-4) and additives were mixed under heating in the blend ratios shown in Table 1 and Table 2 to prepare solvent-free adhesive compositions of Examples 1 to 41 and Comparative Examples 1 to 4.

TABLE-US-00001 TABLE 1 Example Example Example Example Example Example Example Example Example Component 1 2 3 4 5 6 7 8 9 Poly- Trifunctional (C1-1) 25 25 25 25 25 25 6 15 30 isocyanate or higher (C1-2) (A) isocyanate (C1-3) 10 10 10 10 10 10 4 10 10 compound (C1-4) (C1) (C1-5) Alcohol- (E-1) 15 added (E-2) 15 40 25 10 isocyanate (E-3) 15 (E) (E-4) 15 (E-5) 15 (E-6) 15 (E-7) (E-8) (E-9) Alcohol-added isocyanate (F) Alcohol Polyol (B1) (B1-1) 100 100 100 100 100 100 70 100 100 (B) (B1-2) (B1-5) Additives 3-glycidoxy- 1.0 1.0 1.0 1.0 1.0 1.0 0.7 1.0 1.0 propyltrimethoxysilane Phosphoric acid 0.10 0.10 0.10 0.10 0.10 0.10 0.07 0.10 0.10 Ratio of isocyanate groups/ 1.21 1.16 1.04 1.16 1.16 1.14 1.33 1.03 1.22 hydroxyl groups Adhesive Adhesive strength before 7N 10N 6N 8N 12N 11N 7N 8N 8N strength heat sterilization (T-peel Adhesive strength after 7N  8N 6N 7N  9N  9N 6N 7N 7N strength heat sterilization [1] N/15 mm) Contents resistance [1] C B B C B B B B C Pot life (70° C.) C B B B B B C B C Pot life (60° C.) A A A A A A A A A Example Example Example Example Example Example Example Example Example Component 10 11 12 13 14 15 16 17 18 Poly- Trifunctional (C1-1) 15 25 20 21 25 25 25 isocyanate or higher (C1-2) 25 30 (A) isocyanate (C1-3) 10 10 10 10 15 5 10 compound (C1-4) 10 (C1) (C1-5) 10 Alcohol- (E-1) 15 15 added (E-2) 25 15 15 15 24 isocyanate (E-3) 10 (E) (E-4) (E-5) (E-6) (E-7) 15 (E-8) (E-9) Alcohol-added isocyanate (F) Alcohol Polyol (B1) (B1-1) 120 66 50 100 100 100 100 100 (B) (B1-2) 100 (B1-5) Additives 3-glycidoxy- 1.2 0.7 0.5 1.0 1.0 1.0 1.0 1.0 1.0 propyltrimethoxysilane Phosphoric acid 0.12 0.07 0.05 0.10 0.10 0.10 0.10 0.10 0.10 Ratio of isocyanate groups/ 0.86 1.64 2.09 1.23 1.13 1.08 1.14 1.09 1.09 hydroxyl groups Adhesive Adhesive strength before 6N 9N 6N 7N 7N 8N 10N 9N 9N strength heat sterilization (T-peel Adhesive strength after 6N 8N 6N 6N 6N 6N  8N 6N 6N strength heat sterilization [1] N/15 mm) Contents resistance [1] B B C B C B B C C Pot life (70° C.) B B B B B B B C C Pot life (60° C.) A A A A A A A A A Com- Com- Com- Com- Example Example Example parative parative parative parative Component 19 20 21 Example 1 Example 2 Example 3 Example 4 Poly- Trifunctional (C1-1) 25 25 25 40 25 isocyanate or higher (C1-2) 40 25 (A) isocyanate (C1-3) 10 10 10 10 10 10 10 compound (C1-4) (C1) (C1-5) Alcohol- (E-1) 15 added (E-2) isocyanate (E-3) (E) (E-4) (E-5) (E-6) (E-7) (E-8) 15 (E-9) 15 Alcohol-added 15 15 isocyanate (F) Alcohol Polyol (B1) (B1-1) 100 100 100 100 100 100 (B) (B1-2) (B1-5) 100 Additives 3-glycidoxy- 1.0 1.0 1.0 1.0 1.0 1.0 1.0 propyltrimethoxysilane Phosphoric acid 0.10 0.10 0.10 0.10 0.10 0.10 0.10 Ratio of isocyanate groups/ 1.08 1.07 1.26 1.35 1.23 1.26 1.18 hydroxyl groups Adhesive Adhesive strength 9N 9N 7N 6N 5N 7N 6N strength before heat (T-peel sterilization strength Adhesive strength 6N 6N 6N 6N 4N 6N 5N N/15 mm) after heat sterilization [1] Contents resistance [1] C C B D D D D Pot life (70° C.) C C D C C C C Pot life (60° C.) A A B A A A A Numerical values indicate blend proportions (parts by weight)

TABLE-US-00002 TABLE 2 Example Example Example Example Example Example Example Component 22 23 24 25 26 27 28 Poly- Trifunctional or (C1-1) 25 25 25 25 25 25 25 isocyanate higher isocyanate (C1-2) (A) compound (C1) (C1-3) 10 10 10 10 10 10 10 (C1-4) (C1-5) Alcohol-added (E-1) 15 15 15 15 isocyanate (E) (E-2) 15 (E-4) 15 (E-5) 15 (E-6) (E-8) (E-9) Alcohol Polyol (B1) (B1-3) 80 90 80 90 60 60 60 (B) (B1-4) Monofunctional (B2-1) 20 40 alcohol (B2) (B2-2) 10 40 (B2-3) 20 40 (B2-4) 10 Ratio of isocyanate groups/ 1.53 1.20 1.57 1.15 1.58 0.92 1.84 hydroxyl groups Xa/56.1 × Xc − Yh/56.1 × Yc 0.18 −0.01 0.22 −0.09 0.01 −1.12 0.09 Adhesive Adhesive 6N 7N 6N 7N 9N 8N 11N strength strength before (T-peel heat sterilization strength Adhesive 6N 7N 6N 7N 8N 7N  9N N/15 mm) strength after heat sterilization [2] Contents resistance [1] B B B B B B B Contents resistance [2] A A A A C C C Pot life (60° C.) A A A A A A A Example Example Example Example Example Example Example Component 29 30 31 32 33 34 35 Poly- Trifunctional or (C1-1) 25 6 30 15 25 25 isocyanate higher isocyanate (C1-2) 30 (A) compound (C1) (C1-3) 10 4 10 10 10 (C1-4) 10 (C1-5) 10 Alcohol-added (E-1) 40 10 10 15 15 isocyanate (E) (E-2) 25 (E-4) (E-5) (E-6) 15 (E-8) (E-9) Alcohol Polyol (B1) (B1-3) 60 70 100 40 85 85 (B) (B1-4) 80 Monofunctional (B2-1) 30 20 15 15 alcohol (B2) (B2-2) 20 10 (B2-3) (B2-4) 40 Ratio of isocyanate groups/ 0.80 1.39 1.14 1.06 2.13 1.33 1.33 hydroxyl groups Xa/56.1 × Xc − Yh/56.1 × Yc −1.44 0.10 −0.45 0.21 −0.38 0.23 0.23 Adhesive Adhesive strength 10N 7N 8N 6N 7N 8N 8N strength before heat (T-peel sterilization strength Adhesive strength  8N 6N 7N 6N 6N 6N 6N N/15 mm) after heat sterilization [2] Contents resistance [1] B B B B B B B Contents resistance [2] C A B A B B B Pot life (60° C.) A B A B A B B Example Example Example Example Example Example Component 36 37 38 39 40 41 Poly- Trifunctional or (C1-1) 25 25 25 25 25 25 isocyanate higher isocyanate (C1-2) (A) compound (C1) (C1-3) 10 10 10 10 10 10 (C1-4) (C1-5) Alcohol-added (E-1) 15 15 15 15 isocyanate (E) (E-2) (E-4) (E-5) (E-6) (E-8) 15 (E-9) 15 Alcohol Polyol (B1) (B1-3) 85 85 88 97 85 97.5 (B) (B1-4) Monofunctional (B2-1) 15 15 12 alcohol (B2) (B2-2) 3 (B2-3) 15 (B2-4) 2.5 Ratio of isocyanate groups/ 1.31 1.30 1.44 1.28 1.50 1.27 hydroxyl groups Xa/56.1 × Xc − Yh/56.1 × Yc 0.23 0.23 0.25 0.25 0.26 0.24 Adhesive Adhesive strength 8N 8N 6N 7N 6N 7N strength before heat (T-peel sterilization strength Adhesive strength 6N 6N 6N 7N 6N 7N N/15 mm) after heat sterilization [2] Contents resistance [1] B B B B B B Contents resistance [2] B B A A A A Pot life (60° C.) B B C C C C Numerical values indicate blend proportions (parts by weight)

<Preparation of Laminated Composite Films>

[0158] Composite films composed of polyethylene terephthalate (thickness: 12 μm, hereafter abbreviated as PET)/aluminum foil (thickness: 9 μm)/unstretched polypropylene (thickness: 70 μm, hereafter abbreviated as CPP) were prepared using the method described below.

[0159] First, a dry lamination adhesive suitable for high retort (product name: TM-250HV/CAT-RT86L-60, manufactured by Toyo-Morton, Ltd.) was applied to the PET film in an amount of 3.5 g/m.sup.2 using a dry laminator, the coated surface and the aluminum foil were bonded together, and the thus obtained laminate was aged for three days in an environment at 40° C., thus obtaining a PET/aluminum foil laminate.

[0160] Subsequently, the solvent-free adhesive composition of each Example and each Comparative Example was applied to the aluminum foil surface of one of these PET/aluminum foil laminates in a coating amount of 3 g/m.sup.2 at 70° C. using a solvent-free test coater, the coated surface and the CPP were bonded together, and the thus obtained laminate was aged for three days in an environment at 40° C., thus obtaining a PET/aluminum foil/CPP laminated composite film.

[0161] Coating with the test coater was performed at 60° C. and 70° C. for Examples 1 to 21 and Comparative Examples 1 to 4, and was performed at 60° C. for Examples 22 to 41.

<Pot Life (70° C.)>

[0162] For each adhesive composition, the viscosity was measured 40 minutes after uniform mixing at 70° C., and the pot life was then evaluated against the following criteria. The results are shown in Table 1.

[0163] B: viscosity of less than 8,000 mPa.Math.s

[0164] C: viscosity of at least 8,000 mPa.Math.s, but less than 12,000 mPa.Math.s

[0165] D: viscosity of 12,000 mPa.Math.s or greater

<Pot Life (60° C.)>

[0166] For each adhesive composition, the viscosity was measured 30 minutes after uniform mixing at 60° C., and the pot life was then evaluated against the following criteria. The results are shown in Table 1.

[0167] A: viscosity of less than 10,000 mPa.Math.s

[0168] B: viscosity of at least 10,000 mPa.Math.s, but less than 12,000 mPa.Math.s

[0169] C: viscosity of at least 12,000 mPa.Math.s, but less than 15,000 mPa.Math.s

[0170] D: viscosity of 15,000 mPa.Math.s or greater

[0171] For each of the laminated composite films prepared using the method described above, the physical properties of adhesive strength, retort resistance and contents resistance were evaluated using the following methods described below. The results are shown in Table 1.

<Adhesive Strength>

[0172] The laminated composite film prepared using the above method was cut to a width of 15 mm, and in an environment of 25° C. and 50% relative humidity, the film was pulled at a peeling rate of 300 mm/minute peeling rate and the T-peel strength (N/15 mm) between the CPP and the aluminum foil was measured.

<Retort Resistance (Adhesive Strength after Heat Sterilization [1]), Contents Resistance [1]>

[0173] Using the laminated composite film prepared using the above method, a bag of dimensions 14 cm×18 cm was prepared with the CPP on the inside surface under conditions including heat sealing at 190° C. for 1 second. For contents, the bag was filled with a mixture of a 3% aqueous solution of acetic acid, ketchup and salad oil in a weight ratio of 1/1/1. The bag was subjected to hot water sterilization for 30 minutes using a rotational retort test apparatus under pressurized conditions including 30 rpm and 135° C., and the T-peel strength (N/15 mm) between the CPP and the aluminum foil (recorded as “adhesive strength after heat sterilization [1]”) was then measured using the same method as that described above for the adhesive strength. Further, after storage for 4 weeks in an environment at 55° C., any changes in the external appearance of the bag were evaluated visually, and the contents resistance (recorded as “contents resistance [1]”) was evaluated against the following criteria. The results are shown in the tables.

[0174] B: no orange peel-like patterns or small spot-like patterns, adhesive layer appears uniform (good)

[0175] C: some orange peel-like patterns or small spot-like patterns observed (usable)

[0176] D: multitude of orange peel-like patterns or small spot-like patterns observed (unusable)

<Retort Resistance (Adhesive Strength after Heat Sterilization [2]), Contents Resistance [2]>

[0177] With the exception of replacing the contents with a 3% aqueous solution of acetic acid, a bag filled with contents was prepared using the same procedure as that described above. This bag was subjected to hot water sterilization for 30 minutes using a rotational retort test apparatus under pressurized conditions including 30 rpm and 135° C., and the T-peel strength (N/15 mm) between the CPP and the aluminum foil (recorded as “adhesive strength after heat sterilization [2]”) was then measured using the same method as that described above for the adhesive strength. Further, after storage for 4 weeks in an environment at 55° C., any changes in the external appearance of the bag were evaluated visually, and the contents resistance (recorded as “contents resistance [2]”) was evaluated against the following criteria. The results are shown in the tables.

[0178] A: no orange peel-like patterns or small spot-like patterns, adhesive layer appears uniform (extremely good)

[0179] B: very slight orange peel-like patterns or small spot-like patterns observed (good)

[0180] C: some orange peel-like patterns or small spot-like patterns observed (usable)

[0181] D: multitude of orange peel-like patterns or small spot-like patterns observed (unusable)

[0182] As illustrated in Table 1 and Table 2, it was evident that the adhesive composition of the present invention had good workability, and exhibited excellent adhesive strength and acid resistance.