JP3376133B2 - Adhesive composition - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention uses a plurality of various plastic films, metal vapor deposition films or metal foils,
The present invention relates to a urethane-based adhesive composition that gives an excellent adhesion function when producing a composite laminate film for food packaging materials.

[0002]

2. Description of the Related Art In recent years, metal foil such as aluminum foil, or metal vapor deposition film and polyethylene, polypropylene, vinyl chloride, polyester, etc.
A composite film obtained by laminating multiple layers of plastic films such as nylon has been used. As an adhesive for sticking these plastic film and metal foil or metal vapor deposition film, a combination of polyester polyol and polyisocyanate compound is known.

[0003]

However, when such an adhesive requires high-temperature sterilization treatment of boil and retort, it is partially adhered by involuntary bending at the time of stacking after retort. In some cases, defects may occur, the appearance may be poor, or acid resistance and hot water resistance in the content resistance may be a problem, and further deterioration of the performance may occur depending on the content and the base material. For example, polyester or nylon film / aluminum foil /
Vinegar, soy sauce, as a content in a bag made of a general composite film made of unstretched polypropylene film, or foods with high acidity such as sauce, or oil-based foods or foods containing a mixture of these are subjected to retort treatment. When applied, there was a drawback that the adhesive strength was reduced or pinholes were generated in the aluminum foil with the passage of time immediately after the retort.

The present invention can obtain a strong adhesive strength to a laminate substrate, can prevent deterioration of appearance due to involuntary bending at the time of stacking after retort as a packaging material for foods, and further has acid content resistance. Provided is an adhesive composition capable of maintaining strong adhesive strength over a long period of time without deterioration of adhesive strength or generation of pinholes over time, even when the contents are filled with highly food or oily food. .

[0005]

Means for Solving the Problems The present inventors have made an adhesive composition containing a polyester polyurethane polyol, a polyester resin containing a carboxyl group at a molecular end, a phosphoric acid-modified epoxy resin composition and an organic isocyanate compound. Has been found to be a solution to the above problems, and has completed the present invention.

That is, according to the present invention, with respect to 100 parts by weight of polyester polyurethane polyol [1], 10 to 500 parts by weight of a polyester resin [2] containing a carboxyl group at a molecular end, an epoxy represented by the following general formula (a): Phosphoric acid-modified epoxy resin composition [3] 0.1-2 obtained by reacting resin with phosphoric acid compound of general formula (b)
0 parts by weight, and the organic isocyanate compound [4] has an equivalent ratio of isocyanate groups to the total of hydroxyl groups and carboxyl groups in the mixture of [1] to [3] of 1.0 to 5.
There is provided an adhesive composition formulated so as to be in the range of 0.

[0007]

[Chemical 2]

Further, there is provided the above-mentioned adhesive composition containing a silane coupling agent or an epoxy resin. The present invention will be described in detail below.

The polyester polyurethane polyol [1] used in the present invention comprises a polyester polyol having a hydroxyl group at the terminal and an organic diisocyanate, which is NC.
Blend so that the O / OH ratio will be 0.3-0.98,
Obtained by reacting. When the NCO / OH ratio is 0.3 or less, the appearance is deteriorated due to poor adhesion due to bending after retort even when the obtained adhesive composition is used. It is easy to remain and leaves a problem in terms of performance. The polyester polyol having a hydroxyl group at the terminal used here is obtained by reacting a polybasic acid or its ester compound with a polyhydric alcohol and has a molecular weight of 600 to 15,000, preferably 1,000 to 7, Those in the range of 000 are used. When the molecular weight is 600 or less, the cohesive force is small and the adhesive strength is insufficient, and when the molecular weight is 15,000 or more, there is a problem that it is difficult to increase the ratio of NC0 / OH by the reaction with the organic diisocyanate compound in the synthesis.

Well-known starting materials can be used as the polybasic acid and its ester compound. Specifically, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, phthalic anhydride, adipic acid, azelaic acid, sebacic acid, succinic acid, glutaric acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, maleic anhydride, anhydrous Itaconic acid and its ester compound, which may be used alone or in combination of two or more.

Specific examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,6-hexanediol, neopentyl glycol, 1,4-butylene glycol and 1,4-. Cyclohexanedimethanol, trimethylolpropane, glycerin, 1,9-nonanediol, 3-methyl-1,5-
Pentanediol, etc., which are used alone or
Can be used with more than one species.

Well-known raw materials can be used as the organic diisocyanate. Specifically, there are 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, 1,5-naphthalene diisocyanate, hexamethylene diisocyanate, hydrogenated diphenylmethane diisocyanate and the like. These can be used alone or in combination of two or more. The molecular weight of the polyester polyurethane polyol used in the present invention is 1,000 to 100,000, preferably 5,
It is in the range of 000 to 20,000. Molecular weight is 100
If it is less than 0, the cohesive force is small and the adhesive strength is insufficient,
When it is 100,000 or more, unreacted isocyanate compound is likely to remain in the reaction, and the synthesis is difficult.

The polyester resin [2] having a carboxyl group at the molecular end used in the present invention is obtained by reacting a polyester resin having two or more hydroxyl groups at the molecular end with an anhydrous aromatic polycarboxylic acid. can get. The polyester resin containing two or more hydroxyl groups at the molecular ends is obtained by reacting a polybasic acid or its ester compound with a polyhydric alcohol. As the polybasic acid or its ester compound and the polyhydric alcohol, those mentioned above can be used.
Further, as the polyester resin containing two or more hydroxyl groups at the molecular ends, polyester polyurethane polyols urethane-treated with diisocyanate by the above-mentioned method can be used as well. Examples of the aromatic polycarboxylic acid anhydride include phthalic anhydride, trimellitic anhydride, and pyromellitic anhydride. When non-anhydrous aromatic polycarboxylic acid is used, the reaction product may be hydrolyzed and the molecular weight may be lowered.

The molecular weight of the polyester resin containing two or more hydroxyl groups at the molecular ends is 1,000 to 100,0.
00, preferably 3,000 to 10,000 is used. If it is 1,000 or less, the cohesive force is insufficient, and if it is 100,000 or more, it is difficult to react an aromatic polyvalent carboxylic acid anhydride at the terminal in terms of synthesis, and gelation may occur. The reaction of the polyester resin containing two or more hydroxyl groups at the molecular end with the aromatic polycarboxylic acid anhydride is carried out at a reaction temperature of 200 ° C. or lower so that the esterification reaction by the ring-opening reaction of the carboxylic acid anhydride becomes the main reaction. Need to control. The reaction ratio of both is such that the amount of the aromatic polycarboxylic acid anhydride is such that 40 to 90% of the hydroxyl groups at the molecular ends of the polyester resin containing two or more hydroxyl groups at the molecular ends are consumed. Here, "%" is based on the number of terminal hydroxyl groups. If the above value is 40% or less,
The resulting adhesive composition is not sufficiently improved in content resistance. If it is 90% or more, unreacted substances are likely to remain in the reaction,
It is not preferable because it is mixed in the resin in the form of a suspension, and finally the physical properties such as the adhesive strength of the laminate are adversely affected. In addition, when a polyester resin containing two or more hydroxyl groups at the molecular end is reacted with an aliphatic polycarboxylic acid anhydride, a carboxyl group can be similarly introduced at the end, but such a polyester resin has improved resistance to contents. Is not recognized. When synthesizing a polyester resin, it is possible to obtain a resin containing a carboxyl group at a terminal in one step from a polycarboxylic acid and a polyhydric alcohol. However, selecting only an aromatic carboxylic acid as the carboxylic acid raw material of the polyester resin has many problems in controlling the physical properties of the polyester resin. In particular, a trivalent or tetravalent polycarboxylic acid causes branching in the polyester resin, and is apt to gel, and cannot be used in a large amount. In addition, since aromatic polyvalent carboxylic acids have sublimation properties, these sublimates adhere to the reaction vessel and dehydrator during synthesis, which causes manufacturing difficulties. In the present invention, since a polyester resin containing two or more hydroxyl groups at the molecular end synthesized in advance to obtain desired physical properties is used as a starting material and a carboxyl group is introduced at the end, a problem as described above is encountered. Are removed.

The phosphoric acid-modified epoxy resin composition [3] used in the present invention is prepared by adding phosphoric acid to epoxy resin of epoxy resin obtained by ring-opening addition of ε-caprolactone to the secondary hydroxyl group of bisphenol diglycidyl ether type epoxy group. It is a modified product added. In JP-A-61-47771, Shell Co.'s Epicoat 828 and orthophosphoric acid are used as bisphenol diglycidyl ether, but ε-caprolactone is used as the secondary hydroxyl group of bis-phenol diglycidyl ether. Nothing is disclosed about a modified phosphoric acid of the type in which the ring-opening is added. The ring-opening addition of ε-caprolactone to bisphenol diglycidyl ether, which is an epoxy resin represented by the general formula (a), is such that n in the formula is 1 or more, preferably 1 to 20, and m is 1 ~ 100, preferably 1
The range is from -20. Incidentally, other lactones, along with ε-caprolactone, within a range that does not impair the effects of the present invention,
For example, trimethylcaprolactone, valerolactone, etc. may be used. As the epoxy resin, a bisphenol diglycidyl ether type epoxy resin, for example, Arubalide 6071 and Aradalide 608 manufactured by Ciba-Geigy Co., Ltd.
4, Araldide 6097 and the like can be used.
In these, n in the formula corresponding to the general formula (a) is about 2 to 10
It is in the range.

Examples of the phosphoric acid compound represented by the general formula (b) used in the production of the phosphoric acid-modified epoxy resin composition used in the present invention include orthophosphoric acid and monoesters of orthophosphoric acid. Monobutyl phosphate having ² as an alkyl group, monoamyl phosphate, monononyl phosphate, etc., monophenyl phosphate having R ² as an aryl group,
It is possible to use monobenzyl phosphate in which R ² is an aryl group substituted with an alkyl group, monocyclohexyl phosphate in which R ² is a cycloalkyl group, and monoviridine phosphate in which R ² is a hetero substituent. Further, the phosphoric acid compound (b)
The mixing ratio of the epoxy resin (a) with the epoxy resin (a) can be selected at any ratio, but the amount of phosphoric acid compound in which the number of moles of phosphorus in the phosphoric acid compound is about 0.5 to about 4 per mole of the epoxy group. And more preferably about 1 to about 2
Is. Within this range, the produced phosphoric acid-modified epoxy resin composition [3] is stable and the reaction is not difficult to control.

The reaction temperature is preferably in the range of about 25 ° C to about 150 ° C, particularly preferably in the range of about 50 ° C to about 100 ° C. If the reaction temperature is lower than 25 ° C, the reaction is slow,
On the contrary, if the temperature exceeds 150 ° C., it becomes difficult to control the reaction, which is not preferable. This reaction is usually performed in the presence of an inert solvent. As the solvent used, benzene, toluene, aromatic solvents such as xylene, methyl ethyl ketone,
Cyclohexanone, methyl isobutyl ketone, ketone solvents such as isophorone, hexane, heptane, hydrocarbon solvents such as cyclohexane, diethyl ether, tetrahydrofuran, dioxane, ether solvents such as propylene glycol monopropyl ether, ethyl acetate, isopropyl acetate, butyl Examples of the solvent include ester solvents such as diglycol acetate and halogen solvents. The amount of these solvents used is 0.1 to 20 times, preferably 0.5 to 2 times the weight ratio of the epoxy resin. If the amount used is less than 0.1 times, the substrate concentration will be high and the reaction will be difficult to control. The order of preparation when carrying out the reaction is not limited, but an epoxy resin is preferably added dropwise to the phosphoric acid compound and the temperature is raised to the above temperature. The end point of the reaction can be confirmed by, for example, titrating the oxirane oxygen.

The phosphoric acid-modified epoxy resin composition [3] obtained by the above reaction can be directly used for the production of the adhesive composition of the present invention. It can also be isolated by washing with water and distilling off the low-boiling component under reduced pressure, or distilling off the low-boiling component as it is. It is also possible to recrystallize using a solvent insoluble at a low temperature in order to obtain a substance with higher purity.

The mixture of the polyester polyurethane polyol [1], the polyester resin [2] containing a carboxyl group at the molecular end and the phosphoric acid modified epoxy resin composition [3] used in the present invention is a polyester polyurethane polyol [1]. 10 to 500 parts by weight of a polyester resin [2] containing a carboxyl group at the molecular end and 0.1 to 20 parts by weight of a phosphoric acid-modified epoxy resin composition [3] can be added to 100 parts by weight. . Preferably, polyester polyurethane polyol [1]
40 to 300 parts by weight of the polyester resin [2] containing a carboxyl group at the molecular end based on 100 parts by weight,
The phosphoric acid-modified epoxy resin composition [3] is 0.8 to 10 parts by weight. When the content of the polyester resin containing a carboxyl group at the molecular end is 10 parts by weight or less and the phosphoric acid-modified epoxy resin composition is 0.1 parts by weight or less, the adhesive strength of the content resistance decreases with time. In addition, polyester resin containing a carboxyl group at the molecular end is 50
0 parts by weight or more and phosphoric acid-modified epoxy resin composition is 2
If the amount is 0 parts by weight or more, the deterioration of the appearance and the decrease of the adhesive strength, which are presumed to be caused by the deterioration of the moisture resistance during retort, occur.

The organic isocyanate compound [4] that can be used in the adhesive composition of the present invention includes a low molecular weight isocyanate compound, a polyurethane isocyanate obtained by reacting a low molecular weight isocyanate with water or a polyhydric alcohol, and a low molecular weight compound. There are low-polymerization products that are dimers or trimers of isocyanates. Examples of low molecular weight isocyanates include hexamethylene diisocyanate, phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate, diphenylmethane-4,4-diisocyanate, 3,3-dimethyl-4,
4-Biphenylene diisocyanate, dicyclohexylmethane-4,4-diisocyanate, isophorone diisocyanate and mixtures thereof. Examples of the polyhydric alcohol include those described above as the raw material of the polyester polyol in the previous stage of producing the polyester polyurethane polyol [1] used in the present invention.

The resin mixture of the polyester polyurethane polyol [1], the polyester resin [2] containing a carboxyl group at the molecular end and the phosphoric acid-modified epoxy resin composition [3] and the organic isocyanate compound are the hydroxyl group and the carboxyl group in the mixture. For the total of the groups,
It is blended so that the equivalent ratio of the isocyanate group in the organic isocyanate compound is 1.0 to 5.0.

Further, the unmodified epoxy resin or the silane coupling agent may be added to the resin mixture of these [1] to [4] alone or as a mixture thereof. As the unmodified epoxy resin, the above-mentioned ones can be used, and the addition amount thereof is preferably 0 to 20 parts by weight with respect to 100 parts by weight of the corresponding resin mixture. Examples of the silane coupling agent used in the present invention include a vinyl group-containing trialkoxysilane such as vinyltrimethoxysilane and vinyltriethoxysilane, 3-aminopropyltriethoxysilane, N- (2-aminoethyl) 3-. Trialkoxysilanes having amino groups such as aminopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, etc. There is a trialkoxysilane having a glycidyl group. The addition ratio thereof is 0.1 to 5 parts by weight, preferably 0.5 to 3 parts by weight based on 100 parts by weight of the resin mixture of the polyester polyurethane polyol, the polyester resin having a carboxyl group at the molecular end and the phosphoric acid-modified epoxy resin composition. Parts by weight.

In order to prepare a multilayer composite film using the adhesive composition obtained by blending the above-mentioned components of the present invention, the adhesive is applied to one of the base materials by a commonly used method, for example, a dry laminator. After being applied to one side of the above, the solvent is diffused, the other laminated base material is attached and cured at room temperature or under heating. The amount of adhesive applied to the surface of the laminate substrate is 1 to 10 g / square meter.

[0024]

EXAMPLES The present invention will be described in more detail below with reference to examples. In the examples, “part” means part by weight.

Reference Example 1: Synthesis of Epoxy Solution A Araldide 6071 (manufactured by Ciba-Geigy Co., Ltd.) 800 in a flask equipped with a nitrogen inlet tube, thermometer, cooling tube, and stirrer.
g, ε-caprolactone 200 g, and tetrabutyl titanate 0.01 g were reacted at 70 ° C. to obtain a lactone-modified epoxy resin having an epoxy equivalent of 608 and a hydroxyl value of 282.2. Subsequently, 800 g of butyl cellosolve was added to form a uniform solution (epoxy solution A).

Reference Example 2: Synthesis of Epoxy Solution B Araldide 6084 (manufactured by Ciba Geigy) 700 g,
The same procedure as in Reference Example 1 was carried out except that 300 g of ε-caprolactone was added, and the epoxy equivalent was 1443 and the hydroxyl value was 145.9.
A lactone-modified epoxy resin was obtained. Similarly, add 800 g of butyl cellosolve to obtain a uniform solution (epoxy solution B).
And

(Reference Example 3: Synthesis of phosphoric acid-modified epoxy resin composition solution I) 79.0 g of orthophosphoric acid was placed in a four-necked flask equipped with a thermometer, a stirrer, a reflux condenser, a dropping funnel and a nitrogen gas blowing tube. added. Next, 800 g of the epoxy solution A of Reference Example 1 was added to the dropping funnel. Internal temperature is 80 ° C
Then, the epoxy solution was added dropwise in 2 hours. When the oxirane oxygen concentration was measured after completion of the reaction, it was 0 ppm. A part of the resulting solution (phosphoric acid-modified epoxy resin composition solution I) was heated to 100 by a rotary evaporator.
The low boiling point component was distilled off at 2 ° C. and 2 to 5 mmHg for 2 hours. When the infrared spectrum of the reaction product was measured, it was 1014.
absorption derived from P-0 was observed at cm ⁻¹ , 780-8
The peak believed to be derived from the epoxy at 20 cm ^-1 disappeared. Further, in the ¹ H-NMR analysis result, the protons of the epoxy are found to be δ (ppm) of 3.0 to 3.4.
(Ppm) is shifted to a low magnetic field of 3.3 to 3.6,
It was found that the epoxy was ring-opened.

Reference Example 4: Synthesis of phosphoric acid-modified epoxy resin composition solution II Epoxy solution B synthesized in Reference Example 2
Was carried out in the same manner as in Reference Example 3 except that 800 g and 33.2 g of orthophosphoric acid were used. The oxirane oxygen concentration of the solution (phosphoric acid-modified epoxy resin composition solution II) obtained after the reaction was 0 ppm.

(Reference Example 5: Production of Polyester Polyurethane Polyol I) Dimethyl terephthalate 666 parts, ethylene glycol 270 parts, neopentyl glycol 5
25 parts of zinc acetate and 0.1 part of zinc acetate were charged into a reaction vessel, heated to 160 to 220 ° C. under stirring under a nitrogen stream to carry out a transesterification reaction, and 97% of the theoretical amount of methanol was distilled off. Charge 525 parts of acid, 160 ~ 240 ℃
The mixture was heated to the temperature to carry out the esterification reaction. Furthermore, the pressure inside the reaction vessel was gradually reduced to 150 mmHg as it was. Acid value is 2
When the pressure became below, the vacuum reaction was stopped and the molecular weight was 4,0.
A polyester polyol of the previous stage of 00 was obtained. 24.8 parts of isophorone diisocyanate (NCO / OH ratio of 0.56) to 800 parts of the obtained polyester polyol.
Was gradually added, and the mixture was heated and reacted at 100 to 150 ° C. After reacting for 6 hours, a polyester polyurethane polyol having a molecular weight of 12,000 was obtained. To 700 parts of the obtained polyester polyurethane polyol, 700 parts of ethyl acetate was added and dissolved. The obtained resin solution having a solid content of 50% is referred to as polyester polyurethane polyol I.

Reference Example 6: Production of Polyester Polyurethane Polyol II 415 parts isophthalic acid, 365 parts adipic acid, 416 parts neopentyl glycol, 1,6
-Preparing 295 parts of hexanediol in a reaction vessel, heating to 180 to 220 ° C while stirring under a nitrogen stream, carrying out an esterification reaction for 4 hours, and further gradually increasing the inside of the reaction vessel to 150 m.
The pressure was reduced to mHg. When the acid value was 2 or less, the reduced pressure reaction was stopped to obtain a polyester polyol in the previous stage having a molecular weight of 3,000. 35.4 parts of isophorone diisocyanate (NCO / OH
Is gradually added, and the mixture is heated and reacted at 100 to 150 ° C. After reacting for 6 hours, a polyester polyurethane polyol having a molecular weight of 18,000 was obtained, 500 parts of which was dissolved in 500 parts of ethyl acetate to obtain a resin having a solid content of 50%. This is a polyester polyurethane polyol II
And

Reference Example 7 Production of Polyester Polyol I A polyester polyol having a molecular weight of 6,000 and a solid content of 50% was obtained in the same manner as in the production of polyester polyurethane polyol I except that isophorone disisocyanate was omitted. . This is referred to as polyester polyol I.

Reference Example 8 Production of Polyester Resin I Containing Carboxyl Group at Molecular End: Isophthalic Acid 50
0 parts, 290 parts adipic acid, 90 ethylene glycol
, 210 parts of neopentyl glycol, and 300 parts of 1,6-hexanediol were charged into a reaction can and heated to 160 to 240 ° C. with stirring under a nitrogen stream to carry out an esterification reaction. When the acid value became 15 or less, the reactor was gradually depressurized and polymerized at 240 ° C. for 2 hours at 1 mmHg or less to obtain a polyester resin A containing a hydroxyl group having an acid value of 0.7 and a hydroxyl value of 12.0. . To 600 parts of the obtained polyester resin A, 24 parts of trimellitic acid anhydride was added.
The reaction was carried out at 0 ° C for 2 hours. After confirming that there was no unreacted trimellitic anhydride in the reaction vessel using a liquid chromatograph, it was taken out. In the obtained resin, 80% of the terminal hydroxyl groups of polyester resin A were reacted with trimellitic anhydride, and the acid value was 23 and the hydroxyl value was 3.2. The obtained resin (500 parts) was dissolved in ethyl acetate (500 parts) to obtain a resin solution having a solid content of 50%, which was used as a polyester resin I having a carboxyl group at the molecular end.

Reference Example 9 Production of Polyester Resin II Containing Carboxyl Group at Molecular End: Isophthalic Acid 3
20 parts, adipic acid 210 parts, ethylene glycol 12
0 part, 200 parts of neopentyl glycol, and 90 parts of 1,6-hexanediol were charged into a reaction can and heated to 160 to 240 ° C. with stirring under a nitrogen stream to carry out an esterification reaction for about 5 hours. Furthermore, gradually add 1 mmHg to the reaction can.
Then, the pressure was reduced to 240 ° C., and polymerization was performed at 240 ° C. for 2 hours to obtain a polyester resin B having hydroxyl groups at both ends. The resulting resin B has a hydroxyl value of 28.0, an acid value of 0.5, and a molecular weight of 4,
It was 000. Add 28.8 parts of trimellitic anhydride to 500 parts of polyester resin B, and add 2 at 180 ° C.
Reacted for hours. The obtained resin is polyester resin B.
It consumes 60% of the terminal hydroxyl groups and has an acid value of 7.
2, the hydroxyl value was 4.5. 500 parts of ethyl acetate was added to 500 parts of the obtained resin and dissolved to obtain a solid content of 5 parts.
A 0% resin solution was obtained. This is designated as polyester resin II containing a carboxyl group at the molecular end.

Reference Example 10 Production of Polyester Resin III Containing Carboxyl Group at Molecular End: To 500 parts of the polyester resin A, 8.2 parts of trimellitic anhydride was added. This corresponds to the consumption of 30% of the hydroxyl groups of the polyester resin A. By the same operation,
A resin having an acid value of 1.2 and a hydroxyl value of 11.2 was obtained. A solid content of 50% with ethyl acetate is used as a polyester resin III containing a carboxyl group at the molecular end.

(Examples 1 to 6) Polyester polyurethane polyols I and II, resins I to II containing a carboxyl group at the molecular end, and phosphoric acid-modified epoxy resin composition I
-II, 3-glycidoxypropyltrimethoxysilane and a polyisocyanate compound (Coronate HL: manufactured by Nippon Polyurethane Industry Co., Ltd., solid content 75%, ethyl acetate solution) are as shown in Examples 1 to 6 of Table-1. An adhesive was prepared by blending.

(Comparative Examples 1 to 3) Polyester polyurethane polyols I to II, polyester resins I and III containing a carboxyl group at the molecular end, polyester resin A containing two or more hydroxyl groups at the molecular end, phosphoric acid-modified epoxy Resin composition I, Epicoat 1001 (solid content 5
0%), orthophosphoric acid and a polyisocyanate compound (Coronate HL, manufactured by Nippon Polyurethane Industry Co., Ltd., solid content 75%, ethyl acetate solution) are compounded as shown in Comparative Examples 1 to 3 of Table-1 to form an adhesive. Prepared.

[0037]

[Table 1]

Using the adhesives prepared in Examples 1 to 6 and Comparative Examples 1 to 3, composite laminate materials of nylon film / aluminum foil / unstretched polypropylene film were prepared, and peeling test, heat resistance / food resistance test, A performance test of a bending test after the retort was performed. The results are shown in Table-2.

(Peeling test) The adherend was a nylon film (thickness 15 μm), aluminum foil (thickness 9 μm), unstretched polypropylene (thickness 70 μm), the amount of adhesive applied was 4 to 5 g / square meter, and the curing conditions were 40
It was measured at 4 ° C. for 4 days. First, each adhesive composition shown in Table 1 was applied to a nylon film by a dry laminator, the solvent was volatilized, and then the film was matched with the surface of the aluminum foil. The same adhesive composition was applied to the other side of the aluminum foil with a dry laminator, then the solvent was volatilized, and the adhesive side was aligned with the unstretched polypropylene film. Then, the adhesive composition was cured. The test sample was cut into a size of 200 mm × 25 mm. Using these test pieces, ASTM D1876-6
According to the test method of No. 1, the loading speed is 3 by the tensile tester.
A T-type peel test was performed at 00 mm / min. Peel strength between unstretched polypropylene film and aluminum foil (K
(g / 25 mm width) is shown as an average value of 10 test pieces.

(Heat Resistance and Food Resistance Test) A bag having a multilayer structure of nylon film / adhesive / aluminum foil / adhesive / unstretched polypropylene film was prepared by the same method as the test sample used in the peel test. 1% by weight of 3% acetic acid solution, salad oil and tomato ketchup in this bag
The soup was mixed in a 1: 1 ratio. 135 this bag
After hot water sterilization treatment (retort treatment) at 30 ° C. for 30 minutes, the peel strength between the aluminum foil and the polypropylene film and the peel strength after storage at 60 ° C. for 2 hours were measured. The test was conducted on 10 bags each.

(Bending test after retort) In the heat resistance and food resistance test, after the retort, the test piece is bent in two so that the nylon film side is the front side and the back side. The bent portion was strongly pressed against the corner of the 90 ° angle polyethylene structure, and after squeezing 10 times, the presence or absence of peeling of the bent portion and the presence or absence of pinholes in the aluminum foil were observed with the naked eye.

[0042]

[Table 2]

(Results) As is clear from Table 2, the adhesive compositions according to the present invention (Examples 1 to 6) all have excellent bending resistance after retort, and also have long-term storage after retort. No decrease in adhesive strength and no pinholes in the aluminum foil were observed.

[0044]

EFFECTS OF THE INVENTION The adhesive composition of the present invention can obtain a strong adhesive strength as a laminate base material for food packaging materials, and prevents deterioration of the appearance caused by unintentional bending during stacking after retort. Even when food with high acidity or oily food is used as the content resistance, the adhesive strength does not decrease over time and pinholes do not occur, and the adhesive strength is strong over a long period of time. Can be maintained.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C08L 75/06 C08L 75/06 (56) Reference JP-A-8-143639 (JP, A) JP-A-4-248890 (JP , A) JP 63-117030 (JP, A) JP 63-159418 (JP, A) JP 5-148450 (JP, A) JP 59-105056 (JP, A) JP 57-164116 (JP, A) JP-A-1-141971 (JP, A) JP-A-62-141063 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C09J 4/00 -201/10 C08L 63/00-101/16 C08G 18/00-85/00

Claims (2)

(57) [Claims] 1. To 100 parts by weight of polyester polyurethane polyol [1], 10 to 500 parts by weight of a polyester resin [2] containing a carboxyl group at a molecular end, an epoxy resin of the following general formula (a) and a general formula ( 0.1 to 20 parts by weight of a phosphoric acid-modified epoxy resin composition [3] obtained by reacting with the phosphoric acid compound of b), and an organic isocyanate compound [4] in a mixture of [1] to [3]. An adhesive composition prepared by blending such that the equivalent ratio of isocyanate groups to the total of hydroxyl groups and carboxyl groups is in the range of 1.0 to 5.0. [Chemical 1] 2. The adhesive composition according to claim 1, which comprises a silane coupling agent or an epoxy resin.