JP6939011B2 - Urethane-based adhesive composition and laminate - Google Patents

Description

The present invention relates to urethane-based adhesive compositions and laminates.

As a packaging material for foods, medical products, cosmetics, etc., a composite of a metal foil such as aluminum foil or a metal-deposited film and a plastic film such as polyethylene, polypropylene, vinyl chloride, polyester, or nylon is used in multiple layers. There is. As an adhesive for laminating these plastic films with a metal foil or a metal vapor deposition film, those composed of a polymer polyol and an organic isocyanate compound obtained by reacting an aromatic polyvalent carboxylic acid anhydride are known.

For example, Patent Document 1 discloses a urethane-based adhesive composition containing a resin obtained by copolymerizing a (meth) acrylic acid ester and maleic anhydride, a polyol, and an organic isocyanate compound.

Japanese Unexamined Patent Publication No. 2012-184283

In recent years, in the field of food packaging, there has been an increasing movement to improve the sterilization efficiency of foods in line with the trend of improving eating habits, and instead of the conventional hot water storage type retort treatment, hot water spray type retort treatment has been replaced. Interest is growing. In the hot water spray type retort treatment, since a high temperature and high pressure hot water spray is directly applied to the laminate, the adhesive is required to have impact resistance in addition to heat resistance and water resistance.
The urethane-based adhesive composition disclosed in Patent Document 1 can form a laminate having excellent acid resistance. However, with the urethane-based adhesive composition disclosed in Patent Document 1, it was not possible to form a laminate that can withstand the hot water spray type retort treatment having excellent acid resistance.

An object of the present invention is to provide a urethane-based adhesive composition capable of sufficiently exhibiting hot water spray type retort resistance and forming a laminate having excellent acid resistance.

The present invention relates to the adhesive compositions according to [1] to [3] and the laminate according to [4], which contain a specific amount of the monofunctional alcohol (D).
[1] Contains a resin (A), a polyol (B), an isocyanate compound (C), and a monofunctional alcohol (D) obtained by copolymerizing a (meth) acrylic acid ester and maleic anhydride.
With respect to 100 parts by weight of the polyol (B)
A urethane-based adhesive composition containing 0.1 to 10 parts by weight of the resin (A) and 0.1 to 10 parts by weight of the monofunctional alcohol (D).

[2] The urethane-based adhesive composition according to the above [1], wherein the monofunctional alcohol (D) has a molecular weight of 50 or more and 1000 or less.
[3] The urethane-based adhesive composition according to the above [1] or [2], which further contains 0.1 to 10 parts by weight of a silane coupling agent with respect to 100 parts by weight of the polyol (B). ..

[4] A laminate obtained by laminating at least two sheet-like substrates using the urethane-based adhesive composition according to any one of the above [1] to [3].

The urethane-based adhesive composition of the present invention can sufficiently exhibit hot water spray type retort resistance and can provide a laminate having excellent acid resistance.

As described above, the urethane-based adhesive composition of the present invention comprises a resin (A), a polyol (B), an isocyanate compound (C), and a simple material obtained by copolymerizing a (meth) acrylic acid ester and maleic anhydride. Contains functional alcohol (D).

<Resin (A) obtained by copolymerizing (meth) acrylic acid ester and maleic anhydride>
The urethane-based adhesive composition of the present invention will be described. The urethane-based adhesive composition of the present invention is characterized by containing a resin (A), a polymer polyol (B) and an isocyanate compound (C) obtained by copolymerizing a (meth) acrylic acid ester and maleic anhydride. ..

<Resin (A) obtained by copolymerizing (meth) acrylic acid ester and maleic anhydride>
The resin obtained by copolymerizing the (meth) acrylic acid ester and maleic anhydride used in the present invention preferably contains 50 to 95% of the (meth) acrylic acid ester with respect to the total amount at the time of synthesis. , More preferably 50 to 70%, and the content of maleic anhydride is preferably 5 to 50%, more preferably 30 to 50%. When the content of maleic anhydride is 5% or more, the adhesive strength during long-term storage does not deteriorate, and when it is 50% or less, the synthesis of a copolymer of (meth) acrylic acid ester and maleic anhydride Is easy.
The number average molecular weight of the resin obtained by copolymerizing the (meth) acrylic acid ester and maleic anhydride is preferably 300 to 50,000, more preferably 1000 to 12000. When the number average molecular weight is 300 or more, the adhesive strength does not deteriorate during long-term storage, and when it is 50,000 or less, the compatibility with other components to be blended in the adhesive is good, and the adhesive is applied. The appearance is excellent.
The amount of the resin (A) obtained by copolymerizing the (meth) acrylic acid ester and maleic anhydride is 0.1 to 10 parts by weight, preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the polyol (B) described later. 1 to 5 parts by weight. When the amount of the resin (A) added is 0.1 parts by weight or more with respect to the polyol (B), the adhesive strength can be maintained for a long period of time, and when the amount is 10 parts by weight or less, other components to be blended in the adhesive. Good compatibility with and excellent adhesive coating appearance.

Examples of the (meth) acrylic acid ester monomer used in the present invention include methyl methacrylate, ethyl methacrylate, propyl methacrylate, -i-propyl methacrylate, butyl methacrylate, -i-butyl methacrylate, and-methacrylic acid. t-butyl, pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, nonyl methacrylate, decyl methacrylate, hydroxymethyl methacrylate, hydroxyethyl methacrylate, glycidyl methacrylate, 2-ethylhexyl methacrylate, methacrylic acid Examples thereof include cyclohexyl and phenyl methacrylate. Of these, methyl methacrylate is preferable from the viewpoint of copolymerizability with maleic anhydride.
A radical copolymerization method is used as a method for synthesizing the resin (A) obtained by copolymerizing a (meth) acrylic acid ester and maleic anhydride. For example, it is appropriately selected from solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization and the like.

<Polyprethane (B)>
From the viewpoint of curing rate, the polyol used in the present invention preferably has 2 to 10 functional groups in one molecule, more preferably 2 to 8. The number average molecular weight is preferably 500 to 100,000, more preferably 1,000 to 30,000, from the viewpoint of the viscosity of the adhesive composition.
More specifically, as the polyol (B), polyester polyol, polyether polyol, polyether ester polyol, polyesteramide polyol, acrylic polyol, polycarbonate polyol, polyhydroxylalkane, polyurethane polyol, castor oil or a mixture thereof (hereinafter, these are polyols). (1).) Can be mentioned. Among these, polyurethane polyol is preferable from the viewpoint of heat resistance.

Examples of the polyester polyol include dibasic acids such as terephthalic acid, isophthalic acid, adipic acid, azelaic acid, and sebatic acid, dialkyl esters thereof, or mixtures thereof, and examples thereof include ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, and neo. Glycols such as pentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 3,3'-dimethylol heptane, polyoxyethylene glycol, polyoxypropylene glycol, polytetramethylene ether glycol, etc. Examples thereof include polyester polyols obtained by reacting with a mixture thereof or polyester polyols obtained by ring-opening polymerization of lactones such as polycaprolactone, polyvalerolactone, and poly (β-methyl-γ-valerolactone).

As the polyether polyol, for example, an oxylan compound such as ethylene oxide, propylene oxide, butylene oxide, or tetrahydrofuran is polymerized using a low-volume polyol such as water, ethylene glycol, propylene glycol, trimethylolpropane, or glycerin as an initiator. Examples thereof include the obtained polyether polyol.

Examples of the polyether ester polyol include a poly obtained by reacting a dibasic acid such as terephthalic acid, isophthalic acid, adipic acid, azelaic acid, and sebatic acid, a dialkyl ester thereof, or a mixture thereof with the above-mentioned polyether polyol. Examples include ether ester polyols.

The polyester amide polyol can be obtained by using, for example, an aliphatic diamine having an amino group such as ethylenediamine, propylenediamine, and hexamethylenediamine as a raw material in the above esterification reaction.

Examples of acrylic polyols include hydroxyethyl acrylate, hydroxyprople acrylate, acrylic hydroxybutyl, etc., which contain one or more hydroxyl groups in one molecule, or their corresponding methacrylic acid derivatives, such as acrylic acid, methacrylic acid, and the like. It is obtained by copolymerizing with an acid or an ester thereof.

Examples of the polycarbonate polyol include ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, and 1,9-nonane. One selected from diol, 1,8-nonanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, bisphenol A, hydrogenated bisphenol A or Examples thereof include those obtained by reacting two or more kinds of glycols with dimethyl carbonate, diphenyl carbonate, ethylene carbonate, phosgen and the like.

Examples of the polyhydroxyalkane include butadiene or a liquid rubber obtained by copolymerizing butadiene with acrylamide and the like.

The polyurethane polyol is a polyol having a urethane bond in one molecule. For example, a polyether polyol having a number average molecular weight of 200 to 20,000, a polyester polyol, a polyether ester polyol, or the like and a polyisocyanate have an NCO / OH of 1. The reaction is preferably less than, more preferably 0.9 or less.

In the present invention, as the polyol, those having a carboxyl group in the molecule (inside the molecule or at the end of the molecule) (hereinafter referred to as polyol (2)) can be used. The polyol (2) used in the present invention is preferably obtained by reacting the above-mentioned polyol (1) with a polybasic acid or an anhydride thereof. The polyol (1) used at this time contains two or more hydroxyl groups at the molecular ends and has a number average molecular weight of preferably 1,000 to 100,000, more preferably 3,000 to 15,000. .. When the number average molecular weight is 1,000 or more, the cohesive force is sufficient, and when it is 100,000 or less, a polybasic acid or an anhydride thereof can be easily reacted at the terminal in synthesis, and thickening or gelation occurs. There is no.

<Isocyanate compound (C)>
Examples of the isocyanate used in the present invention include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, and 1,3-butylene diisocyanate. , 2,4,4-trimethylhexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanate methyl caproate and other aliphatic diisocyanates;
1,4-Cyclohexanediisocyanate, 1,3-Cyclohexanediisocyanate, 3-Isocyanatemethyl-3,5,5-trimethylcyclohexylisocyanate, 4,4'-methylenebis (cyclohexylisocyanate), methyl2,4-cyclohexanediisocyanate, methyl2 , 6-Cyclohexanediisocyanate, 1,4-bis (isocyanatemethyl) cyclohexane, 1,3-bis (isocyanatemethyl) cyclohexane and other alicyclic diisocyanates;
m-phenylenediocyanate, p-phenylenediocyanate, 4,4'-diphenyldiisocyanate, 1,5-naphthalenediocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-2,6-tolylene diisocyanate or 2,6-tri Toluene diisocyanate or a mixture thereof, aromatic diisocyanates such as 4,4'-toluene diisocyanate, dianisidine diisocyanate, and 4,4'-diphenyl ether diisocyanate;
1,3-1,4-xylylene diisocyanate or 1,4-xylylene diisocyanate or a mixture thereof, ω, ω'-diisocyanate-1,4-diethylbenzene, 1,3-bis (1-isocyanate-1-methylethyl) ) Aromatic diisocyanates such as benzene or 1,4-bis (1-isocyanate-1-methylethyl) benzene or a mixture thereof;
Triisocyanates such as triphenylmethane-4,4', 4 "-triisocyanate, 1,3,5-triisocyanate benzene, 2,4,6-triisocyanate toluene; 4,4'-diphenyldimethylmethane-2, Polyisocyanate monomer such as tetraisocyanate such as 2'-5,5'-tetraisocyanate;
Dimers, trimmers, biurets, allophanates derived from the above polyisocyanate monomers;
Polyisocyanate having a 2,4,6-oxadiazine trione ring obtained from carbon dioxide gas and the above polyisocyanate monomer; ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, neopentyl glycol, 1,6- Molecular weight of hexanediol, 3-methyl-1,5-pentanediol, 3,3'-dimethylolpropane, cyclohexanedimethanol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerol, trimethylolpropane, pentaerythritol, sorbitol, etc. An adduct of less than 200 low molecular weight polyols and the polyisocyanate monomer;
Polyester polyol, polyether ester polyol, polyesteramide polyol, polycaprolactone polyol, polyvalerolactone polyol, acrylic polyol, polycarbonate polyol, polyhydroxyalkane, castor oil, polyurethane polyol, etc. having a molecular weight of 200 to 20,000 and the above polyisocyanate monomer Additive with
Examples thereof include a polyurethane polyol obtained by reacting a polyether polyol and a polyisocyanate with an NCO / OH of less than 1, and an adduct of the polyisocyanate monomer.
These polyisocyanate compounds can be appropriately used alone or as a mixture of two or more kinds depending on the use of the adhesive. For example, from the viewpoint of curing speed and heat resistance, aromatic polyisocyanates are preferable.
From the viewpoint of curing rate, the isocyanate compound (C) is preferably contained in an amount of 1 to 50 parts by weight, more preferably 5 to 30 parts by weight, based on 100 parts by weight of the polyol (B).

<Monofunctional alcohol (D)>
It is important that the adhesive of the present invention contains a monofunctional alcohol in order to improve the resistance to hot water spray retort.
The monofunctional alcohol preferably has a molecular weight of 50 or more and 1000 or less.
For example, 1-butanol, 1-propanol, 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, 1-decanol, undecyl alcohol, lauryl alcohol, tridecyl alcohol, myristyl alcohol, pentadecyl Alcohols, setanols, 1-heptanol, stearyl alcohols, nonadesyl alcohols, benzyl alcohols and the like can be mentioned.
These monofunctional alcohols are preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the polyol (B) and 0.5 to 3 parts by mass with respect to 100 parts by mass of the polyl (B).

<Silane coupling agent>
The adhesive of the present invention may further contain a silane coupling agent in order to increase heat resistance and water resistance. Examples of the silane coupling agent include trialkoxysilane having a vinyl group such as vinyltrimethoxysilane and vinyltriethoxysilane, 3-aminopropyltriethoxysilane, and N- (2-aminoethyl) 3-aminopropyltrimethoxysilane. It has a glycidyl group such as trialkoxysilane having an amino group such as 3-glycidoxypropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane. Examples thereof include trialkoxysilane. The amount of the silane coupling agent added is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 3.0 parts by mass with respect to 100 parts by mass of the polyl (B).

<Phosphorus oxygen acid>
In addition, the adhesive of the present invention may further contain an oxygen acid of phosphorus or a derivative thereof in order to enhance acid resistance. Among the oxygen acids of phosphorus or derivatives thereof, the oxygen acid of phosphorus may be any one having at least one free oxygen acid, for example, hypophosphoric acid, phosphoric acid, orthophosphoric acid, the following. Examples thereof include phosphoric acids such as phosphoric acid, and condensed phosphoric acids such as metaphosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, polyphosphoric acid, and ultraphosphoric acid. Examples of the derivative of the oxygen acid of phosphorus include those in which the oxygen acid of phosphorus is partially esterified with alcohols while leaving at least one free oxygen acid. Examples of these alcohols include aliphatic alcohols such as methanol, ethanol, ethylene glycol and glycerin, aromatic alcohols such as phenol, xylenol, hydroquinone, catechol and fluoroglycinol, and oxygen acids of phosphorus or derivatives thereof. May be used in combination of two or more.
The amount of phosphorus oxygen acid or a derivative thereof added is preferably 0.01 to 10% by weight, more preferably 0.05 to 5% by weight, based on the solid content of the adhesive, and is 0.1. It is particularly preferably ~ 1% by weight.

<Epoxy phosphate>
Further, the adhesive of the present invention can contain an epoxy phosphate in order to improve the metal adhesion performance. Examples of the phosphoric acid epoxy include URAD-DD79 manufactured by DSM Resins Resin Co., Ltd.
The amount of the phosphoric acid epoxy added is preferably 0.01 to 10% by weight, particularly preferably 0.1 to 1% by weight, based on the solid content of the adhesive.

<Other additives>
The adhesive of the present invention further contains, for example, additives such as an antioxidant, an ultraviolet absorber, an antioxidant, a fungicide, a thickener, a plasticizer, a pigment, and a filler, if necessary. Can be made to. In addition, known catalysts, additives and the like can be contained in order to control the curing reaction.
The adhesive of the present invention contains a resin (A), a polyol (B), an isocyanate compound (C) and a monofunctional alcohol obtained by copolymerizing a (meth) acrylic acid ester and maleic anhydride, and has a viscosity thereof. At room temperature to 150 ° C., preferably room temperature to 100 ° C., 100 to 10,000 mPa · s, preferably 100 to 5,000 mPa · s, the solvent-free type can be used. If the viscosity of the adhesive is higher than the above range, it may be diluted with an organic solvent. As the organic solvent, for example, any solvent is used as necessary as long as it is inactive against isocyanates such as ester-based solvents such as ethyl acetate, ketone-based solvents such as methyl ethyl ketone, and aromatic hydrocarbon-based solvents such as toluene and xylene. You may.

The adhesive of the present invention is applied to the film surface with a solvent-type or solvent-free laminator, and in the case of the solvent type, the solvent is volatilized, and in the case of the solvent-free type, the adhesive surface is directly bonded and heated at room temperature or under heating. It can be used by curing it. Generally, it is convenient to use the solvent-free type in the range of the dry solid amount of 1.0 to 2.0 g / m ² and the solvent type in the dry solid amount of 2.0 to 5.0 g / m ^2.

<Laminated body>
Next, the laminated body of the present invention will be described. The laminate of the present invention is one in which at least two sheet-like substrates are laminated via an adhesive layer formed from the adhesive of the present invention.
The sheet-like base material is a plastic film, paper, metal foil, or the like that is usually used for a laminate, and the two sheet-like base materials may be of the same type or different types. As the plastic film, a film made of a thermoplastic resin or a thermosetting resin can be used, but a film made of a thermoplastic resin is preferable. Examples of the thermoplastic resin include polyolefins, polyesters, polyamides, polystyrenes, vinyl chloride resins, vinyl acetate resins, ABS resins, acrylic resins, acetal resins, polycarbonate resins, fibrous plastics and the like.

The thickness of the laminate is usually 10 μm or more. To make a laminate using the adhesive of the present invention, an adhesive is applied to one side of one sheet-like substrate by a commonly used method, for example, a dry laminator, and the solvent is volatilized, and then the solvent is volatilized. It may be bonded to the other sheet-like substrate and cured at room temperature or under heating. The amount of adhesive applied to the surface of the sheet-shaped substrate is about ^{1 to 10 g / m 2.}

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. Parts and% in Examples and Comparative Examples mean parts by weight and% by weight unless otherwise specified.
Further, in the present invention, the "number average molecular weight" was calculated using a calibration curve of standard polystyrene using gel permeation chromatography. The acid value and hydroxyl value are expressed in mg of KOH per 1 g of polymer polyol. The acid value was measured by neutralization titration with KOH, and the hydroxyl value was measured by acetylation using pyridine and acetic anhydride.

(Synthesis Example 1) Synthesis of (meth) acrylic acid ester-maleic anhydride copolymer (A-1) Toluene 200 is placed in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping tank and a nitrogen gas introduction tube. The temperature was raised to 110 ° C. with stirring while introducing nitrogen gas. Next, 90 parts of methyl methacrylate, 60 parts of butyl acrylate, 150 parts of maleic anhydride, and 50 parts of toluene were charged in the dropping tank 1, and 9 parts of benzoyl peroxide was dissolved in 50 parts of toluene in the dropping tank 2. The mixture was charged and dropped under stirring while keeping the temperature in the reaction vessel at 110 ° C. for 2 hours at the same time. After completion of the reaction, the polymer was cooled to room temperature, the polymer was precipitated with a large amount of methanol, filtered, and dried at 120 ° C. for 6 hours. A (meth) acrylic acid ester-maleic anhydride copolymer having a number average molecular weight of 3000 and an acid value of 488. (A-1) was obtained.

(Synthesis Example 2) Synthesis of (meth) acrylic acid ester-maleic anhydride copolymer (A-2) Synthesis example except that the composition is 90 parts of methyl methacrylate, 120 parts of butyl acrylate, and 90 parts of maleic anhydride. The polymer was polymerized and dried in the same manner as in No. 1, to obtain a (meth) acrylic acid ester-maleic anhydride copolymer (A-2) having a number average molecular weight of 3500 and an acid value of 298.

(Synthesis Example 3) Synthesis of styrene-maleic anhydride copolymer (A-3) Polymerized and dried in the same manner as in Synthesis Example 1 except that the composition was 150 parts of styrene and 150 parts of maleic anhydride, and the number average molecular weight was 2800. , A styrene-maleic anhydride copolymer (A-3) having an acid value of 501 was obtained.

(Synthesis Example 5) Synthesis of polyol (B-1) 5.0 parts of ethylene glycol and 16.8 parts of neopentyl glycol are placed in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping tank and a nitrogen gas introduction pipe. , 19.1 parts of 1,6-hexanediol, 42.0 parts of isophthalic acid, 4.4 parts of terephthalic acid, and 17.0 parts of sebacic acid were charged, and the temperature was raised to 260 ° C. with stirring under a nitrogen stream. After continuing the reaction until the acid value became 5 or less, the pressure was gradually reduced to continue the reaction at 1 mmHg to remove excess alcohol, and the polyester polyol having a hydroxyl value of 10 mgKOH / g and a number average molecular weight of 17,000. (B-1) was obtained.

(Synthesis Example 6) Synthesis of Polyol (B-2) 300 g of the above polyester polyol (B-1) is heated while stirring under a nitrogen stream, 4.5 g of isophorone diisocyanate is added in an atmosphere of 150 ° C., and stirring is performed. Continued. Stirring was continued until the absorption derived from unreacted NCO disappeared by IR analysis to obtain a polyester polyurethane polyol (B-2) having a hydroxyl value of 8 mgKOH / g and a number average molecular weight of 25,000.

(Synthesis Example 7) Synthesis of Polyol (B-3) 300 g of the above polyester polyurethane polyol (B-2) was heated to 180 ° C. while stirring under a nitrogen stream, and 4 g of ethylene glycol bisanhydrotritate and anhydrous tri. 1.5 g of meritic acid was charged and held at 180 ° C. for 1 hour to obtain a polyester polyurethane polyol (B-3) having a hydroxyl value of 5 mgKOH / g and a carboxyl group having a number average molecular weight of 26000.

(Example 1)
3.0 g of the (meth) acrylic acid ester-maleic anhydride copolymer (A-1) obtained in Synthesis Example 1 in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping tank and a nitrogen gas introduction tube. , 100 g of the polyester polyol (B-1) obtained in Synthesis Example 5 and 75.7 g of ethyl acetate were charged, the temperature was raised to 78 ° C. with stirring while introducing nitrogen gas, and the temperature was maintained for 1 hour. After cooling to room temperature, 0.05 g of phosphoric acid, 0.9 g of a silane coupling agent (γ-glycidoxypropyltrimethoxysilane), 1 g of benzyl alcohol (D-1), and isophorone as an organic isocyanate compound (C). Ethyl acetate diluent (nonvolatile content 70 weight) of 5/5 (weight ratio) mixture of trimethylolpropane adduct of diisocyanate (IPDI-TMP adduct) and trimethylolpropane adduct of xylylene diisocyanate (XDI-TMP adduct) %) Was blended with 21.4 g and 185 g of ethyl acetate to obtain an adhesive, and spray retort resistance and acid resistance were evaluated according to the method described later. The results are evaluated and the results are shown in Table 1.

(Examples 2 to 7, Comparative Examples 1 to 6)
An adhesive was obtained by the same operation as in Example 1 except that the materials shown in Table 1 were used, evaluated in the same manner, and the results are shown in Table 1.

(Example 8)
An adhesive was obtained in the same manner as in Example 1 except that 5 g of lauryl alcohol (D- 2) was used instead of 1 g of benzyl alcohol ( D -1), evaluated in the same manner, and the results are shown in Table 1.

(Creation of 4-layer composite laminate)
Polyethylene terephthalate (PET) film (thickness 12 μm) / nylon (NY) film (thickness 15 μm) / aluminum (AL) foil (thickness 9 μm) / unstretched polypropylene (CPP) film (thickness 70 μm, surface corona discharge treatment) ) Was prepared by the method described below, with the solid content coating amount of the adhesive being 3.5 g / m ^2.
That is, the adhesive solution was first applied to the printed surface of the polyethylene terephthalate film with a laminator at room temperature, the solvent was volatilized, and then the applied surface was bonded to the nylon film. Further, an adhesive solution was similarly applied to the nylon film surface of the laminate, the solvent was volatilized, and then the coated surface was bonded to the aluminum foil surface. Then, an adhesive solution was similarly applied to the aluminum foil surface of the laminate to volatilize the solvent, and then the coated surface was bonded to an unstretched polypropylene film and kept warm at 40 ° C. for 3 days to form a 4-layer composite laminate. It was created.
When the appearance of the 4-layer composite laminate was observed from both sides of the PET side and the CPP side in an adhered state, no floating or peeling was observed in all the examples and comparative examples, and no repellent was observed.

(Laminate strength test)
A test piece having a size of 15 mm × 300 mm was prepared from the four-layer composite laminate prepared as described above, and peeled by T-type peeling under the conditions of a temperature of 20 ° C. and a relative humidity of 65% using a tensile tester. Laminating strength (N / 15 mm) between PET film / NY film, between NY film / AL foil, and between AL foil / CPP film was measured at a speed of 30 cm / min.
The numerical values in Table 1 are the average values of the five test pieces. Measurements were taken before and after the retort. The retort condition was 10r. p. m. , 135 ° C., 30 minutes, under pressure of 3 MPa, hot water sterilization was performed.

(Creation of test piece for hot water spray type retort resistance evaluation)
Sample 1 having a length of 40 mm and a width of 40 mm was cut out from each of the four-layer composite laminates. The sample 1 was folded in half so that the unstretched polypropylene film faced inward to prepare a sample 2 having a length of 20 mm and a width of 40 mm. The entire surface (= 18mm × 40 mm) Co., Ltd. Tester Sangyo Co. of TP-701-A heat seal tester to 18mm toward the open end from the crease sample 2, 200 ° C., of 20N / ^cm 2, 2 seconds Sample 3 was prepared by heat-sealing under the conditions.
Next, a position 1 mm from the fold ridge of the sample 3 toward the open end was cut off in parallel with the fold ridge to prepare a sample 4 having a length of 19 mm and a width of 40 mm. A triangular notch with a base of 1 mm and a height of 1.5 mm was provided at an arbitrary position at the end of the heat seal having a width of 40 mm to form a test piece. The bottom of 1 mm shall overlap with the heat seal end (side) of 40 mm in width, and the apex of 1.5 mm in height shall face the open end of 40 mm in width.

(Hot water spray type retort resistance)
Fifty test pieces were prepared from each of the four-layer composite laminates formed using the adhesives of each example and each comparative example, and the test pieces were bundled so that the notched ends were located in the same direction. ..
Using the "RCS-60SPXTG" hot water spray type retort sterilizer manufactured by Nisaka Seisakusho Co., Ltd., install it so that the notched end of the bundled test piece is located at a distance of 5 mm from the hot water spray nozzle. Then, the retort treatment was performed under the conditions of 135 ° C., 40 minutes, 3.0 kg / cm ^{2 G, and water pressure 3 MPa G.}
The state of the test piece after retort was visually observed and evaluated by the presence or absence of peeling of each film layer constituting the test piece.
⊚: Less than 2 out of 50 with peeling.
〇: Of the 50 pieces, 2 or more and less than 5 with peeling.
Δ: 5 or more and less than 10 with peeling out of 50.
X: Of the 50 pieces, 10 or more pieces with peeling.

(Acid resistance test)
Using each of the four-layer composite laminates, a pouch having a size of 9 cm × 13 cm was prepared so that the unstretched polypropylene was on the inside, and the content was filled with vinegar having a concentration of 4.2% by weight or more. ..
As it is (before the rotary retort), or by using the "RCS-40RTGN" high-temperature and high-pressure cooking sterilization tester manufactured by Hisaka Works Co., Ltd., 3r. p. m. After hot water sterilization at 135 ° C. for 30 minutes under a pressure of 3 MPa (after rotary retort), the peeling state between the AL foil / CPP film after storage at 50 ° C. for 2 weeks or 4 weeks was observed.
◎: No peeling No decrease in laminate strength ○: No peeling With decrease in laminate strength △: With partial peeling With decrease in laminate strength ×: With peeling on the entire surface With decrease in laminate strength

Claims (4)

It contains a resin (A), a polyol (B), an isocyanate compound (C), and a monofunctional alcohol (D) obtained by copolymerizing a (meth) acrylic acid ester and maleic anhydride.
With respect to 100 parts by weight of the polyol (B)
A urethane-based adhesive composition containing 0.1 to 10 parts by weight of the resin (A) and 0.5 to 3 parts by weight of the monofunctional alcohol (D). The urethane-based adhesive composition according to claim 1, wherein the monofunctional alcohol (D) has a molecular weight of 50 or more and 1000 or less. The urethane-based adhesive composition according to claim 1 or 2, wherein the silane coupling agent is further contained in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the polyol (B). A laminate obtained by laminating at least two sheet-like substrates using the urethane-based adhesive composition according to any one of claims 1 to 3.