Method for producing urethane prepolymer

Abstract

The present invention provides a urethane prepolymer for a two-component curable adhesive which has a fast PAA decrease rate and excellent storage stability. Provided is a method for producing a urethane prepolymer for a two-component curable adhesive, comprising: a first step for obtaining a urethane prepolymer (I) by reacting, at 65-85°C, an isocyanate composition (i) in which the content of 2,2'-diphenylmethane diisocyanate is not more than 0.5 mass%, the content of 2,4'-diphenylmethane diisocyanate is not more than 5.0 mass%, and the content of 4,4'-phenylmethane diisocyanate is not less than 75.0 mass%, and a polyol composition (ii), under conditions so that there is an excess of isocyanate groups contained in the isocyanate group with respect to active hydrogen groups contained in the polyol composition; and a second step for obtaining a urethane prepolymer (II) by heat-treating the urethane prepolymer (I) at 95-110°C.

Description

TECHNICAL FIELD

[0001] The present invention relates to a method for producing a urethane prepolymer thatis suitable for a two-component curable adhesive. BACKGROUND ART

[0002] In a laminated body used in various packaging materials, labels, or the like, design,functionality, storability, convenience, shipping resistance, and the like are imparted bylaminating a variety of substrates, such as plastic films, metal foils, and papers. A packagingmaterial of the laminated body formed into a bag is used as a packaging material for foods,drugs, detergents, and the like.

[0003] Conventionally, a laminated body used for a packaging material is mainly obtainedby a dry lamination method in which an adhesive dissolved in a volatile organic solvent(sometimes referred to as a solvent-type lamination adhesive) is applied on a substrate, theorganic solvent is volatilized during the substrate passes an oven, and another substrate is bonded thereto. However, in recent years, from the viewpoints of reducing theenvironmental load and improving the work environment, there has been a growing demandalso for a reactive two-component type lamination adhesive that is free from a volatile organicsolvent (hereinafter referred to as non-solvent type adhesive) (PTL 1). CITATION LIST PATENT LITERATURE

[0004] PTL 1: JP 2014-159548 A SUMMARY OF INVENTION TECHNICAL PROBLEM

[0005] In manufacturing a laminated body for packaging a food by using such a two-component type urethane-based adhesive, isocyanate monomers remaining in an adhesivelayer are sometimes a problem. When aromatic isocyanate monomers remain in an adhesivelayer, the isocyanate monomers react with ambient water to produce a primary aromatic amine (PAA). The produced PAA possibly goes through a film and is eluted into the content(food). There is a concern about the toxicity of PAA to the human body. Thus, variousregulations are provided, for example, the European Commission provides a detection limit thereof in a rule regarding plastic materials and products for food contact.

[0006] Since PAA produced by a reaction of an aromatic isocyanate and water furtherreacts with water, the concentration of PAA gradually decreases even if the aromaticisocyanate remains in the adhesive layer, to finally fall below the detection limit. In manufacturing a laminated body for packaging a food, the rate of reduction in PAA concentration is preferably higher. From this point of view, an isocyanate component of anadhesive is preferably obtained by using 4,4’-diphenylmethane diisocyanate which has a relatively better reactivity as a raw material. However, 4,4’-diphenylmethane diisocyanate has a high crystallinity, and thus, a urethane prepolymer that has a high 4,4’-diphenylmethane diisocyanate content tends to crystallize in storage even at room temperature and to cause cloudiness, and thus, is poor in the storage stability.

[0007] The present invention has been made in view of the above circumstance, and has anobject to provide a urethane prepolymer for a two-component curable adhesive that has a high rate of reduction in PAA and is superior in storage stability. SOLUTION TO PROBLEM

[0008] The present invention relates to a method for producing a urethane prepolymer for atwo-component curable adhesive, the method including a first step of reacting an isocyanate composition (i) having a content of 2,2’-diphenylmethane diisocyanate of 0.5% by mass or less, a content of 2,4’-diphenylmethanediisocyanate of 5.0% by mass or less, and a content of 4,4’-phenylmethane diisocyanate of75.0% by mass or more and a polyol composition (ii) at 65°C or higher and 85°C or lower insuch a condition that isocyanate groups contained in the isocyanate group are excessive relative to active hydrogen groups contained in the polyol composition, to produce a urethane prepolymer (I), and a second step of subjecting the urethane prepolymer (I) to a heat treatment at 95°Cor higher and 110°C or lower to produce a urethane prepolymer (II). ADVANTAGEOUS EFFECTS OF INVENTION

[0009] According to the adhesive of the present invention, it is possible to provide aurethane prepolymer for a two-component curable adhesive that has a high rate of reduction in PAA and is superior in storage stability. DESCRIPTION OF EMBODIMENTS

[0010] <Production Method>(Isocyanate Composition (i)) The isocyanate composition (i) used in the production method of the present invention contains 75.0% by mass or more of 4,4’-diphenylmethane diisocyanate (hereinafter also referred to as 4,4’-MDI) which causes no concern about PAA even when remaining as amonomer. In addition, the content of 2,2’-diphenylmethane diisocyanate (hereinafter, 2,2’-MDI) is 0.5% by mass or less and the content of 2,4’-diphenylmethane diisocyanate (2,4’- MDI) is 5.0% by mass. 2,2’-MDI and 2,4’-MDI have a lower reactivity than 4,4’-MDI andthe rate of reduction in PAA is relatively lower, and thus, the content thereof is preferablylower, but, when 4,4’-MDI is synthesized and isolated, 2,2’-MDI and 2,4’-MDI may be mixedtherein as impurities. Such contents as above have no significant influence on the rate of reduction in PAA.

[0011] The isocyanate composition (i) used in the production method of the present invention may contain an isocyanate compound other than 4,4’-MDI, 2,2’-MDI, and 2,4’-MDI. The isocyanate compound used in combination with these isocyanates is preferably anon-aromatic isocyanate compound, such as an araliphatic diisocyanate, an aliphatic diisocyanate, an alicyclic diisocyanate, and derivatives (biuret form, isocyanurate form,adduct form, allophanate form) thereof.

[0012] The araliphatic diisocyanate means an aliphatic isocyanate that has in the moleculeone or more aromatic rings, and examples thereof include, but not limited to, m- or p-xylylene diisocyanate (synonym: XDI) and α,α,α’,α’-tetramethylxylylene diisocyanate (synonym:TMXDI).

[0013] Examples of the aliphatic diisocyanate include, but not limited to, trimethylenediisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (synonym: HDI),pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0014] Examples of the alicyclic diisocyanate include, but not limited to, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, isophorone diisocyanate (synonym:IPDI), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexanediisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4’-methylenebis(cyclohexyl isocyanate), and 1,4-bis(isocyanatomethyl)cyclohexane.

[0015] When the isocyanate composition (i) contains a non-aromatic isocyanate, from theviewpoints of the reaction rate and the like in a resulting two-component curable adhesivedescribed later, the amount of the non-aromatic isocyanate blended is preferably 20% by mass or less of the total amount of the isocyanate composition (i).

[0016] (Polyol Composition (ii))The polyol composition (ii) used in the production method of the present inventioncontains a polyol compound. The polyol compound is not particularly limited, and any onethat can be generally used as a urethane prepolymer can be appropriately used. Examplesthereof include: glycols, such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol,neopentyl glycol, dimethylbutanediol, butylethylpropanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol,bishydroxyethoxybenzene, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol;

[0017] trifunctional or tetrafunctional aliphatic alcohols, such as glycerol,trimethylolpropane, and pentaerythritol; bisphenols, such as bisphenol A, bisphenol F, hydrogenated bisphenol A, andhydrogenated bisphenol F; dimerdiol;polyether polyols obtained by addition polymerization of an alkylene oxide, such asethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin,tetrahydrofuran, or cyclohexylene, in the presence of a polymerization initiator, such as theglycols or trifunctional or tetrafunctional aliphatic alcohols mentioned above;polyether urethane polyols obtained by further increasing the molecular weight of a polyether polyol with an isocyanate compound;

[0018] a polyester polyol (1) which is a reaction product of a polyester obtained by ringopening polymerization reaction of a cyclic ester compound, such as propiolactone,butyrolactone, ε-caprolactone, σ-valerolactone, or β-methyl-σ-valerolactone and a polyhydricalcohol, such as the glycols mentioned above, glycerol, trimethylolpropane, or pentaerythritol; a polyester polyol (2) obtained by a reaction of a bifunctional polyol, such as theglycols mentioned above, dimerdiol, or the bisphenols mentioned above, and a polybasiccarboxylic acid:a polyester polyol (3) obtained by a reaction of a trifunctional or tetrafunctionalaliphatic alcohol and a polybasic carboxylic acid; a polyester polyol (4) obtained by a reaction of a bifunctional polyol, thetrifunctional or tetrafunctional aliphatic alcohols mentioned above, and a polybasic carboxylicacid;a polyester polyol (5) which is a polymer of a hydroxyl acid, such as dimethylolpropionic acid or castor oil fatty acid;

[0019] a polyester polyether polyurethane polyol obtained by a reaction of at least one ofthe polyester polyols (1) to (5), a polyether polyol, and an isocyanate compound;a polyester polyurethane polyol obtained by increasing the molecular weight of thepolyester polyols (1) to (5) with an isocyanate compound; and castor oil-based polyols, such as castor oil, dehydrated castor oil, hydrogenatedcastor oil which is a hydrogenation product of castor oil, and a 5-50 mol alkylene oxideadduct of castor oil, and a mixture thereof.

[0020] Examples of the polybasic carboxylic acid used in synthesis of the polyester polyols (2) to (4) include:aromatic polybasic acids, such as orthophthalic acid, terephthalic acid, isophthalic acid, phthalic anhydride, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid,2,6-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic anhydride, naphthalic acid,trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride,biphenyldicarboxylic acid, 1,2-bis(phenoxy)ethane-p,p’-dicarboxylic acid, benzophenonetetracarboxylic acid, benzophenonetetracarboxylic dianhydride, 5-sodiosulfoisophthalic acid, tetrachlorophthalic anhydride, and tetrabromophthalic anhydride;methyl esters of aromatic polybasic acids, such as dimethylterephthalic acid anddimethyl 2,6-naphthalene dicarboxylate;

[0021] aliphatic polybasic acids, such as malonic acid, succinic acid, succinic anhydride,glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, maleic anhydride, and itaconic acid;alkyl esters of aliphatic polybasic acids, such as dimethyl malonate, diethylmalonate, dimethyl succinate, dimethyl glutarate, dimethyl adipate, diethyl pimelate, diethylsebacate, dimethyl fumarate, diethyl fumarate, dimethyl maleate, and diethyl maleate;

[0022] alicyclic polybasic acids, such as 1,1-cyclopentanedicarboxylic acid, 1,2-cyclopentanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, tetrahydrophthalic anhydride, 4-methylhexahydrophthalicanhydride, hexahydrophthalic anhydride, cyclohexane-1,2,4-tricarboxylic-1,2-anhydride, himic anhydride, and het anhydride, and one of them can be used or two or more thereof canbe used in combination.

[0023] Among the isocyanate compounds used in synthesis of a polyurethane polyol, as anon-aromatic isocyanate, the same compounds as those that can be used for the isocyanate composition (i) can be used. Examples of the aromatic isocyanate include, but not limitedto, 2,2’-diphenylmethane diisocyanate, 2,4’-diphenylmethane diisocyanate, 4,4’-diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate (also referred to aspolymeric MDI or crude MDI), 1,3-phenylene diisocyanate, 4,4’-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4’-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidinediisocyanate, 4,4’-diphenyl ether diisocyanate, 4,4’,4”-triphenylmethane triisocyanate, andderivatives of the diisocyanates (biuret form, isocyanurate form, adduct form, allophanateform).

[0024] The polyol compound preferably contains at least one of a polyether polyol and apolyester polyol.

[0025] The number average molecular weight of the polyol compound is not particularlylimited, but, as an example, is preferably 300 or more and 4000 or less. The number averagemolecular weight herein is a value measured by gel permeation chromatography (GPC) underthe following conditions.

[0026] Measurement apparatus; HLC-8320GPC, manufactured by TOSOHCORPORATIONColumn: TSKgel 4000HXL, TSKgel 3000HXL, TSKgel 2000HXL, TSKgel1000HXL, manufactured by TOSOH CORPORATION Detector: RI (refractive index detector) Data processor: Multistation GPC-8020 model II, manufactured by TOSOHCORPORATION Measurement conditions: Column temperature: 40°CSolvent: tetrahydrofuran Flow rate: 0.35 ml / min Standard: monodispersed polystyrenes Sample: obtained by filtering a tetrahydrofuran solution having a resin solid contentof 0.2% by mass through a microfilter (100 μl)

[0027] The polyol composition (ii) used in production of the present invention preferablyhas a water content of 0.01% by mass or more and 0.5% by mass or less. Thus, even in thecase of synthesis by using 4,4’-MDI as a main component, a urethane prepolymer that is superior in storage stability without crystallization or cloudiness can be produced. When thewater content of the polyol composition is too low, water may be added. When the water content of the polyol is too high, the polyol may be heated to 80 to 100°C to eliminate water under a reduced pressure.

[0028] The polyol composition (ii) used in production of the present invention preferablycontains a primary or secondary monoamine compound. Thus, even in the case of synthesisby using 4,4’-MDI as a main component, a urethane prepolymer that is superior in storagestability without crystallization or cloudiness can be produced.

[0029] Examples of the primary monoamine compound include methylamine, ethylamine,propylamine, isopropylamine, butylamine, amylamine, hexylamine, cyclohexylamine ,heptylamine, octylamine, nonylamine, decylamine, undecylamine, dodecylamine (laurylamine), tridodecylamine, tetradecylamine (myristylamine), pentadecylamine, cetylamine,stearylamine, oleylamine, cocoalkylamine, tallow alkylamine, hydrogenated tallow alkylamine, an aliphatic unsaturated primary amine such as allylamine, aniline, and benzylamine.

[0030] Examples of the secondary monoamine compound include dimethylamine, diethylamine, dipropylamine, diisopropylamine, dibutylamine, diamylamine, an aliphatic unsaturated secondary amine such as diallylamine, and methylaniline, ethylaniline, dibenzylamine, diphenylamine, dicocoalkylamine, dihydrogenated tallow alkylamine, anddistearylamine.

[0031] From the viewpoint of the balance between the suppression of crystallization and cloudiness of the urethane prepolymer and the reactivity of the resulting adhesive describedlater, the amount of the monoamine compound blended is preferably 40% by mass or less ofthe total amount of the polyol composition (ii).

[0032] (First Step) In the first step of the present invention, the isocyanate composition (i) and thepolyol composition (ii) are reacted at 65°C or higher and 85°C or lower under such acondition that the isocyanate groups contained in the isocyanate group (i) is excessive relativeto the active hydrogen groups contained in the polyol composition (ii) to produce a urethaneprepolymer (I). The equivalent ratio of the isocyanate groups to the active hydrogen groups [NCO] / [active hydrogen groups] can be appropriately adjusted according to the purpose, but,as an example, is 2.0 or more and 20.0 or less.

[0033] In addition, in the first step, the isocyanate composition (i) and the polyolcomposition (ii) may be reacted at once. Alternatively, the polyol composition (ii) may bedivided into several portions and be added to the isocyanate composition (i) portionwise.The urethane prepolymer (I) may be produced by reacting a part of the isocyanatecomposition (i) and the polyol composition (ii) at an equivalent ratio of the isocyanate groups to the active hydrogen groups of 1 or less to produce a polyurethane polyol having an activehydrogen group at an end, and then, adding the remaining isocyanate composition (i) thereto.

[0034] The first step is performed until the most of the active hydrogen groups aresubjected to the reaction. Whether the most of the active hydrogen groups are subjected to the reaction is determined based on the calculated value of the NCO% of the urethaneprepolymer (I) on the assumption that all the active hydrogen groups are reacted, which valueis calculated from the molar ratio of the isocyanate groups contained in the isocyanatecomposition (i) to the active hydrogen groups contained in the polyol composition (ii)subjected to the reaction, and an actually measured NCO%. At the time when the actual measurement value of the NCO% becomes lower the calculated value and the difference from the actual measurement value of 2 hours before falls 0.05% or less, the first step is completed.

[0035] In the first step, a known urethanization catalyst, such as an organic tin compound,an organic carboxylic acid tin salt, a lead carboxylic acid salt, a bismuth carboxylic acid salt, a titanium compound, or a zirconium compound, can be used. One of the urethanizationcatalysts may be used alone or two or more thereof may be used in combination. Theamount of the urethanization catalyst used may be any that can sufficiently promote the reaction between the polyisocyanate composition (i) and the polyol composition (ii), and as anexample, is 0.001% by mass or more and 0.1% by mass or less relative to the total amount of the polyisocyanate composition (i) and the polyol composition (ii).

[0036] The first step may be performed under a solventless condition or may be performedin an organic solvent that does not have a reactivity with the isocyanate composition (i).Examples of such organic solvents include aliphatic hydrocarbon solvents, such as hexane, heptane, and octane; alicyclic hydrocarbon solvents, such as cyclohexane andmethylcyclohexane; ketone solvents, such as acetone, methyl ethyl ketone, methyl isobutylketone, and cyclohexanone; ester solvents, such as methyl acetate, ethyl acetate, butyl acetate,isobutyl acetate, methyl lactate, and ethyl lactate; aromatic solvents, such as toluene, xylene,diethylbenzene, mesitylene, anisole, benzyl alcohol, phenyl glycol, and chlorobenzene; glycolsolvents, such as ethylene glycol monoethyl ether acetate, 3-methyl-3-methoxybutyl acetate,dipropylene glycol monomethyl ether, and propylene glycol monomethyl ether; ethersolvents, such as diethyl ether, tetrahydrofuran, and dioxane; halogenated hydrocarbon solvents, such as dichloromethane, 1,2-dichloroethane, and chloroform; a pyrrolidone solvent, such as N-methyl-2-pyrrolidone; amide solvents, such as N,N-dimethylacetamide and N,N-dimethylformamide; a sulfoxide solvent, such as dimethyl sulfoxide; a lactone solvent, suchas γ-butyrolactone; an amine solvent, such as morpholine; and a mixture thereof. One of the solvents may be used alone or two or more thereof may be used in combination.

[0037] (Second Step)In the second step, the urethane prepolymer (I) produced in the first step is subjected to a heat treatment with stirring while holding the urethane prepolymer (I) at 95°Cor higher and 110°C. Such a temperature change that temporarily exceeds 110°C is noproblem, but when the temperature in the second step is lower than 95°C or exceeds 110°C,the effect to suppress the crystallization or cloudiness of the urethane prepolymer decreases. The second step is more preferably performed at 95°C or higher and 105°C or lower. Thesecond step can be performed in the same reaction container subsequently to the first step, andpurification and the like between the first step and the second step is unnecessary. The product obtained through the second step is referred to as a urethane prepolymer (II).

[0038] An indicator for completing the second step is the viscosity or the NCO%. Byperforming the second step even for only a short period of time, the effect to suppress thecrystallization or cloudiness of the urethane prepolymer is expected, but for more securely producing a urethane prepolymer superior in long-term storage stability, the second step ispreferably performed until the viscosity of urethane prepolymer (II) becomes 1.1 times ormore the viscosity of the urethane prepolymer (I), the second step is more preferablyperformed until the viscosity of urethane prepolymer (II) becomes 1.15 times or more theviscosity of the urethane prepolymer (I). Since the effect to suppress the crystallization or cloudiness of the urethane prepolymer reaches a plateau and from the viewpoint of thebalance with the applicability of a resulting adhesive as described later, the second step ispreferably completed before the viscosity of the urethane prepolymer (II) exceeds 15.0 timesthe viscosity of the urethane prepolymer (I), the second step is more preferably completedbefore the viscosity of the urethane prepolymer (II) exceeds 10 times the viscosity of theurethane prepolymer (I). The viscosities of the urethane prepolymers (I) and (II) are valuesmeasured with a rotation viscometer with a cone plate of 1° × 50 mm diameter at a shear rate of 100 sec-1 and at 25°C±1°C.

[0039] Alternatively, the NCO% may be used as an indicator and the second step may becontinued until the actual measurement value of the NCO% of the urethane prepolymer (II)falls in 99% or less of the actual measurement value of the NCO% of the urethane prepolymer(I). Since the effect to suppress the crystallization or cloudiness of the urethane prepolymer reaches a plateau and from the viewpoint of the balance with the applicability of a resultingadhesive as described later, the second step is preferably completed before the actualmeasurement value of the NCO% of the urethane prepolymer (II) falls below 80% of theactual measurement value of the urethane prepolymer (I).

[0040] (Third Step)The urethane prepolymer (II) produced through the second step may be used as it isor the viscosity thereof may be adjusted by further adding an isocyanate compound. Thisstep is referred to as a third step. Examples of the isocyanate compound used in the thirdstep include a non-aromatic isocyanate or a derivative thereof, a urethane prepolymer obtained from a non-aromatic isocyanate and a polyol, a carbodiimide-modified diphenylmethane diisocyanate, an allophanate-modified diphenylmethane diisocyanate, and a polymeric diphenylmethane diisocyanate.

[0041] As the non-aromatic isocyanate or a derivative thereof, the same compounds as exemplified as the compound that can be used in combination with the isocyanatecomposition (i) can be used. As the polyol used for synthesis of the urethane prepolymer obtained from a non-aromatic isocyanate and a polyol, the same compounds as exemplified asthe polyol compound to be used for the polyol composition (ii) can be used.

[0042] The carbodiimide-modified diphenylmethane diisocyanate, the allophanate-modified diphenylmethane diisocyanate, and the polymeric diphenylmethane diisocyanate generally contain a diphenylmethane diisocyanate monomer. In the present invention, thosehaving a 2,2’-MDI content of 2.0% by mass or less and a 2,4’-MDI content of 5.0% by massor less are used.

[0043] <Adhesive> A urethane prepolymer produced by the production method of the present invention has a high rate of reduction in PAA and does not have a problem of crystallization orcloudiness occurring over time, and thus, can be suitably used as an isocyanate component fora two-component curable adhesive. An example of a two-component curable adhesive usinga urethane prepolymer produced by the production method of the present invention will bedescribed below. The two-component curable adhesive contains a polyol composition (X) and a polyisocyanate composition (Y).

[0044] (Polyol Composition (X))The polyol composition (X) contains a polyol compound having a plurality of hydrogen groups. As the polyol compound, the same compounds as exemplified as the polyol compound that can be used for the polyol composition (ii) can be used. At least oneof a polyester polyol, a polyether polyol, and a castor oil-based polyol is preferably contained.

[0045] When the adhesive of the present invention is used as a non-solvent type one, theviscosity of the polyol composition (X) is adjusted within the range that is suited to a nonsolventlamination method. As an example, the viscosity at 40°C is adjusted within therange of 100 to 5000 mPas, more preferably 100 to 3000 mPas. The viscosity of the polyolcomposition (X) can be adjusted by the skeleton of the polyol compound, a plasticizerdescribed later, and the like. In adjusting the viscosity by the skeleton of the polyolcompound, for example, the viscosity can be decreased by using polypropylene glycol or a polyester polyol produced by a reaction of an aliphatic carboxylic acid and a polyol. On theother hand, the viscosity can be increased by using a polyester polyol produced by a reactionof an aromatic carboxylic acid and a polyol.

[0046] (Polyisocyanate Composition (Y)) The polyisocyanate composition (Y) contains a urethane prepolymer produced bythe production method of the present invention. Furthermore, another isocyanate compoundcan be used in combination therewith to the extent that does not impair the effect of thepresent invention. As the isocyanate compound that can be used in combination with the urethane prepolymer, the same compounds as exemplified as a compound that can be used inthe third step in the production method of the present invention can be used.

[0047] When the adhesive of the present invention is used as a non-solvent type one, the viscosity of the polyisocyanate composition (Y) is adjusted within the range that is suited to anon-solvent lamination method. As an example, the viscosity at 40°C is adjusted within therange of 500 to 5000 mPas, more preferably 500 to 3000 mPas. The viscosity of thepolyisocyanate composition (Y) can be adjusted by, as an example, the amount of theurethane prepolymer or the isocyanate monomer blended.

[0048] (Other Components of Adhesive) The adhesive of the present invention may contain a component other than thecomponents mentioned above. The other components may be contained in one or both ofthe polyol composition (X) and the polyisocyanate composition (Y), or may be adjusted separately therefrom and be mixed with the polyol composition (X) and the polyisocyanatecomposition (Y) immediately before application of the adhesive in use. The componentswill be described below.

[0049] (Catalyst) As a catalyst, a metallic catalyst, an amine-based catalyst, an aliphatic cyclic amidecompound, and the like are exemplified.

[0050] Examples of the metallic catalyst include a metal complex-based, an inorganicmetal-based, and an organic metal-based catalyst. As the metal complex-based catalyst, acetylacetonate salts of a metal selected from the group consisting of Fe (iron), Mn(manganese), Cu (copper), Zr (zirconium), Th (thorium), Ti (titanium), Al (aluminum), andCo (cobalt), such as iron acetylacetonate, manganese acetylacetonate, copper acetylacetonate,and zirconia acetylacetonate, are exemplified.

[0051] Examples of the inorganic metal-based catalyst include those selected from Sn, Fe,Mn, Cu, Zr, Th, Ti, Al, and Co.

[0052] Examples of the organic metallic catalyst include organic zinc compounds, such aszinc octylate, zinc neodecanoate, and zinc naphthenate, organic tin compounds, such asstannous diacetate, stannous dioctoate, stannous dioleate, stannous dilaurate, dibutyl tindiacetate, dibutyl tin dilaurate, dioctyl tin dilaurate, dibutyl tin oxide, and dibutyl tindichloride, organic nickel compounds, such as nickel octylate and nickel naphthenate, organic cobalt compounds, such as cobalt octylate and cobalt naphthenate, organic bismuthcompounds, such as bismuth octylate, bismuth neodecanoate, and bismuth naphthenate, andtitanium compounds, such as tetraisopropyloxy titanate, dibutyl titanium dichloride, tetrabutyltitanate, butoxytitanium trichloride, a titanium chelate complex having at least one of analiphatic diketone, an aromatic diketone, and an alcohol having 2 to 10 carbon atoms as a ligand.

[0053] Examples of the amine-based catalyst include triethylenediamine, 2-methyltriethylenediamine, quinuclidine, 2-methylquinuclidine, N,N,N’,N’-tetramethylethylenediamine, N,N,N’,N’-tetramethylpropylenediamine, N,N,N’,N”,N”- pentamethyldiethylenetriamine, N,N,N’,N”,N”-pentamethyl-(3-aminopropyl)ethylenediamine, N,N,N’,N”,N”-pentamethyldipropylenetriamine, N,N,N’,N’-tetramethylhexamethylenediamine, bis(2-dimethylaminoethyl) ether, dimethylethanolamine, dimethylisopropanolamine, dimethylaminoethoxyethanol, N,N-dimethyl-N’-(2-hydroxyethyl)ethylenediamine, N,N-dimethyl-N’-(2-hydroxyethyl)propanediamine, bis(dimethylaminopropyl)amine, bis(dimethylaminopropyl)isopropanolamine, 3-quinuclidinol, N,N,N’,N’-tetramethylguanidine, 1,3,5-tris(N,N-dimethylaminopropyl)hexahydro-S-triazine, 1,8-diazabicyclo[5.4.0]undecene-7, N-methyl-N’-(2-dimethylaminoethyl)piperazine, N,N’-dimethylpiperazine, dimethylcyclohexylamine,N-methylmorpholine, N-ethylmorpholine, 1-methylimidazole, 1,2-dimethylimidazole, 1- isobutyl-2-methylimidazole, 1-dimethylaminopropylimidazole, N,N-dimethylhexanolamine,N-methyl-N’-(2-hydroxyethyl)piperazine, 1-(2-hydroxyethyl)imidazole, 1-(2-hydroxypropyl)imidazole, 1-(2-hydroxyethyl)-2-methylimidazole, and 1-(2-hydroxypropyl)-2-methylimidazole.

[0054] Examples of the aliphatic cyclic amide compound include δ-valerolactam, ε-caprolactam, ω-enantholactam, η-caprylolactam, and β-propiolactam. Among them, ε-caprolactam is more effective for promoting curing.

[0055] (Acid Anhydride) Examples of the acid anhydride include a cyclic aliphatic acid anhydride, an aromatic acid anhydride, and an unsaturated carboxylic acid anhydride, and one or two ormore thereof can be used in combination. More specifically, examples thereof include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride,benzophenonetetracarboxylic anhydride, dodecenylsuccinic anhydride, polyadipic anhydride,polyazelaic anhydride, polysebacic anhydride, poly(ethyloctadecanedioic acid) anhydride,poly(phenylhexadecanedioic acid) anhydride, tetrahydrophthalic anhydride,methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, methylhimic anhydride, trialkyltetrahydrophthalic anhydride,methylcyclohexenedicarboxylic anhydride, methylcyclohexenetetracarboxylic anhydride,ethylene glycol bistrimellitate dianhydride, het anhydride, nadic anhydride, methylnadicanhydride, 5-(2,5-dioxotetrahydro-3-franyl)-3-methyl-3-cyclohexane-1,2-dicarboxylic anhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalenesuccinic dianhydride, and 1- methyl-dicarboxy-1,2,3,4-tetrahydro-1-naphthalenesuccinic dianhydride.

[0056] In addition, a compound obtained by modifying the compounds mentioned above asan acid anhydride with a glycol may be used. Examples of the glycol that can be used inmodification include alkylene glycols, such as ethylene glycol, propylene glycol, and neopentyl glycol; and polyether glycols, such as polyethylene glycol, polypropylene glycol,and polytetramethylene ether glycol. Furthermore, a copolymerized polyether glycol of twoor more glycols and / or polyether glycols thereof can also be used.

[0057] (Coupling Agent) Examples of the coupling agent include a silane coupling agent, a titanate-basedcoupling agent, and an aluminum-based coupling agent.

[0058] Examples of the silane coupling agent include aminosilanes, such as γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethyldimethoxysilane,and N-phenyl-γ-aminopropyltrimethoxysilane; epoxysilanes, such as β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-glycidoxypropyltriethoxysilane; vinylsilanes, such as vinyltris(β-methoxyethoxy)silane,vinyltriethoxysilane, vinyltrimethoxysilane, and γ-metacryloxypropyltrimethoxysilane;hexamethyldisilazane, and γ-mercaptopropyltrimethoxysilane.

[0059] Examples of the titanate-based coupling agent include titanium tetraisopropoxide,titanium tetra-n-butoxide, butyl titanate dimer, tetrastearyl titanate, titanium acetylacetonate,titanium lactate, tetraoctylene glycol titanate, titanium lactate, and titanium tetrastearoxide.

[0060] An example of the aluminum-based coupling agent is acetoalkoxyaluminumdiisopropylate.

[0061] (Pigment) The pigment is not particularly limited, and examples thereof include extenderpigments, and organic pigments and inorganic pigments, such as white pigments, blackpigments, gray pigments, red pigments, brown pigments, green pigments, blue pigments, metal powder pigments, self-luminous pigments, and pearl pigments, and plastic pigments,which are listed in Toryo Genryo Binran (handbook for paint raw material), 1970 edition,(edited by Japan Paint Manufacturers Association).

[0062] Examples of the extender pigment include settleable barium sulfate, Gohun, settleable calcium carbonate, calcium bicarbonate, Kansuiseki (white marble), alumina white,silica, hydrated fine powder silica (white carbon), superfine powder anhydrous silica (aerosil),silica sand, talc, settleable magnesium carbonate, bentonite, clay, kaolin, and loess.

[0063] Specific examples of the organic pigment include various insoluble azo pigments, such as Benzidine Yellow, Hanza Yellow, and Lake Red 4R; soluble azo pigments, such asLake Red C, Carmin 6B, and Bordeaux 10; various (copper) phthalocyanine-based pigments,such as Phthalocyanine Blue and Phthalocyanine Green; various chloric dyeing lakes, such asRhodamine Lake and Methyl Violet Lake; various mordant dye pigments, such as QuinolineLake and Fast Sky Blue; various vat dye pigments, such as an anthraquinone-based pigment, a thioindigo-based pigment, and a perinone-based pigment; various quinacridone-basedpigments, such as Cinquasia Red B; various dioxazine-based pigments, such as DioxazineViolet; various condensed azo pigments, such as Chromophthal; and aniline black.

[0064] Examples of the inorganic pigment include various chromate salts, such as ChromeYellow, zinc chromate, and Molybdate Orange; various ferrocyanic compounds, such asPrussian Blue; various metal oxides, such as titanium oxide, zinc flower, Mapico Yellow, ironoxide, red oxide, Chromium Oxide Green, and zirconium oxide; various sulfide or selenide, such as Cadmium Yellow, Cadmium Red, and mercury sulfide; various sulfate salts, such asbarium sulfate and lead sulfate; various silicate salts, such as calcium silicate and UltramarineBlue; various carbonate salts, such as calcium carbonate and magnesium carbonate; variousphosphate salts, such as Cobalt Violet and Manganese Violet; various metal powder pigments,such as aluminum powder, gold powder, silver powder, copper powder, bronze powder, and brass powder; flake pigments of these metals, mica flake pigment; metallic pigments andpearl pigments, such as a mica flake pigment coated with a metal oxide and a mica-like ironoxide pigment; and charcoal and carbon black.

[0065] Examples of the plastic pigment include “Grandol PP-1000” and “PP-2000S”manufactured by DIC Corporation.

[0066] The pigment used may be appropriately selected according to the purpose, and,because of, for example, superior durability, weather resistance, and design, an inorganicoxide, such as titanium oxide or zinc flower, is preferably used as a white pigment, and carbon black is preferably used as a black pigment.

[0067] The amount of the pigment blended is, as an example, 1 to 400 parts by massrelative to 100 parts by mass of the total amount of the non-volatile components of the polyolcomposition (X) and the polyisocyanate composition (Y), and for better adhesiveness and blocking resistance, more preferably 10 to 300 parts by mass.

[0068] (Plasticizer)Examples of the plasticizer include a phthalic acid-based plasticizer, a fatty acid-based plasticizer, an aromatic polycarboxylic acid-based plasticizer, a phosphoric acid-based plasticizer, a polyol-based plasticizer, an epoxy-based plasticizer, a polyester-basedplasticizer, and a carbonate-based plasticizer.

[0069] Examples of the phthalic acid-based plasticizer include phthalate ester-basedplasticizers, such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutylphthalate, dihexyl phthalate, diheptyl phthalate, di-(2-ethylhexyl) phthalate, di-n-octylphthalate, dinonyl phthalate, diisononyl phthalate, didecyl phthalate, diisodecyl phthalate, ditridecyl phthalate, diundecyl phthalate, dilauryl phthalate, distearyl phthalate, diphenyl phthalate, dibenzyl phthalate, butylbenzyl phthalate, dicyclohexyl phthalate, octyldecylphthalate, dimethyl isophthalate, di-(2-ethylhexyl) isophthalate, and diisooctyl isophthalate,and tetrahydrophthalate ester-based plasticizers, such as di-(2-ethylhexyl) tetrahydrophthalate,di-n-octyl tetrahydrophthalate, and diisodecyl tetrahydrophthalate.

[0070] Examples of the fatty acid-based plasticizer include adipic acid-based plasticizers,such as di-n-butyl adipate, di-(2-ethylhexyl) adipate, diisodecyl adipate, diisononyl adipate,di(C6-C10 alkyl) adipate, and dibutyldiglycol adipate, azelaic acid-based plasticizers, such asdi-n-hexyl azelate, di-(2-ethylhexyl) azelate, and diisooctyl azelate, sebacic acid-basedplasticizers, such as di-n-butyl sebacate, di-(2-ethylhexyl) sebacate, and diisononyl sebacate, maleic acid-based plasticizers, such as dimethyl malate, diethyl malate, di-n-butyl malate, anddi-(2-ethylhexyl) malate, fumaric acid-based plasticizers, such as di-n-butyl fumarate and di-(2-ethylhexyl) fumarate, itaconic acid-based plasticizers, such as monomethyl itaconate,monobutyl itaconate, dimethyl itaconate, diethyl itaconate, dibutyl itaconate, and di-(2-ethylhexyl) itaconate, stearic acid-based plasticizers, such as n-butyl stearate, glycerol monostearate, and diethylene glycol distearate, oleic acid-based plasticizers, such as butyloleate, glyceryl monooleate, and diethylene glycol monooleate, citric acid-based plasticizers,such as triethyl citrate, tri-n-butyl citrate, acetyltriethyl citrate, acetyltributyl citrate, andacetyltri-(2-ethylhexyl) citrate, ricinoleic acid-based plasticizers, such as methylacetylricinoleate, butylacetyl ricinoleate, glyceryl monoricinoleate, and diethylene glycol monoricinoleate, and other fatty acid-based plasticizers, such as diethylene glycolmonolaurate, diethylene glycol dipelargonate, and pentaerythritol fatty acid ester.

[0071] Examples of the aromatic polycarboxylic acid-based plasticizer include trimellitic acid-based plasticizers, such as tri-n-hexyl trimellitate, tri-(2-ethylhexyl) trimellitate, tri-n- octyl trimellitate, triisooctyl trimellitate, triisononyl trimellitate, tridecyl trimellitate, andtriisodecyl trimellitate, and pyromellitic acid-based plasticizers, such as tetra-(2-ethylhexyl)pyromellitate and tetra-n-octyl pyromellitate.

[0072] Examples of the phosphoric acid-based plasticizer include triethyl phosphate,tributyl phosphate, tri-(2-ethylhexyl) phosphate, tributoxyethyl phosphate, triphenylphosphate, octyldiphenyl phosphate, cresyldiphenyl phosphate, cresylphenyl phosphate,tricresyl phosphate, trixylenyl phosphate, tris(chloroethyl) phosphate, tris(chloropropyl) phosphate, tris(dichloropropyl) phosphate, and tris(isopropylphenyl) phosphate.

[0073] Examples of the polyol-based plasticizer include glycol-based plasticizers, such asdiethylene glycol dibenzoate, dipropylene glycol dibenzoate, triethylene glycol dibenzoate,triethylene glycol di-(2-ethylbutylate), triethylene glycol di-(2-ethylhexoate), and dibutyl methylenebisthioglycolate, and glycerol-based plasticizers, such as glycerol monoacetate,glycerol triacetate, and glycerol tributylate.

[0074] Examples of the epoxy-based plasticizer include epoxylated soy bean oil,epoxybutyl stearate, di-2-ethylhexyl epoxyhexahydrophthalate, diisodecyl epoxyhexahydrophthalate, epoxytriglyceride, epoxylated octyl oleate, and epoxylated decyloleate.

[0075] Examples of the polyester-based plasticizer include an adipic acid-based polyester, asebacic acid-based polyester, and a phthalic acid-based polyester.

[0076] Examples of the carbonate-based plasticizer include propylene carbonate and ethylene carbonate.

[0077] In addition, other examples of the plasticizer include a partially hydrogenated terphenyl, an adhesive plasticizer, and polymerizable plasticizers, such as diallyl phthalate andan acrylic monomer and oligomer. One of the plasticizers can be used alone or two or morethereof can be used in combination.

[0078] (Phosphoric acid compound) Examples of the phosphoric acid compound (C6) include phosphoric acid,pyrophosphoric acid, triphosphoric acid, methyl acid phosphate, ethyl acid phosphate, butylacid phosphate, dibutyl phosphate, 2-ethylhexyl acid phosphate, bis(2-ethylhexyl) phosphate,isododecyl acid phosphate, butoxyethyl acid phosphate, oleyl acid phosphate, tetracosyl acidphosphate, 2-hydroxyethyl methacrylate acid phosphate, and a polyoxyethylene alkyl etherphosphate.

[0079] (Form of Adhesive) The form of the adhesive of the present invention may be any of a solvent type or anon-solvent type. In particular, the adhesive of the present invention is suitable for a non-solvent type which contains no organic solvent and thus, tends to have an insufficient storagestability in the case of using a urethane prepolymer synthesized by using 4,4’-MDI as a maincomponent. As used herein, the “solvent-type” adhesive refers to a form used in a so-called dry lamination method in which a substrate is coated with an adhesive, then, is heated in anoven or the like to volatile an organic solvent in the coating film, and then, is bonded toanother substrate. Any one or both of the polyol composition (X) and the polyisocyanatecomposition (Y) contain an organic solvent that can dissolve (dilute) the constitutionalcomponents of the polyol composition (X) and the polyisocyanate composition (Y) used in the present invention.

[0080] Examples of the organic solvent include esters, such as ethyl acetate, butyl acetate,and cellosolve acetate, ketones, such as acetone, methyl ethyl ketone, isobutyl ketone, andcyclohexanone, ethers, such as tetrahydrofuran and dioxane, aromatic hydrocarbons, such as toluene and xylene, halogenated hydrocarbons, such as methylene chloride and ethylenechloride, dimethyl sulfoxide, and dimethylsulfamide. An organic solvent used as a reactionmedium in producing a constitutional component of the polyol composition (X) or thepolyisocyanate composition (Y) is sometimes further used as a diluent in coating.

[0081] As used herein, the “non-solvent type” adhesive refers to a form of an adhesive inwhich the polyol composition (X) and the polyisocyanate composition (Y) containsubstantially none of organic solvents having a high solubility, such as esters, such as ethylacetate, butyl acetate, and cellosolve acetate, ketones, such as acetone, methyl ethyl ketone,isobutyl ketone, and cyclohexanone, ethers, such as tetrahydrofuran and dioxane, aromatic hydrocarbons, such as toluene and xylene, halogenated hydrocarbons, such as methylenechloride and ethylene chloride, dimethyl sulfoxide, and dimethylsulfamide, in particular,contain substantially no ethyl acetate or methyl ethyl ketone, and which is used in a so-callednon-solvent lamination method in which a substrate is coated with an adhesive, and then, isbonded to another substrate without a step of heating in an oven or the like to volatile asolvent. Such a case where an organic solvent used as a reaction medium in producing aconstitutional component of the polyol composition (X) or the polyisocyanate composition(Y) or a raw material thereof is not sufficiently removed so that a small amount of the organic solvent remains in the polyol composition (X) or the polyisocyanate composition (Y) isconsidered as containing substantially no organic solvent. In addition, when the polyolcomposition (X) contains an alcohol having a low molecular weight, the alcohol having a lowmolecular weight reacts with the polyisocyanate composition (Y) to form a part of a coatingfilm, and thus, is not required to be volatilized after coating. Accordingly, such a form is also taken as a non-solvent type adhesive and such an alcohol having a low molecular weightis not considered as an organic solvent.

[0082] The adhesive of the present invention is preferably blended so that the ratio of thenumber of moles of isocyanate groups contained in the polyisocyanate composition (Y) [NCO] to the number of moles of hydrogen groups contained in the polyol composition (X)[OH], [NCO] / [OH], is 1.0 to 3.0 in use. Thus, an appropriate curability can be achievedwithout depending on the environmental humidity in application.

[0083] <Laminated Body> The adhesive produced by using a urethane prepolymer produced by the productionmethod of the present invention can be suitably used in producing a laminated body, inparticular, a laminated body for packaging a food. Such a laminated body is produced bybonding a plurality of substrates (films or papers) with the adhesive by the dry laminationmethod or non-solvent lamination method. The film used is not particularly limited, and afilm can be appropriately selected depending on the use purpose. Examples of the film forpackaging a food include a polyethylene terephthalate (PET) film, a polystyrene film, apolyamide film, a polyacrylonitrile film, polyolefin films, such as a polyethylene film(LLDPE: low density polyethylene film, HDPE: high density polyethylene film) and apolypropylene film (CPP: cast polypropylene film, OPP: oriented polypropylene film), apolyvinyl alcohol film, and an ethylene-vinyl alcohol copolymer film.

[0084] In addition, a biomass film formed from a material containing a biomass-derivedcomponent is also preferably used. A biomass film is available from various manufacturers,and in addition, for example, a sheet as shown in the List of Biomass Qualified Productprovided from General Incorporated Foundation, Japan Organic Recycling Association can beused.

[0085] A specific example of the biomass film that is known well is one produced by usinga biomass-derived ethylene glycol as a raw material. The biomass-derived ethylene glycol isobtained by using as a raw material an ethanol that is produced by using a biomass as a rawmaterial (biomass ethanol). A biomass-derived ethylene glycol can be obtained, forexample, by a method in which ethylene glycol is produced from a biomass ethanol via ethylene oxide by a conventionally known method. In addition, a commercially available biomass ethylene glycol may be used, and, for example, a biomass ethylene glycolcommercially available from India Glycol can be suitably used.

[0086] For example, as a substitute for a conventional polyethylene terephthalate film using a petroleum raw material, a film containing a biomass polyester, a biomass polyethyleneterephthalate, or the like that is composed of a biomass-derived ethylene glycol as a diol unitand a fossil fuel-derived dicarboxylic acid as a dicarboxylic acid unit is known.

[0087] As a dicarboxylic acid unit of the biomass polyester, a fossil fuel-derived dicarboxylic acid is used. As the dicarboxylic acid, an aromatic dicarboxylic acid, analiphatic dicarboxylic acid, and a derivative thereof can be used with no limitation.In addition, the biomass polyester may be a copolymer polyester which contains, inaddition to the aforementioned diol component and dicarboxylic acid component, acopolymer component added as a third component, such as a bifunctional oxycarboxylic acid or, for forming a crosslinking structure, at least one polyfunctional compound selected fromthe group consisting of a tri- or higher functional polyhydric alcohol, a tri- or higherfunctional polybasic carboxylic acid and / or an anhydride thereof, and a tri-or higherfunctional oxycarboxylic acid.

[0088] In addition, for example, as a substitute for a conventional polyolefin film using apetroleum raw material, biomass polyolefin films, such as a biomass polyethylene filmcontaining a polyethylene resin produced by using a biomass-derived ethylene glycol as a rawmaterial and a biomass polyethylene-polypropylene film, are also known.The polyethylene resin is not particularly limited as long as the biomass-derivedethylene glycol is used as a part of the raw materials, and examples thereof include an ethylene homopolymer and a copolymer of ethylene as a main component and an α-olefin(ethylene-α-olefin copolymer containing 90% by mass or more of ethylene units). One of them can be used alone or two or more thereof can be used in combination.

[0089] Note that, the α-olefin that constitutes the copolymer of ethylene and an α-olefin is not particularly limited, and examples thereof include α-olefins having 4 to 8 carbon atoms,such as 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene. A known polyethylene resin, such as a low density polyethylene resin, a medium density polyethylene resin, and a linear low density polyethylene resin, can be used. Among them, from the viewpoint of morehardly causing damages, such as hole opening and tear, even when films rub each other, alinear low density polyethylene resin (LLDPE) (a copolymer of ethylene and 1-hexene or acopolymer of ethylene and 1-octene) is preferred, and a linear low density polyethylene resin having a density of 0.910 to 0.925 g / cm3 is more preferred.

[0090] As the biomass film, those produced by using a biomass raw material distinguishedby the biomass plastic degree defined in ISO 16620 or ASTM D6866 are also distributed. Inthe atmosphere, radioactive carbon 14C exists in a proportion of one out of 1012. This proportion is the same as in carbon dioxide in the atmosphere, and is also the same as inplants in which such carbon dioxide is fixed by photosynthesis. Thus, carbon of a plant-derived resin contains the radioactive carbon 14C. In contrast, carbon of a fossil fuel-derived resin contains almost no radioactive carbon 14C. Then, the proportion of a plant-derived resin contained in a resin, that is, the biomass plastic degree can be determined bymeasuring the concentration of the radioactive carbon 14C in the resin with an acceleratormass spectrometer.

[0091] Examples of the plant-derived low density polyethylene which is a biomass plastichaving a biomass plastic degree defined in ISO 16620 or ASTM D6866 of 80% or more, preferably 90% or more include the trade name “SBC818”, “SPB608”, “SBF0323HC”,“STN7006”, “SEB853”, and “SPB681” all manufactured by Braskem, and a film produced byusing such a plant-derived low density polyethylene as a raw material can be suitably used.

[0092] In addition, a film and sheet in which starch or polylactic acid which is a biomassraw material is blended are also known. The film and sheet can be appropriately selectedand used depending on the use purpose.

[0093] The biomass film may be a laminated body in which a plurality of biomass films arelaminated, or may be a laminated body of a conventional petroleum film and a biomass film. In addition, the biomass films may be a non-oriented film or an oriented film, and theproduction method thereof is also not limited.

[0094] The film may be subjected to an orientation treatment. In a general method for theorientation treatment, a resin is melt-extruded and formed into a sheet by an extrusion filmforming method or the like, and then, is subjected to simultaneous biaxial orientation orsequential biaxial orientation. In addition, in the case of the sequential biaxial orientation, ingeneral, a longitudinal orientation treatment is performed first, followed by a lateral orientation. Specifically, a method in which longitudinal orientation using the difference inspeed between rolls and lateral orientation using a tenter are combined is often used.

[0095] The film surface may be subjected to various surface treatments, such as a flametreatment and a corona discharge treatment, as required, so that an adhesive layer without a defect, such as cutting of film or crawling, is formed.

[0096] Alternatively, a film in which a deposited layer of a metal, such as aluminum, or ametal oxide, such as silica or alumina, is laminated, or a barrier film which contains a gasbarrier layer of a polyvinyl alcohol, an ethylene-vinyl alcohol copolymer, vinylidene chloride, or the like may be used. By using such a film, a laminated body having a barrierperformance against steam, oxygen, an alcohol, an inert gas, a volatile organic compound(fragrance), or the like can be obtained.

[0097] As the paper, a known paper substrate can be used with no particular limitation. Specifically, the paper is produced by using a natural fiber for papermaking, such as woodpulp, with a known paper machine, and the papermaking conditions are not particularlydefined. Examples of the natural fiber for papermaking include wood pulps, such as softwood pulp and hard wood pulp, non-wood pulps, such as Manila hemp pulp, sisal hemp pulp,and flax pulp, and a pulp obtained by subjecting the pulps to a chemical modification. Regarding the kind of the pulp, a chemical pulp obtained by a sulfate cooking method, anacidic / neutral / alkaline sulfite cooking method, a sodium salt cooking method, or the like, aground pulp, a chemiground pulp, a thermomechanical pulp, and the like can be used. In addition, various commercially available papers, such as a fine paper, a coated paper, a liningpaper, an impregnated paper, a card paper, and a paper board, can also be used.

[0098] Specific preferred examples of the configuration of the laminated body in whichcharacteristics of the present invention are exhibited include PET film / adhesive layer’ / aluminum foil / adhesive layer / CPP film, PET film / adhesive layer’ / Ny film / adhesivelayer” / aluminum foil / adhesive layer / CPP film, and PET film / adhesive layer’ / aluminumfoil / adhesive layer / Ny film / adhesive layer / CPP film. These laminated bodies are oftenused in a packaging material in which a boiling treatment or a retorting treatment is required. Since PAA is easily transferred from an adhesive layer to the content in the boiling treatment or retorting treatment, a high rate of reduction in PAA is required for an adhesive used in alaminated body to be subjected to such a treatment. An adhesive produced by using aurethane prepolymer produced by the production method of the present invention meets sucha requirement. The aforementioned adhesive is preferably used in an adhesive layer placedbetween an aluminum foil and a sealant film. The adhesive layer’ and adhesive layer” may be or may not be formed by using the aforementioned adhesive.

[0099] Other preferred examples of the configuration include, but not limited to, OPP film / adhesive layer / CPP film, OPP film / adhesive layer / LLDPE film, OPP / adhesive layer / aluminum-deposited CPP film, PET film / adhesive layer / LLDPE film, PET film / adhesive layer / aluminum-deposited CPP film, Ny film / adhesive layer / LLDPE film, OPP film / adhesive layer’ / aluminum-deposited PET film / adhesive layer / LLDPE film, PET film / adhesive layer’ / aluminum-deposited PET film / adhesive layer / LLDPE film, and Ny film / adhesive layer’ / aluminum-deposited PET film / adhesive layer / LLDPE film. Note that inthe configurations, the adhesive layer is a cured coating film of the aforementioned adhesive. The adhesive layer’ may be a cured coating film of the aforementioned adhesive or may be a cured coating film of another adhesive.

[0100] In the laminated body, a printed layer may be provided between an adhesive layerand a substrate (generally a substrate which is an outermost layer relative to the content). The printed layer is formed of various printing inks, such as a photogravure ink, aflexographic ink, an offset ink, a stencil ink, and an inkjet ink by a general printing methodused in printing on a conventional film.

[0101] When the adhesive is a solvent-type one, the adhesive of the present invention isapplied on one substrate with a roll, such as a gravure roll, an organic solvent is volatilized byheating in an oven or the like, and then, another substrate is bonded thereto, thus producingthe laminated body of the present invention. After lamination, an aging treatment is preferably performed. The aging temperature is preferably a room temperature to 80°C andthe aging time is preferably 12 to 240 hours.

[0102] When the adhesive is a non-solvent type one, the adhesive of the present inventionpreviously heated to about 40°C to 100°C is applied on one substrate using a roll, such as acoating roll, and then, another substrate is immediately bonded thereto to produce thelaminated body of the present invention. After lamination, an aging treatment is preferablyperformed. The aging temperature is preferably a room temperature to 70°C and the agingtime is preferably 6 to 240 hours.

[0103] The amount of the adhesive applied is appropriately adjusted. In the case of asolvent-type adhesive, as an example, the amount of the adhesive applied is adjusted so as togive a solid content of 1 g / m2 or more and 10g / m2 or less, preferably 2g / m2 or more and5g / m2 or less. In the case of a non-solvent type adhesive, the amount of the adhesive appliedis, as an example, 1 g / m2 or more and 5 g / m2 or less, preferably 1 g / m25 2 or more and 3 g / m2 orless.

[0104] The laminated body may be one in which two substrates are bonded with the adhesive of the present invention, or may contain another substrate as required. A methodfor laminating another substrate may be a known method, for example, a dry lamination method, a non-solvent lamination method, a heat lamination method, a heat sealing method,or an extrusion lamination method. The adhesive used here may be or may not be theaforementioned adhesive. As said another substrate, the same substrate as mentioned abovecan be used.

[0105] <Packaging Material>The aforementioned laminated body can be suitably used as a packaging material, in particular as a packaging material for packaging a food. The packaging material is obtained by forming the aforementioned laminated body into a bag, followed by heat sealinginto a form of packaging material. As a form of packaging material, there are various forms,such as a three-side sealed bag, a four-side sealed bag, a gusset packaging bag. a pillowpackaging bag, a gable top bottomed container, a tetra classic, a brick type, a tube container, apaper cup, and a lid member. In addition, a packaging material may be appropriately subjected to an easily unsealable treatment or provided with a resealable means.

[0106] The packaging material of the present invention can be suitably used as a packagingmaterial, mainly for a food, or for containing a detergent or a drug. Specific examples of the use purpose include for a detergent or a drug, such as a liquid detergent for laundry, a liquid detergent for kitchen, a liquid detergent for bath, a liquid soap for bath, a liquid shampoo, aliquid conditioner, or a tablet for a drug. In addition, the packaging material can be used in asecondary packaging material for packaging the above containers.Examples

[0107] The present invention will be described in detail below with reference to specificsynthetic examples and examples, but the present invention is not to be limited to theexamples. Note that, in the following examples, the “parts” and “%” respectively represent“parts by mass” and “% by mass”, unless otherwise specified.

[0108] (Example 1)[Synthesis of Polyester Polyol]Into a polyester reaction container equipped with a stirrer, a thermometer, a nitrogengas introducing pipe, a Snyder tube, and a condenser, 122 parts of ethylene glycol, 267 partsof neopentyl glycol, and 6 parts of trimethylolpropane were charged, and were heated to 80°C with stirring under a nitrogen gas flow. With further stirring, 516 parts of adipic acid and 90parts of isophthalic acid were charged into the reaction container, and the temperature wasslowly increased to 240°C so that the temperature of an upper part of the Snyder tube did notexceed 100°C to allow an esterification reaction to proceed. When the acid value fell to 5mgKOH / g or less, the pressure in the reaction container was slowly reduced to allow areaction to proceed at 1 mmHg or less and 240°C for 2 hours, thus producing a polyesterpolyol having an acid value of 0.8 mgKOH / g, a molecular weight of about 1650, a hydroxylvalue of about 68 mgKOH / g, and a water content of 0.016% by mass.

[0109] [First Step] Into a reaction container equipped with a stirrer, a thermometer, a nitrogen gasintroducing pipe, and a condenser, 48.6 parts of an isocyanate composition (i-1) having acontent of 2,2-diphenylmethane diisocyanate of 0.1% by mass, a content of 2,4- diphenylmethane diisocyanate of 0.8% by mass, a content of 4,4’-diphenylmethane diisocyanate of 80.8% by mass, and a content of SUMIJUR N3300 (manufactured by SumikaCovestro Urethane Co., Ltd.) of 18.3% by mass was charged, and was heated to 60°C withstirring under a nitrogen gas flow. A polyol composition (ii-1) that contained 26.4 parts ofpolyester polyol, 11.9 parts of a polypropylene glycol having a number average molecular weight of 2000, and 0.00264 parts of phosphoric acid and that had a water content of 0.042%was divided into several portions, which were then added dropwise thereto, and the mixturewas further heated and was held at an internal temperature of 80°C for 3 hours to allow aurethanization reaction to proceed, thereby producing a urethane prepolymer (I-1) having anisocyanate group at both ends and having an NCO% of 15.0% and a viscosity of 3873 mPa·s.

[0110] [Second Step]The urethane prepolymer (I-1) in the reaction container was heated to 100°C over 1hour with stirring under a nitrogen gas flow, and the temperature was further held for 3 hoursto allow a reaction to proceed, thereby producing a urethane prepolymer (II-1) having an NCO% of 14.7% and a viscosity of 4377 mPa·s.

[0111] [Third Step]The urethane prepolymer (II-1) in the reaction container was cooled to 50°C, and13.1 parts of a carbodiimide-modified diphenylmethane diisocyanate (product name: LUPRANETE MM103, manufactured by BASF) was added thereto and the mixture wasstirred into a uniform state, thereby producing a urethane prepolymer of Example 1 having anNCO% of 16.7%.

[0112] (Example 2)-(Example 8)Urethane prepolymers of Examples 2 to 8 were synthesized in the same manner asin Example 1 except for changing the polyisocyanate composition (i) and the polyolcomposition (ii) used, the heat treatment conditions in the first step and the second step, and the amount of the additive in the third step to those shown in Tables 1 and 2.

[0113] (Comparative Example 1)A urethane prepolymer of Comparative Example 1 was synthesized in the samemanner as in Example 1 except for changing the polyisocyanate composition (i) and thepolyol composition (ii) used and the amounts of additives in the first step and the third step tothose shown in Table 2 and omitting the second step.(Comparative Example 2)Urethane prepolymers of Comparative Examples 1 and 2 were synthesized in thesame manner as in Example 1 except for changing the polyisocyanate composition (i) and the polyol composition (ii) used, the heat treatment conditions in the first step and the secondstep, and the amount of the additive in the third step to those shown in Table 2.

[0114] Note that, in the tables, the NCO% and the viscosity in the first step respectivelyrepresent the NCO% and the visc20 osity at the time of completing the first step, and the NCO%and the viscosity in the second step respectively represent the NCO% and the viscosity at thetime of completing the second step. The NCO% decrement represents the NCO% at the time of completing the second step relative to the NCO% at the time of completing the firststep, and the viscosity increase represents the magnification of the viscosity at the time of completing the second step to the viscosity at the time of completing the first step.

[0115] <Evaluation>(Storage Stability) A 15-ml glass bottle was filled with a urethane prepolymer of each of Examples andComparative Examples, and was stored at a normal temperature for a certain period of time, and then, the apparent cloudiness was visually evaluated. The evaluation was made according to the following criteria. A: Not clouded for two month or moreB: Clouded in one to two monthsC: Clouded in one month

[0116] [Table 1]

[0117] [Table 2]..

Claims

1. A method for producing a urethane prepolymer for a two-component curable adhesive, the method comprising a first step of reacting a isocyanate composition (i) having a content of 2,2'- diphenylmethane diisocyanate of 0.5% by mass or less, a content of 2,4'-diphenylmethane diisocyanate of 5.0% by mass or less, and a content of 4,4'-phenylmethane diisocyanate of 75.0% by mass or more and a polyol composition (ii) at 65°C or higher and 85°C or lower in such a condition that isocyanate groups contained in the isocyanate group are excessive relative to active hydrogen groups contained in the polyol composition, to produce a urethane prepolymer (I), and a second step of subjecting the urethane prepolymer (I) to a heat treatment at 95°C or higher and 110°C or lower to produce a urethane prepolymer (II).

2. The production method according to claim 1, wherein the method comprises a step of adjusting a water content of the polyol composition (ii) to 0.01% by mass or more and 0.5% by mass or less.

3. The production method according to claim 1 or 2, wherein the polyol composition (ii) comprises at least one monoamine selected from a primary monoamine and a secondary monoamine, the polyol composition (ii) having a content of the monoamine of 10% by mass or less.

4. The production method according to any one of claims 1 to 3, wherein the second step is performed until a viscosity of the urethane prepolymer (II) at 25°C reaches 1.1 times or more a viscosity of the urethane prepolymer (I).

5. The production method according to any one of claims 1 to 3, wherein the second step is completed before a viscosity of the urethane prepolymer (II) at 25°C exceeds 15.0 times a viscosity of the urethane prepolymer (I).

6. The production method according to any one of claims 1 to 3, wherein the second step is performed until an NCO% of the urethane prepolymer (II) falls to 99% or less of an NCO% of the urethane prepolymer (I).

7. The production method according to any one of claims 1 to 3, wherein the second step is completed before an NCO% of the urethane prepolymer (II) falls below 80% of an NCO% of the urethane prepolymer (I).

8. The production method according to any one of claims 1 to 7, wherein the polyol composition (ii) comprises at least one of a polyether polyol and a polyester polyol.