Method for producing adhesive and method for producing laminate

Abstract

To provide an adhesive and a laminate that exhibit superior gas barrier property and adhesion, and also exhibit superior initial tack.SOLUTION: An adhesive comprises an isocyanate group-terminated prepolymer. The isocyanate group-terminated prepolymer comprises a reaction product of a polyisocyanate component containing xylylene diisocyanate and a polyol component containing a polyester polyol and a low molecular weight diol. The isocyanate group-terminated prepolymer comprises a skeleton represented by structural formula (A). The content ratio of the skeleton represented by structural formula (A) is 40 mass% or more relative to the total amount of the isocyanate group-terminated prepolymer. (In the formula below, X represents a low molecular weight diol residue.)SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to adhesives and laminates. [Background technology]

[0002] In the field of packaging materials, laminates in which a plastic film and a gas barrier layer are laminated are known. Examples of gas barrier layers include metal-deposited layers formed by depositing a metal layer and / or a metal oxide on a plastic film. In recent years, polyurethane layers have been proposed as gas barrier layers. Laminating a polyurethane layer and a metal-deposited layer has also been proposed.

[0003] More specifically, for example, the following laminate is known. That is, the laminate includes a film and a gas barrier layer. The gas barrier layer includes a cured product of a gas barrier polyurethane resin composition. The gas barrier polyurethane resin composition includes component A and component B. Component A includes a TMP adduct of XDI. Component B includes ethylene glycol and ethanol. Furthermore, a film having a metal vapor deposition layer is used (see, for example, Patent Document 1 (Example 13)).

[0004] In the above laminate, the gas barrier layer has excellent gas barrier properties and adhesive strength. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-24986 Summary of the Invention [Problem to be solved by the invention]

[0006] On the other hand, gas barrier polyurethane resin compositions are also required to have good adhesion immediately after application (initial tack).

[0007] The present invention provides an adhesive and a laminate that are excellent in gas barrier properties and adhesion, and also in initial tack. [Means for solving the problem]

[0008] The present invention [1] provides an adhesive comprising an isocyanate-terminated prepolymer, wherein the isocyanate-terminated prepolymer comprises a reaction product of a polyisocyanate component containing xylylene diisocyanate with a polyol component containing a polyester polyol and a low-molecular-weight diol, and the isocyanate-terminated prepolymer comprises a skeleton represented by structural formula (A), and the content of the skeleton represented by structural formula (A) is 40 mass% or more relative to the total amount of the isocyanate-terminated prepolymer.

[0009] [ka] (In the formula, X represents a low-molecular-weight diol residue.)

[0010] The present invention [2] includes the adhesive according to the above [1], in which the low molecular weight diol includes ethylene glycol and / or propylene glycol.

[0011] The present invention [3] includes the adhesive according to the above [1] or [2], in which the number average molecular weight of the polyester polyol is 400 or more and 2,000 or less.

[0012] The present invention [4] includes the adhesive according to any one of the above [1] to [3], which is a moisture-curing adhesive.

[0013] The present invention [5] is a two-component curing adhesive, and comprises the adhesive according to any one of the above [1] to [3], which comprises a first component containing the isocyanate group-terminated prepolymer and a second component containing a low-molecular-weight polyol.

[0014] The present invention [6] includes the adhesive according to the above [5], in which the content of the skeleton represented by the structural formula (A) is 50 mass% or more relative to the total amount of the cured product of the two-component curing adhesive.

[0015] The present invention [7] includes a laminate comprising a substrate, an adhesive layer disposed on the substrate, and an inorganic thin film disposed on the adhesive layer, wherein the adhesive layer is a cured product of the adhesive described in any one of [1] to [6] above.

[0016] The present invention [8] is a two-component curing adhesive, which comprises a first component containing an isocyanate-terminated prepolymer and a second component containing a low-molecular-weight polyol, wherein the isocyanate-terminated prepolymer comprises a reaction product of a polyisocyanate component containing xylylene diisocyanate and a polyol component containing a polyester polyol and a low-molecular-weight diol, and the isocyanate-terminated prepolymer comprises a skeleton represented by structural formula (A), and the content of the skeleton represented by structural formula (A) relative to the total amount of the cured product of the two-component curing adhesive is 50 mass% or more. [ka] (In the formula, X represents a low-molecular-weight diol residue.) [Effects of the Invention]

[0017] The adhesive of the present invention comprises an isocyanate-terminated prepolymer. The isocyanate-terminated prepolymer comprises a reaction product of a polyisocyanate component containing xylylene diisocyanate with a polyol component containing a polyester polyol and a low-molecular-weight diol. Therefore, the adhesive of the present invention has excellent initial tack. Furthermore, the adhesive of the present invention contains a skeleton represented by the above structural formula (A) in the isocyanate-terminated prepolymer at a ratio equal to or greater than a predetermined value. Therefore, the adhesive of the present invention has excellent gas barrier properties and adhesion.

[0018] The adhesive of the present invention contains the skeleton represented by structural formula (A) at a ratio equal to or greater than a predetermined value relative to the total amount of the cured product of the two-component curing adhesive, and therefore has excellent gas barrier properties and adhesion.

[0019] The laminate of the present invention includes an adhesive layer that is a cured product of the above-described adhesive. Furthermore, an inorganic thin film is disposed on the adhesive layer. Therefore, the laminate of the present invention has excellent initial tack, gas barrier properties, and adhesion of the adhesive layer. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a laminate film as one embodiment of the laminate of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] The adhesive of the present invention, which will be described in detail later, is a two-component curing adhesive or a moisture-curing (one-component curing) adhesive. The adhesive contains an isocyanate group-terminated prepolymer as an essential component.

[0022] The isocyanate-terminated prepolymer comprises the reaction product of a polyisocyanate component and a polyol component. Preferably, the isocyanate-terminated prepolymer is the reaction product of a polyisocyanate component and a polyol component.

[0023] The polyisocyanate component contains xylylene diisocyanate as an essential component. Examples of xylylene diisocyanate include 1,2-xylylene diisocyanate (o-XDI), 1,3-xylylene diisocyanate (m-XDI), and 1,4-xylylene diisocyanate (p-XDI). These can be used alone or in combination of two or more. Preferably, 1,3-xylylene diisocyanate is used.

[0024] Xylylene diisocyanate may be modified to the extent that the excellent effects of the present invention are not impaired. Examples of the modified products include uretdione modified products, isocyanurate modified products, iminooxadiazinedione modified products, biuret modified products, allophanate modified products, polyol adducts, oxadiazinetrione modified products, and carbodiimide modified products.

[0025] The polyisocyanate component may optionally contain other isocyanates. The other isocyanates are isocyanates other than xylylene diisocyanate.

[0026] Examples of other isocyanates include aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, and araliphatic polyisocyanates (excluding xylylene diisocyanate). Examples of aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), 1,2-propane diisocyanate, 1,2-butane diisocyanate, 2,3-butane diisocyanate, 1,3-butane diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and 2,6-diisocyanate methyl caproate. Examples of alicyclic polyisocyanates include isophorone diisocyanate (IPDI), norbornene diisocyanate (NBDI), and methylenebis(cyclohexyl isocyanate) (H 12 MDI), and bis(isocyanatomethyl)cyclohexane (H6XDI). Examples of aromatic polyisocyanates include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), toluidine diisocyanate (TODI), paraphenylene diisocyanate, and naphthalene diisocyanate (NDI). Examples of aromatic aliphatic polyisocyanates include tetramethylxylylene diisocyanate (TMXDI). Furthermore, other polyisocyanates may be modified as described above, provided that the excellent effects of the present invention are not impaired. These may be used alone or in combination of two or more types.

[0027] The content of other isocyanates relative to the total amount of polyisocyanate components is, for example, 50% by mass or less, preferably 30% by mass or less, more preferably 10% by mass or less, and particularly preferably 0% by mass. Furthermore, the content of xylylene diisocyanate relative to the total amount of polyisocyanate components is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass. That is, the polyisocyanate component particularly preferably consists of xylylene diisocyanate.

[0028] The polyol component includes a macropolyol and a low molecular weight polyol. Preferably, the polyol component consists of a macropolyol and a low molecular weight polyol.

[0029] Macropolyols are organic compounds with two or more hydroxyl groups in the molecule and a relatively high molecular weight. By relatively high molecular weight, we mean a number average molecular weight of 400 or more.

[0030] The macropolyol contains a polyester polyol as an essential component.

[0031] Examples of polyester polyols include polycondensates obtained by reacting a polyhydric alcohol with a polybasic acid under known conditions.

[0032] Examples of polyhydric alcohols include low-molecular-weight polyols, which will be described later. More specifically, examples of polyhydric alcohols include dihydric alcohols, trihydric alcohols, and tetrahydric or higher alcohols, which will be described later. These may be used alone or in combination of two or more. From the viewpoint of initial tackiness, dihydric alcohols are preferred, and ethylene glycol, diethylene glycol, 1,3-butanediol, and neopentyl glycol are more preferred, and from the viewpoint of initial tackiness, diethylene glycol, butanediol, and neopentyl glycol are particularly preferred.

[0033] Examples of polybasic acids include saturated aliphatic dicarboxylic acids, unsaturated aliphatic dicarboxylic acids, aromatic dicarboxylic acids, alicyclic dicarboxylic acids, other carboxylic acids, acid anhydrides, and acid halides. Examples of saturated aliphatic dicarboxylic acids include oxalic acid, malonic acid, succinic acid, methylsuccinic acid, glutaric acid, adipic acid, 1,1-dimethyl-1,3-dicarboxypropane, 3-methyl-3-ethylglutaric acid, azelaic acid, and sebacic acid. Examples of unsaturated aliphatic dicarboxylic acids include maleic acid, fumaric acid, and itaconic acid. Examples of aromatic dicarboxylic acids include orthophthalic acid, isophthalic acid, terephthalic acid, toluenedicarboxylic acid, and naphthalenedicarboxylic acid. Examples of alicyclic dicarboxylic acids include hexahydrophthalic acid. Examples of other carboxylic acids include dimer acid, hydrogenated dimer acid, and HET acid. Examples of acid anhydrides include oxalic anhydride, succinic anhydride, maleic anhydride, phthalic anhydride, alkylsuccinic anhydride, tetrahydrophthalic anhydride, and trimellitic anhydride. Examples of acid halides include oxalic acid dichloride, adipic acid dichloride, and sebacic acid dichloride. These can be used alone or in combination of two or more. From the viewpoint of initial tack, saturated aliphatic dicarboxylic acids and aromatic dicarboxylic acids are preferred, and adipic acid and isophthalic acid are more preferred.

[0034] Further, examples of polyester polyols include plant-derived polyester polyols, which are specifically obtained by condensation reaction of hydroxycarboxylic acids of hydroxyl group-containing vegetable oil fatty acids using polyhydric alcohols as initiators under known conditions.

[0035] Further, examples of polyester polyols include lactone-based polyester polyols. Lactone-based polyester polyols are obtained, for example, by ring-opening polymerization of lactones using a polyhydric alcohol as an initiator. Examples of lactones include ε-caprolactone and γ-valerolactone. More specifically, examples of lactone-based polyester polyols include polycaprolactone polyols and polyvalerolactone polyols. Further, examples of polyester polyols include alcohol-modified lactone-based polyester polyols obtained by copolymerizing lactone-based polyester polyols with the above-mentioned dihydric alcohols.

[0036] These polyester polyols can be used alone or in combination of two or more. Preferred polyester polyols include polycondensates of polyhydric alcohols and polybasic acids.

[0037] The number average molecular weight of the polyester polyol is, for example, 400 or more, preferably 500 or more. The number average molecular weight of the polyester polyol is, for example, 20,000 or less, preferably 10,000 or less, more preferably 5,000 or less, even more preferably 2,000 or less, still more preferably 1,000 or less, and particularly preferably 800 or less. When the number average molecular weight of the polyester polyol is within the above range, an adhesive that is particularly excellent in gas barrier properties, adhesion, and initial tack can be obtained.

[0038] The polyester polyol has an average number of hydroxyl groups of, for example, 1.8 or more, or preferably 2 or more. The polyester polyol has an average number of hydroxyl groups of, for example, 4 or less, preferably 3 or less, or more preferably 2.5 or less.

[0039] The macropolyol may contain other macropolyols as optional components. The other macropolyols are macropolyols other than polyester polyols.

[0040] Other macropolyols include, for example, polyether polyols, polycarbonate polyols, polyurethane polyols, epoxy polyols, vegetable oil polyols, polyolefin polyols, acrylic polyols, and vinyl monomer-modified polyols. These can be used alone or in combination of two or more.

[0041] The content ratio of other macropolyols relative to the total amount of macropolyols is, for example, 50% by mass or less, preferably 30% by mass or less, more preferably 10% by mass or less, and particularly preferably 0% by mass. Also, the content ratio of polyester polyols relative to the total amount of macropolyols is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass. That is, the macropolyol is particularly preferably composed of polyester polyol.

[0042] From the viewpoint of gas barrier properties and initial tack, the number average molecular weight of the macropolyol is, for example, 400 or more, preferably 500 or more. The number average molecular weight of the macropolyol is, for example, 20,000 or less, preferably 10,000 or less, more preferably 5,000 or less, even more preferably 2,000 or less, still more preferably 1,000 or less, and particularly preferably 800 or less.

[0043] The average number of hydroxyl groups in the macropolyol is, for example, 1.8 or more, or preferably 2 or more. The average number of hydroxyl groups in the macropolyol is, for example, 4 or less, preferably 3 or less, or more preferably 2.5 or less.

[0044] A low-molecular-weight polyol is an organic compound having two or more hydroxyl groups in the molecule and having a relatively low molecular weight. A relatively low molecular weight means that the molecular weight is less than 400. That is, the molecular weight of a low-molecular-weight polyol is less than 400, preferably 300 or less, and more preferably 150 or less. The molecular weight of a low-molecular-weight polyol is usually 40 or more.

[0045] In order to obtain excellent gas barrier properties and adhesive strength by incorporating the specific skeleton (Structural Formula (A)) described below into the isocyanate-terminated prepolymer, the low-molecular-weight polyol contains a low-molecular-weight diol as an essential component. That is, the polyol component as a raw material for the isocyanate-terminated prepolymer contains a low-molecular-weight diol as the low-molecular-weight polyol.

[0046] The low-molecular-weight polyol is preferably a low-molecular-weight diol. Examples of low-molecular-weight diols include dihydric alcohols. Examples of dihydric alcohols include ethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol, and dipropylene glycol. Examples of dihydric alcohols include polymers obtained by addition polymerization of alkylene oxides with dihydric alcohols to give a number-average molecular weight of 400 or less.

[0047] These low molecular weight diols can be used alone or in combination of two or more. The low molecular weight diol preferably contains ethylene glycol, propylene glycol, diethylene glycol, and / or dipropylene glycol, more preferably contains ethylene glycol, diethylene glycol, and / or propylene glycol, even more preferably consists of ethylene glycol, diethylene glycol, and / or propylene glycol, and particularly preferably consists of ethylene glycol and diethylene glycol.

[0048] The low-molecular-weight polyol may optionally contain a trihydric or higher low-molecular-weight polyol. Examples of trihydric or higher low-molecular-weight polyols include trihydric alcohols and tetrahydric or higher alcohols. Examples of trihydric alcohols include glycerin and trimethylolpropane. Examples of trihydric alcohols include polymers obtained by addition polymerization of alkylene oxides with trihydric alcohols so that the number-average molecular weight is 400 or less. Examples of tetrahydric or higher alcohols include diglycerin, pentaerythritol, and dipentaerythritol. These may be used alone or in combination of two or more.

[0049] The content of the trivalent or higher low-molecular-weight polyol relative to the total amount of the low-molecular-weight polyol is, for example, 50% by mass or less, preferably 30% by mass or less, more preferably 10% by mass or less, and particularly preferably 0% by mass. Furthermore, the content of the low-molecular-weight diol relative to the total amount of the low-molecular-weight polyol is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass. That is, the low-molecular-weight polyol particularly preferably consists of a low-molecular-weight diol.

[0050] In the polyol component, the content ratio of the macropolyol and the content ratio of the low molecular weight polyol are appropriately set so that the ratio of the specific skeleton (structural formula (A)) described later in the isocyanate group-terminated prepolymer is within a predetermined range.

[0051] For example, the macropolyol is, for example, 50% by mass or more, preferably 60% by mass or more, based on the total amount of polyol components. The macropolyol is, for example, 90% by mass or less, preferably 80% by mass or less. The low molecular weight polyol is, for example, 10% by mass or more, preferably 20% by mass or more. The low molecular weight polyol is, for example, 50% by mass or less, preferably 40% by mass or less.

[0052] The isocyanate-terminated prepolymer can be obtained by subjecting a polyisocyanate component and a polyol component to a urethane reaction at a predetermined equivalent ratio.

[0053] More specifically, the equivalent ratio (NCO / OH) of the isocyanate groups in the polyisocyanate component to the hydroxyl groups in the polyol component exceeds 1, for example, 1.1 or more, preferably 1.5 or more, and more preferably 2.0 or more, and for example, 15.0 or less, preferably 10.0 or less, and more preferably 8.0 or less.

[0054] In the urethanization reaction, the reaction temperature is, for example, 20° C. or more, preferably 50° C. or more, and for example, 150° C. or less, preferably 120° C. or less. The reaction time is, for example, 0.5 hours or more, preferably 1 hour or more, and for example, 18 hours or less, preferably 10 hours or less.

[0055] In addition, an organic solvent can be added to the urethanization reaction if necessary. Examples of organic solvents include ketones, nitriles, alkyl esters, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, ethers, glycol ether esters, halogenated aliphatic hydrocarbons, and polar aprotic solvents. These can be used alone or in combination of two or more. The amount of organic solvent added can be appropriately determined depending on the purpose and application.

[0056] In the polymerization reaction, a urethanization catalyst may be added as needed, such as amines, organometallic compounds, and potassium salts. These may be used alone or in combination of two or more. The amount of the urethanization catalyst to be added is appropriately determined depending on the purpose and application.

[0057] The components are then reacted until the isocyanate group content reaches a predetermined value, thereby obtaining an isocyanate-terminated prepolymer.

[0058] The isocyanate group content of the isocyanate group-terminated prepolymer is, for example, 5.0 mass% or more, more preferably 10.0 mass% or more, more preferably 15.0 mass% or more, and for example, 30.0 mass% or less, preferably 25.0 mass% or less. The isocyanate group content can be determined by titration with di-n-butylamine and FT-IR analysis.

[0059] After the reaction, the unreacted polyisocyanate component can be removed by a known method, such as distillation or extraction.

[0060] The isocyanate-terminated prepolymer can be prepared as a solution in the organic solvent. In this case, the solids concentration of the solution is appropriately set depending on the purpose and application. If necessary, the organic solvent may be removed by the removal method described above.

[0061] In the above method, when the polyisocyanate component, which is a raw material for the isocyanate-terminated prepolymer, contains xylylene diisocyanate and the polyol component, which is a raw material for the isocyanate-terminated prepolymer, contains a dihydric alcohol, the isocyanate-terminated prepolymer contains a urethane skeleton formed by the xylylene diisocyanate and the dihydric alcohol. More specifically, the isocyanate-terminated prepolymer contains a skeleton represented by the following structural formula (A):

[0062] [ka] (In the formula, X represents a low-molecular-weight diol residue.)

[0063] In structural formula (A), X represents a low-molecular-weight diol residue. More specifically, X includes a residue of a low-molecular-weight diol contained in a low-molecular-weight polyol used as a raw material for the isocyanate-terminated prepolymer. Preferably, the isocyanate-terminated prepolymer contains a skeleton represented by structural formula (A) in a proportion of a predetermined amount or more.

[0064] More specifically, the content of the skeleton represented by structural formula (A) relative to the total amount of isocyanate-terminated prepolymer is 40% by mass or more, and from the viewpoint of gas barrier property, it is preferably 45% by mass or more, more preferably 50% by mass or more. Also, from the viewpoint of initial tack and adhesion, the content of the skeleton represented by structural formula (A) relative to the total amount of isocyanate-terminated prepolymer is, for example, 80% by mass or less, preferably 70% by mass or less.

[0065] The content of the skeleton represented by structural formula (A) can be calculated based on the amount of raw material charged and the yield of the isocyanate-terminated prepolymer.

[0066] When the content of the skeleton represented by the structural formula (A) in the isocyanate group-terminated prepolymer is equal to or greater than a predetermined amount, an adhesive having excellent gas barrier properties and adhesion, as well as excellent initial tack, can be obtained.

[0067] More specifically, examples of adhesives include moisture-curing adhesives (hereinafter referred to as moisture-curing adhesives) and two-component curing adhesives (hereinafter referred to as two-component curing adhesives).

[0068] When the adhesive is a moisture-curing adhesive (one-component curing adhesive), the adhesive consists of only one agent (one-component) containing an isocyanate group-terminated prepolymer.

[0069] More specifically, the moisture-curable adhesive contains, as an essential component, an isocyanate-terminated prepolymer having a skeleton represented by the above structural formula (A).

[0070] The moisture-curable adhesive may also contain additives as optional components. Examples of additives include phosphoric acid, phosphoric acid derivatives, silane coupling agents, antifoaming agents, epoxy resins, catalysts, coating property improvers, leveling agents, antioxidants, ultraviolet absorbers, plasticizers, surfactants, pigments, fillers, organic fine particles, inorganic fine particles, and antifungal agents. The blending ratio of the additives is determined appropriately depending on the purpose and application.

[0071] Furthermore, the moisture-curing adhesive may contain the above-mentioned organic solvent as an optional component. That is, the moisture-curing adhesive may be a solvent-based adhesive. The blending ratio of the organic solvent is appropriately set depending on the purpose and application. Furthermore, the moisture-curing adhesive may not contain an organic solvent. That is, the moisture-curing adhesive may be a solventless adhesive.

[0072] Moisture-curing adhesives are cured by, for example, moisture. That is, the isocyanate groups at the ends of the isocyanate-terminated prepolymer molecules react with moisture to cure the adhesive. Moisture includes, for example, water in the atmosphere and amine vapor.

[0073] Such moisture-curable adhesives contain an isocyanate-terminated prepolymer having a skeleton represented by the above structural formula (A). Therefore, the cured product formed by curing the moisture-curable adhesive with moisture contains the skeleton represented by the above structural formula (A).

[0074] The content of the skeleton represented by structural formula (A) relative to the total amount of the cured product of the moisture-curable adhesive is, for example, 40% by mass or more, and from the viewpoint of gas barrier properties, preferably 45% by mass or more, more preferably 50% by mass or more. Furthermore, from the viewpoint of initial tack and adhesion, the content of the skeleton represented by structural formula (A) relative to the total amount of the cured product of the moisture-curable adhesive is, for example, 80% by mass or less, preferably 70% by mass or less.

[0075] The content of the skeleton represented by structural formula (A) can be calculated based on the amount and yield of the raw materials for the moisture-curable adhesive.

[0076] In such moisture-curing adhesives, the isocyanate-terminated prepolymer contains a reaction product of a polyisocyanate component containing xylylene diisocyanate and a polyol component containing a polyester polyol and a low-molecular-weight diol, and the isocyanate-terminated prepolymer contains a skeleton represented by the above structural formula (A) in a proportion of a predetermined amount or more. Therefore, the moisture-curing adhesive has excellent initial tack, gas barrier properties, and adhesion. In particular, the moisture-curing adhesive can exhibit excellent gas barrier properties by adhering to the inorganic thin film described below.

[0077] Furthermore, when the adhesive is a two-component curing adhesive, the adhesive is a resin kit that includes a first component and a second component separately. The first component and the second component are prepared as a set and are mixed at the time of use.

[0078] In the two-component curing adhesive, the first component contains the above-mentioned isocyanate-terminated prepolymer as an essential component. The content of the above-mentioned isocyanate-terminated prepolymer is, for example, 80% by mass or more, preferably 90% by mass or more, relative to the total amount of the first component. The first component may also contain additives and organic solvents as needed. In other words, the first component preferably consists of the above-mentioned isocyanate-terminated prepolymer, additives that are blended as needed, and an organic solvent that is blended as needed.

[0079] In the two-component curing adhesive, the second component contains, for example, the above-mentioned low-molecular-weight polyol, and preferably contains the above-mentioned low-molecular-weight diol.

[0080] In the second liquid, the low-molecular-weight diol preferably comprises ethylene glycol, propylene glycol, and / or dipropylene glycol, more preferably comprises ethylene glycol and / or propylene glycol, even more preferably consists of ethylene glycol and / or propylene glycol, and particularly preferably consists of ethylene glycol.

[0081] The low-molecular-weight diol contained in the second liquid may be different from or the same as the low-molecular-weight diol contained in the isocyanate-terminated prepolymer. That is, the low-molecular-weight diol contained in the second liquid and the low-molecular-weight diol used as a raw material for the isocyanate-terminated prepolymer may contain the same type of dihydric alcohol, or may contain different types of dihydric alcohol. Preferably, the low-molecular-weight diol contained in the second liquid and the low-molecular-weight diol used as a raw material for the isocyanate-terminated prepolymer contain the same type of dihydric alcohol, and more preferably, are made of the same type of dihydric alcohol.

[0082] The second liquid may further contain the above-mentioned trihydric or higher low-molecular-weight polyol. Preferably, the second liquid does not contain a trihydric or higher low-molecular-weight polyol. The second liquid may further contain the above-mentioned macropolyol. Examples of macropolyols include polyester polyols, polyether polyols, polycarbonate polyols, polyurethane polyols, epoxy polyols, vegetable oil polyols, polyolefin polyols, acrylic polyols, and vinyl monomer-modified polyols. Preferably, the second liquid does not contain a macropolyol.

[0083] The second liquid may contain additives and organic solvents as needed. In other words, the second liquid preferably contains the low-molecular-weight diol, additives that are added as needed, and an organic solvent that is added as needed.

[0084] The two-component curing adhesive may contain the above-mentioned additives as optional components. The additives may be added to the first component, the second component, or both the first and second components. The blending ratio of the additives is determined appropriately depending on the purpose and application.

[0085] Furthermore, the two-component curing adhesive can contain the above-mentioned organic solvent as an optional component. The organic solvent may be contained in the first liquid, the second liquid, or both the first and second liquids. Furthermore, when the first liquid, which does not contain an organic solvent, is mixed with the second liquid, which does not contain an organic solvent, the first liquid and / or the second liquid can be dissolved in the organic solvent. In other words, the two-component curing adhesive may be a solvent-based adhesive. The blending ratio of the organic solvent is appropriately set depending on the purpose and application. Furthermore, the two-component curing adhesive does not need to contain an organic solvent. In other words, the two-component curing adhesive may be a solventless adhesive.

[0086] Two-component curing adhesives cure when the first and second components are mixed, causing the isocyanate groups at the molecular ends of the isocyanate-terminated prepolymer in the first component to react with the hydroxyl groups of the low-molecular-weight polyol in the second component.

[0087] When using a two-component curing adhesive, the blending ratio of the first and second components is appropriately set depending on the purpose and application. For example, the equivalent ratio R(NCO / OH) of the isocyanate groups of the isocyanate-terminated prepolymer of the first component to the hydroxyl groups of the low-molecular-weight polyol of the second component is, for example, 0.5 or more, preferably 0.8 or more. Furthermore, the equivalent ratio R(NCO / OH) of the isocyanate groups of the isocyanate-terminated prepolymer of the first component to the hydroxyl groups of the low-molecular-weight polyol of the second component is, for example, 5 or less, preferably 2 or less, more preferably 1.5 or less, and even more preferably 1.2 or less.

[0088] Such a two-component curing adhesive contains the above-mentioned isocyanate-terminated prepolymer in the first component. Therefore, the cured product obtained by curing the two-component curing adhesive by mixing the first and second components contains the skeleton represented by the above-mentioned structural formula (A). Furthermore, when the second component contains a low-molecular-weight diol, the skeleton represented by structural formula (A) is formed by the reaction between the first and second components. Therefore, the cured product obtained by curing the two-component curing adhesive can contain, as the skeleton represented by structural formula (A), a skeleton formed by the reaction between the first and second components in addition to the skeleton contained in the above-mentioned isocyanate-terminated prepolymer.

[0089] The content of the skeleton represented by structural formula (A) relative to the total amount of the cured product of the two-component curing adhesive is, for example, 50% by mass or more, and from the viewpoint of gas barrier properties, preferably 55% by mass or more, more preferably 60% by mass or more. Furthermore, from the viewpoint of initial tack and adhesion, the content of the skeleton represented by structural formula (A) relative to the total amount of the cured product of the two-component curing adhesive is, for example, 80% by mass or less, preferably 70% by mass or less.

[0090] The content of the skeleton represented by structural formula (A) can be calculated based on the amounts and yields of the raw materials used in the two-component curing adhesive and the blending ratios of the first and second components.

[0091] In such two-component curing adhesives, the isocyanate-terminated prepolymer contains a reaction product of a polyisocyanate component containing xylylene diisocyanate and a polyol component containing a polyester polyol and a low-molecular-weight diol, and the isocyanate-terminated prepolymer contains a skeleton represented by the structural formula (A) above in a proportion of at least a predetermined amount. Therefore, the two-component curing adhesive has excellent initial tack, gas barrier properties, and adhesion. In particular, the two-component curing adhesive can exhibit excellent gas barrier properties by adhering to an inorganic thin film, which will be described later.

[0092] Furthermore, as long as the content of the skeleton represented by structural formula (A) in the total amount of the cured product of the two-component curing adhesive is within the above range, the content of the skeleton represented by structural formula (A) in the isocyanate group-terminated prepolymer in the first component may be less than 40 mass%.

[0093] Such adhesives also contain the skeleton represented by structural formula (A) above at a ratio equal to or greater than a predetermined value relative to the total amount of the cured product of the two-component curing adhesive, and therefore the adhesives of the present invention have excellent gas barrier properties and adhesion.

[0094] The above adhesives (moisture-curing adhesives and two-component curing adhesives) are suitably used in the production of laminates.

[0095] In Figure 1, the laminate film 1 as a laminate comprises a substrate 2, an adhesive layer 3 arranged on the substrate 2, an inorganic thin film 4 arranged on the adhesive layer 3, and a film 5 arranged on the inorganic thin film 4.

[0096] Examples of the substrate 2 include a resin film and a paper substrate having a resin layer. In the resin film, examples of the resin include an olefin polymer, a polyester polymer, a polyamide polymer, and a vinyl polymer. Examples of the olefin polymer include polyethylene and polypropylene. Examples of the polyester polymer include polyalkylene terephthalate and polyalkylene naphthalate. Examples of the polyamide polymer include nylon 6 and nylon 66. Examples of the vinyl polymer include polyvinyl chloride, ethylene-vinyl acetate copolymer, and ethylene-vinyl alcohol copolymer. The paper substrate having a resin layer includes, for example, a paper substrate and a resin layer formed on at least one side of the paper substrate. The resin layer is formed, for example, by a coating resin. Examples of the coating resin include styrene-butadiene copolymer, acrylic polymer, and styrene-acrylic copolymer. These can be used alone or in combination. A resin film is preferred.

[0097] The resin film may be subjected to a surface treatment, if necessary, such as a corona discharge treatment or a primer treatment.

[0098] The resin film may be an unstretched film or a stretched film. Examples of stretched films include uniaxially stretched films and biaxially stretched films. The resin film may be a single-layer film or a multilayer film.

[0099] The thickness of the substrate 2 is not particularly limited, but is, for example, 5 μm or more, preferably 10 μm or more, and for example, 200 μm or less, preferably 100 μm or less.

[0100] The adhesive layer 3 is a cured product of the above adhesive. The adhesive layer 3 is disposed between the substrate 2 and the inorganic thin film 4, and bonds the substrate 2 and the inorganic thin film 4 together. The adhesive layer 3 also exhibits gas barrier properties by being in close contact with the inorganic thin film 4. When the substrate 2 is a paper substrate having a resin layer, the adhesive layer 3 is disposed on top of the resin layer.

[0101] Such an adhesive layer 3, which will be described in detail later, is obtained by applying the above-mentioned adhesive (a moisture-curing adhesive and / or a two-component curing adhesive) to a substrate 2, laminating an inorganic thin film 4 (composite film 6) on the coating, and then curing the adhesive.

[0102] The thickness of the adhesive layer 3 is not particularly limited, but is, for example, 5 μm or more, or preferably 10 μm or more. The thickness of the adhesive layer 3 is, for example, 200 μm or less, or preferably 100 μm or less.

[0103] The inorganic thin film 4 is a thin film made of an inorganic material. Examples of inorganic materials include metals and metal oxides. Examples of metals include magnesium, calcium, barium, titanium, zirconium, aluminum, indium, silicon, germanium, and tin. Examples of metal oxides include magnesium oxide, titanium oxide, aluminum oxide, indium oxide, silicon oxide, tin oxide, and silicon oxynitride. These can be used alone or in combination of two or more. From the viewpoints of gas barrier properties and production efficiency, aluminum, silicon, and their oxides are preferred.

[0104] The thickness of the inorganic thin film 4 is not particularly limited, but is, for example, 1 nm or more, preferably 2 nm or more, and for example, 500 nm or less, preferably 300 nm or less.

[0105] The film 5 is a plastic film prepared separately from the substrate 2. Examples of the film 5 include the resin films mentioned above as the substrate 2.

[0106] The thickness of the film 5 is not particularly limited, but is, for example, 5 μm or more, or preferably 10 μm or more, and for example, 200 μm or less, or preferably 100 μm or less.

[0107] The inorganic thin film 4 and the film 5 are preferably formed as a composite film 6. That is, the inorganic thin film 4 is preferably formed on the film 5. This results in a composite film 6 including the inorganic thin film 4 and the film 5. Methods for forming the inorganic thin film 4 include, for example, vapor deposition (vacuum vapor deposition, EB vapor deposition, etc.), sputtering, ion plating, lamination, and plasma vapor deposition (CVD). From the viewpoint of production efficiency, vacuum vapor deposition is preferred.

[0108] To obtain such a laminate film 1, for example, first, a substrate 2 and a composite film 6 are prepared. Then, in this method, the adhesive is applied to one surface of the substrate 2 in the thickness direction. Examples of application methods include bar coating, curtain coating, roll coating, and blade coating. The application temperature for a solvent-based adhesive is, for example, room temperature. The application temperature for a solventless adhesive is, for example, 35°C or higher, preferably 40°C or higher. The application temperature for a solventless adhesive is, for example, 100°C or lower, preferably 90°C or lower. The application amount, in terms of solid content, for both the solvent-based adhesive and the solventless adhesive is, for example, 0.5 g / m 2 More than 1.0 g / m 2 More preferably, 1.5 g / m 2 The amount of coating is, for example, 5 g / m 2 The following is the result.

[0109] Next, the composite film 6 is laminated on the adhesive coating. More specifically, the inorganic thin film 4 of the composite film 6 is adhered to the adhesive coating. Furthermore, if the adhesive contains an organic solvent, the organic solvent in the adhesive is volatilized at room temperature or under heating.

[0110] The adhesive coating is then cured at room temperature or under elevated temperature. The curing temperature is, for example, 20°C or higher, preferably 30°C or higher. The curing temperature is, for example, 100°C or lower, preferably 80°C or lower. The curing time is, for example, 1 hour or longer, preferably 5 hours or longer. The curing time is, for example, 7 days or shorter, preferably 5 days or shorter.

[0111] As a result, an adhesive layer 3 made of a cured product of the adhesive is formed between the substrate 2 and the inorganic thin film 4. As a result, a laminate film 1 is obtained.

[0112] Such a laminate film 1 includes an adhesive layer 3 that is a cured product of the adhesive. An inorganic thin film 4 is disposed on the adhesive layer 3. Therefore, the laminate film 1 has excellent initial tack, gas barrier properties, and adhesion of the adhesive layer 3.

[0113] In the above description, the laminate film 1 includes the film 5, but the laminate film 1 does not necessarily include the film 5. In such a case, the inorganic thin film 4 is formed as a separate thin film and is laminated on the adhesive coating film. [Example]

[0114] Next, the present invention will be described based on examples and comparative examples, but the present invention is not limited to the following examples. Note that "parts" and "%" are by mass unless otherwise specified. Furthermore, specific numerical values such as blending ratios (content ratios), physical property values, and parameters used in the following description can be substituted with the corresponding upper limit values (numeric values defined as "equal to or less than") or lower limit values (numeric values defined as "equal to or more than" or "exceeding") of the blending ratios (content ratios), physical property values, parameters, etc. described in the above "Form for Carrying Out the Invention."

[0115] 1. Macropolyol Preparation Examples 1 to 3 (Polyester Polyols A to C) A polybasic acid and a polyhydric alcohol were mixed according to the formulation shown in Table 1. The mixture was subjected to an esterification reaction at 160 to 220°C under a nitrogen stream. A predetermined amount of condensed water was distilled off. This resulted in a polyester polyol. The number average molecular weight (polystyrene equivalent) of each polyester polyol was measured by gel permeation chromatography. The results are shown in Table 1.

[0116] Preparation Example 4 (Polyether Polyol D) As polyether polyol D, commercially available polytetramethylene ether glycol (trade name PTMEG-650, manufactured by PTG Korea, number average molecular weight 650) was prepared.

[0117] 2. Isocyanate-terminated prepolymer Synthesis Examples 1 to 8 and Comparative Synthesis Examples 1 to 3 A polyisocyanate component, a low-molecular-weight polyol, and a macropolyol were mixed according to the formulations shown in Tables 2 and 3. This mixture was subjected to a urethane reaction at 80°C under a nitrogen stream. It was then confirmed that the amine equivalent of the reaction solution had reached a predetermined value (see Table (before distillation)). The reaction solution was then subjected to thin-film distillation to remove unreacted polyisocyanate components. This yielded an isocyanate-terminated prepolymer. Tables 2 and 3 show the mass proportions (wt) of each raw material and the amine equivalent of the isocyanate-terminated prepolymer (after distillation).

[0118] The content of the skeleton represented by structural formula (A) in each isocyanate-terminated prepolymer (structural formula (A) content) was calculated based on the charged amount and yield. The results are shown in Tables 2 and 3.

[0119] 3. Two-component curing adhesive Examples 1 to 12 and Comparative Examples 1 to 3 An isocyanate-terminated prepolymer was prepared as the first component according to the formulations shown in Tables 4 to 6. A low-molecular-weight polyol was prepared as the second component. This resulted in a two-component curing adhesive. The equivalent ratio (NCO / OH) of the isocyanate groups in the first component to the hydroxyl groups in the second component was approximately 1.5.

[0120] In Example 1, acetone was contained as an organic solvent in the first liquid. In Examples 6, 8, 9 to 11 and Comparative Examples 1 to 3, ethyl acetate was contained as an organic solvent in the first liquid. In other words, a solvent-based adhesive was prepared as a two-component curing adhesive.

[0121] Furthermore, no organic solvent was contained in the first liquid and the second liquid in Examples 2 to 5, 7, and 12. That is, a solventless adhesive was prepared as a two-component curing adhesive.

[0122] Comparative Examples 4-5 According to the formulation shown in Table 7, an ethyl acetate solution (solid content 75% by mass) of xylylene diisocyanate trimethylolpropane adduct (XDI-TMP) was prepared as the first liquid. A low molecular weight polyol was prepared as the second liquid. Furthermore, in Comparative Example 7, ethanol was mixed into the second liquid. This resulted in the preparation of a two-component curing adhesive.

[0123] 4. Laminate (two-component curing adhesive) As a first substrate, a corona-treated biaxially stretched polypropylene film (trade name Pylen (registered trademark) Film OT P-2161, thickness 20 μm, manufactured by Toyobo Co., Ltd., hereinafter referred to as OPP film) was prepared.

[0124] Furthermore, an aluminum-deposited unstretched polypropylene film (product name: MLCP WS, thickness 25 μm, manufactured by Mitsui Chemicals Tohcello, hereinafter referred to as VM-CPP film) was prepared as a second substrate.

[0125] The first and second parts of a two-component curing adhesive were mixed. The two-component curing adhesive (mixture) was then applied to the corona-treated surface of the OPP film. The solvent-based adhesive was applied using a bar coater. The solventless adhesive was applied using a solventless laminator. The coating amount is 2.0 g / m2 (solid weight). 2 It was.

[0126] The adhesive-coated surface of the OPP film was then bonded to the aluminum-deposited surface of the VM-CPP film to obtain a laminate, which was then cured at 40°C for 3 days.

[0127] 5. Moisture-curing adhesive Examples 13-14 According to the formulation shown in Table 8, an isocyanate group-terminated prepolymer was prepared as a moisture-curable adhesive.

[0128] In Example 13, ethyl acetate was added as an organic solvent to the isocyanate-terminated prepolymer, that is, a solvent-based adhesive was prepared as a moisture-curing adhesive.

[0129] In Example 14, no organic solvent was added to the isocyanate group-terminated prepolymer, that is, a solventless adhesive was prepared as a moisture-curable adhesive.

[0130] 6. Laminates (moisture-curing adhesives) A corona-treated OPP film was prepared as the first substrate. A VM-CPP film was prepared as the second substrate. A moisture-curing adhesive was then applied to the corona-treated surface of the OPP film. The amount of adhesive applied was 2.0 g / m2 solids weight. 2 It was.

[0131] The adhesive-coated surface of the OPP film was then bonded to the aluminum-deposited surface of the VM-CPP film to obtain a laminate, which was then cured at 40°C for 3 days.

[0132] 7. Evaluation (1) Oxygen permeability The oxygen permeation rate of the laminate was measured using an oxygen permeation measuring device (OX-TRAN2 / 20, manufactured by MOCON) at a temperature of 20°C and a relative humidity of 80% (80% RH). The unit is cc / m. 2 ·24hrs·1atm.

[0133] (2) Initial tack (initial adhesive strength) Immediately after laminating the OPP film and the VM-CPP film, the OPP film and the VM-CPP film were peeled off by hand. This allowed the tackiness (initial tackiness) of the adhesive-coated surface to be evaluated. The evaluation criteria are as follows: ○: There was clearly a tack. △: There was a slight tack. ×: There was no tuck.

[0134] (3) Adhesive strength The adhesive strength of the laminate was measured by a T-peel test in accordance with JIS K 6854 (1999).

[0135] [Table 1]

[0136] [Table 2]

[0137] [Table 3]

[0138] [Table 4]

[0139] [Table 5]

[0140] [Table 6]

[0141] [Table 7]

[0142] [Table 8]

[0143] Details of the abbreviations in the table are given below. XDI: Xylylene diisocyanate XDI-TMP: ethyl acetate solution of xylylene diisocyanate trimethylolpropane adduct (solid content 75% by mass) EG: Ethylene glycol PG: Propylene glycol DEG: Diethylene glycol DPG: Dipropylene glycol MF: Substrate failure (OPP film breakage, OPP film surface peeling, transfer of VM-CPP inorganic thin film) [Explanation of symbols]

[0144] 1. Laminating film 2 Base material 3 Adhesive layer 4. Inorganic thin films 5 Film 6 Composite Film

Claims

1. An adhesive containing an isocyanate group-terminated prepolymer, The isocyanate group-terminated prepolymer is a polyisocyanate component including xylylene diisocyanate; a polyol component including a polyester polyol and a low molecular weight diol; and The isocyanate group-terminated prepolymer contains a skeleton represented by structural formula (A), An adhesive, wherein the content of the skeleton represented by structural formula (A) is 40 mass% or more relative to the total amount of the isocyanate group-terminated prepolymer. 【Chemical 1】 (In the formula, X represents a low-molecular-weight diol residue.)

2. The adhesive of claim 1 , wherein the low molecular weight diol comprises ethylene glycol and / or propylene glycol.

3. The adhesive according to claim 1 , wherein the number average molecular weight of the polyester polyol is 400 or more and 2,000 or less.

4. The adhesive of claim 1 which is a moisture-curing adhesive.

5. It is a two-component curing adhesive, a first liquid containing the isocyanate group-terminated prepolymer; and a second part comprising a low molecular weight polyol.

6. 6. The adhesive according to claim 5, wherein the content of the skeleton represented by structural formula (A) is 50 mass% or more relative to the total amount of the cured product of the two-component curing adhesive.

7. A substrate; an adhesive layer disposed on the substrate; an inorganic thin film disposed on the adhesive layer, A laminate, wherein the adhesive layer is a cured product of the adhesive according to claim 1.

8. It is a two-component curing adhesive, a first liquid containing an isocyanate group-terminated prepolymer; a second liquid containing a low molecular weight polyol; The isocyanate group-terminated prepolymer is a polyisocyanate component including xylylene diisocyanate; a polyol component including a polyester polyol and a low molecular weight diol; and The isocyanate group-terminated prepolymer contains a skeleton represented by structural formula (A), An adhesive, wherein the content of the skeleton represented by structural formula (A) is 50 mass% or more relative to the total amount of the cured product of the two-component curing adhesive. 【Chemistry 2】 (wherein X represents a low molecular weight diol residue.

Images