JP2020066639A - Adhesive composition, laminate and packaging material using the same - Google Patents

Abstract

To provide an adhesive composition exhibiting excellent appearance and adhesive strength, and having economically advantage even when a printing surface of a substrate having a printing layer and a barrier substrate are laminated by using the adhesive composition, and a laminate and a packaging material exhibiting excellent appearance and adhesive strength, and having economically advantage even when the printing surface of the substrate having the printing layer and the barrier substrate are laminated by using the adhesive composition.SOLUTION: The above described problem is solved by an adhesive composition containing a polyisocyanate component (A) and a polyol component (B), in which the polyisocyanate component (A) contains an urethane prepolymer (a1) having an isocyanate group at both terminals, which is a reaction product of a polyol component (X) and a diisocyanate component, and a reaction product (a2) of a monoalcohol component having molecular weight of 500 or less and the diisocyanate component.SELECTED DRAWING: None

Description

  The present invention relates to an adhesive composition, and a laminate and a packaging material using the same, more specifically, a solventless adhesive composition useful as a packaging material for foods, medical products, cosmetics, and the like, The laminated body and the packaging material used.

  The pasting of various plastic films together and the pasting of plastic films with metal vapor deposition films and metal foils have hitherto been carried out by a dry laminating method using a hydroxyl group / isocyanate solvent-based adhesive composition. However, since the dry laminating method uses an adhesive composition containing an organic solvent, special equipment for suppressing / preventing environmental pollution and fire is required.

In recent years, there has been a strong demand for a solvent-free adhesive composition due to the demand for simple equipment, and research for solvent-free use has been actively conducted.
For example, Patent Document 1 discloses a solventless adhesive composition for laminating containing a polyol component (1) and a polyisocyanate component (2) composed of two kinds of polyisocyanate compounds.
Patent Document 2 contains a polyol component (1) and a polyisocyanate component (2) containing a trifunctional polyisocyanate compound as an essential component, and the branch point concentration is within a specific range. A solventless laminating adhesive composition having a molar number of 1: 1 to 1: 3 is disclosed.

Further, Patent Document 3 discloses an adhesive composition containing a polyisocyanate component (a) and a polyol component (b), wherein the polyisocyanate component (a) is a monomer-based 4,4 ′ methylenediphenyldiene An adhesive composition comprising isocyanate (i) and isocyanate functional prepolymer (ii) is disclosed.
Further, Patent Document 4 contains a polyisocyanate component (A) and a polyol component (B), and the polyisocyanate component (A) is 2,4′-diphenylmethane diisocyanate (a1) and 4,4′-diphenylmethane diisocyanate ( a2) and a polyol in which the polyether polyol (a3) is essential are reacted under conditions of excess isocyanate groups, and the polyol component (B) has a number average molecular weight of 500 or more and 3000 or less. Disclosed is an adhesive composition which essentially comprises the polyester diol (b1) of 1) and further contains at least one of a diol (b2) and a triol (b3) having a number average molecular weight of 50 or more and less than 500.
Further, in claim 2 of Patent Document 5, a polyethylene terephthalate film layer (F1) for the exterior, a dry coating layer (P) for printing ink, a dry coating layer (C) for a coating resin, and a solventless adhesive layer (A). ), A metal vapor deposition layer or metal foil (M), and an internal plastic film layer (F2) in this order are described.

  Further, in Patent Document 6, a specific polyisocyanate component (A) containing a urethane prepolymer made from a polyether polyol as a raw material, 4,4′-diphenylmethane diisocyanate and 2,4′-diphenylmethane diisocyanate, and a polyester diol are described. A solventless adhesive composition containing a specific polyol component (B) as an essential component is described.

JP-A-8-60131 JP, 2003-96428, A JP2012-131980A JP, 2014-159548, A JP, 2010-280122, A Patent No. 5812219

  The laminate as a packaging material has a printing ink layer, an adhesive layer, and a base material on one surface (hereinafter, also referred to as a back surface or back side) of a transparent base material. The printing ink layer will be seen from the opposite side of the transparent substrate (hereinafter, also referred to as the front surface or the front side). The printing ink layer may be provided so as to cover the entire surface or may be provided partially. The printing ink layer may be a single layer or a plurality of layers may be laminated. The portion where the printing ink layer is provided is also called the ink portion, and the portion where the printing ink layer is not provided is also called the plain portion.

  Solvent-free adhesive composition has no drying process and no solvent discharge, energy saving and good running cost, laminated body after laminating plastic films, plastic film and metal foil or metal vapor deposition It has many merits such as no concern that the solvent will remain in the laminated body after the layers are stuck together. However, when a laminate as a packaging material is formed using a solventless adhesive composition and a substrate having a high gas barrier property in which a metal vapor deposition layer is provided on a film (hereinafter, also referred to as a barrier substrate) However, there is a problem in that a defective appearance of yuzu skin is likely to occur on the ink portion.

  Patent Documents 1 and 2 describe that a polyisocyanate component having a relatively mild reaction, specifically, an alicyclic polyisocyanate component or an aliphatic polyisocyanate component is used. However, there is a problem that the aging step requires 2 to 5 days at 40 to 50 ° C. for the polyisocyanate component which reacts relatively gently. Further, Patent Documents 1 and 2 do not describe the improvement of the appearance defect in the ink portion. The aging step means "a step of advancing the curing of the adhesive layer".

  Patent Document 3 describes that a polyisocyanate component containing 4,4'-MDI and a prepolymer derived from 4,4'-MDI is used. However, the adhesive composition described in Patent Document 3 has a problem that the pot life is extremely short. Especially in the case of a solvent-free type, the increase in viscosity in a short time not only has a great influence on the productivity but also deteriorates the coatability, and particularly when used for a film substrate having a high gas barrier property, The coated surface is extremely rough.

  Further, Patent Document 4 discloses an adhesive composition which controls the reactivity with water and has a good adhesive performance and a good pot life even at high humidity. However, Patent Document 4 also does not mention improvement of the appearance defect in the ink portion.

  In [0013] and [0014] of Patent Document 5, when a dry coating layer (P) of printing ink is provided between the polyethylene terephthalate film layer (F1) of the exterior and the dry coating layer (C) of the coating resin. It is disclosed that the coating resin constituting the dry film layer (C) of the coating resin uses a binder for printing ink to improve the appearance of the ink portion. However, the processing speed specifically shown in the examples, that is, the coating speed of the adhesive is as low as only 10 m / min. Since the solvent-free adhesive composition is solvent-free, the coating surface becomes rough when the coating speed is increased, so that it has not been possible to achieve both improvement in coating speed and improvement in appearance. From the viewpoint of improving productivity, a solventless adhesive composition is desired to have a laminate having a good appearance in the ink portion at the same level as that of the solvent adhesive composition, for example, at a coating speed of about 200 m / min. Is starting to appear.

  Further, Patent Document 6 describes that a laminate having excellent appearance can be obtained by coating at a speed of 200 m / min or more and aging at a low temperature for a short time. It has been desired to improve the appearance of the printed portion while increasing the proportion of'-diphenylmethane diisocyanate.

  That is, an object of the present invention is to provide excellent appearance and adhesive strength and economically even when a printed surface of a substrate having a printed layer and a barrier substrate are laminated with an adhesive composition. It is to provide an advantageous adhesive composition. Further, an object of the present invention is to provide excellent appearance and adhesive strength and economically even when a printed surface of a substrate having a printed layer and a barrier substrate are laminated with an adhesive composition. An object is to provide an advantageous laminated body and packaging material.

  The present invention relates to the following [1] to [17].

[1] An adhesive composition comprising a polyisocyanate component (A) and a polyol component (B),
The polyisocyanate component (A) is a reaction product of a polyol component (X) and a diisocyanate component, a urethane prepolymer (a1) having an isocyanate group at the terminal, and a monoalcohol component and a diisocyanate component having a molecular weight of 500 or less. An adhesive composition comprising a reaction product (a2) with.

[2] The adhesive composition according to [1], wherein the polyol component contains a polyether polyol.

[3] The adhesive composition according to [2], wherein the content of the polyether polyol in the polyol component is 70 to 100% by mass.

[4] The diisocyanate component requires at least one selected from the group consisting of 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, xylylene diisocyanate and tolylene diisocyanate, [1] to [1] 3] The adhesive composition according to any one of items.

[5] The adhesive composition according to any one of [1] to [4], wherein the diisocyanate component contains 4,4′-diphenylmethane diisocyanate.

[6] The polyisocyanate component (A) contains at least one selected from the group consisting of 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, xylylene diisocyanate and tolylene diisocyanate,
The total amount of 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, xylylene diisocyanate and tolylene diisocyanate in 100 mass% of the polyisocyanate component (A) is 20 to 40 mass%. 1] to [5] the adhesive composition according to any one of items.

[7] The adhesive composition according to any one of [1] to [6], wherein the monoalcohol component is a primary or secondary alcohol having 2 to 20 carbon atoms.

[8] The adhesive composition according to any one of [1] to [7], wherein the monoalcohol component has a molecular weight of 200 or less.

[9] The adhesive composition according to any one of [1] to [8], wherein the isocyanate group content in the polyisocyanate component (A) is 18 to 22% by mass.

[10] The adhesive composition according to any one of [1] to [9], wherein the polyol component (B) contains a polyester polyol.

[11] The adhesive composition according to [10], wherein the polyester polyol has a number average molecular weight of 1,000 to 3,000.

[12] Any of [1] to [11], wherein the content of 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, xylylene diisocyanate and tolylene diisocyanate in the adhesive composition is 16% or less. The adhesive composition according to item 1.

[13] The adhesive composition according to any one of [1] to [12], which is a solventless type.

[14] The adhesive composition according to any one of [1] to [13], which is an adhesive for laminating a packaging material.

[15] A laminate in which the adhesive composition according to any one of [1] to [14] is laminated between at least two sheet-shaped substrates.

[16] The adhesive composition according to any one of [1] to [14] is applied to a first sheet-shaped substrate to form an adhesive layer, and the adhesive layer is provided with a second sheet-shaped material. A method for manufacturing a laminate, comprising: stacking base materials and then curing the adhesive layer.

[17] A packaging material comprising the laminate according to [15].

  According to the present invention, an adhesive which exhibits excellent appearance and adhesive strength and is economically advantageous even when the printed surface of the substrate having a printed layer and the barrier substrate are laminated with the adhesive composition. A composition can be provided. Further, even when the printed surface of the substrate having a printed layer and the barrier substrate are laminated using the adhesive composition, a laminate and a package exhibiting excellent appearance and adhesive strength and being economically advantageous. Material can be provided.

The adhesive composition of the present invention contains a polyisocyanate component (A) and a polyol component (B), and the polyisocyanate component (A) is a reaction product of a polyol component (X) and a diisocyanate component. In addition, a urethane prepolymer (a1) having an isocyanate group and a reaction product (a2) of a monoalcohol component and a diisocyanate component having a molecular weight of 500 or less are contained.
When a printed surface of a substrate having a printed layer and a barrier substrate are laminated with an adhesive composition by containing a reaction product (a2) of a monoalcohol component having a molecular weight of 500 or less and a diisocyanate component. In addition to maintaining a high adhesive strength, the reaction product (a2) functions similarly to a lubricant, and exhibits good leveling properties at the time of coating an adhesive, and is excellent in printing ink. It becomes possible to show the appearance.

<Polyisocyanate component (A)>
The polyisocyanate component (A) is a reaction product of a polyol component (X) and a diisocyanate component, a urethane prepolymer (a1) having isocyanate groups at both ends, a monoalcohol component having a molecular weight of 500 or less, and a diisocyanate. The reaction product (a2) with the components is included.

[Urethane prepolymer (a1)]
The urethane prepolymer (a1) of the present invention has an isocyanate group at the terminal, and preferably, the polyol component (X) and the diisocyanate component are reacted under conditions of excess of isocyanate groups with respect to hydroxyl groups in the polyol. Is a urethane prepolymer.

(Polyol component (X))
The polyol component of the present invention is not particularly limited, and examples thereof include polycarbonate polyol, polycaprolactone polyol, polyester polyol, polyether polyol, polyolefin polyol, acrylic polyol, silicone polyol, castor oil-based polyol, fluorine-based polyol, etc. Can be used together or two or more kinds can be used in combination. Among these, at the time of obtaining the polyisocyanate component (A) in the absence of a solvent, it is preferable to select a polyol component having a low viscosity in a molten state. Therefore, at least one selected from polyester polyols and polyether polyols is preferable, and more preferable. Indicates that polyether polyol is essential.

≪Polyether polyol≫
Polyether polyol generally has a lower viscosity in a molten state than polyester polyol, and is an optimum and important component as a polyol when obtaining the urethane prepolymer (a1) in the absence of a solvent. The method for producing the polyether polyol is not particularly limited, for example, ethylene oxide, propylene oxide, butylene oxide, oxirane compounds such as tetrahydrofuran, for example, water, ethylene glycol, propylene glycol, trimethylol propane, low molecular weight polyols such as glycerin. It is obtained by polymerization as an initiator. The number of functional groups of the polyether polyol is not limited, but bifunctional and trifunctional or higher functional groups can be used, and normally bifunctional polypropylene glycol and trifunctional polypropylene glycol are preferably used.

  The number average molecular weight of the polyether polyol is preferably 200 or more and 10,000 or less, more preferably 300 or more and 3,000 or less, and particularly preferably 200 or more and 2,000 or less. These polyether polyols may be used in combination of a plurality having different functional groups and different number average molecular weights. It is possible to enhance the compatibility with (B) and enhance the cohesive force of the adhesive composition.

  The content of the polyether polyol is preferably 60 to 100% by mass, more preferably 70 to 100% by mass, and particularly preferably 80 to 100% by mass, based on all the polyol components. Within this range, the low-viscosity polyisocyanate component can be adjusted, and the leveling property improving effect is further exhibited.

≪Polyester polyol≫
Examples of polyester polyols include polyester polyols obtained by reacting a polyvalent carboxylic acid component and a glycol component.
Examples of the polyvalent carboxylic acid component include polyvalent carboxylic acids such as terephthalic acid, isophthalic acid, adipic acid, azelaic acid, sebacic acid, dialkyl esters thereof, and mixtures thereof. Examples of the glycol component include ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 3,3′-dimethylolheptane, poly Examples thereof include glycols such as oxyethylene glycol, polyoxypropylene glycol, and polytetramethylene ether glycol, or a mixture thereof.

  Examples of the low molecular weight diol include ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 3,3'-dimethylolheptane. , Low-molecular diols such as 2-methyl-1,3-propanediol, and mixtures thereof.

  When a polyester polyol is used in combination with the polyether polyol, it is preferably 50% by mass or less in 100% by mass of the polyol from the viewpoint of the viscosity of the adhesive composition.

(Diisocyanate component)
The diisocyanate component of the present invention, that is, the bifunctional isocyanate component is not particularly limited, and examples thereof include hexamethylene diisocyanate (hereinafter, also referred to as HDI), tolylene diisocyanate (hereinafter, also referred to as TDI), 4,4 ′. -Diphenylmethane diisocyanate (hereinafter also referred to as 4,4'-MDI), 2,4'-diphenylmethane diisocyanate (hereinafter also referred to as 2,4'-MDI), xylylene diisocyanate (hereinafter also referred to as XDI), isophorone diisocyanate ( Hereinafter, also referred to as IPDI) and the like. The diisocyanate (bifunctional isocyanate) may be referred to as a “monomer” or an “isocyanate monomer” in order to distinguish it from a buret body or a nurate body derived from the bifunctional isocyanate.

  From the viewpoint of improving the reactivity, it is preferable that the diisocyanate component essentially comprises at least one selected from the group consisting of 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, xylylene diisocyanate and tolylene diisocyanate. , And more preferably 4,4′-diphenylmethane diisocyanate is essential. From the economical viewpoint, the content of 4,4'-diphenylmethane diisocyanate is preferably as high as possible, more preferably 50% by mass or more, and particularly preferably 100% by mass with respect to the total diisocyanate component.

[Reaction product (a2)]
The reaction product (a2) is a reaction product of a monoalcohol component having a molecular weight of 500 or less and the above-mentioned diisocyanate component, wherein one isocyanate group of the diisocyanate component is reacted with the monoalcohol component and a diisocyanate component. It is a mixture of two isocyanate groups reacted with a monoalcohol component. The presence of such a reaction product of a part of the isocyanate groups of the isocyanate component and the hydroxyl groups of the monoalcohol component having a molecular weight of 500 or less makes it possible to reduce the viscosity of the polyisocyanate component (A). When applied as a solvent-type adhesive composition, the wettability to the base material is improved and a good appearance can be obtained.

(A monoalcohol component having a molecular weight of 500 or less)
The monoalcohol component having a molecular weight of 500 or less is not particularly limited, and examples thereof include methanol, ethanol, propan-1-ol, butan-1-ol, pentan-1-ol, hexane-1-ol, heptane-. 1-ol, octan-1-ol, nonan-1-ol, decane-1-ol, undecane-1-ol, dodecane-1-ol, tridecane-1-ol, tetradecane-1-ol, pentadecane-1- All, hexadecane-1-ol, heptadecane-1-ol, octadecane-1-ol, nonadecane-1-ol, icosan-1-ol, heneicosan-1-ol, docosan-1-ol, tricosan-1-ol, Tetracosan-1-ol, Pentacosan-1-ol, Hexacosan-1-o , Primary alcohols such as heptacosan-1-ol, octacosan-1-ol, nonacosan-1-ol, 2-methylpropan-1-ol, 2-ethylhexan-1-ol, and 3-methylbutan-1-ol. ,
Secondary alcohols such as propan-2-ol, butan-2-ol, pentan-2-ol, hexan-2-ol, heptan-2-ol, cyclohexanol,
2-methylpropan-2-ol, 2-methylbutan-2-ol, 2-methylpentan-2-ol, 2-methylhexan-2-ol, 2-methylheptan-2-ol, 3-methylpentan-3 Examples thereof include tertiary alcohols such as -ol and 3-methyloctane-3-ol, and among them, primary or secondary alcohols having 2 to 20 carbon atoms are preferable.

  The molecular weight of the monoalcohol component of the monoalcohol component is preferably 300 or less, and more preferably 200 or less. Within the above range, remarkable thickening is suppressed during modification, and the effect of improving coatability is exhibited. The monoalcohol component is preferably in the range of 1 to 50% equivalent with respect to the isocyanate group.

  The polyisocyanate component (A) preferably has a number average molecular weight of 200 to 2,000, more preferably 300 or more and 1,500 or less, and particularly preferably 500 or more and 1500 or less. Although the polyisocyanate component (A) contains the urethane prepolymer (a1) and the reaction product (a2), it is preferable that the polyisocyanate component (A) further contains an isocyanate monomer to exhibit the above-mentioned molecular weight. The isocyanate monomer has the same meaning as the item of the diisocyanate component described above.

The polyisocyanate component (A) preferably contains an isocyanate monomer, and more preferably selected from the group consisting of 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, xylylene diisocyanate and tolylene diisocyanate. At least one is included.
The total content of isocyanate monomers in 100 mass% of the polyisocyanate component (A) is preferably 20 mass% or more and 40 mass% or less. More specifically, in 100 mass% of the polyisocyanate component (A), the total amount of 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, xylylene diisocyanate and tolylene diisocyanate is 20 to 40 mass%. Preferably there is.

  The isocyanate group content in the polyisocyanate component (A) is preferably 10% by mass or more and 30% by mass or less, more preferably 15% by mass or more and 25% by mass or less, and particularly preferably 18% by mass or more and 22% by mass or more. It is not more than mass%. Within the above range, when a film substrate having a high gas barrier property is used, a laminate having a better appearance can be formed. The isocyanate group content (mass%) is determined by titration with hydrochloric acid.

<Polyol component (B)>
The polyol component (B) is not particularly limited, and examples thereof include polycarbonate polyol, polycaprolactone polyol, polyester polyol, polyether polyol, polyolefin polyol, acrylic polyol, silicone polyol, castor oil-based polyol, and fluorine-based polyol. They can be used alone or in combination of two or more. Among them, at least one selected from polyester polyol and polyether polyol is preferably used, and polyester polyol is more preferable. By using the polyester polyol as an essential component, sufficient adhesive strength can be obtained.

[Polyester polyol (b1)]
Examples of the polyester polyol include dibasic acids such as terephthalic acid, isophthalic acid, adipic acid, azelaic acid and sebacic acid, or dialkyl esters thereof or a mixture thereof, for example, ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, Glycols such as neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 3,3'-dimethylolheptane, polyoxyethylene glycol, polyoxypropylene glycol and polytetramethylene ether glycol. , Trimethylolpropane, glycerin or a mixture thereof, a polyester polyol obtained by reacting with polycaprolactone, polyvalerolactone, poly (β-meth Le -γ- valerolactone) polyester polyols obtained by ring-opening polymerization of lactones, and the like. In addition, vegetable oils such as castor oil and polyester compounds derived from vegetable oils can also be used.

  Typical examples of vegetable oils are asa seed oil, linseed oil, eno oil, deer oil, olive oil, cacao oil, kapok oil, kaya oil, mustard oil, kyounin oil, kiri oil, kukui oil, walnut oil, poppy oil, sesame oil. , Safflower oil, radish seed oil, soybean oil, gall oil, camellia oil, corn oil, rapeseed oil, niger oil, nuka oil, palm oil, castor oil, sunflower oil, grape seed oil, gentian oil, pine seed oil , Cottonseed oil, coconut oil, peanut oil, dehydrated castor oil and the like.

  The number average molecular weight of the polyester polyol is preferably 500 to 5,000, more preferably 700 to 4,000, further preferably 1,000 to 3,000, and particularly preferably 1,200 to 2,600. Within the above range, the effect of balancing the coatability, the adhesive performance, and the heat resistance is exhibited.

(Polyester polyurethane polyol)
Further, as the polyester polyol, polyester polyurethane polyol which is a reaction product of polyester polyol and polyisocyanate can be used. The polyester polyurethane polyol is obtained, for example, by blending the above-mentioned polyester polyol and polyisocyanate so that the NCO / OH molar ratio is less than 1, preferably 0.3 to 0.98, and reacting them. A polyester polyurethane polyol having a urethane bond introduced therein is preferable because it has high cohesive force and excellent adhesion to metal.

(Acid modification)
Further, the above polyester polyol may be a reaction product obtained by reacting a part of the hydroxyl groups in the polyester polyol with trimellitic anhydride and trimellitic acid anhydride. By using the polyester polyol to which the acid anhydride is added, it is possible to improve the adhesiveness when applied to a sheet-shaped substrate that is difficult to adhere. The amount of trimellitic anhydride or the like to be added is preferably 0.1 to 5 mass% in 100 mass% of the polyester polyol after the reaction. By using a polyester polyol having a number average molecular weight within the above range, the compatibility is improved and sufficient adhesive performance can be exhibited particularly when the polyisocyanate component (A) contains polyether polyurethane.

[Polyether polyol (b2)]
As the polyether polyol, for example, ethylene oxide, propylene oxide, butylene oxide, oxirane compounds such as tetrahydrofuran, for example, water, ethylene glycol, propylene glycol, trimethylol propane, a low molecular weight polyol such as glycerin is polymerized as an initiator. The polyether polyol etc. which are obtained are mentioned.
As the polyether polyol, not only bifunctional but also trifunctional or more can be used. Further, it is also possible to use a combination of plural functional groups having different numbers of functional groups. As the polyether polyol, those having a number average molecular weight of 100 or more and 5,000 or less are preferable. It is more preferably 500 or more and 5,000 or less, and particularly preferably 1,000 or more and 3,000 or less. Further, a plurality of different molecular weights can be used in combination.

(Polyether polyurethane polyol)
Further, as the polyether polyol, it is also possible to use a polyether polyurethane polyol which is a reaction product obtained by reacting a polyether polyol and a polyisocyanate under the condition of excess hydroxyl group, and usually, a number average molecular weight of about 400 to 2, Polyether polyurethane polyol can be synthesized from 000 bifunctional polypropylene glycol, trifunctional polypropylene glycol having a number average molecular weight of about 400 to 4,000, and an isocyanate component such as 4,4-diphenylmethane diisocyanate and tolylene diisocyanate. . Above all, it is preferable that 4,4-diphenylmethane diisocyanate is essential as the isocyanate component as the curing agent component of the polyether polyurethane polyol.

  The isocyanate component may be hexamethylene diisocyanate (hereinafter, also referred to as HDI), tolylene diisocyanate (hereinafter, may be abbreviated as TDI), 4,4′-diphenylmethane diisocyanate (hereinafter, may be abbreviated as 4,4′-MDI). Yes, 2,4'-diphenylmethane diisocyanate (hereinafter sometimes abbreviated as 2,4'-MDI), xylylene diisocyanate (hereinafter sometimes abbreviated as XDI), isophorone diisocyanate (hereinafter sometimes abbreviated as IPDI). There is) and the like.

[Other polyols]
The polyol component (B) may contain, in addition to the above-mentioned polyol component, other polyol components within a range not impairing the object of the present invention. Among them, preferably, a polyester polyol having a number average molecular weight of 500 or more and 5,000 or less is essential, and further, a diol having a number average molecular weight of 50 or more and less than 500, a triol having a number average molecular weight of 50 or more and less than 500, and a number average molecular weight of 500 or more 5, It includes at least one selected from the group consisting of 000 or less polyether polyol and a compound having one hydroxyl group having a number average molecular weight of 500 or less.
A group consisting of a diol having a number average molecular weight of 50 or more and less than 500, a triol having a number average molecular weight of 50 or more and less than 500, a polyether polyol having a number average molecular weight of 500 or more and 5,000 or less, and a compound having one hydroxyl group having a number average molecular weight of 500 or less. By including at least one selected from the above, the strength under high humidity is improved. More preferably, it contains at least one selected from the group consisting of a diol having a number average molecular weight of 50 or more and less than 500 and a polyether polyol having a number average molecular weight of 500 or more and 5,000 or less.

  Examples of the diol having a number average molecular weight of 50 or more and less than 500 include polyester diol, polyether diol, polyether ester diol, polyester amide diol, acryl diol, polycarbonate diol and ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, neopentyl glycol. 1,6-hexanediol, 3-methyl-1,5-pentanediol, 3,3′-dimethylolheptane, 2-methyl-1,3-propanediol, and other low-molecular diols or mixtures thereof Can be mentioned. Among these, low molecular weight diols are preferable from the viewpoint of reactivity.

  As the polyether diol, for example, a polymer obtained by polymerizing an oxirane compound such as ethylene oxide, propylene oxide, butylene oxide, or tetrahydrofuran with a bifunctional low-molecular-weight polyol such as water, ethylene glycol, or propylene glycol as an initiator. Examples include ether diol.

  Examples of the polyether ester polyol include a polyester obtained by reacting a dibasic acid such as terephthalic acid, isophthalic acid, adipic acid, azelaic acid, sebacic acid or a dialkyl ester thereof or a mixture thereof with the above polyether diol. Examples include ether ester diols.

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

  Examples of the acrylic diol include hydroxyethyl acrylate having one or more hydroxyl groups in one molecule, hydroxypropyl acrylate, acrylhydroxybutyl, and the like, or their corresponding methacrylic acid derivatives and the like, such as acrylic acid and methacrylic acid. It is obtained by copolymerizing with an acid or its ester.

  Examples of the polycarbonate diol include ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, and 1,9-nonane. Dimethyl or glycol selected from the group consisting of diol, 1,8-nonanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1,4-cyclohexane diol and 1,4-cyclohexane dimethanol is used. Examples thereof include those obtained by the reaction with carbonate, diphenyl carbonate, ethylene carbonate, phosgene and the like.

  Examples of the triol having a number average molecular weight of 50 or more and less than 500 include low molecular weight triols such as polyether triol, castor oil, trimethylolpropane, and glycerin, or a mixture thereof. Among these, low molecular weight triols and polyether triols are preferable from the viewpoint of reactivity.

  Examples of the polyether triols include polyether triols obtained by polymerizing oxirane compounds such as ethylene oxide, propylene oxide, butylene oxide, and tetrahydrofuran with, for example, trimethylolpropane, glycerol and other low-content triols as initiators. .

  Examples of the polyether polyol used as the polyether diol having a number average molecular weight of 500 or more and less than 5,000 include, for example, oxirane compounds such as ethylene oxide, propylene oxide, butylene oxide and tetrahydrofuran, for example, water, ethylene glycol, propylene glycol, trimethylol. Examples thereof include polyether polyols obtained by polymerization using a low molecular weight polyol such as propane and glycerin as an initiator.

  Examples of the compound having one hydroxyl group include methanol, ethanol, propan-1-ol, butan-1-ol, pentan-1-ol, hexan-1-ol, heptan-1-ol, octan-1-ol. , Nonane-1-ol, decane-1-ol, undecane-1-ol, dodecane-1-ol, tridecane-1-ol, tetradecane-1-ol, pentadecane-1-ol, hexadecane-1-ol, heptadecane -1-ol, octadecan-1-ol, nonadecane-1-ol, icosan-1-ol, heneicosan-1-ol, docosan-1-ol, tricosan-1-ol, tetracosan-1-ol, pentacosan-1. -Ol, hexacosan-1-ol, heptacosan-1-ol, octacosa Primary such as -1-ol, nonacosan-1-ol, triacontan-1-ol, policosanol, 2-methylpropan-1-ol, 2-ethylhexan-1-ol, 3-methylbutan-1-ol Secondary alcohols such as alcohol, propan-2-ol, butan-2-ol, pentan-2-ol, hexan-2-ol, heptan-2-ol, cyclohexanol, 2-methylpropan-2-ol, 2-methylbutan-2-ol, 2-methylpentan-2-ol, 2-methylhexan-2-ol, 2-methylheptan-2-ol, 3-methylpentan-3-ol, 3-methyloctane-3 -Examples include tertiary alcohols such as oars.

  The polyol component (B) is 60 mass% or more and 99 mass% or less, more preferably 80 mass% or more and 99 mass% of a polyester polyol having a number average molecular weight of 500 or more and 5,000 or less in 100 mass% of the polyol component (B). 1 mass% or more and 40 mass% or less, including a diol having a number average molecular weight of 50 or more and less than 500, a triol having a number average molecular weight of 50 or more and less than 500, and a polyether polyol having a number average molecular weight of 500 or more and 5,000 or less, preferably It is preferable to contain 1 mass% or more and 20 mass% or less. In some cases, it is preferable to use a compound having one hydroxyl group having a number average molecular weight of 500 or less in combination. Within the above range, a laminate having a better appearance can be obtained when a film substrate having a high gas barrier property is used and coating / bonding is performed at high speed. A compound having one hydroxyl group with a number average molecular weight of 500 or less functions as a low-viscosity reactive diluent, so that it is possible to reduce the viscosity when coating and laminating at high speed, and a much better appearance. Can be obtained.

<Adhesive composition>
In the adhesive composition of the present invention, when the number of moles of hydroxyl groups in the polyol component (B) is 100 moles, the number of moles of isocyanate groups in the polyisocyanate component (A) is preferably 100 moles or more and 300 moles or less. It is more preferably 100 mol or more and 200 mol or less, and particularly preferably 100 mol or more and 150 mol or less. Within the above range, a good adhesive force can be exhibited even when aged under high humidity.

  The adhesive composition in the present invention has a total content of isocyanate monomers contained in 100% by mass of the polyisocyanate component (A) and the polyol component (B) in total of preferably 10% or more, and more preferably Is 12% or more. Further, it is preferably 20% or less, more preferably 17% or less, further preferably 16% or less, and particularly preferably 15% or less. Within the above range, a laminate having a better appearance can be obtained when using a film substrate having a high gas barrier property.

The adhesive composition in the present invention preferably does not contain a solvent, and it is preferable to mix each component at the lowest possible temperature within the range where fluidity can be secured, specifically, at 25 ° C or higher and 80 ° C or lower. It is preferable to mix them. The viscosity at 60 ° C. immediately after mixing the polyisocyanate component (A) and the polyol component (B) is preferably 50 mPa · s or more and 5,000 mPa · s or less, more preferably 50 mPa · s or more and 3,000 mPa · s or less. Is.
In the present invention, “immediately after mixing” means within 1 minute after uniform mixing, and the melt viscosity indicates a value determined by a B-type viscometer. If the melt viscosity at 60 ° C. exceeds 5,000 mPa · s, it becomes difficult to ensure good workability, and if the coating temperature is 60 ° C. or lower, a good coating appearance may not be obtained. There is. On the other hand, when the melt viscosity at 60 ° C. is less than 50 mPa · s, sufficient adhesive performance cannot be obtained because the initial cohesive force is weak, or the thickness of the coating film is uniform when the adhesive composition is applied to the substrate. However, the appearance may be deteriorated or warpage may occur.

  The adhesive composition further contains additives such as an antioxidant, an ultraviolet absorber, an anti-hydrolysis agent, a fungicide, a thickener, a plasticizer, an antifoaming agent, a pigment and a filler, if necessary. can do. Further, in order to further improve the adhesion performance, an adhesion aid such as a silane coupling agent, phosphoric acid, a phosphoric acid derivative, an acid anhydride or an adhesive resin can be used. Further, known catalysts, additives and the like can be used for controlling the curing reaction.

  As the silane coupling agent, those having a functional group such as a vinyl group, an epoxy group, an amino group, an imino group and a mercapto group and a functional group such as a methoxy group and an ethoxy group can be used. For example, chlorosilane such as vinyltrichlorosilane, aminosilane such as N- (dimethoxymethylsilylpropyl) ethylenediamine, N- (triethoxysilylpropyl) ethylenediamine, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxy. Examples thereof include epoxysilane such as silane and vinylsilane such as vinyltriethoxysilane. The addition amount of the silane coupling agent is preferably 0.1 to 5 mass% with respect to the entire adhesive composition.

  Of the phosphorus oxyacids or derivatives thereof, the phosphorus oxyacids may be any as long as they have at least one free oxygen acid, for example, hypophosphorous acid, phosphorous acid, orthophosphorus. Examples thereof include acids, phosphoric acids such as hypophosphoric acid, and condensed phosphoric acids such as metaphosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, polyphosphoric acid, and ultraphosphoric acid. Examples of the phosphorus oxyacid derivative include those obtained by partially esterifying the phosphorus oxyacid with alcohols in the state where at least one free oxygen acid remains. Examples of these alcohols include aliphatic alcohols such as methanol, ethanol, ethylene glycol and glycerin, and aromatic alcohols such as phenol, xylenol, hydroquinone, catechol and phloroglicinol. The oxygen acid of phosphorus or its derivative may use 1 type (s) or 2 or more types. The amount of phosphorus oxyacid or its derivative added is 0.01 to 10% by mass, preferably 0.05 to 5% by mass, and more preferably 0.1 to 1% by mass, based on the total composition.

<Laminates, packaging materials>
The laminate of the present invention is formed by laminating at least two sheet-like base materials using the above-mentioned adhesive composition. Specifically, it has an adhesive layer composed of the adhesive composition of the present invention between the first sheet-shaped base material and the second sheet-shaped base material. The adhesive composition is applied to a first sheet-shaped base material to form an adhesive layer, the second sheet-shaped base material is overlaid on the adhesive layer, and the adhesive layer is placed between the sheet-shaped base materials. The agent layer is cured. For example, there is a method in which the adhesive composition is applied to the first sheet-shaped base material by a roll coater coating method, and then the second sheet-shaped base material is attached to the first sheet-shaped base material without a drying step. In a normal roll coater, the coating condition is preferably about 300 to 3000 mPa · s at 40 ° C. in the viscosity of the liquid mixture of the adhesive in a state of being heated to 30 ° C. to 90 ° C. Further, the coating amount is preferably 0.5 to 5 g / m ² , and more preferably about 0.5 to 3 g / m ² .
When the adhesive composition of the present invention is a solvent-free type, after laminating, the curing reaction of the adhesive composition proceeds after 12 to 72 hours at room temperature or under heating, thereby exhibiting practical physical properties.

As the first sheet-shaped substrate, a plastic film is preferable, and a PET (polyethylene terephthalate) film, a nylon film, an OPP (biaxially oriented polypropylene) film, a K coat film such as polyvinylidene chloride, and a base film such as various vapor deposition films. And aluminum foil.
The first sheet-shaped substrate may be a substrate on which a printing ink layer is formed by gravure- or flexographic-printing a printing ink on the substrate, and even in this case, a good laminate appearance is exhibited. You can The above-mentioned printing ink can be used without limitation, and solvent-based ink, water-based ink, active energy ray-curable ink, or the like can be used.

  Further, as the second sheet-shaped substrate, a plastic film is preferable, and in addition to the substrates mentioned in the first sheet-shaped substrate, a CPP (non-stretched polypropylene) film, VMCPP (aluminum vapor-deposited unstretched polypropylene film), Sealant films such as LLDPE (linear low-density polyethylene), LDPE (low-density polyethylene), HDPE (high-density polyethylene), and VMLDPE (aluminum-deposited low-density polyethylene film) film can be used.

  By using the adhesive composition of the present invention, it is possible to obtain a laminate that exhibits an excellent laminated film appearance even when high-speed laminating is performed in the form of a solventless adhesive. For example, in the case of a PET (polyethylene terephthalate) film / VMCPP (aluminum vapor-deposited unstretched polypropylene film) film structure, 200 m / min or more, and in the case of an OPP / CPP film structure, even high-speed processing of 350 m / min or more, It can exhibit an excellent laminated appearance. Furthermore, by using this laminate, a packaging material exhibiting an excellent laminated film appearance can be obtained.

  Hereinafter, the present invention will be described in more detail with reference to examples. All percentages and parts in the examples and comparative examples are on a mass basis unless otherwise noted.

<Method for measuring hydroxyl value (OHV)>
About 1 g of a sample was accurately weighed in a ground-in stopper Erlenmeyer flask, and 100 ml of a toluene / ethanol (volume ratio: toluene / ethanol = 2/1) mixed solution was added and dissolved. Further, exactly 5 ml of an acetylating agent (a solution in which 25 g of acetic anhydride was dissolved in pyridine to make the volume 100 ml) was added, and the mixture was stirred for about 1 hour. To this, phenolphthalein reagent solution is added as an indicator, and this is continued for 30 seconds. Then, the solution was titrated with a 0.1N alcoholic potassium hydroxide solution until it turned pink. The hydroxyl value was calculated by the following (formula 1). The hydroxyl value was the numerical value of the dry state of the resin (unit: mgKOH / g).
(Equation 1)
Hydroxyl value (mgKOH / g) = [{(ba) × F × 28.25} / S] / (nonvolatile component concentration / 100) + D
However, S: sampling amount (g)
a: Consumption of 0.1N alcoholic potassium hydroxide solution (ml)
b: Empty experiment consumption of 0.1N alcoholic potassium hydroxide solution (ml)
F: titer of 0.1N alcoholic potassium hydroxide solution
D: Acid value (mgKOH / g)

<Method of measuring acid value (AV)>
About 1 g of a sample was precisely weighed in a ground-in stopper Erlenmeyer flask, and 100 ml of a toluene / ethanol (volume ratio: toluene / ethanol = 2/1) mixed solution was added and dissolved. To this, a phenolphthalein reagent solution was added as an indicator, held for 30 seconds, and then titrated with a 0.1N alcoholic potassium hydroxide solution until the solution became a bright red color. The acid value was calculated by the following (formula 2). The acid value is the numerical value of the dry state of the resin (unit: mgKOH / g)
(Formula 2): Acid value (mgKOH / g) = {(5.661 × a × F) / S} / (nonvolatile matter concentration / 100)
However, S: sampling amount (g)
a: Consumption of 0.1N alcoholic potassium hydroxide solution (ml)
F: titer of 0.1N alcoholic potassium hydroxide solution

<Method of measuring NCO content (mass%)>
About 1 g of a sample was weighed in a 200 mL Erlenmeyer flask, and 10 mL of 0.5N di-n-butylamine (toluene solution) and 10 mL of toluene were added and dissolved. To this, a phenolphthalein reagent solution was added as an indicator, held for 30 seconds, and then titrated with a 0.25N hydrochloric acid solution until the solution became a pink color. The NCO content (mass%) was calculated by the following (formula 3).
(Formula 3): NCO (mass%) = {(ba) × 4.220 × F × 0.25} / S
However, S: sampling amount (g)
a: Consumption of 0.25N hydrochloric acid solution (ml)
b: Consumption (ml) of 0.25N hydrochloric acid solution in blank experiment
F: Titer of 0.25N hydrochloric acid solution

<Method of measuring number average molecular weight (Mn)>
The number average molecular weight (Mn) was measured using Showa Denko GPC (gel permeation chromatography) “Shodex GPC System-21”. GPC is a liquid chromatography in which a substance dissolved in a solvent is separated and quantified by the difference in its molecular size. Tetrohydrofuran was used as the solvent, and the value converted into polystyrene was used.

<Production of polyisocyanate component (A)>
(Synthesis example 101) Polyisocyanate component A- (1)
Polypropylene glycol having a number average molecular weight of about 400 (hereinafter referred to as PPG-400) 300 parts, polypropylene glycol having a number average molecular weight of about 2,000 (hereinafter referred to as PPG-2000) 300 parts, number average molecular weight obtained by adding polypropylene glycol to glycerin About 400 parts of triol (hereinafter referred to as PPG-400-3 functional) of about 400 and 800 parts of 4,4′-diphenylmethane diisocyanate (hereinafter referred to as 4,4′-MDI) were charged into a reaction vessel and stirred under a nitrogen gas stream. While heating at 80 ° C. to 90 ° C. for 3 hours to carry out the urethanization reaction, the isocyanate group content is 12.4% and the 4,4′-MDI (hereinafter, also referred to as MDI monomer) content is 20.9%. A urethane prepolymer having isocyanate groups at both ends (hereinafter referred to as polyetherpolyure It was obtained also called emissions polyisocyanate resin) corresponds to ((a1)).
Next, 50 parts of isopropyl alcohol, which is a monoalcohol having a molecular weight of about 60, is added, and the mixture is heated at 60 ° C. for 1 hour to react the remaining MDI monomer with isopropyl alcohol to form a monoalcohol component and a polyisocyanate component. A reaction product (corresponding to (a2)) was obtained. To this mixture of the polyether polyurethane polyisocyanate resin and the reaction product of the monoalcohol component and the polyisocyanate component, 150 parts of 4,4′-MDI, 2,4′-diphenylmethane diisocyanate (hereinafter referred to as “polyisocyanate component”) , 2,4'-MDI), and 650 parts of crude MDI (hereinafter referred to as crude MDI) which is a mixture of polymeric MDI and 4,4'-MDI are added, and the mixture is stirred for 30 minutes to prepare isocyanate at both ends. A polyisocyanate component A- (1) containing a urethane prepolymer (a1) having a group and a reaction product (a2) of a monoalcohol component having a molecular weight of 500 or less and an isocyanate component was obtained.

(Synthesis examples 102 to 107) Polyisocyanate components A- (2) to (7)
Polyisocyanate components A- (2) to (7) were obtained in the same manner as in Synthesis Example 101, except that the types and blending amounts of the raw materials shown in Table 1 were changed.

(Synthesis example 108) Polyisocyanate component A- (8)
Except that the step of obtaining the reaction product of the residual MDI monomer and isopropyl alcohol is not performed, the urethane prepolymer (a1) having isocyanate groups at both ends is contained in the same manner as in Synthesis Example 101, and the number average molecular weight is 500 or less. A polyisocyanate component A- (8) containing no reaction product (a2) of a monoalcohol component and an isocyanate component was obtained.

The abbreviations in Table 1 are shown below.
PPG-400: Polypropylene glycol having a number average molecular weight of about 400 PPG-2000: Polypropylene glycol having a number average molecular weight of about 2,000 PPG-400-3 Functional: Triol PPG-1000 having a number average molecular weight of about 400 in which polypropylene glycol is added to glycerin Trifunctional polyester polyol having a number average molecular weight of about 1,000, in which polypropylene glycol is added to glycerin 1: 304 parts of adipic acid, 115 parts of isophthalic acid, 75 parts of neopentyl glycol, 305 parts of diethylene glycol. Polyester polyol having an average molecular weight of about 1,400 4,4'-MDI: 4,4'-diphenylmethane diisocyanate 2,4'-MDI: 2,4'-diphenylmethane diisocyanate TDI: tolylenedi Socyanate XDI: xylylene diisocyanate crude MDI: mixture of polymeric MDI and 4,4′-MDI HDI trimer: hexamethylene diisocyanate buret isopropyl alcohol: molecular weight 60 monoalcohol benzyl alcohol: molecular weight 108 monoalcohol stearyl alcohol: 270 molecular weight monoalcohol

<Production of polyol component (B)>
[Synthesis of polyester polyol]
(Synthesis example 201) Polyester polyol (b1) -1
115 parts of terephthalic acid (hereinafter referred to as TPA), 304 parts of adipic acid (hereinafter referred to as ADA), 305 parts of diethylene glycol (hereinafter referred to as DEG), and 75 parts of neopentyl glycol (hereinafter referred to as NPG) were charged into a reaction vessel, and nitrogen was charged. The mixture was heated to 150 ° C. to 240 ° C. with stirring under a gas stream to carry out an esterification reaction. When the acid value becomes 10.0 (mgKOH / g) or less, the reaction temperature is set to 200 ° C., the pressure inside the reaction vessel is gradually reduced, and the reaction is performed at 1.3 kPa or less, and the acid value is 0.4 (mgKOH / g). A polyester polyol (b1) -1 having a hydroxyl value of 135 (mgKOH / g) and a number average molecular weight of about 800, which is a polyester diol resin having hydroxyl groups at both ends, was obtained.

(Synthesis examples 202 to 205) Polyester polyol (b1) -2 to 5
Polyester polyols (b1) -2 to (b1) -5, which are polyester diol resins having hydroxyl groups at both ends, were obtained in the same manner as in Synthesis Example 201 except that the composition was changed to those shown in Table 2.

[Synthesis of polyether polyol]
(Synthesis example 301) Polyether polyol (b2)
330 parts of PPG-400, 190 parts of PPG-2000, 330 parts of PPG-400-3 functional group, 130 parts of 4,4′-MDI were charged in a reaction vessel and stirred at 80 ° C. under a nitrogen gas stream. Urethane reaction was carried out by heating at 90 ° C. for 3 hours, and disappearance of the isocyanate group was confirmed by IR to obtain a polyether polyol (b2) which is a polyether polyurethane resin.

The abbreviations in Tables 2 and 3 are shown below.
IPA: isophthalic acid TPA: terephthalic acid ADA: adipic acid EG: ethylene glycol 1,6 HD: 1,6-hexanediol DEG: diethylene glycol NPG: neopentyl glycol PPG-400: polypropylene glycol PPG-2000 having a number average molecular weight of about 400: Polypropylene glycol having a number average molecular weight of about 2,000 PPG-400-3 functional: Triol 4,4′-MDI having a number average molecular weight of about 400 having polypropylene glycol added to glycerin: 4,4′-diphenylmethane diisocyanate

[Blending of polyol component (B)]
(Formulation example 401)
94 parts of polyester diol (b1) -1 obtained in Synthesis Example 201 and 6 parts of 2-methyl-1,3-propanediol were mixed to obtain polyol component B- (1).

(Formulation examples 402 to 408)
Polyol components B- (2) to (8) were obtained in the same manner as in Formulation Example 401, except that the composition shown in Table 4 was changed. B- (6) shown in Table 4 was used as the castor oil alone, and B- (8) was used alone as the polyether polyol (b2) which is a polyether polyurethane resin, as the polyol component (B).

<Production of adhesive composition>
[Example 1]
(Production Example 501: Adhesive composition AD1)
75 parts of polyisocyanate component A- (1) and 100 parts of polyol component B- (4) were mixed at 40 ° C. to obtain a solvent-free adhesive composition AD1. The adhesive composition AD1 contains 130 mol of the isocyanate group derived from the polyisocyanate component (A) with respect to 100 mol of the hydroxyl group in the polyol component (B).
The molar amount of isocyanate groups with respect to 100 mol of hydroxyl groups is determined as follows.
Molar amount of isocyanate group per 100 moles of hydroxyl group = [isocyanate group (eq.) / Hydroxyl group (eq.)] × 100
Isocyanate group (eq.) = NCO group content of polyisocyanate component (A) (mass%) / (42 × 100)
Hydroxyl group (eq.) = Hydroxyl group value (mgKOH / g) / 56100

The total content of 4,4′-MDI, 2,4′-MDI, TDI, and XDI (hereinafter referred to as isocyanate monomer) contained in 100% by mass of the adhesive composition is 14.6%. there were. The isocyanate monomer content is the total area of the peak areas derived from the MDI monomer near Mn = 200 to 300 and the peak areas derived from the TDI monomer and XDI monomer around Mn = 100 to 200, observed on the GPC chart. , Divided by the total area of all peaks observed on the GPC chart.
Isocyanate monomer content (%)
= (Total peak area of isocyanate monomer / total area of all peaks) x 100

[Examples 2 to 18, Comparative Examples 1 to 3]
(Production Examples 502 to 521: Adhesive Compositions AD2 to AD21)
According to the composition shown in Table 5, adhesive compositions AD2 to AD21 were obtained in the same manner as in Production Example 501. Table 5 shows the amount of isocyanate groups derived from the polyisocyanate component (A), and the total content of the isocyanate monomers contained in 100% by mass of the adhesive composition, relative to 100 mol of hydroxyl groups in the polyol component (B).

<Evaluation of adhesive composition>
A laminate was prepared from the obtained adhesive composition, and the adhesive strength and laminate appearance of the laminate were evaluated according to the following methods. The results are shown in Table 5.

[Production of laminated body]
Urethane type laminated ink (Dynastar; manufactured by Toyo Ink Co., Ltd.) was adjusted to 14 seconds (25 ° C.) by Zan cup # 3 manufactured by Riaisha Co., Ltd., and printing speed was 50 m / m by a gravure printing machine equipped with a plate depth of 30 μm. Minutes, printed on a corona-treated PET (polyethylene terephthalate) film (TOYOBO ester film E5100 # 12) which is the first sheet-shaped substrate, dried or cured by passing through an oven at 60 ° C., and then printed on a PET film. A print layer was formed. Next, using a solventless test coater, the solventless adhesive composition AD1 was applied to the surface of the printing layer printed on the PET film under the environment of a temperature of 50 ° C. and a humidity of 60% RH, and a coating speed of 200 m. / Minute (application amount: 2 g / m ² ), and the vapor deposition surface of the aluminum vapor-deposited unstretched polypropylene film (hereinafter referred to as VMCPP; thickness: 25 μm) which is the second sheet-shaped substrate is applied to this application surface. Overlapped to obtain a pre-laminate. Next, the pre-laminate was aged in an environment of 30 ° C. and 65% RH for 1 day to cure the adhesive layer, thereby producing a laminate having a configuration of PET / printing layer / adhesive layer / VMCPP. .

(Adhesive strength)
The obtained laminate was cut into a test piece having a length of 300 mm and a width of 15 mm. Using an Instron type tensile tester, the sample was pulled at a peeling rate of 300 mm / min in an environment of 25 ° C., and the T-type peeling strength (N) between PET / VMCPP was measured in a width of 15 mm. This test was performed 5 times, the average value thereof was calculated and evaluated according to the following criteria.
5: Adhesive strength of 1.5N or more (very good)
4: Adhesive strength is 1.0 N or more and less than 1.5 N (good)
3: Adhesive strength is 0.6N or more and less than 1.0N (usable)
2: Adhesive strength is 0.3N or more and less than 0.6N (cannot be used)
1: Adhesive strength is less than 0.3N (poor)

(Laminate appearance of laminate)
The ink layer and the adhesive layer were passed through from the PET side, and the vapor deposition surface was visually observed, and evaluated according to the following criteria.
5: There is no yuzu skin pattern or small speckled pattern on the vapor deposition surface, and the adhesive layer is uniform (very good).
4: There is no small spot-like pattern on the vapor-deposited surface, but there is a slight yuzu-skin-like pattern (good).
3: There is no small spotted pattern on the vapor deposition surface, but there are many yuzu-skin-like patterns (can be used).
2: There is a slight yuzu-skin pattern or small speckled pattern on the vapor deposition surface (cannot be used)
1: A lot of yuzu skin-like patterns and small spot-like patterns are present on the vapor deposition surface (defective)

As shown in Table 5, in Examples 1 to 18 in which an adhesive layer of the present invention was used to form an adhesive layer, both the adhesive strength and laminate appearance after aging at 30 ° C., 65% RH, and 1 day were in use. The performance was higher than the normal level. On the other hand, in Comparative Examples 1 to 3, the adhesion performance was at a level where there was no problem in use, but the laminate appearance was not sufficient. This is because the reaction product of the isocyanate monomer and the monoalcohol existing in the system acts in the same manner as the lubricant, whereby the adhesive exhibits good leveling properties during film coating, and the laminate appearance is improved. Inferred.
Further, when the isocyanate monomer content in the composition was 15% or less, a particularly good laminate appearance was exhibited. This is because the lower the isocyanate monomer content, the less likely it is that bubble-like laminate appearance defects due to carbon dioxide gas foaming caused by the reaction between the isocyanate monomer occurring during film coating and aging and the moisture in the atmosphere occur. Inferred.

Claims (17)

An adhesive composition comprising a polyisocyanate component (A) and a polyol component (B),
The polyisocyanate component (A) is a reaction product of a polyol component (X) and a diisocyanate component, a urethane prepolymer (a1) having an isocyanate group at the terminal, and a monoalcohol component and a diisocyanate component having a molecular weight of 500 or less. An adhesive composition comprising a reaction product (a2) with.   The adhesive composition according to claim 1, wherein the polyol component (X) contains a polyether polyol.   The adhesive composition according to claim 2, wherein the content of the polyether polyol in the polyol component (X) is 70 to 100% by mass.   4. The diisocyanate component essentially comprises at least one selected from the group consisting of 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, xylylene diisocyanate and tolylene diisocyanate. The adhesive composition according to the item.   The adhesive composition according to any one of claims 1 to 4, wherein the diisocyanate component contains 4,4'-diphenylmethane diisocyanate. The polyisocyanate component (A) contains at least one selected from the group consisting of 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, xylylene diisocyanate and tolylene diisocyanate,
The total amount of 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, xylylene diisocyanate and tolylene diisocyanate in 100 mass% of the polyisocyanate component (A) is 20 to 40 mass%. Item 6. The adhesive composition according to any one of items 1 to 5.   The adhesive composition according to any one of claims 1 to 6, wherein the monoalcohol component is a primary or secondary alcohol having 2 to 20 carbon atoms.   The adhesive composition according to any one of claims 1 to 7, wherein the monoalcohol component has a molecular weight of 200 or less.   The adhesive composition according to any one of claims 1 to 8, wherein the polyisocyanate component (A) has an isocyanate group content of 18 to 22% by mass.   The adhesive composition according to any one of claims 1 to 9, wherein the polyol component (B) contains a polyester polyol.   The adhesive composition according to claim 10, wherein the polyester polyol has a number average molecular weight of 1,000 to 3,000.   The content of 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, xylylene diisocyanate, and tolylene diisocyanate in the adhesive composition is 16% or less, 12. Adhesive composition.   The adhesive composition according to any one of claims 1 to 12, which is a solventless type.   The adhesive composition according to any one of claims 1 to 13, which is a laminating adhesive for forming a packaging material.   A laminate in which the adhesive composition according to any one of claims 1 to 14 is laminated between at least two sheet-shaped substrates.   The adhesive composition according to any one of claims 1 to 14 is applied to a first sheet-shaped base material to form an adhesive layer, and a second sheet-shaped base material is superposed on the adhesive layer. And then curing the adhesive layer.   A packaging material comprising the laminate according to claim 15.