AU2017368512B2

AU2017368512B2 - Reactive adhesive, multilayer film, and packaging

Info

Publication number: AU2017368512B2
Application number: AU2017368512A
Authority: AU
Inventors: Shuuichi Nitta; Hideo Tanabe; Kiyokazu Umetsu
Original assignee: DIC Corp; Dainippon Ink and Chemicals Co Ltd
Current assignee: DIC Corp
Priority date: 2016-12-02
Filing date: 2017-11-28
Publication date: 2019-12-19
Anticipated expiration: 2037-11-28
Also published as: TW201833287A; CN109983097A; AU2017368512A1; JPWO2018101242A1; TWI753975B; CN109983097B; WO2018101242A1; JP6451021B2

Abstract

Provided is a reactive adhesive which comprises a polyol component A containing a polyol compound and an isocyanate component B containing an isocyanate compound, and wherein: the isocyanate component B contains a reaction product (B-1) of a polyol and an isocyanate and a reactive diluent (B-2) having an isocyanate group that has a number average molecular weight within the range of 400-1,000; and the viscosity as determined by blending the polyol component A and the isocyanate component B at the weight ratio and leaving the resulting blend to stand for 30 minutes in an atmosphere at 40°C is 5,000 mPa·s or less. Also provided are a multilayer film and a package. It is preferable that the reactive diluent (B-2) having an isocyanate group is an aromatic diisocyanate, an aliphatic diisocyanate, or a dimer or trimer of one of these diisocyanates.

Description

DESCRIPTION

Title of Invention: REACTIVE ADHESIVE, MULTILAYER FILM, AND PACKAGING

Technical Field [0001]

The present invention relates to a reactive adhesive and to a multilayer film and packaging that are produced by using the reactive adhesive.

Background Art [0002]

Multilayer films (also referred to as laminate films) used for various types of packaging, labels, and the like are provided with design flexibility, functionality, preservability, convenience, and transportability by laminating a large variety of plastic film, metal foil, paper, and the like. In particular, packaging produced by forming the multilayer films into the shape of a bag is used as packaging for foods, drugs, detergents, and the like. [0003]

To date, mainstream laminate films have been produced by a dry lamination system in which a film is coated with an adhesive dissolved into a volatile organic solvent (also referred to as a solvent-type laminate adhesive), the organic solvent is volatilized during passing through an oven, and another film is bonded. However, in recent years, due to the viewpoint of reducing environmental load and improving the operational environment, demands for reactive two-part-type laminate adhesives (also referred to as reactive adhesives or solventless laminate adhesives) containing no volatile organic solvent have increased (refer to, for example, PTL 1).

[0004]

The reactive adhesive described in PTL 1 above is effective for adhesive strength and for reducing the aging time of a solventless adhesive but has a relatively short pot life as a resin for a solventless adhesive due to combining an aromatic isocyanate and a polyester diol. In the case where the pot life is short, variations in the amount of coating tend to occur and, as a result, the appearance of the laminate may be impaired significantly. In addition, when a lamination apparatus is temporarily stopped during, for example, exchanging of an original fabric in the case of an adhesive having a short pot life, operability may be impaired significantly because operations of, for example, exchanging the adhesive and cleaning a roll are required.

[0005]

Further, the reactive adhesive may be eluted through a film after lamination into the contents because a reactive monomer having a somewhat lower molecular weight than the solvent-type laminate adhesive is used as a raw material.

Particularly in recent years, in Europe and other countries, regulation of components containing chemical substances eluted (migrated) from a plastic container has been elaborately defined, and products including small amounts of such components containing chemical substances eluted from a plastic container have been desired. In general, regarding elution of chemical substances used for adhesives, a SML (specific migration limit) is regulated, and eluted materials can be readily controlled. However, elution of a non-intentionally added substance (NIAS) generated by synthesis or the like is a problem that is not readily addressed.

[0006]

Meanwhile, it is known that an adhesive containing an isocyanate-terminated polyurethane prepolymer and a polyol is an adhesive for generating a low-concentration extractive primary aromatic amine (PAA), the isocyanate-terminated polyurethane prepolymer being a reaction product of modified diphenylmethane diisocyanate (MDI) selected from a group

consisting of	a carbodiimide-modified diphenylmethane
diisocyanate,	an allophanate-modified diphenylmethane
diisocyanate,	a biuret-modified diphenylmethane
diisocyanate,	and a polymeric diphenylmethane diisocyanate

and a combination of these (refer to, for example, PTL 2).

2017368512 06 Dec 2019

However, the adhesive is used by reacting the modified diphenylmethane diisocyanate with a polyol and, as a result, the viscosity tends to increase and the pot life tends to remain short.

Therefore, under the present circumstances, a practically satisfactory reactive adhesive that does not cause elution of a large amount of non-intentionally added substances and that has a 5 long pot life has not been obtained.

Citation List

Patent Literature [0007]

PTL1: Japanese Unexamined Patent Application Publication No. 2014-159548

PTL 2: Japanese Unexamined Patent Application Publication (Translation of PCT

Application) No. 2014-516321 [0007A]

Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of 15 these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each of the appended claims.

[0007B]

Throughout this specification the word comprise, or variations such as comprises 20 or comprising, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

Summary of Invention [0007C]

In one aspect of the invention there is provided a reactive adhesive comprising:

a polyol component containing a polyol compound; and an isocyanate component containing an isocyanate compound, wherein the isocyanate component contains a reaction product of a polyol and an isocyanate and a reactive diluent having an isocyanate group that has a number average 30 molecular weight within the range of 400 to 1,000, and the polyol component and the isocyanate component are mixed at a weight ratio and the viscosity after being left to stand for 30 minutes in an environment at 40°C is 5,000 mPa-s or less.

2017368512 06 Dec 2019

4A

Technical Problem [0008]

An issue to be addressed by the present invention is the provision of a reactive adhesive that contains a very small amount of non-intentionally added substances that are 5 eluted into contents through a film after lamination and that has a long pot life.

Solution to Problem [0009]

The present inventors found that a reactive adhesive in which an isocyanate compound having a number average molecular weight within a specific range was used as a reactive diluent and a polyol component and an isocyanate component were mixed at a weight ratio and which had a viscosity of 5,000 mPa-s or less after being left to stand for 30 minutes in an environment at 40°C could address the above-described issue.

[0010]

Accordingly, the present invention provides a reactive adhesive including polyol component A containing a polyol compound and isocyanate component B containing an isocyanate compound, wherein the isocyanate component B contains reaction product (B-l) of a polyol and an isocyanate and reactive diluent (B-2) having an isocyanate group that has a number average molecular weight within the range of 400 to 1,000, polyol component A and isocyanate component B are mixed at a weight ratio, and the viscosity after being left to stand for 30 minutes in an environment at 40°C is 5,000 mPa-s or less.

[0011]

In addition, the present invention provides a multilayer film in which an adhesive layer is stacked between a first plastic film and a second plastic film, wherein the adhesive layer is a layer of the above-described reactive adhesive.

[0012]

In addition, the present invention provides packaging produced by forming a multilayer film, in which an adhesive layer is stacked between a first plastic film and a second plastic film, into the shape of a bag, wherein the adhesive layer is a layer of the above-described reactive adhesive. Advantageous Effects of Invention [0013]

According to the present invention, the amount of nonintent ionally added substances that are eluted into contents through a film after lamination is very small. Therefore, peeling of laminate constituents, for example, delamination, does not occur during filling with the contents, for example, detergents, drugs, and the like, and after a lapse of time since the filling, so as to exhibit excellent adhesiveness and excellent resistance to the contents. In addition, excellent operability after mixing of the adhesive is exhibited because of low viscosity and long pot life. Description of Embodiments [0014] (Solvent)

The adhesive used in the present invention is a reactive two-part-type laminate adhesive, as described above, and is also called a solventless laminate adhesive because it contains no volatile organic solvent as in the related art.

In the present invention, an adhesive that is cured by a chemical reaction between an isocyanate group and a hydroxy group is used. In this regard, in the present invention, a solvent of the solventless adhesive refers to a volatile organic solvent having high solubility that can dissolve polyisocyanates and polyols used in the present invention, and solventless denotes that such a volatile organic solvent having high solubility is not contained. Examples of the organic solvent having high solubility includes toluene, xylene, methylene chloride, tetrahydrofuran, methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, acetone, methyl ethyl ketone (MEK), cyclohexanone, toluol, xylol, n-hexane, and cyclohexane. Of these, toluene, xylene, methylene chloride, tetrahydrofuran, methyl acetate, and ethyl acetate are known as organic solvents having particularly high solubility.

[0015]

Meanwhile, in the case where low viscosity or the like is required, the adhesive according to the present invention may be used after being appropriately diluted with the organic solvent having high solubility in accordance with the predetermined viscosity. In this case, any one of polyisocyanate composition (X) and polyol composition (Y) may be diluted, or both may be diluted. Examples of the organic solvent used in this case include methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, acetone, methyl ethyl ketone (MEK), cyclohexanone, toluol, xylol, nhexane, and cyclohexane. Of these, ethyl acetate and methyl ethyl ketone (MEK) are preferable from the viewpoint of solubility, and ethyl acetate is particularly preferable. The amount of the organic solvent used is determined in accordance with the predetermined viscosity, and in many cases, the amount of usage is within the range of about 0.1% to 10% by mass.

In addition, to reduce the viscosity of the adhesive according to the present invention, a solvent having a carbonyl group and no hydroxy group and having a boiling temperature of 200°C or higher, for example, triacetin or propylene carbonate, may be used. The amount of the highboiling-temperature organic solvent used is determined in accordance with the predetermined viscosity and the physical properties of a coating, and in many cases, the amount of usage is within the range of about 0.1% to 10% by mass. [0016] (Polyol component A containing polyol compound)

In the present invention, there is no particular limitation regarding the polyol compound contained in polyol component A, and known polyols can be used. Examples include polymeric polyols selected from polyester polyols, polyether polyols, polyurethane polyols, polyether ester polyols, polyester(polyurethane) polyols, polyether(polyurethane) polyols, polyester amide polyols, acryl polyols, polycarbonate polyols, polyhydroxylalkanes, castor oil, and mixtures of these.

Examples of the polyester polyol include polyester polyols obtained by reacting a dibasic acid, for example, terephthalic acid, isophthalic acid, adipic acid, azelaic acid, or sebacic acid, a dialkyl ester of these, or a mixture of these, with glycol, for example, ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, neopentyl glycol,

1,6-hexanediol, 3-methyl-l,5-pentanediol,

3,3'-dimethylolheptane, a polyoxyethylene glycol, a polyoxypropylene glycol, or a polytetramethylene ether glycol, or a mixture of these and polyester polyols obtained by ring-opening polymerization of a lactone, for example, a polycaprolactone, a polyvalerolactone, or a poly(β-methyl-yvalerolactone).

Examples of the polyether polyol include polyether polyols obtained by polymerizing an oxirane compound, for example, ethylene oxide, propylene oxide, butylene oxide, or tetrahydrofuran, by using water or a low-molecular-weight polyol, for example, ethylene glycol, propylene glycol, trimethylolpropane, or glycerin, as an initiator. Examples of the polyether ester polyol include polyether ester polyols obtained by reacting a dibasic acid, for example, terephthalic acid, isophthalic acid, adipic acid, azelaic acid, or sebacic acid, a dialkyl ester of these, or a mixture of these, with the above-described polyether polyol. [0019]

Examples of the polyurethane polyol include polyols having an urethane bond in the molecule, for example, a polyol that is a reaction product of a polyether polyol having a number average molecular weight of 200 to 20,000 and an organic polyisocyanate and that has an NCO/OH of preferably less than 1 and more preferably 0.9 or less. Regarding the organic polyisocyanate, polyisocyanate compounds described later, and in particular diisocyanate compounds, may be used.

[0020]

Examples of the polyether (polyurethane) polyol and the polyester(polyurethane) polyol include reaction products of a polyester polyol, a polyether ester polyol, or the like and an organic polyisocyanate that have an NCO/OH of preferably less than 1 and more preferably 0.9 or less.

[0021]

The polyester amide polyols are obtained by further using an aliphatic diamine having an amino group, for example, ethylenediamine, propylenediamine, or hexamethylenediamine, as a raw material in the abovedescribed esterification reaction.

The acryl polyol is obtained by, for example, copolymerizing a hydroxyethyl acrylate, a hydroxypropyl acrylate, a hydroxybutyl acrylate, or the like that has at least one hydroxy group in the molecule or a derivative of methacrylate corresponding to each of the above-described acrylates with an acrylic acid, a methacrylic acid, or the like or an ester of these.

[0022]

Examples of the polycarbonate polyol include products obtained by reacting at least one glycol selected from ethylene glycol, propylene glycol, 1,4-butanediol, 1,5pentanediol, 1,6-hexanediol, 3-methyl-l,5-pentanediol, 1,9nonanediol, 1,8-nonanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanediol, 1,4cyclohexanedimethanol, bisphenol A, and hydrogenated bisphenol A with dimethyl carbonate, diphenyl carbonate, ethylene carbonate, phosgene, or the like.

[0023]

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

Of these, polyether(polyurethane) polyols are particularly preferable.

[0024]

In addition, products obtained by reacting a polyisocyanate with a bis(hydroxyalkyl) amine and having an urethane bond group at a terminal can also be preferably used as the polyol compound used in the present invention. [0025] (Isocyanate component B containing isocyanate compound)

In the present invention, isocyanate component B contains a reaction product (B-l) of a polyol and an isocyanate and reactive diluent (B-2) having an isocyanate group that has a number average molecular weight within the range of 400 to 1,000.

[0026] (Reaction product (B-l) of polyol and isocyanate)

Examples of the isocyanate that is a raw material for forming reaction product (B-l) include aromatic polyisocyanates, for example, tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, 1,5naphthalene diisocyanate, and triphenylmethane triisocyanate; aliphatic polyisocyanates, for example, 1,6hexamethylene diisocyanate, isophorone diisocyanate, 4,4'methylenebis(cyclohexyl isocyanate), lysine diisocyanate, trimethylhexamethylene diisocyanate, and 1,3-(isocyanate methyl) cyclohexane; derivatives (modified materials) of polyisocyanates, for example, biuret bodies of these aromatic or aliphatic polyisocyanates and isocyanurate bodies of these aromatic or aliphatic polyisocyanates, and adducts produced by modifying these aromatic or aliphatic polyisocyanates with trimethylolpropane.

[0027]

Examples of the polyol that is the raw material for forming reaction product (B-l) include alkylene glycols, for example, ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-l,5-pentanediol, 1,6-hexanediol, neopentyl glycol, methylpentanediol, dimethylbutanediol, butylethylpropanediol, 1,4cyclohexanediol, and 1,4-cyclohexanedimethanol; bisphenols, for example, bisphenol A, bisphenol F, hydrogenated bisphenol A, and hydrogenated bisphenol F; dimer diols; bishydroxyethoxybenzene; polyalkylene glycols, for example, polyethylene glycols such as diethylene glycol and triethylene glycol, polypropylene glycols, and polybutylene glycols; urethane-bond-containing polyether polyols produced by further increasing the molecular weights of the abovedescribed polyalkylene glycols by using the above-described aromatic or aliphatic polyisocyanates; polyester polyols obtained by reacting the above-described alkylene glycols or polyalkylene glycols with aliphatic dicarboxylic acids having a carbon atom number within the range of 2 to 13, for example, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, suberic acid, azelaic acid, sebacic acid, undecane diacid, dodecane diacid, and tridecane diacid; and polyester polyols that are reaction products of polyesters obtained by a ring-opening polymerization reaction of cyclic ester compounds, for example, propiolactone, butyrolactone, ε-caprolactone, σvalerolactone, and β-methyl-valerolactone, with polyhydric alcohols, for example, the above-described glycols, glycerin, trimethylolpropane, and pentaerythritol.

[0028]

Of these polyols used for the reaction with the aromatic or aliphatic polyisocyanate, from the viewpoint of possibilities of reducing the viscosity of the adhesive itself and, in addition, enhancing the adhesion strength, polyalkylene glycols and polyester polyols are preferable. Regarding the polyalkylene glycols, the number average molecular weight (Mn) is preferably within the range of 200 to 6,000. Meanwhile, the polyester polyols are preferably produced by reacting the above-described alkylene glycols or polyalkylene glycols having a molecular weight of 300 or less with aliphatic polyvalent carboxylic acids having a carbon atom number of 2 to 30. Regarding the latter polyester polyols, trifunctional or higher alcohols, for example, glycerin, trimethylolpropane, and pentaerythritol, may be used as the raw material alcohol component of the polyol components in a proportion of 10% by mass or less. [002 9]

Of reaction products (B-l) above, polyisocyanates obtained by reacting aromatic polyisocyanates with polyalkylene glycols having a number average molecular weight within the range of 200 to 6,000 and polyisocyanates obtained by reacting aromatic polyisocyanates with polyester polyols having a number average molecular weight within the range of 200 to 3,000 are preferably used for soft packaging base materials because cured materials are provided with appropriate flexibility. Specifically, the resulting polyisocyanates having an isocyanate content of 5% to 20% by mass on the basis of a titration method (using di-nbutylamine) are preferable because appropriate resin viscosity is provided so as to exhibit excellent coating performance .

[0030]

Meanwhile, polyisocyanates obtained by reacting aromatic polyisocyanates with polyester polyols having a number average molecular weight within the range of 200 to 3,000; and polyisocyanates obtained by reacting aromatic polyisocyanates with mixtures of polyester polyols having a number average molecular weight within the range of 200 to

3,000 and polyalkylene glycols having a number average molecular weight within the range of 200 to 6,000 are preferably used for hard base materials of the reactive adhesive from the viewpoint of excellent adhesive strength. Specifically, the resulting polyisocyanates having an isocyanate content of 5% to 20% by mass on the basis of a titration method (using di-n-butylamine) are preferable because appropriate resin viscosity is also provided so as to exhibit excellent coating performance.

[0031]

In this regard, the reaction ratio of the aromatic polyisocyanate to the mixture with the polyalkylene glycol or polyester polyol is preferably within the range of 1.5 to 5.0 in terms of the equivalent ratio [isocyanate/hydroxy group] of the isocyanate in the aromatic polyisocyanate to the hydroxy group in the polyol because an appropriate range of adhesive viscosity is provided so as to exhibit excellent coating performance.

[0032] (Reactive diluent (B-2) having isocyanate group that has number average molecular weight within the range of 400 to 1,000)

The present invention is characterized by including reactive diluent (B-2) having an isocyanate group that has a number average molecular weight within the range of 400 to 1,000. When reactive diluent (B-2) is included, the viscosity is reduced, excellent handleability is exhibited, and a favorable pot life can be obtained.

Specifically, examples of preferable reactive diluent (B-2) include aromatic diisocyanates, aliphatic diisocyanates, dimers of aromatic diisocyanates, dimers of aliphatic diisocyanates, trimers of aromatic diisocyanates, and trimers of aliphatic diisocyanates. More specifically, examples include aromatic polyisocyanates, for example, carbodiimide-modified diphenylmethane diisocyanates, allophanate-modified diphenylmethane diisocyanates, biuretmodified diphenylmethane diisocyanates, and xylylene diisocyanate; aliphatic polyisocyanates, for example, 1,6hexamethylene diisocyanate, isophorone diisocyanate, 4,4'methylenebis(cyclohexyl isocyanate), lysine diisocyanate, trimethylhexamethylene diisocyanate, and 1,3-(isocyanate methyl) cyclohexane; derivatives (modified materials) of polyisocyanates, for example, allophanate bodies or biuret bodies of these aromatic or aliphatic polyisocyanates and isocyanurate bodies of these aromatic or aliphatic polyisocyanates, and adducts produced by modifying these aromatic or aliphatic polyisocyanates with trimethylolpropane .

[0033]

Regarding the mixing ratio of reaction product (B-l) to reactive diluent (B-2) in isocyanate component B, reaction product (B-l)/reactive diluent (B-2) is preferably within the range of 30/70 to 99/1 and more preferably within the range of 50/50 to 95/5.

[0034]

Regarding the mixing ratio of polyol component A containing the above-described polyol compound to isocyanate component B containing the above-described isocyanate compound, the equivalent ratio [(a)/(b)] of the solid content hydroxyl equivalent (a) of the polyol compound to the solid content isocyanate equivalent (b) of the isocyanate compound is 1.0 to 5.0 and more preferably 2.0 to 3.0. Details of production will be described in the example .

Meanwhile, the isocyanate group concentration in isocyanate component B is preferably within the range of 5% to 20%. [0035]

In the present invention, the number average molecular weight (Mn) is denoted as a value measured by gel permeation chromatography (GPC) under the following condition.

[0036]

Measuring apparatus: HLC-8220GPC produced by Tosoh Corporation

Column: TSK-GUARDCOLUMN SuperHZ-L produced by Tosoh

Corporation + TSK-GEL SuperHZM-MX4 produced by Tosoh

Corporation

Detector: RI (differential refractometer)

Data processing: Multistation GPC-8020 model II produced by Tosoh Corporation

Measurement condition: column temperature 40°C solvent tetrahydrofuran flow rate 0.35 ml/min

Standard: monodisperse polystyrene

Sample: tetrahydrofuran solution that has a resin content of 0.2% by mass in terms of solid content and that has been filtrated by microfilter (100 μΐ) [0037]

The number average molecular weight of reactive diluent (B-2) is preferably within the range of 400 to 1,000 and more preferably within the range of 450 to 900.

[0038] (Viscosity)

Regarding the reactive adhesive according to the present invention, polyol component A and isocyanate component B are mixed at a weight ratio and the viscosity after being left to stand for 30 minutes in an environment at 40°C is 5,000 mPa-s or less. In the present invention, the viscosity is a value measured by a rotational viscometer under the following condition.

Measuring apparatus: MCR-302 produced by Anton Paar

Measurement condition: temperature of 40°C, cone plate diameter of 50 mm [0039]

The viscosity is preferably within the range of 500 to 5,000 mPa-s and more preferably within the range of 1,500 to 4,500 mPa-s.

[0040]

As described above in detail, the reactive adhesive used in the present invention includes polyol component A and isocyanate component B as indispensable components. When an alicyclic amide compound is further mixed into any one of polyol component A and isocyanate component B or mixed as a third component in the step of coating, regarding laminate packaging, harmful low-molecular-weight chemical substances represented by aromatic amines can be effectively suppressed from being eluted into the contents.

[0041]

Examples of the alicyclic amide compound used here include δ-valerolactam, ε-caprolactam, ω-enanthollactam, ηcaprillactam, and β-propiolactam. Of these, ε-caprolactam is preferable from the viewpoint of excellent effect of reducing the amount of low-molecular-weight chemical substances eluted. Regarding the amount of mixing, it is preferable that the alicyclic amide compound within the range of 0.1 to 5 parts by mass be mixed relative to 100 parts by mass of polyol component A.

[0042]

The reactive adhesive used in the present invention may be used in combination with a pigment, as the situation demands. There is no particular limitation regarding the pigment usable in this case, and examples include organic pigments and inorganic pigments, for example, extender pigments, white pigments, black pigments, gray pigments, red pigments, brown pigments, green pigments, blue pigments, metal powder pigments, light-emitting pigments, and pearl pigments and also plastic pigments, which are described in Toryou Genryou Benran (Handbook of Raw Material for Paint) fiscal 1970 (edited by Japan Paint Manufacturers Association). Specific examples of the coloring agents include various materials. Examples of the organic pigment include various insoluble azo pigments, for example, Benzidine Yellow, Hansa Yellow, and Lake Red 4R; soluble azo pigments, for example, Lake Red C, Carmine 6B, and Bordeaux 10; various (copper) phthalocyanine pigments, for example, Phthalocyanine Blue and Phthalocyanine Green; various basic dyeing lakes, for example, Rhodamine Lake and Methyl Violet Lake; various mordant-dye-based pigments, for example, Quinoline Lake and Fast Sky Blue; various vat-dye-based pigments, for example, anthraquinone-based pigments, thioindigo-based pigments, and perinone-based pigments; various quinacridone-based pigments, for example, Cinquasia Red B; various dioxazine-based pigments, for example, Dioxazine Violet; various condensed azo pigments, for example, Cromophthal; and Aniline Black.

[0043]

Examples of the inorganic pigment include various chromates, for example, chrome yellow, zinc chromate, and molybdate orange; various ferrocyanides, for example, Prussian Blue; various metal oxides, for example, titanium oxide, zinc flower, Mapico Yellow, iron oxide, red iron oxide, chrome oxide green, and zirconium oxide; various sulfides or selenides, for example, cadmium yellow, cadmium red, and mercury sulfide; various sulfates, for example, barium sulfate and lead sulfate; various silicates, for example, calcium silicate and ultramarine; various carbonates, for example, calcium carbonate and magnesium carbonate; various phosphates, for example, cobalt violet and manganese violet; various metal powder pigments, for example, aluminum powder, gold powder, silver power, copper powder, bronze powder, and brass powder; flake pigments of these metals and mica-flake pigments; mica-flake pigments in the form of covering metal oxide, metallic pigments such as micaceous iron oxide pigments, and pearl pigments; and

- 23 graphite and carbon black.

[0044]

Examples of the extender pigment include precipitated barium sulfate, whitewash, precipitated calcium carbonate, calcium bicarbonate, white limestone, alumina white, silica, hydrous fine powder silica (white carbon), ultrafine powder anhydrous silica (AEROSIL), silica sand, talc, precipitated magnesium carbonate, bentonite, clay, kaoline, and loess.

[0045]

In addition, examples of the plastic pigment include GRANDOLL PP-1000 and PP-2000S produced by DIC Corporation .

[0046]

Regarding the pigment used in the present invention, inorganic oxides, for example, titanium oxide and zinc flower, as the white pigment and carbon black as the black pigment are more preferable because of excellent durability, weatherability, and design flexibility.

[0047]

The mass ratio of the pigment used in the present invention is more preferably 1 to 400 parts by mass and particularly 10 to 300 parts by mass relative to 100 parts by mass of the total of isocyanate component B and polyol component A because of excellent adhesiveness, blocking resistance, and the like.

[0048]

In addition, an adhesion accelerator may be used for the reactive adhesive used in the present invention. Examples of the adhesion accelerator include silane coupling agents, titanate-based coupling agents, and coupling agents of aluminum base or the like, and epoxy resins.

[0049]

Examples of the silane coupling agent include aminosilanes, for example, γ-aminopropyltriethoxysilane, γaminopropyltrimethoxysilane, Ν-β(aminoethyl)-γaminopropyltrimethoxysilane, Ν-β(aminoethyl)-γaminopropyltrimethyldimethoxysilane, and N-phenyl-γaminopropyltrimethoxysilane; epoxysilanes, for example, β(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γglycidoxypropyltrimethoxysilane, and γglycidoxypropyltriethoxysilane; vinylsilanes, for example, vinyltris(β-methoxyethoxy) silane, vinyltriethoxysilane, vinyltrimethoxysilane, and γmethacryloxypropyItrimethoxysilane; hexamethyldisilazane, and γ-melcaptopropyltrimethoxysilane.

[0050]

Examples of the titanate-based coupling agent include tetraisopropoxytitanium, tetra-n-butoxytitanium, butyltitanate dimer, tetrastearyltitanate, titanium acetylacetonate, titanium lactate, tetraoctylene glycol titanate, titanium lactate, and tetrastearoxytitanium.

[0051]

Examples of the aluminum-based coupling agent include acetoalkoxyaluminum diisopropylate .

[0052]

Examples of the epoxy resin include various epoxy resins, for example, generally commercially available bisphenol A type epoxy resins, novolak type epoxy resins, bisphenol β-methylglycidyl ethers, novolak resin βmethylglycidyl ethers, cyclic oxirane type epoxy resins, and resorcin type epoxy resins.

[0053]

The reactive adhesive used in the present invention may contain additives other than those described above, as the situation demands. Examples of the additive include leveling agents; inorganic fine particles, for example, colloidal silica and alumina sol; polymethyl methacrylatebased organic fine particles; defoaming agents; dropping inhibitors; wet dispersing agents; viscosity controlling agents; ultraviolet absorbers; metal deactivators; peroxide decomposing agents; flame retardants; reinforcing agents; plasticizers; lubricants; rust inhibitors; fluorescent bleaching agents; inorganic heat-absorbing agents; flameproofing agents; antistatic agents; and dehydrating agents.

[0054]

The pigments, the adhesion accelerators, and the additives may be used by being mixed into any one component of isocyanate component B and polyol component A or mixed as a third component in the step of coating. Of these, it is preferable that a premix in which the pigment, the adhesion accelerator, and the additive are mixed into polyol component A in advance be prepared as a laminate adhesive polyol composition and used as a two-part-type adhesive from the viewpoint of operability.

[0055] (Multilayer film)

The multilayer film according to the present invention is produced by stacking an adhesive layer composed of the above-described reactive adhesive between a first plastic film and a second plastic film. Specifically, the multilayer film is obtained by coating the first plastic film with the reactive adhesive, stacking the second plastic film on the coated surface, and curing the adhesive layer. Examples of the method include a method in which the first plastic film is coated with the reactive adhesive by a roll coater coating system and, thereafter, other base material is bonded without performing a drying step. Regarding the coating condition for a common roll coater, it is preferable that the viscosity of a mixed solution of the adhesive be about 300 to 3,000 mPa-s at 40°C in the state of being heated to 30°C to 90°C, whereas the viscosity of the adhesive according to the present invention is 5,000 mPa-s or less after being mixed and left to stand for 30 minutes in an atmosphere at 40°C and, therefore, coating can be performed with no problems. In this regard, the amount of coating in the use is preferably 0.5 to 5 g/m² and more preferably about 0.5 to 3 g/m².

[0056]

Alternatively, the first plastic film printed with a printing ink by gravure printing or flexography may be used, and even in this case, a favorable laminate appearance is exhibited. Regarding the printing ink, a solution-type, aqueous, or active-energy-ray-curable ink may be used.

[0057]

When the reactive adhesive used in the present invention is used, the adhesive after lamination is cured in 12 to 72 hours at ambient temperature or under heating, and the physical properties are practically realized.

[0058]

Examples of the first plastic film used here include

PET (polyethylene terephthalate) films, nylon films, OPP (biaxially oriented polypropylene) films, K-Coat films by using polyvinylidene chloride or the like, base films of various evaporated films, and aluminum foil. Regarding the second plastic film, examples of the above-described other base material include sealant films, for example, CPP (cast polypropylene) films, VMCPP (vacuum-metallized cast polypropylene film), LLDPE (linear low density polyethylene), LDPE (low density polyethylene), HOPE (high density polyethylene), and VMLDPE (vacuum-metallized low density polyethylene film) films.

[0059]

In the present invention, an excellent multilayer film appearance is obtained by performing high-speed lamination processing with a solventless laminator. For example, a favorable appearance can be provided even by high-speed processing of 200 m/min or more when the film configuration is PET (polyethylene terephthalate) film/VMCPP (vacuummetallized cast polypropylene film) and 350 m/min or more when the film configuration is OPP/CPP.

[0060] (Packaging)

The packaging according to the present invention is produced by forming the above-described multilayer film into the shape of a bag. Specifically, the multilayer film is made into the form of packaging by being heat-sealed. As the situation demands, other layers may be stacked in consideration of an application of the packaging, performance (ease of tearing and ease of hand cutting) required, rigidity and durability (for example, impact resistance and pin-hole resistance) required of the packaging. Usually, a base material layer, a paper layer, a second sealant layer, a nonwoven fabric layer, and the like are used together. A known method may be used as the method for stacking the other layers. For example, an adhesive layer is disposed between the other layer and the multilayer film and stacking may be performed by a dry lamination method, a heat lamination method, a heat sealing method, an extrusion lamination method, or the like. Regarding the adhesive, the above-described reactive adhesive may be used, or other one-part-type urethane-based adhesive, epoxy-based adhesive, aqueous dispersion of an acid-modified polyolefin, or the like may be used.

[0061]

Specific examples of the multilayer body configuration include first plastic film layer/adhesive layer/second plastic layer and base material layer/adhesive layer/first plastic film layer/adhesive layer/second plastic layer in which the first plastic film layer serves as a barrier layer, that can be favorably used for common packaging and lid members, refill containers, and the like, second plastic layer/paper layer/adhesive layer/first plastic film layer/adhesive layer/second plastic, second plastic layer/paper layer/polyolefin resin layer/base material layer/first plastic layer/adhesive layer/second plastic layer, and paper layer/first plastic film layer/adhesive layer/sealant layer that can be favorably used for paper containers, paper cups, and the like, and second plastic layer/adhesive layer/first plastic layer/adhesive layer/second plastic layer that can be favorably used for tube containers and the like. These multilayer bodies may include a printed layer, a top coat layer, and the like, as the situation demands.

[0062]

Regarding the first plastic film layer, for example, polyester resin films of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polylactic acid (PLA), and the like; olefin resin films of polypropylene and the like; polystyrene resin films; polyamide resin films of nylon 6, poly-p-xylylene adipamide (nylon MXD6), and the like; polycarbonate resin films; polyacrylonitrile resin films; polyimide resin films; and multilayer bodies of these (e.g., nylon 6/MXD6/nylon 6 and nylon 6/ethylene-vinyl alcohol copolymer/nylon 6) and mixtures of these are used. Most of all, films having mechanical strength and dimension stability are preferable. Of these, biaxially and freely oriented films are particularly preferably used.

[0063]

Regarding the first plastic film layer, to provide a barrier function, for example, evaporated layers based on aluminum evaporation, silica evaporation, alumina evaporation, silica-alumina binary evaporation, and the like; and organic barrier layers composed of vinylidenechloride-based resins, modified polyvinyl alcohols, ethylene vinyl alcohol copolymers, MXD nylons, and the like, other than soft metal foil such as aluminum foil, may be adopted. [0064]

Regarding the second plastic film layer, previously known sealant resins may be used. Examples include polyethylenes, for example, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE), and polyolefin resins, for example, acid-modified polyethylene, polypropylene (PP), acidmodified polypropylene, copolymerized polypropylene, ethylene-vinyl acetate copolymers, ethylene-(meth)acrylic acid ester copolymers, ethylene-(meth)acrylic acid copolymers, and ionomers. Of these, polyethylene-based resins are preferable from the viewpoint of low-temperature sealing property, and polyethylenes are particularly preferable because of low price. There is no particular limitation regarding the thickness of the sealant layer, and the thickness is preferably within the range of 10 to 60 pm and more preferably within the range of 15 to 40 pm in consideration of workability into a packaging material, heat sealing performance, and the like. Meanwhile, when the sealant layer is provided with unevenness having a height difference of 5 to 20 pm, the sealant layer can be provided with slippiness and an ability to tear a packaging material. [0065]

Examples of the paper layer include natural paper and synthetic paper. A first sealant layer and a second sealant layer may be formed of the same material as the material for forming the above-described sealant layer. As the situation demands, a printed layer may be disposed on the outer surface or the inner surface of the base material layer and the paper layer.

[0066]

The other layer may contains known additives and stabilizers, for example, antistatic agents, easy-to-adhere coat agents, plasticizers, lubricants, and antioxidants. In addition, the other layer may undergo pretreatment in which the film surface is subjected to corona treatment, plasma treatment, ozone treatment, chemical agent treatment, solvent treatment, or the like to improve the adhesiveness when being stacked on other materials.

[0067]

Regarding the packaging according to the present invention, there are various forms, for example, a threesided seal bag, a four-sided seal bag, a gusset packaging bag, a pillow packaging bag, a goebel-top type container with a bottom, Tetra Classic, a brick type, a tube container, a paper cup, and a lid member. In addition, the packaging according to the present invention may be provided with an easy-opening device or a resealing device appropriately.

[0068]

The packaging according to the present invention may be industrially used as packaging to be mainly filled with foods, detergents, or chemical agents. Regarding specific applications, examples of the detergent and the chemical agent include laundry liquid detergents, kitchen liquid detergents, bath liquid detergents, bath liquid soaps, liquid shampoos, liquid conditioners, and medical tablets. In addition, an application to secondary packaging in which the above-described containers are packed is also possible. In particular, the above-described reactive adhesive is used and, therefore, the packaging can be favorably used for application to foods and drugs, in which elution may cause problems .

EXAMPLES [0069]

Next, the present invention will be specifically described with reference to the examples and the comparative examples. In the examples, part or % is on a mass basis, unless otherwise specified.

[0070]

Synthesis example 1 Synthesis of polyol component Al

After 560 parts by mass of diethylene glycol was charged into a reaction container, heating to 80°C was performed under agitation in a nitrogen gas stream. Further, under agitation, 600 parts by mass of adipic acid was charged into the reaction container and heating to 150°C to 240°C was performed so as to perform an esterification reaction. When the acid value became 5 mgKOH/g or less, the reaction container was gradually decompressed, and the reaction was performed at 1 mmHg or less and 200°C to 240°C for 1 hour so as to obtain a polyester polyol resin having an acid value of 0.8 mgKOH/g, a molecular weight of about 840, and hydroxy groups at both terminals (hereafter this is simply referred to as polyol component Al).

[0071]

Synthesis example 2 Synthesis of polyol component A2

After 690 parts by mass of diethylene glycol and 8 parts by mass of trimethylolpropane were charged into a reaction container, heating to 80°C was performed under agitation in a nitrogen gas stream so as to perform dissolution. Further, under agitation, 810 parts by mass of adipic acid was charged into the reaction container and heating to 150°C to 240°C was performed so as to perform an esterification reaction. When the acid value became 5 mgKOH/g or less, the reaction container was gradually decompressed, and the reaction was performed at 1 mmHg or less and 200°C to 220°C for 1 hour so as to obtain a polyester polyol resin having an acid value of 0.8 mgKOH/g, a molecular weight of about 1,270, and hydroxy groups at both terminals (hereafter this is simply referred to as polyol component A2).

[0072]

Synthesis example 3 Synthesis of polyol component A3

After 333 parts by mass of 2-methyl-propanediol, 179 parts by mass of ethylene glycol, and 39 parts by mass of trimethylolpropane were charged into a reaction container, heating to 80°C was performed under agitation in a nitrogen gas stream so as to perform dissolution. Further, under agitation, 106 parts by mass of isophthalic acid and 610 parts by mass of adipic acid were charged into the reaction container and heating to 150°C to 240°C was performed so as to perform an esterification reaction. When the acid value became 5 mgKOH/g or less, the reaction container was gradually decompressed, and the reaction was performed at 1 mmHg or less and 200°C to 240°C for 1 hour so as to obtain a polyester polyol resin having an acid value of 0.5 mgKOH/g, a molecular weight of about 2,100, and hydroxy groups at both terminals (hereafter this is simply referred to as polyol component A3).

[0073]

Synthesis example 4 Preparation of isocyanate component Bl

After 271 parts of diphenylmethane diisocyanate (trade name MILLIONATE MT-F produced by Tosoh Corporation), 425 parts of polypropylene glycol (molecular weight of about 1,000), and 18 parts of polypropylene glycol (molecular weight of about 400) were charged into a reaction container, heating to 80°C was performed under agitation in a nitrogen gas stream so as to perform a reaction. When the reaction was completed, the reaction container was cooled so as to obtain reaction product (B-l-1) of the polyol and the isocyanate, the reaction product having isocyanate groups at both terminals .

Subsequently, 285 parts of carbodiimide-modified diphenylmethane diisocyanate (trade name Lupranate MM103 produced by BIP) serving as reactive diluent (B-2) having an isocyanate group was added to the container, and agitation was performed until homogeneity was ensured so as to obtain isocyanate component Bl having an isocyanate group concentration of about 13.5%.

[0074]

Synthesis example 5 Synthesis of isocyanate component

B2

After 489 parts of diphenylmethane diisocyanate (trade name MILLIONATE MT-F produced by Tosoh Corporation), 422 parts of polypropylene glycol (molecular weight of about 1,000), and 19 parts of polypropylene glycol (molecular weight of about 400) were charged into a reaction container, heating to 80°C was performed under agitation in a nitrogen gas stream so as to perform a reaction. When the reaction was completed, the reaction container was cooled so as to obtain reaction product (B-l-2) of the polyol and the isocyanate, the reaction product having isocyanate groups at both terminals.

Subsequently, 50 parts of an isocyanurate body of 1,6hexamethylene diisocyanate (trade name Desmodur N3300 produced by Covestro) serving as reactive diluent (B-2) having an isocyanate group was added to the container, and agitation was performed until homogeneity was ensured so as to obtain isocyanate component B2 having an isocyanate group concentration of about 13.5%.

[0075]

Synthesis example 6 Synthesis of isocyanate component

B3

After 479 parts of diphenylmethane diisocyanate (trade name MILLIONATE MT-F produced by Tosoh Corporation), 452 parts of polypropylene glycol (molecular weight of about 1,000), and 19 parts of polypropylene glycol (molecular weight of about 400) were charged into a reaction container, heating to 80°C was performed under agitation in a nitrogen gas stream so as to perform a reaction. When the reaction was completed, the reaction container was cooled so as to obtain reaction product (B-l-3) of the polyol and the isocyanate, the reaction product having isocyanate groups at both terminals.

Subsequently, 50 parts of polymeric diphenylmethane diisocyanate (trade name Lupranate MM20S produced by BIP) serving as reactive diluent (B-2) having an isocyanate group was added to the container, and agitation was performed until homogeneity was ensured so as to obtain isocyanate component B3 having an isocyanate group concentration of about 13.5%.

[0076]

Synthesis example 7 Synthesis of isocyanate component

B4

After 456 parts of diphenylmethane diisocyanate (trade name MILLIONATE MT-F produced by Tosoh Corporation) , 473 parts of polypropylene glycol (molecular weight of about 1,000), and 20 parts of polypropylene glycol (molecular weight of about 400) were charged into a reaction container, heating to 80°C was performed under agitation in a nitrogen gas stream so as to perform a reaction. When the reaction was completed, the reaction container was cooled so as to obtain reaction product (B-l-4) of the polyol and the isocyanate, the reaction product having isocyanate groups at both terminals .

Subsequently, 50 parts of 1,6-hexamethylene diisocyanate (trade name Desmodur H produced by Covestro) serving as reactive diluent (B-2) having an isocyanate group was added to the container, and agitation was performed until homogeneity was ensured so as to obtain isocyanate component B4 having an isocyanate group concentration of about 13.5%.

[0077]

Synthesis example 8 Synthesis of isocyanate component

B5

After 474 parts of diphenylmethane diisocyanate (trade name MILLIONATE MT-F produced by Tosoh Corporation), 457 parts of polypropylene glycol (molecular weight of about 1,000), and 19 parts of polypropylene glycol (molecular weight of about 400) were charged into a reaction container, heating to 80°C was performed under agitation in a nitrogen gas stream so as to perform a reaction. When the reaction was completed, the reaction container was cooled so as to obtain reaction product (B-l-5) of the polyol and the isocyanate, the reaction product having isocyanate groups at both terminals.

Subsequently, 50 parts of 3-isocyanatomethyl-3,5,5trimethylcyclohexyl isocyanate (trade name Desmodur I produced by Covestro) serving as reactive diluent (B-2) having an isocyanate group was added to the container, and agitation was performed until homogeneity was ensured so as to obtain isocyanate component B5 having an isocyanate group concentration of about 13.5%.

[0078]

Comparative synthesis example 1 Synthesis of isocyanate resin Cl

After 589 parts of carbodiimide-modified diphenylmethane diisocyanate (trade name Lupranate MM103 produced by BIP), 394 parts of polypropylene glycol (molecular weight of about 1,000), and 17 parts of polypropylene glycol (molecular weight of about 400) were charged into a reaction container, heating to 80°C was performed under agitation in a nitrogen gas stream so as to perform a reaction. When the reaction was completed, the reaction container was cooled so as to obtain isocyanate resin (Cl) that was a reaction product of the polyol and the isocyanate, the isocyanate resin having isocyanate groups at both terminals. The isocyanate group concentration was about 13.5%.

[0079]

Comparative synthesis example 2 Synthesis of isocyanate resin C2

After 208 parts of liquid diphenylmethane diisocyanate (trade name Lupranate MI produced by BIP), 320 parts of diphenylmethane diisocyanate (trade name MILLIONATE MT-F produced by Tosoh Corporation), 453 parts of polypropylene glycol (molecular weight of about 1,000), and 19 parts of polypropylene glycol (molecular weight of about 400) were charged into a reaction container, heating to 80°C was performed under agitation in a nitrogen gas stream so as to perform a reaction. When the reaction was completed, the reaction container was cooled so as to obtain isocyanate resin (C2) that was a reaction product of the polyol and the isocyanate, the isocyanate resin having isocyanate groups at both terminals. The isocyanate group concentration was about 13.5%.

[0080] (Examples and comparative examples)

Reactive adhesives were obtained in accordance with the combinations shown in Tables 1 and 2.

[0081] (Evaluation method) [Evaluation of amount of harmful component (PAA) eluted]

A multilayer film was produced by coating a PET film with the reactive adhesive in which mixing was performed in accordance with the combination of each of the examples and the comparative examples such that the amount of coating became about 3.0 g/m² on a solid content basis, and bonding the resulting coated surface of the film to a CPP film by a laminator. The resulting multilayer film was stored in a constant-temperature bath at 40°C for 3 days.

The resulting multilayer film was cut into 120 mm x 220 mm and folded with CPP inside. Three-sided heat-sealing in a width of 10 mm each was performed at 1 atm and 180°C for 1 sec so as to produce a pouch, 2 dm² of which was in contact with the contents. Regarding the contents, a 3% acetic acid solution was added. The pouch after filling was subjected to 121°C-0.5 hr retort sterilization and, subsequently, PAA was measured by LC/MS/MS.

[0082] [Measurement of viscosity 40°C-30 min after mixing]

The viscosity was measured by a rotational viscometer under the following condition and expressed as a value in mP a·s .

Measuring apparatus: MCR-302 produced by Anton Paar

Measurement condition: temperature of 40°C, cone plate diameter of 50 mm

Viscosity evaluation was as described below.

Viscosity	evaluation	A:	1,000	to	2,	mPa · s
Viscosity	evaluation	B:	2,000	to	3,	mPa · s
Viscosity	evaluation	C:	3,000	to	4,	mPa · s
Viscosity	evaluation	D:	4,000	to	5,	mPa · s

Viscosity evaluation E: 5,000 mPa-s or more [0083] [Laminate strength]

A PET film gravure-printed with a pattern by a printing ink UNIVURE NT (produced by DIC Corporation) was coated with the reactive adhesive in which mixing was performed in accordance with the combination of each of the examples and the comparative examples such that the amount of coating became about 3.0 g/m² on a solid content basis. Thereafter, the resulting coated surface of the film was bonded to an LLDPE film by a laminator so as to form a multilayer film. The resulting multilayer film was stored in a constanttemperature bath at 40°C for 3 days so as to form a multilayer film for a laminate strength test.

A test piece with a width of 15 mm was cut from the resulting multilayer film, and adhesion strength (N/15 mm) was measured on the basis of T-type peeling at a peeling rate of 300 mm/min by using a tensile tester.

[0084] (Laminate strength of isocyanate component B stored for a time)

Isocyanate components Bl to B5, Cl, and C2 were produced and, thereafter, were left to stand at 60°C for 10 days. Subsequently, the reactive adhesive was prepared in accordance with the combination shown in the table, and the laminate strength was measured in the same manner.

[0085] [Laminate strength and appearance after retort sterilization]

A PET film gravure-printed with a pattern by a printing ink (UNIVURE NT produced by DIC Corporation) was coated with the reactive adhesive in which mixing was performed in accordance with the combination of each of the examples and the comparative examples such that the amount of coating became about 3.0 g/m² on a solid content basis. Thereafter, the resulting coated surface of the film was bonded to an LLDPE film by a laminator so as to form a multilayer film. The resulting multilayer film was stored in a constanttemperature bath at 40°C for 3 days.

The resulting multilayer film was cut into 150 mm x 300 mm and folded with LLDPE inside. Heat-sealing was performed at 1 atm and 180°C for 1 sec so as to produce a pouch. Regarding the contents, 1/1/1 sauce (meat sauce: vegetable oil:vinegar = 1:1:1) was added.

The pouch after filling was subjected to 121°C-30 min steam sterilization, the contents were removed, and strength of the heat seal portion was measured on the basis of T-type peeling.

The appearance of each pouch after taking out was observed and evaluated, as described below, on the basis of whether delamination occurred.

Evaluation O: no delamination

Evaluation Δ: delamination portions were 5 or less

Evaluation x: delamination portions were 6 or more [0086] (Laminate strength and appearance after retort sterilization of isocyanate component B stored for a time)

Isocyanate components Bl to B5, Cl, and C2 were produced and, thereafter, left to stand at 60°C for 10 days. Subsequently, the reactive adhesive was prepared in accordance with the combination shown in the table, and the laminate strength after retort sterilization was measured in the same manner.

[0087]

The results are shown in Table 1 and Table 2.

[0088] [Table 1]

Table 1	Example 1	Example 2	Example 3	Example 4	Example 5
Mixing	Polyol component A2	50	50	50	50	50
Isocyanate component B1	100
Isocyanate component B2		100
Isocyanate component B3			100
Isocyanate component B4				100
Isocyanate component B5					100
Evaluation	Amount of PAA eluted	Wppbor less	10ppb or less	Wppbor less	Wppbor less	Wppb or less
Laminate strength	5	4.8	4.9	4.4	4.4
Laminate strength after retort	5.2	5	5.1	4.5	4.4
Appearance after retort	O	O	O	O	O
Viscosity mPa-s 40°C-10 min after mixing	B	B	B	B	B
Viscosity mPa-s 40°C-20 min after mixing	C	C	C	C	C
Viscosity mPa-s 40°C-30 min after mixing	D	D	D	D	D
After isocyanate component B was stored for a time
Laminate strength	4.9	4.7	5	4.3	4.3
Laminate strength after retort	5.1	4.9	5.1	4.5	4.5
Appearance after retort	O	O	O	O	O
Viscosity mPa-s 40°C-10 min after mixing	B	B	B	B	B
Viscosity mPa-s 40°C-20 min after mixing	C	C	C	C	C
Viscosity mPa-s 40°C-30 min after mixing	D	D	D	D	D

[0089] [Table 2]

Table 2	Comparative example 1	Comparative example 2
Mixing	Polyol component A2	50	50
Isocyanate resin C1	100
Isocyanate resin 02		100
Evaluation	Amount of PAA eluted	Wppborless	100ppb or more
Laminate strength	5	4.8
Laminate strength after retort	5.2	5.1
Appearance after retort	O	O
Viscosity mPa-s 40°C-10 min after mixing	C	B
Viscosity mPa-s 40°C-20 min after mixing	E	C
Viscosity mPa-s 40°C-30 min after mixing	E	D
After isocyanate component was stored for a time
Laminate strength	4.9	4.8
Laminate strength after retort	5.1	5
Appearance after retort	O	O
Viscosity mPa-s 40°C-10 min after mixing	C	B
Viscosity mPa-s 40°C-20 min after mixing	E	C
Viscosity mPa-s 40°C-30 min after mixing	E	D

[0090]

According to the results, the reactive adhesive obtained in each of the examples had viscosity 40°C-30 min after mixing of 5,000 mPa-s or less, a long pot life was exhibited, and the amount of PAA eluted was 10 ppb or less.

In addition, excellent laminate strength and excellent appearance were exhibited.

Comparative examples did not contain reactive diluent (B-2) having an isocyanate group that had a number average molecular weight within the range of 400 to 1,000. Regarding comparative example 1, a reaction product of polyol and carbodiimide-modified diphenylmethane diisocyanate was used, and the amount of PAA eluted was 10 ppb or less. However, the viscosity 40°C-30 min after mixing, even at an early stage after mixing (20 min after) , was more than 6,000 mPa-s. Meanwhile, regarding comparative example 2, a reaction product of polyol and diphenylmethane diisocyanate was used, the viscosity 40°C-30 min after mixing was 5,000 mPa-s or less, and there was no problem in the pot life. However, the amount of PAA eluted was 100 ppb or more and, therefore, a very high value was exhibited.

Claims

1. A reactive adhesive comprising:

a polyol component containing a polyol compound; and an isocyanate component containing an isocyanate compound, wherein the isocyanate component contains a reaction product of a polyol and an isocyanate and a reactive diluent having an isocyanate group that has a number average molecular weight within the range of 400 to 1,000, and the polyol component and the isocyanate component are mixed at a weight ratio and the viscosity after being left to stand for 30 minutes in an environment at 40°C is 5,000 mPa-s or less.

2. The reactive adhesive according to Claim 1, wherein the reactive diluent having an isocyanate group is an aromatic diisocyanate, an aliphatic diisocyanate, a dimer of an aromatic diisocyanate, a dimer of an aliphatic diisocyanate, a trimer of an aromatic diisocyanate, or a trimer of an aliphatic diisocyanate.

3. A multilayer film in which an adhesive layer is stacked between a first plastic film and a second plastic film, wherein the adhesive layer is a layer of the reactive adhesive according to Claim 1 or Claim 2.

4. Packaging produced by forming a multilayer film, in which an adhesive layer is stacked between a first plastic film and a second plastic film, into the shape of a bag, wherein the adhesive layer is a layer of the reactive adhesive according to Claim 1 or Claim 2.