JP7206891B2 - Laminate adhesive and its laminate - Google Patents

Description

The present invention provides a laminate containing an adhesive layer having excellent resistance to boiling and retorting.

In recent years, in the field of packaging materials, plastic containers have been used from the viewpoint of weight reduction and ecology. Among them, the demand for voile and retort pouch packaging for food packaging is increasing because of its advantages such as long-term storage, lighter weight and lower cost compared to bottles and cans, and easy disposal.

Packaging materials for boil/retort pouches are mainly obtained by laminating a plurality of films, and various plastic films, metal films, metal-deposited films, and the like are used as the films. Adhesives are used to bond films made of different materials.

In boiling/retort pouch packaging for food packaging, the most required performance is resistance to boiling/retorting (Patent Documents 1 and 2). In particular, sterilization of heat-resistant bacteria such as Clostridium botulinum requires a long sterilization time of 6 hours or more at 100°C. However, since the long sterilization time of 6 hours is a big disadvantage in manufacturing, a laminate that can be retort sterilized at a high temperature of 120 ° C. or 135 ° C. for the purpose of shortening the sterilization time and an adhesive used for it are required. there is

There are various curing methods for adhesives, and examples thereof include photocurable adhesives that are cured by ultraviolet rays or electron beams (Patent Document 3). Photocurable adhesives generally have a problem in that the cured film after curing becomes rigid, and the resulting laminate cannot follow the base material during boiling or retorting, especially during high-temperature retorting, resulting in cracks. rice field. In addition, there is also a problem that the photocurable adhesive is difficult to cure because printed films and the like are often used in packaging materials that require packaging properties, and light is difficult to pass through.

Therefore, urethane-based adhesives are often used as adhesives for boiling and retorting. However, the development of a urethane-based adhesive that maintains stable and high adhesion during high retort was a challenge.

JP 2018-30905 A JP 2016-117801 A JP-A-2004-98693

An object of the present invention is to provide a laminate having a cured resin layer having high moist heat resistance.

As a result of intensive studies by the present inventors, in order to solve the above problems, a laminate formed by laminating an aluminum foil layer and a cured resin layer, wherein the cured resin layer comprises a polyisocyanate compound and a hydroxyl group-containing compound A cured product of a resin composition containing and characterized by having two peaks in the temperature spectrum of the loss tangent obtained from a dynamic viscoelasticity test of the cured product of the resin composition. offer.

Also provided is a laminate having a storage modulus of 1.5×10 ⁵ to 3.5×10 ⁶ at 135° C. obtained from a dynamic viscoelasticity test of a cured product of the resin composition.

Also provided is a laminate in which one of the first base material and the second base material is metal or metal oxide, and the other base material is plastic.

Also provided is a laminate comprising an aluminum foil layer, the cured resin layer, and a second substrate in this order.

The laminate of the present invention is a laminate having an adhesive layer that is excellent in both adhesiveness and resistance to moist heat.
Moreover, since it has particularly excellent adhesiveness to aluminum foil, it can be suitably used as a packaging sheet for boiling and retort packaging.

The present invention provides a laminate obtained by laminating an aluminum foil layer and a cured resin layer, wherein the cured resin layer is a cured product of a resin composition containing a polyisocyanate compound and a hydroxyl group-containing compound, Provided is a laminate characterized by having two peaks in a loss tangent temperature spectrum obtained from a dynamic viscoelasticity test of a cured product of the resin composition.

<Peak in temperature spectrum of loss tangent obtained from dynamic viscoelasticity test>
The resin composition of the present invention contains a polyisocyanate compound and a hydroxyl group-containing compound, and is characterized by having two peaks in the loss tangent temperature spectrum obtained from a dynamic viscoelasticity test of the cured product. do.

Two peak temperatures in the temperature spectrum of the loss tangent obtained from the dynamic viscoelasticity test of the cured product are defined as Tg1 and Tg2, respectively. A peak fit analysis using a Lorentzian function was used to confirm Tg1 and Tg2 and the loss tangent strength at these temperatures.
Generally, in a urethane-based cured product obtained by curing a polyisocyanate compound and a hydroxyl group-containing compound, there is one peak in the temperature spectrum of the loss tangent obtained from the dynamic viscoelasticity test. By having two peaks, it is possible to provide a cured product that is highly resistant to a wide range of temperature and humidity changes such as retort treatment.

In the cured product of the present invention, Tg1 and Tg2 preferably satisfy the following formulas (1) and (2).
Tg1<Tg2 (1)
Tg2-Tg1=15-50 (°C) (2)

When the difference in Tg is 15° C. or more, the change in the cured resin layer due to temperature change is moderate, and when it is 50° C. or less, the change occurs continuously. More preferably, Tg2-Tg1=25 to 35°C.

It is more preferable that the Tg difference is as shown in the formula (2), Tg1 is 5 to 30°C, and Tg2 is 30 to 60°C. Within this range, the adhesive strength is good near room temperature, and furthermore, the change in the cured resin layer occurs gradually and continuously during the retort treatment, which changes from room temperature to high temperature, as described above.

Further, it is particularly preferable that the loss tangent strength ratio (Tg2/Tg1) at Tg1 and Tg2 is 0.03 to 0.5. This is because within this range, the adhesive strength between the aluminum foil layer and the cured resin layer at around room temperature is excellent. It is more preferably 0.1 to 0.4.

The cured product of the present invention is not particularly limited. Interfacial delamination from the foil is likely to occur. A preferred storage modulus is 1.5×10 ⁵ to 3.5×10 ⁶ , more preferably 2.0×10 ⁵ to 2.5×10 ⁶ .

<Resin composition>
The cured product of the present invention is characterized by having two peaks in the temperature spectrum of the loss tangent obtained from the dynamic viscoelasticity test. Such a cured product can be obtained by introducing a dangling chain into a urethane resin obtained by reacting a polyisocyanate compound and a hydroxyl group-containing compound.

Although the method of introducing a dangling chain into the urethane resin is not particularly limited, the following two methods can be used for production.
1) When the isocyanate equivalent/hydroxyl equivalent in the resin composition is <1 By blending the hydroxyl group-containing compound excessively with respect to the polyisocyanate compound, it is possible to introduce a dangling chain having a hydroxyl group at the end. A preferable blending amount is isocyanate equivalent/hydroxy group equivalent=0.95 to 0.5, and particularly preferably 0.9 to 0.7.

2) When the isocyanate equivalent/hydroxyl equivalent in the resin composition is >1 By blending a monool compound together with a polyol compound as a hydroxyl group-containing compound, a dangling chain having a carbon chain at the end can be introduced. As for the compounding amount, the amount of the monool compound is preferably 30 to 60% by weight based on the total amount of the hydroxyl group-containing compound of the present invention. When it is 30 wt % or more, the temperature followability of the cured product layer is excellent. Moreover, when it is 60 wt % or less, the cross-linking is sufficient and the adhesion is excellent. It is preferably 35 wt % or more and 45 wt % or less.

(Hydroxyl group-containing compound)
The hydroxyl group-containing compound in the present invention is a general term for compounds having one or more hydroxyl groups in the molecule. The hydroxyl group may be either an alcoholic hydroxyl group or a phenolic hydroxyl group, but is preferably an alcoholic hydroxyl group from the viewpoint of reactivity.
The present invention may also contain polyol compounds and monool compounds.

<Polyol compound>
A polyol compound is a compound having two or more alcoholic hydroxyl groups. Although the polyol compound of the present invention is not particularly limited, examples thereof include polyester polyols and/or polyether polyols. These polyols may be used singly or in combination of two or more.

Examples of polyester polyols include reaction products of dicarboxylic acids or polycarboxylic acids (or salts thereof, or acid anhydrides) and polyhydric alcohols, ring-opening polymers of caprolactone, and the like. In the former case, dicarboxylic acids include aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, succinic acid and glutaric acid, alicyclic dicarboxylic acids such as 1,3-cyclopentanedicarboxylic acid, orthophthalic acid and isophthalic acid. Acids, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, 1,2-bis(phenoxy)ethane-p,p'- Aromatic dicarboxylic acids such as dicarboxylic acids, anhydrides of these dicarboxylic acids, polyvalent carboxylic acids such as pyromellitic acid and trimellitic acid, and anhydrides of these polyvalent carboxylic acids are applicable. and they can be used singly or in mixtures of two or more. Polyhydric alcohols include ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, dimethylbutanediol, butylethylpropanediol, diethylene glycol, triethylene glycol, and tetraethylene. C1-C12 alkylene diols such as glycol and dipropylene glycol, and diols having a carboxylic acid such as 2,2-bis(hydroxymethyl)propionic acid. Examples of the latter include ring-opening polymers such as ε-caprolactam, γ-valerolactam and β-propyrolactam.

Examples of polyether polyols include polytetramethylene ether glycol, polypropylene glycol, polyethylene glycol, polyethylene glycol/polypropylene glycol block copolymer, propylene glycol propylene oxide adduct, bisphenol A propylene oxide adduct, glycerin propylene oxide adduct, ethylenediamine. Examples include propylene oxide adducts, ethylenediamine propylene oxide adducts, sorbitol-based propylene oxide adducts, sucrose-based propylene oxide adducts, and propylene oxide/ethylene oxide random polyethers.

Further, the polyester polyol and the polyether polyol may be urethane-extended as necessary. The polyisocyanate used for urethane elongation is not particularly limited, and known and commonly used polyisocyanates can be used. Examples include aromatic polyisocyanates, aliphatic or alicyclic polyisocyanates, blocked isocyanates, and modified products thereof. These polyisocyanates may be used singly or in combination of two or more.

<Monool compound>
A monool compound is a compound having one alcoholic hydroxyl group. The monool compound of the present invention preferably has a weight average molecular weight of 300-1800.

The main chain of the monool compound is not particularly limited, and may be vinyl resin, acrylic resin, ester resin, epoxy resin, urethane resin, or the like. Moreover, it may be an aliphatic alcohol, alkylene glycol, or the like. Preferred are hydroxyl group-containing acrylic resins, aliphatic alcohols, and alkylene glycols.

The structure of the monol compound of the present invention may be linear or branched. The bonding position of the hydroxyl group is also not particularly limited, but it is preferably present at the end of the molecular chain.

Examples of the monool compound of the present invention include hydroxyl group-containing polymethyl acrylate, hydroxyl group-containing polybutyl acrylate, octanol, dodecanol and the like, preferably polypropylene glycol monomethyl ether and polypropylene monobutyl ether.

(Polyisocyanate compound)
The polyisocyanate compound in the present invention is a compound containing multiple isocyanate groups. The polyisocyanate compound is not particularly limited, but examples thereof include aromatic polyisocyanate, aliphatic or alicyclic polyisocyanate, blocked isocyanate, and modified products thereof. These polyisocyanates may be used singly or in combination of two or more.

Moreover, the resin composition of the present invention may contain polyurethane polyisocyanate. Polyurethane polyisocyanate is a compound having two or more urethane bonds and two or more isocyanate groups in the molecule.

A polyurethane polyisocyanate is obtained by reacting a polyisocyanate compound with a hydroxyl group of a polyol.

The polyol used here is not particularly limited, but examples thereof include polyester polyols and polyether polyols. These polyols may be used singly or in combination of two or more.

Examples of polyester polyols include reaction products of dicarboxylic acids or polycarboxylic acids (or salts thereof, or acid anhydrides) and polyhydric alcohols, ring-opening polymerization products of caprolactone, and the like. In the former case, dicarboxylic acids include aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, succinic acid and glutaric acid, alicyclic dicarboxylic acids such as 1,3-cyclopentanedicarboxylic acid, orthophthalic acid and isophthalic acid. Acids, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, 1,2-bis(phenoxy)ethane-p,p'- Aromatic dicarboxylic acids such as dicarboxylic acids, anhydrides of these dicarboxylic acids, polyvalent carboxylic acids such as pyromellitic acid and trimellitic acid, and anhydrides of these polyvalent carboxylic acids are applicable. and they can be used singly or in mixtures of two or more. Polyhydric alcohols include ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, dimethylbutanediol, butylethylpropanediol, diethylene glycol, triethylene glycol, and tetraethylene. C1-C12 alkylene diols such as glycol and dipropylene glycol, and diols having a carboxylic acid such as 2,2-bis(hydroxymethyl)propionic acid. Examples of the latter include ring-opening polymers such as ε-caprolactam, γ-valerolactam and β-propyrolactam.

Examples of polyether polyols include polytetramethylene ether glycol, polypropylene glycol, polyethylene glycol, polyethylene glycol/polypropylene glycol block copolymer, propylene glycol propylene oxide adduct, bisphenol A propylene oxide adduct, glycerin propylene oxide adduct, ethylenediamine. Examples include propylene oxide adducts, ethylenediamine propylene oxide adducts, sorbitol-based propylene oxide adducts, sucrose-based propylene oxide adducts, and propylene oxide/ethylene oxide random polyethers.

The polyisocyanate compound used for the polyurethane polyisocyanate is not particularly limited. and compounds obtained by modifying some of the NCO groups of these polyisocyanates with carbodiimide, alphanate compounds derived from these polyisocyanates, isophorone diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1 , 3-(isocyanatomethyl)cyclohexane and other polyisocyanates having an alicyclic structure in the molecular structure, 1,6-hexamethylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate and other linear aliphatic polyisocyanates, and these allophanate compounds, isocyanurates of these polyisocyanates, allophanates derived from these polyisocyanates, biuret compounds derived from these polyisocyanates, trimethylolpropane-modified adducts, and the like.

Diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, and 4,4'-methylenebis(cyclohexyl isocyanate) are preferred. Polyisocyanates having an alicyclic structure or an aromatic structure in their molecular structure are preferable from the viewpoint of obtaining an adhesive having excellent lamination strength and curability. In addition, linear aliphatic polyisocyanates and allophanate compounds thereof, isocyanurates of these polyisocyanates, and allophanates derived from these polyisocyanates also impart flexibility to laminates and improve retort resistance. preferable.

In the present invention, the blending amount of the polyurethane polyisocyanate is preferably 60 wt % or more based on the total amount of the polyisocyanate compound in order to obtain a sufficient pot life when mixed with the polyol.

<Hardened layer>
The resin composition of the present invention is cured to form a cured product layer by reacting the contained hydroxyl group-containing compound with the polyisocyanate compound. At that time, the resin composition of the present invention adheres very well to the aluminum foil. In the reaction between the hydroxyl group-containing compound and the polyisocyanate, the equivalent ratio of the isocyanate group of the polyisocyanate compound to the hydroxyl group of the hydroxyl group-containing compound is preferably 0.5 to 10, more preferably 1.5 to 5.0. more preferred. This is because if the equivalent ratio of the isocyanate groups of the polyisocyanate compound to the hydroxyl groups of the hydroxyl group-containing compound is within the above range, the adhesiveness and the resistance to moist heat will be better.

<Other ingredients>
The resin composition of the present invention can be used without using a solvent, but may contain a solvent depending on the intended use. Examples of solvents include organic solvents such as methyl ethyl ketone, acetone, ethyl acetate, butyl acetate, toluene, dimethylformamide, acetonitrile, methyl isobutyl ketone, methanol, ethanol, propanol, methoxypropanol, cyclohexanone, methyl cellosolve, ethyl diglycol acetate, and propylene glycol monomethyl ether acetate. The type and amount of solvent to be used may be appropriately selected according to the intended use.

If necessary, the resin composition of the present invention may be used in combination with a pigment. The pigments that can be used in this case are not particularly limited. Organic and inorganic pigments such as pigments, brown pigments, green pigments, blue pigments, metal powder pigments, luminescent pigments and pearlescent pigments, and plastic pigments can be used. Specific examples of these coloring agents include various ones, and examples of organic pigments include various insoluble azo pigments such as Benzidine Yellow, Hansa Yellow, Laked 4R; soluble pigments such as Laked C, Carmine 6B, and Bordeaux 10; Azo pigments; various (copper) phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green; various chlorine dyeing lakes such as rhodamine lake and methyl violet lake; various mordant pigments such as quinoline lake and fast sky blue; vat dye-based pigments such as thioindigo-based pigments, perinone-based pigments; various quinacridone-based pigments such as Cincasia Red B; various dioxazine-based pigments such as dioxazine violet; pigments; aniline black and the like;

Examples of inorganic pigments include various chromates such as yellow lead, zinc chromate, and molybdate orange; various ferrocyanic compounds such as Prussian blue; titanium oxide, zinc white, mapico yellow, iron oxide, red iron oxide, and chromium oxide. various metal oxides such as green and zirconium oxide; various sulfides and selenides such as cadmium yellow, cadmium red, and mercury sulfide; various sulfates such as barium sulfate and lead sulfate; various types such as calcium silicate and ultramarine blue various carbonates such as calcium carbonate and magnesium carbonate; various phosphates such as cobalt violet and manganese purple; various metal powders such as aluminum powder, gold powder, silver powder, copper powder, bronze powder and brass powder. pigments; flake pigments of these metals, mica flake pigments; metallic pigments and pearl pigments such as mica flake pigments coated with metal oxides and mica-like iron oxide pigments; graphite, carbon black and the like.

Extender pigments include, for example, precipitated barium sulfate, rice flour, precipitated calcium carbonate, calcium bicarbonate, Kansui stone, alumina white, silica, hydrous fine silica (white carbon), ultrafine anhydrous silica (Aerosil), silica sand (silica sand), talc, precipitated magnesium carbonate, bentonite, clay, kaolin, loess, and the like.

Furthermore, examples of plastic pigments include “Glandol PP-1000” and “PP-2000S” manufactured by DIC Corporation.

As the pigments used in the present invention, inorganic oxides such as titanium oxide and zinc oxide as white pigments, and carbon black as black pigments are more preferable because they are excellent in durability, weather resistance, and design.

The mass ratio of the pigment used in the present invention is 1 to 400 parts by mass, especially 10 to 300 parts by mass, with respect to the total of 100 parts by mass of the hydroxyl group-containing compound and polyisocyanate. It is more preferable because it is excellent.

An adhesion promoter can also be used in the resin composition of the present invention. Adhesion promoters include silane coupling agents, titanate-based coupling agents, aluminum-based coupling agents, and epoxy resins.

Silane coupling agents include, for example, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β (aminoethyl)-γ-aminopropyltrimethoxysilane, N-β (aminoethyl)-γ - aminosilanes such as N-phenyl-γ-aminopropyltrimethoxysilane; β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxysilane; Epoxysilanes such as sidoxypropyltriethoxysilane; Vinylsilanes such as vinyltris(β-methoxyethoxy)silane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane; hexamethyldisilazane, γ-mercapto Propyltrimethoxysilane and the like can be mentioned.

Titanate-based coupling agents include, for example, tetraisopropoxytitanium, tetra-n-butoxytitanium, butyl titanate dimer, tetrastearyl titanate, titanium acetylacetonate, titanium lactate, tetraoctylene glycol titanate, titanium lactate, tetrastearoxy Titanium etc. can be mentioned.

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

As the epoxy resin, generally commercially available epibis type, novolac type, β-methyl epichloro type, cyclic oxirane type, glycidyl ether type, glycidyl ester type, polyglycol ether type, glycol ether type, epoxidized fatty acid ester type, poly Various epoxy resins such as carboxylic acid ester type, aminoglycidyl type and resorcinol type can be used.

Moreover, the resin composition of the present invention may contain various additives as long as the effects of the present invention are not impaired. Additives include, for example, leveling agents; inorganic fine particles such as colloidal silica and alumina sol; polymethylmethacrylate-based organic fine particles; antifoaming agents; deactivator; peroxide decomposer; flame retardant; reinforcing agent; plasticizer; lubricant; rust inhibitor; Examples thereof include aromatic vinyl/maleic anhydride copolymers. These pigments, adhesion promoters and additives can be used by mixing with either the hydroxyl group-containing compound or the polyisocyanate, or by blending them during coating.

<Laminate>
A laminate of an embodiment is a laminate having an aluminum foil and a cured product layer. The laminate of the present invention is characterized in that it has heat resistance, particularly resistance to moist heat, so that it does not deform even at high temperatures.

The aluminum foil is not particularly limited, and a known and commonly used one may be used. The thickness is preferably 6-40 μm, particularly preferably 9-15 μm. Moreover, the aluminum foil may be surface-treated.

The laminate of the present invention may have an aluminum foil layer, a cured resin layer, and a second substrate in this order.
The material of the second base material is not particularly limited, and may be appropriately selected according to the application. Examples include wood, metal, metal oxide, plastic, paper, silicon, or modified silicon. It may be the obtained base material. The shape of the substrate is not particularly limited, and may be any shape according to the purpose, such as a flat plate, a sheet, or a three-dimensional shape having a curvature over its entire surface or part thereof. Further, there are no restrictions on the hardness, thickness, etc. of the base material.
Each base material may be a single resin or may contain other compounds. Other formulations may be similar to the adhesive formulations described above. Moreover, the surface of each base material may be printed. The printed surface may be formed on the adhesive layer side or may be formed on the outer side.

The plastic substrate is not particularly limited as long as it is made of plastic. low-density polyethylene) film, and the like.

Metal and metal oxide substrates include aluminum, chromium, zinc, gold, silver, platinum, nickel, SiO2, TiO2, ZrO2, and the like. Metal and metal oxide substrates may be formed by vapor deposition.

Although the second base material is not particularly limited, a laminate having a layer structure made of plastic layers such as nylon, polyethylene terephthalate, and CPP is preferable.

As for the laminate, a sealant film can be produced by having a sealant layer in the layer structure. For example, a sealant film having a layer structure of a second base material layer, a first cured material layer, an aluminum foil layer, a second cured material layer, and a sealant layer can be given as an example.

Depending on the case, the laminate may have a layer structure of four or more layers. At this time, the adhesive layer of the present invention may be one layer or two or more layers.
For example, in the case of a retort package for food, a layer configuration of five or more layers of second substrate layer-first cured material layer-aluminum foil layer-second cured material layer-third substrate layer is preferable. In the case of a laminate having a layer structure of 5 or more layers, examples of combinations of the second substrate/third substrate include PET/LLDPE, nylon/LLDPE, PET/CPP, nylon/CPP, and the like. At this time, the cured product layer of the present invention may be the first cured product layer or the second cured product layer, or both may be the cured product layer of the present invention. Also, a laminate having a layer structure of six or more layers may of course be used.

When the laminate of the present invention has a structure of three or more layers, the step of applying the resin composition of the present invention on an aluminum foil and then the step of laminating a second substrate, or the step of laminating the resin composition of the present invention It has a step of coating on the second substrate and then a step of laminating an aluminum foil.
The method of applying the resin composition is not particularly limited, and can be spray method, spin coating method, dip method, roll coating method, blade coating method, doctor roll method, doctor blade method, curtain coating method, slit coating method, or screen printing method. , inkjet method, and the like.

<Lamination>
Since the resin composition of the present invention has very high adhesive strength, it can be suitably used as an adhesive for lamination. As a lamination method, for example, there is a method of applying the present adhesive to an aluminum foil or a second base material by a roll coating method, and then bonding the second base material or the aluminum foil together without passing through a drying step. Also, the coating weight is preferably in the range of 0.5 to 10.0 g/m ² , more preferably 1.5 to 4.0 g/m ² . If it is 1.5 g/m ² or more, the adhesion is good, and if it is 4.0 g/m ² or less, the windability after lamination is good, so the balance between adhesion and workability is excellent. there is

Moreover, it is preferable that the laminate for lamination of the present invention is aged after being produced. The aging conditions are preferably 15 to 60° C. for 6 to 168 hours, during which adhesive strength is produced.

<Boiled and retort packaging sheets>
Since the laminate of the present invention is excellent in adhesiveness and resistance to moist heat and can be used without solvent, it can be suitably used as a boil/retort packaging sheet.

Hereinafter, the present invention will be described in more detail with specific synthesis examples and examples, but the present invention is not limited to these examples. In the following examples, "parts" and "%" represent "mass parts" and "mass%", respectively, unless otherwise specified.

In the present invention, the number-average molecular weight was measured using gel permeation chromatography (GPC) under the following conditions.

Pump: Waters 600 controller
Column: Shodex LF-804 four connected RI detector: Waters2414
Measurement conditions: column temperature 40°C, solvent tetrahydrofuran, flow rate 1.0 ml/min standard: polystyrene sample: 0.4% tetrahydrofuran solution in terms of resin solid content filtered through a microfilter

The polyol compounds, monool compounds, and polyisocyanate compounds used as raw materials in each example and comparative example are shown below.

<Polyol compound>
LX-906: Dick Dry LX-906 (polyester polyol, DIC Graphics Co., Ltd.)
Polyol compound (A): The synthesis method is shown in Synthesis Example 1 below.
(Synthesis example 1)
179 parts of ethylene glycol, 89 parts of neopentyl glycol, and 119 parts of 1,6-hexanediol were charged into a reaction vessel and heated to 80° C. while stirring under a nitrogen gas stream. Further, while stirring, 517 parts of isophthalic acid and 89 parts of sebacic acid were introduced into the reactor and heated to 150° C. to 240° C. to carry out an esterification reaction. When the acid value becomes 5 mgKOH/g or less, the pressure in the reaction vessel is gradually reduced, and the reaction is allowed to proceed at 1 mmHg or less and 200 to 240°C for 1 hour to obtain a polyol compound (A) having an acid value of 0.8 mgKOH/g and a molecular weight of about 2000. Obtained.

<Monool compound>
UMM-1001: Actflow UMM-1001 (weight average molecular weight 1000, Soken Chemical Co., Ltd.)
MP-40: Sumac MP-40 (weight average molecular weight 400, Kao Corporation)

<Polyisocyanate compound>
KW-75: KW-75 (DIC Graphics Co., Ltd.)
Polyisocyanate compound (B): Synthesis method is shown in Synthesis Example 2 below.
(Synthesis example 2)
140 parts of ethylene glycol, 85 parts of neopentyl glycol, 155 parts of 1,6-hexanediol, and 70 parts of 3-methyl-1,5-pentanediol are charged into a reaction vessel and heated to 80° C. while stirring under a nitrogen gas stream. bottom. Further, while stirring, 310 parts of isophthalic acid and 240 parts of sebacic acid were introduced into the reactor and heated to 150° C. to 240° C. to carry out an esterification reaction. When the acid value becomes 5 mgKOH/g or less, the pressure in the reaction vessel is gradually reduced, and the mixture is reacted at 1 mmHg or less at 200 to 240°C for 1 hour to obtain an acid value of 0.8 mgKOH/g and a molecular weight of about 460. An intermediate was obtained. Next, with respect to 339 parts of the intermediate, 157 parts of xylylene diisocyanate, 439 parts of hexamethylene diisocyanate allophanate, and 65 parts of hexamethylene diisocyanate nurate are charged into a reaction vessel, and heated to 85° C. while stirring under a nitrogen gas stream. and reacted for about 10 hours to obtain a polyisocyanate compound (B) having an isocyanate percentage of 9.9% by titration (using di-n-butylamine).

<Example 1>
60 parts of polyol compound (A), 40 parts of MP-40, and 210 parts of polyisocyanate compound (B) were blended to prepare resin composition 1.

<Method for preparing cured product for dynamic viscoelasticity measurement>
The obtained resin composition 1 is applied to an OPP film (“Alphan E-201F” manufactured by Oji F-Tex Co., Ltd.) using an applicator (No. 11 manufactured by AS ONE) and stored in a constant temperature bath at 40 ° C. for 4 days. and cured to form a cured resin layer 1. The obtained cured resin layer 1 was removed from the OPP film and used as a cured product 1 for dynamic viscoelasticity measurement.

<How to create a laminate film>
The resulting resin composition 1 was applied to a PET film ("Ester Film E5102" 12 µm, manufactured by Toyobo Co., Ltd.) on which a design was gravure-printed with a printing ink ("Univia NT" manufactured by DIC Corporation), and the coating amount was 2.0 µm solids. The coating was applied so as to be about 0 g/m ² , and the coated surface of this film and a nylon film ("EMBLEM ONBC" 15 µm, manufactured by Unitika Ltd.) were laminated with a laminator. After that, an adhesive is applied to the nylon surface of the laminate film so that the amount of solid content is about 2.0 g / m ² , and the coated surface of this film and aluminum foil (Toyo Aluminum Co., Ltd. "Aluminum Foil - O material (9 μm), and stored in a constant temperature bath at 40° C. for 3 days. After that, a CPP film (“Torayfan ZK207” 70 μm, manufactured by Toray Advanced Film Co., Ltd.) was laminated on the aluminum foil surface. This composite film was stored in a constant temperature bath at 40° C. for 3 days to complete the laminate 1 of the present invention.

<Dynamic viscoelasticity measurement of cured product>
A test piece for viscoelasticity measurement was measured under the following conditions using a dynamic viscoelasticity measuring device (RSA III manufactured by TA Instruments) to obtain loss tangent and storage modulus.
Sample: length 10mm (excluding gripping allowance) x width 5mm
Measurement temperature range: -50 to 150°C
Frequency: 1.0Hz
Heating rate 5°C/min

(Evaluation criteria)
・The number of loss tangent peaks 1: ×
2: ○
・135°C storage modulus
Less than 1.5×10 ⁵ P: ×
1.5×10 ⁵ to 3.5×10 ⁶ Pa: ○
Exceeding 3.5×10 ⁶ Pa: ×
・The temperature difference between Tg1 and Tg2 is less than 15°C: ×
15 to 50°C: ○
Exceeding 50°C: ×

<Appearance evaluation of nylon/aluminum foil after retort treatment>
The laminate was cut into a size of 150 mm×300 mm, folded so that the CPP was inside, and heat-sealed at 1 atm and 210° C. for 1 second to prepare a pouch. Water was added as content. The filled pouches were subjected to steam sterilization at 135°C for 30 minutes or 121°C for 30 minutes, and the appearance of each pouch after removal was observed. was evaluated.

(Evaluation criteria)
No peeling: ◎
1 or less peeling points: ○
7 or less peeling points: △
Eight or more peeling points: ×

<Appearance evaluation of aluminum foil/CPP after retort treatment>
The laminate was cut into a size of 150 mm×300 mm, folded so that the CPP was inside, and heat-sealed at 1 atm and 210° C. for 1 second to prepare a pouch. A 1/1/1 sauce (meat sauce: vegetable oil: vinegar=1:1:1) was added as a content. The filled pouch was subjected to steam sterilization at 135° C.-30 minutes or 121° C.-30 minutes, and each pouch was opened after removal. did

(Evaluation criteria)
No peeling: ◎
1 or less peeling points: ○
7 or less peeling points: △
Eight or more peeling points: ×

<Example 2>
80 parts of the polyol compound (A), 20 parts of MP-40, and 205 parts of the polyisocyanate compound (B) were blended to prepare a resin composition 2, which was evaluated in the same manner as in Example 1.

<Example 3>
80 parts of the polyol compound (A), 20 parts of UMM-1001, and 184 parts of the polyisocyanate compound (B) were blended to prepare a resin composition 3, which was evaluated in the same manner as in Example 1.

<Example 4>
100 parts of the polyol compound LX-906 and 10 parts of the polyisocyanate compound KW-75 were blended to prepare a resin composition 4, which was evaluated in the same manner as in Example 1.

<Example 5>
40 parts of polyol compound (A), 60 parts of UMM-1001, and 151 parts of polyisocyanate compound (B) were blended to prepare resin composition 5, which was evaluated in the same manner as in Example 1.

<Comparative Example 1>
100 parts of the polyol compound (A) and 200 parts of the polyisocyanate compound (B) were blended to prepare a comparative resin composition 1, which was evaluated in the same manner as in Example 1.

The results of Examples and Comparative Examples are listed in Table 1.

Since the adhesive of the present invention exhibits high adhesiveness and resistance to moist heat, it can be suitably used as an adhesive for lamination, and the resulting laminate can be suitably used as a sheet for retort packaging.

Claims (7)

A laminate obtained by laminating an aluminum foil layer and a cured resin layer,
The cured resin layer is a cured product of a resin composition containing a polyisocyanate compound and a hydroxyl group-containing compound, and the peak in the loss tangent temperature spectrum obtained from a dynamic viscoelasticity test of the cured product of the resin composition there are two
A laminate having a storage modulus of 1.5×10 ⁵ to 3.5×10 ⁶ at 135° C. obtained from a dynamic viscoelasticity test of a cured product of the resin composition. When the two peaks in the temperature spectrum of the loss tangent obtained from the dynamic viscoelasticity test of the cured product of the resin composition are Tg1 and Tg2, respectively, the following formulas (1) and (2) are established. 2. Laminate according to claim 1 , characterized in that.
Tg1<Tg2 (1)
Tg2-Tg1=15-50 (°C) (2) 3. The laminate according to claim 2 , wherein Tg1 is 5 to 30.degree. C. and Tg2 is 30 to 60.degree. 4. The laminate according to claim 2 , wherein the loss tangent intensity ratio (Tg2/Tg1) at Tg1 and Tg2 is 0.03 to 0.5. 5. The laminate according to any one of claims 1 to 4 , wherein the hydroxyl group-containing compound in the resin composition contains a polyol compound and a monool compound. 6. The laminate according to any one of claims 1 to 5 , characterized by having an aluminum foil layer, a cured resin layer, and a second substrate in this order. The laminate according to any one of claims 1 to 6 , which is a sheet for boiling/retort packaging.