JP7567467B2 - Laminating adhesives, laminates and packaging materials - Google Patents

Description

The present invention relates to a laminating adhesive that is suitable for laminating various plastic films and metal-deposited films, and a laminate using the same. Furthermore, the present invention relates to a package using the laminate that is used for food, medicines, cosmetics, detergents, miscellaneous goods, etc.

Conventionally, a laminate in which at least a base layer containing an oriented plastic or the like and a sealant layer for welding the packaging materials together has been used as a packaging material for constituting a packaged product for filling and packaging various items such as food and drink, medicines, cosmetics, sanitary products, daily necessities, etc. Usually, the laminate further includes an adhesive layer for bonding the layers of the laminate.
In recent years, with the growing demand for the creation of a recycling-oriented society, there is a desire to move away from fossil fuels in the field of laminates that make up packaging materials, and the use of biomass has attracted attention.
Biomass is a non-exhaustible resource that is an industrial resource originating from the constituent materials of living organisms, and is a carbon-neutral renewable energy source.

In response to such demands, for example, Patent Document 1 discloses an adhesive composition containing a polyol component containing urethane-modified castor oil, which is a reaction product of some of the hydroxyl groups in castor oil and a diisocyanate, and a polyisocyanate component.
Furthermore, Patent Document 2 discloses a laminating adhesive containing a polyisocyanate component including a reaction product of a polyol containing a castor oil and a polyisocyanate, and a polyol component.

JP 2018-030905 A JP 2019-137712 A

The adhesives described in Patent Documents 1 and 2 use castor oil, which improves the biomass ratio and has a fast curing rate. However, because castor oil has a wide molecular weight distribution and contains a large amount of low molecular weight components, adhesives using castor oil have poor initial cohesive strength, and the laminate after bonding has a problem of streaky lift (tunneling) in the width direction. The tunneling phenomenon is more likely to occur the more the stretchability of the two substrates bonded with the adhesive is different. For example, a laminate bonded to a biaxially oriented polypropylene (OPP) film, which is easy to stretch, and an aluminum-deposited polyethylene terephthalate (VMPET) film, which is difficult to stretch, is particularly prone to tunneling.
Furthermore, the adhesive described in Patent Document 2 uses castor oil on the polyisocyanate curing agent side, and therefore has the problem that the curing agent becomes cloudy over time, impairing the transparency of the adhesive.
Therefore, an object of the present invention is to provide a laminating adhesive that has an improved biomass degree, a fast curing rate, and is capable of suppressing tunneling even in configurations in which tunneling is likely to occur, and has excellent transparency, as well as a laminate and packaging body that use the adhesive and have an improved biomass degree and suppressed tunneling.

As a result of extensive research into resolving the above-mentioned issues, we have discovered that the following embodiment can resolve the above-mentioned issues, and have completed the present invention.

The laminating adhesive according to one embodiment of the present invention is a laminating adhesive containing a polyol composition, a polyisocyanate composition, and a silane compound, characterized in that the polyol composition contains a polyol containing castor oils and polyether polyols, and a polyether urethane polyol which is a reaction product of the polyisocyanate, the castor oil content is 5 to 33 mass% based on the solid mass of the polyol composition, and the silane compound contains an aminosilane compound.

The laminating adhesive according to one embodiment of the present invention is characterized in that the aminosilane compound is an aminosilane compound having a primary amino group.

The laminating adhesive according to one embodiment of the present invention is characterized in that the content of the aminosilane compound is 0.05 to 0.5 mass % based on the solid mass of the polyol composition.

The laminating adhesive according to one embodiment of the present invention is characterized in that the silane compound further contains an epoxy silane compound.

The laminating adhesive according to one embodiment of the present invention is characterized in that the content of the epoxy silane compound is 0.1 to 0.5 mass % or less based on the solid mass of the polyol composition.

A laminate according to one aspect of the present invention is characterized in that an adhesive layer made of the laminating adhesive described above is disposed between at least two substrates.

A packaging body according to one aspect of the present invention is characterized by using the laminate described above.

The present invention can provide a laminate adhesive that has an improved biomass ratio, a fast curing rate, and can suppress tunneling even in configurations where tunneling is likely to occur, and has excellent transparency, as well as a laminate and package that use the adhesive and has an improved biomass ratio and suppresses tunneling.

<Laminating adhesive>
The laminating adhesive of the present invention contains a polyol composition, a polyisocyanate composition, and a silane compound, the polyol composition containing a polyol containing a castor oil and a polyether polyol, and a polyether urethane polyol which is a reaction product of a polyisocyanate, the castor oil content is 5 to 33 mass% based on the solids mass of the polyol composition, and the silane compound contains an aminosilane compound.
It is common to use polyols such as castor oils to improve the biomass ratio. However, polyether urethane polyols made using castor oils tend to have a large molecular weight distribution and contain a large amount of low molecular weight components, so the adhesive finally obtained has poor cohesive strength at the initial stage of lamination and is prone to streaky lifting (tunneling) in the width direction of the laminate after bonding.
In contrast to the above, the laminating adhesive of the present invention can improve the interface adhesion and suppress the occurrence of tunneling by combining a predetermined amount of polyol, which is castor oil, with an aminosilane compound. Furthermore, since the laminating adhesive of the present invention uses castor oil on the polyol composition (polyol base) side, even when an aged polyol base is mixed to make an adhesive, it has excellent transparency.
The present invention will be described in detail below.

<Polyol Composition>
The polyol composition used in the present invention is a composition containing a polyol compound having two or more hydroxyl groups as a main component. The polyol composition in the present invention is characterized in that it contains a polyol containing castor oils and polyether polyol, and a polyether urethane polyol which is a reaction product of polyisocyanate, and the castor oil content is in the range of 5 to 33 mass% based on the solid mass of the polyol composition.
When a polyether urethane polyol obtained by urethane-modifying castor oil and polyether polyol is contained, the branching ratio of the adhesive layer formed by the reaction with the polyisocyanate composition described later is lower than when only castor oil is used. This lowers the glass transition point (Tg) of the adhesive layer, resulting in excellent adhesive strength of the laminate.
In addition, by setting the content of castor oils in the range of 5 to 33 mass% based on the solid content mass of the polyol composition, it is possible to achieve both an excellent curing speed and tunneling suppression while increasing the biomass degree. The content of castor oils is preferably in the range of 5 to 25 mass%.

[Polyether urethane polyol]
The polyol that is the raw material of the polyether urethane polyol contains at least castor oil and polyether polyol.

(Castor oil)
The castor oils are not particularly limited, and any known castor oil or castor oil derivative containing a hydroxyl group can be used. One type may be used alone, or two or more types may be used in combination.
Examples of castor oil derivatives containing hydroxyl groups include dehydrated castor oil, hydrogenated castor oil which is a hydrogenated product of castor oil, castor oil fatty acid, dehydrated castor oil fatty acid, castor oil fatty acid condensate, ethylene oxide 5 to 50 mole adduct of castor oil, and castor oil-based polyols.
Among these, from the viewpoint of the production quality stability of the polyether urethane polyol, the acid value of the castor oil is preferably in the range of 0.1 to 5.0 mgKOH/g, more preferably in the range of 0.1 to less than 2.0 mgKOH/g, and even more preferably in the range of 0.1 to 1.0 mgKOH/g.
The polyol that is the raw material of the polyether urethane polyol preferably contains castor oil in an amount of 5 to 33% by mass based on the mass of the polyurethane polyol.

(Polyether polyol)
The polyether polyol may be any compound having two or more hydroxyl groups and two or more ether bonds in the molecule, and one type may be used alone or two or more types may be used in combination.
Examples of polyether polyols include polyalkylene glycols such as polyethylene glycol, polytrimethylene glycol, polypropylene glycol, polytetramethylene glycol, and polybutylene glycol; polyethylene glycol/polypropylene glycol block copolymers; and propylene oxide/ethylene oxide random polyethers.
Alternatively, an addition polymer obtained by addition polymerization of an oxirane compound such as ethylene oxide, propylene oxide, butylene oxide, or tetrahydrofuran to a low molecular weight polyol initiator such as water, ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, or sucrose may be used as the polyether polyol. Examples of the addition polymer include a propylene glycol propylene oxide adduct, a glycerin propylene oxide adduct, a sorbitol-based propylene oxide adduct, and a sucrose-based propylene oxide adduct.
The polyether polyol is preferably a polyalkylene glycol.

The number average molecular weight of the polyether polyol is preferably 100 to 5,000, and more preferably 300 to 2,500.
The number average molecular weight in this specification is a value measured using a gel permeation chromatography (GPC) "Shodex GPC System-21" manufactured by Showa Denko KK, using tetrahydrofuran as a solvent, and converted into a standard polystyrene equivalent.
When the polyether polyol contains a plurality of polyether polyols, the number average molecular weight of the polyether polyol can be determined from the number average molecular weights of the individual polyether polyols and the mass ratio thereof.

(Polyisocyanate)
The polyisocyanate that is the raw material of the polyether urethane polyol is not particularly limited, and any known polyisocyanate compound can be used.
As specific examples of such polyisocyanate compounds, the description in the <Polyisocyanate composition> described below can be cited, and one type may be used alone, or two or more types may be used in combination.
Among these, from the viewpoints of rigidity and heat resistance, aromatic diisocyanates such as diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, phenylene diisocyanate, tolylene diisocyanate, and naphthalene diisocyanate; and aromatic polyisocyanates such as polymethylene polyphenyl polyisocyanate are preferred.

The weight average molecular weight of the polyetherurethane polyol, which is a reaction product of a polyol containing castor oil and a polyether polyol, and a polyisocyanate, is preferably in the range of 5,000 to 45,000. The polyetherurethane polyol may be modified, or may be a polyetherurethane polyol reacted with an acid anhydride to introduce a carboxyl group. As the acid anhydride, the acid anhydrides described in the section [Other polyol compounds] below can be used.

[Other polyol compounds]
The polyol composition in the present invention may contain other polyol compounds as long as the effects of the present invention are not impaired. The other polyol compounds may be used alone or in combination of two or more.
Other polyol compounds include, for example, polyester polyol, polyether polyol, polyurethane polyol, polyesteramide polyol, acrylic polyol, polycarbonate polyol, polycaprolactone polyol, polyvalerolactone polyol, polyolefin polyol, polyhydroxyalkane, castor oil, and mixtures thereof, as well as ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-5-pentanediol, 1,6-hexanediol, neopentanediol, and the like. Examples of the glycols that can be used include glycols such as diethyl glycol, methylpentane glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, bishydroxyethoxybenzene, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, and triethylene glycol; polyalkylene glycols having a number average molecular weight of 200 to 3,000; trifunctional or tetrafunctional aliphatic alcohols such as glycerin, trimethylolpropane, and pentaerythritol; and polyols in which the above-mentioned glycols or polyols are added to the above-mentioned trifunctional or tetrafunctional aliphatic alcohols.

The other polyol compounds may be acid-modified compounds in which some of the hydroxyl groups in the polyol are acid-modified, compounds in which a carboxyl group is introduced by reacting with an acid anhydride, or compounds in which a urethane bond is introduced by reacting with a diisocyanate.
Examples of the acid anhydride include pyromellitic anhydride, mellitic anhydride, trimellitic anhydride, and trimellitic ester anhydride. Examples of the trimellitic ester anhydride include ester compounds obtained by esterifying an alkylene glycol or alkanetriol having 2 to 30 carbon atoms with trimellitic anhydride, and specific examples thereof include ethylene glycol bisanhydrotrimellitate, propylene glycol bisanhydrotrimellitate, and the like.
Examples of the diisocyanate include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, 1,5-naphthalene diisocyanate, hexamethylene diisocyanate, and hydrogenated diphenylmethane diisocyanate.

<Polyisocyanate Composition>
The polyisocyanate composition used in the present invention is a composition containing a polyisocyanate compound as a main component. The polyisocyanate compound is a compound having two or more isocyanate groups, and one kind may be used alone or a plurality of kinds may be used in combination.
Examples of the polyisocyanate compound include aromatic polyisocyanates, araliphatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates, and these may be modified products.

Examples of the aromatic polyisocyanate include aromatic diisocyanates such as diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, phenylene diisocyanate, tolylene diisocyanate, and naphthalene diisocyanate; and aromatic polyisocyanates such as polymethylene polyphenyl polyisocyanate.
Examples of the araliphatic polyisocyanate include araliphatic diisocyanates such as 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, ω,ω'-diisocyanato-1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanato-1-methylethyl)benzene or a mixture thereof.
Examples of the aliphatic polyisocyanate include aliphatic diisocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanate methyl caproate, lysine diisocyanate, and dimer acid diisocyanate.
Examples of the alicyclic polyisocyanate include alicyclic diisocyanates such as 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, isophorone diisocyanate, 4,4'-methylenebis(cyclohexylisocyanate), methyl 2,4-cyclohexane diisocyanate, methyl 2,6-cyclohexane diisocyanate, 1,4-bis(isocyanatemethyl)cyclohexane, 1,3-bis(isocyanatemethyl)cyclohexane, and norbornene diisocyanate.

Examples of modified polyisocyanates include allophanate-type modified products, isocyanurate-type modified products, biuret-type modified products, adduct-type modified products, and polyurethane polyisocyanates obtained by reacting the above-mentioned polyisocyanate compounds with a polyol component under conditions of excess isocyanate groups.
The polyol component that forms the modified product of the polyisocyanate is not particularly limited and can be selected from known polyols. Examples of the polyol include polyester polyols, polyester urethane polyols, polycarbonate polyols, polycaprolactone polyols, polyether polyols such as polyalkylene glycols, polyether urethane polyols, polyolefin polyols, acrylic polyols, silicone polyols, castor oil-based polyols, and fluorine-based polyols, as well as low molecular weight polyols such as ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, and sucrose.

The polyisocyanate composition preferably contains a compound having a structural unit derived from an aromatic polyisocyanate, more preferably contains a modified product of an aromatic polyisocyanate, and even more preferably contains a polyurethane polyisocyanate obtained by reacting an aromatic polyisocyanate with a polyalkylene glycol, or a trimethylolpropane adduct of an aromatic polyisocyanate. Such polyisocyanate compounds are preferred from the viewpoints of adhesive strength and economy.

<Silane Compound>
The silane compound in the present invention is a compound having a hydrolyzable silyl group, and has the function of improving the adhesive strength to a metal foil or a metal vapor deposition layer.
The silane compound in the present invention must contain an aminosilane compound having an amino group and a hydrolyzable silyl group. Examples of such aminosilane compounds include aminosilane compounds having a primary amino group such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, and N-2-(aminoethyl)-3-aminopropyltrimethyldimethoxysilane; and aminosilane compounds having a secondary amino group such as N-phenyl-3-aminopropyltrimethoxysilane.
Among these, from the viewpoint of reactivity, preferred are aminosilane compounds having a primary amino group, more preferred are aminosilane compounds having one primary amino group in one molecule, and even more preferred is 3-aminopropyltrimethoxysilane.
The content of the aminosilane compound is preferably in the range of 0.05 to 0.5 mass %, more preferably in the range of 0.1 to 0.3 mass %, based on the solid content mass of the polyol composition. The above range is preferable because it provides excellent interface adhesion without impairing solution stability.

The silane compound may contain other silane compounds other than the aminosilane compound, so long as the effect of the present invention is not impaired. Examples of other silane compounds include epoxy silane compounds such as β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-glycidoxypropyltriethoxysilane; vinyl silane compounds such as vinyltris(β-methoxyethoxy)silane, vinyltriethoxysilane, vinyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane; hexamethyldisilazane, and γ-mercaptopropyltrimethoxysilane.
From the viewpoint of solution stability, the silane compound in the present invention preferably further contains an epoxy silane compound.
When the silane compound further contains an epoxy silane compound, the content of the epoxy silane compound is preferably in the range of 0.1 to 0.7 mass %, more preferably in the range of 0.1 to 0.5 mass %, based on the solid content mass of the polyol composition. The above range is preferable because it provides excellent interface adhesion.

<Solvent>
The laminating adhesive of the present invention can be used as a solvent-based or solventless adhesive, and may contain a solvent as necessary. Note that the "solvent" in the present invention refers to an organic solvent having high solubility and capable of dissolving the polyol compound, the polyisocyanate compound, and the silane compound.
Examples of the organic solvent having high solubility include toluene, xylene, methylene chloride, tetrahydrofuran, methanol, ethanol, isopropyl alcohol, methyl acetate, ethyl acetate, n-butyl acetate, acetone, methyl ethyl ketone, cyclohexanone, toluene, xylol, n-hexane, and cyclohexane. The organic solvent is preferably inactive against polyisocyanates, and examples of the organic solvent include ester solvents such as ethyl acetate, ketone solvents such as methyl ethyl ketone, and aromatic hydrocarbon solvents such as toluene and xylene.

The viscosity of the laminating adhesive of the present invention is preferably 100 to 10,000 mPa·s, more preferably 100 to 5,000 mPa·s, at room temperature to 150°C, and even more preferably 100 to 10,000 mPa·s, more preferably 100 to 5,000 mPa·s, at room temperature to 100°C.
When the viscosity is 100 to 5,000 mPa·s at room temperature to 100° C., it can be used as a solvent-free adhesive.
If the viscosity of the lamination adhesive is higher than the above range, it may be diluted with the above organic solvent. The content of the organic solvent depends on the required viscosity, but it is generally desirable to include the organic solvent in the range of 50 to 70 mass % relative to the adhesive resin.

The laminating adhesive of the present invention is a reactive adhesive obtained by blending the aforementioned polyol composition, polyisocyanate composition, silane compound, and, as necessary, other components. The silane compound may be blended when the polyol composition and the polyisocyanate composition are mixed, or may be blended in advance in the polyol composition and/or the polyisocyanate composition.
The blending ratio of the polyol composition and the polyisocyanate composition is preferably such that the molar equivalent ratio [NCO/OH] of the total isocyanate groups in the polyisocyanate composition to the total hydroxyl groups in the polyol composition is in the range of 1.0 to 5.0, more preferably 1.3 to 3.0.

The acid value immediately after mixing the laminating adhesive is preferably 3.0 mgKOH/g or less, and more preferably 1.0 mgKOH/g or less.

<Other ingredients>
The laminating adhesive of the present invention may further contain other components in order to satisfy various physical properties required for the adhesive or packaging material. The other components may be blended in advance with the polyol composition and/or the polyisocyanate composition, or may be blended when the polyol composition and the polyisocyanate composition are mixed. The other components may be used alone or in combination of two or more.

(Phosphoric acid or phosphoric acid derivative)
The laminating adhesive of the present invention may contain phosphoric acid or a phosphoric acid derivative from the viewpoint of improving adhesive strength to metallic materials such as metal foil.
The phosphoric acid may be any phosphoric acid having at least one free oxygen acid, and examples of the phosphoric acid include phosphoric acids such as hypophosphorous acid, phosphorous acid, orthophosphoric acid, and hypophosphoric acid; and condensed phosphoric acids such as metaphosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, polyphosphoric acid, and ultraphosphoric acid. Examples of phosphoric acid derivatives include those obtained by partially esterifying the above phosphoric acid with alcohols while leaving at least one free oxygen acid. Examples of the alcohols include aliphatic alcohols such as methanol, ethanol, ethylene glycol, and glycerin; and aromatic alcohols such as phenol, xylenol, hydroquinone, catechol, and phloroglucinol.
The content of phosphoric acid or a derivative thereof is preferably 0.01 to 10 mass %, more preferably 0.05 to 5 mass %, and particularly preferably 0.05 to 1 mass %, based on the solid mass of the laminating adhesive.

(Leveling agent or defoamer)
The laminating adhesive of the present invention may further contain a leveling agent or an antifoaming agent in order to improve the appearance of the laminate. Examples of the leveling agent include polyether-modified polydimethylsiloxane, polyester-modified polydimethylsiloxane, aralkyl-modified polymethylalkylsiloxane, polyester-modified hydroxyl-containing polydimethylsiloxane, polyetherester-modified hydroxyl-containing polydimethylsiloxane, acrylic copolymer, methacrylic copolymer, polyether-modified polymethylalkylsiloxane, acrylic acid alkyl ester copolymer, methacrylic acid alkyl ester copolymer, and lecithin.
Examples of the defoaming agent include silicone resin, silicone solution, and copolymers of alkyl vinyl ether, alkyl acrylate, and alkyl methacrylate.

(Reaction accelerator)
The laminating adhesive of the present invention may further contain a reaction accelerator to accelerate the curing reaction. Examples of the reaction accelerator include metal catalysts such as dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, and dibutyltin dimaleate, tertiary amines such as 1,8-diaza-bicyclo(5,4,0)undecene-7 and 1,5-diazabicyclo(4,3,0)nonene-5,6-dibutylamino-1,8-diazabicyclo(5,4,0)undecene-7, and reactive tertiary amines such as triethanolamine.

(Other additives)
The laminate composition of the present invention may contain various additives within the range that does not impair the effects of the present invention. Examples of additives include inorganic fillers such as silica, alumina, mica, talc, aluminum flakes, and glass flakes, layered inorganic compounds, stabilizers (antioxidants, heat stabilizers, ultraviolet absorbers, hydrolysis inhibitors, etc.), rust inhibitors, thickeners, plasticizers, antistatic agents, lubricants, antiblocking agents, colorants, fillers, crystal nucleating agents, and catalysts for adjusting the curing reaction.

<Laminate>
The laminate of the present invention is one in which an adhesive layer made of the above-mentioned laminating adhesive is disposed between at least two substrates. The laminate can be formed, for example, by applying the laminating adhesive to a first substrate, optionally drying the same, bonding the second substrate, and curing the adhesive layer located between the two substrates under a temperature condition of 20° C. to 60° C. However, the laminate is not limited to this configuration, and another layer may be laminated via an adhesive layer or the like.
The amount of the laminate adhesive applied after drying is optional, but from the viewpoints of laminate appearance and stability of adhesive performance, in the case of a solventless adhesive, it is preferably in the range of 1 to 4 g/m ² , more preferably 1 to 2 g/m ² , and in the case of a solvent-based adhesive, it is preferably in the range of 1 to 6 g/m ² , more preferably 2 to 4 g/m ^2. In addition, from the viewpoints of strength and durability as a packaging material, the thickness of the laminate is preferably 10 μm or more.

[Substrate]
The substrate is not particularly limited and examples thereof include plastic films, papers, gas barrier substrates, sealants, etc., which are generally used for packaging applications, and the two substrates may be the same or different.
Examples of plastic films that can be used include polyester resin films such as polyethylene terephthalate, polyethylene naphthalate (PEN), and polylactic acid (PLA); polyolefin resin films such as polyethylene (PE) and polypropylene (PP); polystyrene resin films; polyamide resin films such as nylon 6 and poly-p-xylylene adipamide (MXD6 nylon); polycarbonate resin films; polyacrylonitrile resin films; polyimide resin films; laminates thereof (for example, nylon 6/MXD6/nylon 6, nylon 6/ethylene-vinyl alcohol copolymer/nylon 6) and mixtures thereof. Among these, those having mechanical strength and dimensional stability are preferred.
The plastic film preferably has a thickness of 5 to 50 μm, more preferably 10 to 30 μm.

The paper includes natural paper and synthetic paper.
As the gas barrier substrate, aluminum foil and plastic films having a vapor-deposited layer of aluminum, silica, alumina, etc. are preferable. For example, in the case of aluminum foil, a thickness in the range of 3 to 50 μm is preferable from an economical point of view.

Examples of the sealant include polyethylenes such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE), acid-modified polyethylene, polypropylene (PP), acid-modified polypropylene, copolymerized polypropylene, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid ester copolymer, ethylene-(meth)acrylic acid copolymer, polyolefin resins such as ionomers, etc. Among these, polypropylene-based resins are preferred from the viewpoint of heat resistance during retort, and unstretched polypropylene is particularly preferred from the viewpoint of heat sealability.
The thickness of the sealant is not particularly limited, but is preferably in the range of 10 to 60 μm, more preferably in the range of 15 to 40 μm, taking into consideration processability into packaging, heat sealing properties, etc. In addition, by providing the sealant with unevenness with a height difference of 5 to 20 μm, it is possible to impart slipperiness to the sealant and tearability of the packaging.
Furthermore, the various sealants may have a vapor-deposited layer of aluminum, silica, alumina, or the like in addition to the aluminum foil.

[Printed layer]
The laminate of the present invention may further have a printed layer.
The printed layer is a layer on which any desired printed pattern such as letters, numbers, pictures, figures, symbols, patterns, etc. is formed for decoration, display of contents, display of expiration date, display of manufacturer, seller, etc., or for imparting aesthetics, and includes a solid printed layer. The printed layer can be formed using a conventionally known pigment or dye, and the method for forming the printed layer is not particularly limited.
Generally, the printing layer is formed on the substrate using a printing ink containing a colorant such as a pigment or dye. The method for applying the printing ink is not particularly limited, and the printing ink can be applied by a method such as gravure coating, flexo coating, roll coating, bar coating, die coating, curtain coating, spin coating, inkjet, etc. The printing layer is formed by leaving the ink alone or, if necessary, blowing air, heating, drying under reduced pressure, irradiating with ultraviolet light, etc.
The thickness of the printing layer is preferably 0.1 to 10 μm, more preferably 1 to 5 μm, and even more preferably 1 to 3 μm.

The structure of the laminate is not particularly limited, but is preferably a structure in which at least one plastic film or gas barrier substrate and a sealant are laminated. Specific examples of the structure are listed below, but are not limited thereto.
Biaxially oriented polypropylene (OPP) / printing layer / adhesive layer / CPP,
OPP/printed layer/adhesive layer/Al-deposited CPP,
OPP/printing layer/adhesive layer/PE,
Printing layer/OPP/adhesive layer/CPP,
NY/printing layer/adhesive layer/PE,
Printing layer/NY/Adhesive layer/CPP
NY/printing layer/adhesive layer/CPP,
PET/printing layer/adhesive layer/CPP,
Printing layer/PET/adhesive layer/CPP
PET/printing layer/adhesive layer/NY/adhesive layer/CPP,
Transparent vapor-deposited PET/printed layer/adhesive layer/NY/adhesive layer/CPP,
PET/printed layer/adhesive layer/AL-deposited PET/adhesive layer/PE,
PET/printing layer/adhesive layer/AL/adhesive layer/CPP,
PET/printing layer/adhesive layer/AL/adhesive layer/PE,
PET/printing layer/adhesive layer/NY/adhesive layer/AL/adhesive layer/CPP,
PET/Printing layer/Adhesive layer/AL/Adhesive layer/NY/Adhesive layer/CPP

The present invention will be described in more detail below with reference to examples and comparative examples. In the examples and comparative examples, "parts" and "%" mean "parts by mass" and "% by mass" unless otherwise specified.

<Production of Polyether Urethane Polyol>
(Polyether urethane polyol A1)
18 parts of castor oil polyol A, 40 parts of bifunctional polypropylene glycol having a number average molecular weight of about 400, 20 parts of bifunctional polypropylene glycol having a number average molecular weight of 2,000, and 22 parts of tolylene diisocyanate (hereinafter, TDI) were charged into a reaction vessel, and dioctyltin dilaurate was added as a reaction catalyst at 0.1% relative to the total mass of castor oil polyol A, bifunctional polypropylene glycol having a number average molecular weight of about 400, bifunctional polypropylene glycol having a number average molecular weight of 2,000, and tolylene diisocyanate, and the mixture was heated at 80 to 90 ° C. for 2 to 4 hours while stirring under a nitrogen gas flow to cause a urethane reaction. The disappearance of the isocyanate group was confirmed by FT-IR, and the mixture was diluted with ethyl acetate to obtain a solution of polyether urethane polyol (A1) having a solid content concentration of 70%.

(Polyether urethane polyols A2 to A8)
Solutions of polyether urethane polyols A2 to A8 were obtained in the same manner as A1, except that the blending compositions were changed to those shown in Table 1. The values in Table 1 represent "parts" unless otherwise specified, and blanks represent no blending.

The abbreviations in Table 1 are as follows.
Castor oil-based polyol A: "Industrial No. 1 Castor Oil" manufactured by Toyokuni Oil Co., Ltd., acid value 0.5 mg KOH/g
Castor oil-based polyol B: "Kaku Koichi" manufactured by Ito Oil Co., Ltd., acid value 1.5 mg KOH/g
Castor oil-based polyol C: "Koichi" manufactured by Ito Oil Mills, acid value 3.0 mgKOH/g
PPG400: Bifunctional polypropylene glycol with a number average molecular weight of about 400 PPG2000: Bifunctional polypropylene glycol with a number average molecular weight of 2,000 TDI: 80% 2.4-tolylene diisocyanate, 20% 2.6-tolylene diisocyanate

<Production of Polyisocyanate Compound>
(Polyether urethane polyisocyanate B1)
35 parts of castor oil-based polyol C ("Koichi" manufactured by Ito Oil Co., Ltd., acid value 1.5 mgKOH/g), 20 parts of bifunctional polypropylene glycol having a number average molecular weight of 2,000, 10 parts of bifunctional polypropylene glycol having a number average molecular weight of 400, and 35 parts of 4,4'-diphenylmethane diisocyanate were charged into a reaction vessel, and the mixture was heated at 70 to 80°C for 4 to 7 hours while stirring under a nitrogen gas flow to carry out a urethane reaction. After completion of the reaction, the mixture was diluted with ethyl acetate to a nonvolatile content of 75%, to obtain a solution of polyether urethane polyisocyanate B1. The viscosity of the B1 solution was 3,000 mPa·s/25°C.

<Manufacture of Laminating Adhesive>
[Example 1]
A polyether urethane polyol solution and a polyisocyanate solution were mixed to obtain the solid content mass shown in Table 1, and diluted with ethyl acetate to obtain a laminating adhesive with a solid content of 30%. The biomass degree of the obtained adhesive is shown in Table 2.

[Examples 2 to 13, Comparative Examples 1 to 5]
Except for changing the blending composition to that shown in Table 2, the same procedure as in Example 1 was carried out to obtain laminating adhesives each having a solid content of 30%.

<Evaluation of Laminating Adhesives>
The obtained adhesive was used to prepare a laminate, which was then used to carry out the following evaluations. The results are shown in Table 2.

[Production of Laminate]
[Preparation of laminate: OPP/adhesive layer/VMPET, coating speed 200 m/min]
The adhesive obtained above was applied to a corona-treated OPP film (P-2161 manufactured by Toyobo, thickness 20 μm) using a laminator at a coating speed of 200 m/min, and the solvent was evaporated using a drying oven (triple oven at 60°C-70°C-80°C, oven length 2.5 m), after which the adhesive-coated surface was bonded to a 12 μm-thick VMPET film (Dialastar H27 manufactured by Reiko, thickness 12 μm, aluminum-deposited PET) to obtain a laminate. The solid coating amount of the adhesive was 2.5 g/ ^m2 .

[Tunneling]
The laminate was stored in an atmosphere of 40° C. for 24 hours, and then visually observed to evaluate whether streaky lifting (tunneling) occurred from the ends in the width direction.
〇: No tunneling occurs (very good)
◯△: Tunneling occurred less than 5 mm from the end (good)
△: Tunneling occurs at a length of 5 mm or more and less than 10 mm from the end (usable)
×: Tunneling occurs at a length of 10 mm or more from the end (unusable)

[Curing speed]
The laminate was stored in a desiccator containing silica gel at 40° C. for 24 hours, and the disappearance of isocyanate groups was confirmed every hour by FT-IR and evaluated according to the following criteria.
◯: The disappearance of the isocyanate group is less than 24 hours. ×: The disappearance of the isocyanate group is more than 24 hours.

[Solution appearance, viscosity]
A 70% solids solution of polyetherurethane polyols (A1 to A8) and a 75% solids solution of polyisocyanates (CAT-29B, CAT-16B, B2) were aged for one month in a room temperature (20°C) environment. The 70% solids solution of polyetherurethane polyols (A1 to A8) and the 75% solids solution of polyisocyanates (CAT-29B, CAT-16B, B2) after aging were mixed in the same manner as in Examples 1 to 13 and Comparative Examples 1 to 5 to obtain adhesives. The appearance of the solution of the obtained adhesive was visually observed in a 25°C environment. In addition, the solution viscosity (seconds) of the adhesive was measured using a Zahn cup #3, and the difference in seconds was calculated when compared with the solution viscosity (seconds) of an adhesive made of polyetherurethane polyol and polyisocyanate before aging, and evaluated according to the following criteria.
◯: The solution appearance is transparent and the difference in solution viscosity is within 2.0 seconds. ×: The solution appearance is cloudy or the difference in solution viscosity exceeds 2.0 seconds.

The abbreviations in Table 2 are as follows:
PPG1000: Trifunctional polypropylene glycol with a number average molecular weight of 1,000 CAT-29B: Polyisocyanate manufactured by Toyo-Morton Co., Ltd. (weight average molecular weight: approx. 9,000, solid content: 75%)
CAT-16B: Polyisocyanate manufactured by Toyo-Morton Co., Ltd. (weight average molecular weight: approx. 5,000, solid content: 75%)
KBM-903: 3-aminopropyltrimethoxysilane manufactured by Shin-Etsu Silicone Co., Ltd. KBE-903: 3-aminopropyltriethoxysilane manufactured by Shin-Etsu Silicone Co., Ltd. KBM-603: N-2-(aminoethyl)-3-aminopropyltrimethoxysilane manufactured by Shin-Etsu Silicone Co., Ltd. KBM-403: 3-glycidoxypropyltrimethoxysilane manufactured by Shin-Etsu Silicone Co., Ltd.

According to Table 2, the adhesive of the present invention, which contains a polyether urethane polyol made from castor oil in the polyol composition and an aminosilane compound, has an improved biomass content, does not cause tunneling after lamination, has an excellent curing speed, and even when aged polyol compositions and polyisocyanate compositions are used, the transparency and viscosity of the adhesive do not change, and the adhesive has excellent stability.

Claims (7)

A lamination adhesive comprising a polyol composition, a polyisocyanate composition, and a silane compound,
The polyol composition includes a polyether urethane polyol which is a reaction product of a polyol and a polyisocyanate, and the polyol includes castor oil and a polyether polyol;
The content of the castor oil is 5 to 33 mass% based on the solid content mass of the polyol composition,
A laminating adhesive, wherein the silane compound comprises an aminosilane compound. The laminating adhesive according to claim 1, wherein the aminosilane compound is an aminosilane compound having a primary amino group. The laminating adhesive according to claim 1 or 2, wherein the content of the aminosilane compound is 0.05 to 0.5 mass % based on the solid mass of the polyol composition. The laminating adhesive according to any one of claims 1 to 3, wherein the silane compound further comprises an epoxy silane compound. The laminating adhesive according to claim 4, wherein the content of the epoxy silane compound is 0.1 to 0.5 mass % or less based on the solid mass of the polyol composition. A laminate in which an adhesive layer made of the laminating adhesive according to any one of claims 1 to 5 is disposed between at least two substrates. A package using the laminate described in claim 6.