JP7704058B2 - Packaging material and its manufacturing method - Google Patents

Description

The present invention relates to a packaging material and a method for manufacturing the same.

In recent years, there has been an increasing demand for packaging materials to be recycled, not only for their traditional functions such as lamination strength and tearability, but also from the perspective of environmental friendliness and efficient use of resources. For example, multi-layer packaging materials that contain multiple different materials are difficult to separate and sort, so mono-material packaging materials that are suitable for material recycling are being considered (Patent Document 1).

Generally, packaging materials are given patterns such as pictures, and a printed layer made of ink is provided to make the contents invisible. An adhesive layer and a thermoplastic base material are further laminated onto the printed layer in that order to form a laminate for packaging materials. The thermoplastic base materials of the outermost layers of this laminate are then heat-sealed to form a packaging bag. Such packaging bags are often used in the food packaging field, and if the adhesion between the layers is low, peeling between the layers occurs during filling or transportation of the contents, resulting in problems such as a decrease in design and leakage of the contents, so laminates in the food packaging field are required to have good adhesion strength.

Furthermore, in the case of food packaging bags, the bag is often opened by directly tearing it with one's hands to remove the contents. In this case, if the bag has poor tearability, excessive force may be applied or the bag may tear in an unexpected direction, causing the contents to spill, and so good tearability is required.

For example, Patent Document 2 describes a technology in which an isocyanate-based curing agent is used in an ink containing a polyurethane resin to increase laminate strength and thereby realize easy tearability. Patent Document 3 describes a technology in which a silane coupling agent is used in addition to an isocyanate-based curing agent. However, both of these relate to packaging materials made of different types of substrates, and issues remain in terms of recyclability. For these reasons, no technology has been disclosed to date that combines recyclability with physical properties suitable for packaging materials, such as laminate strength and easy tearability.

JP 2021-160258 A JP 2017-031298 A JP 2019-199509 A

The problem that this invention aims to solve is to provide a packaging material that has excellent lamination strength, is easy to tear, and has excellent recyclability.

As a result of intensive research, the inventors discovered that the above problems could be solved by using the packaging material of the present invention, and thus completed the present invention.

That is, the present invention provides a packaging material having a substrate, a printing layer, an adhesive layer, and a sealant,
The packaging material contains 80% by mass or more of polyolefin resin in the total mass of the packaging material,
the printing layer contains a pigment and a binder resin,
The packaging material relates to the above-mentioned adhesive layer, which is made of a cured product of a reactive adhesive containing a polyol compound (D) and an isocyanate compound (I), and the molecular weight distribution (Mw/Mn) of the above-mentioned polyol compound (D) is 1.5 to 10.0.

The present invention also relates to the above packaging material, in which the polyol compound (D) contains structural units derived from a polyether polyol, and the molecular weight distribution (Mw/Mn) of the polyol compound (D) is 3.0 to 10.0.

The present invention also relates to the above packaging material, in which the polyol compound (D) contains structural units derived from a polyester polyol, and the molecular weight distribution (Mw/Mn) of the polyol compound (D) is 1.5 to 5.0.

The present invention also relates to the above packaging material, in which the chlorine content of the binder resin is 5% by mass or less.

The present invention also relates to the above packaging material, in which the binder resin contains a polyester-based urethane resin (B), and the molecular weight distribution (Mw/Mn) of the polyester-based urethane resin (B) is 2.0 to 8.0.

The present invention also relates to the above packaging material, in which the polyester-based urethane resin (B) contains structural units derived from a polyester that is a condensate of a dibasic acid and a diol, and the dibasic acid includes sebacic acid and/or succinic acid.

The present invention also relates to the above packaging material, in which the diol includes a branched diol and a linear diol.

The present invention also relates to the above packaging material, in which the binder resin contains a urethane resin and at least one resin selected from the group consisting of polyvinyl acetal resin, cellulose-based resin, rosin-based resin, and acrylic resin.

The present invention also relates to the above packaging material, in which the content of the pigment is 30% by mass or less of the total mass of the printed layer.

The present invention also relates to the above packaging material, in which the printed layer further contains an isocyanate-based curing agent having a weight average molecular weight of 800 to 8,000.

The present invention also relates to the above packaging material, in which the substrate and sealant contain polyolefin resin.

The present invention also relates to the above packaging material, in which the polyolefin resin is a polypropylene-based resin.

The present invention also relates to the above packaging material, in which the chlorine content is 0.4 mass% or less based on the total mass of the packaging material.

The present invention also provides a method for producing a packaging material having a substrate, a printed layer, an adhesive layer, and a sealant, and containing an olefin resin in an amount of 80% by mass or more based on the total mass of the packaging material, comprising the steps of:
The method includes a step of printing a gravure ink containing a polyester-based urethane resin (B) on a substrate to form a printing layer, and a step of applying a reactive adhesive containing a polyol compound (D) and an isocyanate compound (I) to form an adhesive layer,
The polyol compound (D) has a molecular weight distribution (Mw/Mn) of 1.5 to 10.0.

This invention makes it possible to provide a packaging material that has excellent laminate strength, is easy to tear, and has excellent recyclability.

The following describes in detail the embodiments of the present invention. However, the following description of the components is merely an example (representative example) of the embodiment of the present invention, and the present invention is not limited to these details as long as it does not exceed the gist of the invention.

In the present invention, "gravure ink" is one embodiment of ink. In addition, ink consisting of a mixture of "gravure ink" and "isocyanate-based hardener" is also "gravure ink". The ink constituting the printing layer may be "gravure ink" or any other ink form. The printing layer formed by printing may be simply referred to as "ink layer", but this has the same meaning.

In the following description, the polyester-based urethane resin (B) used as the binder resin of the printed layer refers to a urethane resin containing a structural unit derived from a polyester, preferably an embodiment of a urethane resin further having a urea bond.
On the other hand, polyester polyol, polyether polyol, and other polyols used in reactive adhesives are in the form of having hydroxyl groups at multiple ends. Note that the polyol compound (D) is preferably in the form of having a urethane bond, and is preferably in the form of not having a urea bond. Note that even a very small amount of urea bond unintentionally formed due to the inclusion of moisture during the production of the polyol compound (D) is not excluded.

The packaging material of the present invention will be described in detail below.
The present invention relates to a packaging material having a substrate, a printing layer, an adhesive layer, and a sealant,
The packaging material contains 80% by mass or more of polyolefin resin in the total mass of the packaging material,
the printing layer contains a pigment and a binder resin,
The packaging material is characterized in that the adhesive layer is made of a reactive adhesive containing a polyol compound (D) and an isocyanate compound (I), and the molecular weight distribution (Mw/Mn) of the polyol compound (D) is 1.5 to 10.0.
By containing 80% by mass or more of polyolefin resin in the total mass of the packaging material, it is possible to obtain a molding material that exhibits recyclability, has good moldability after recycling, and can be used for various applications. In addition, by using an adhesive containing a polyol compound (D) having a molecular weight distribution (Mw/Mn) of 1.5 to 10.0, the leveling property during adhesive application and the adhesion between each layer are improved, and easy tearing properties can be imparted to the packaging material. Easy tearing properties contribute to improving recyclability not only in terms of convenience in simplifying opening of the packaging material, but also in terms of shortening and streamlining the process of crushing and pulverizing the packaging material during material recycling.

<Packaging material>
The packaging material of the present invention is a packaging material having a structure in which at least a substrate, a printed layer, an adhesive layer, and a sealant are laminated. Specific examples of the structure include, but are not limited to, the following structures. In the structure descriptions (1) to (3) below, "/" indicates the boundary between layers. Specific examples of the laminate structure include, in order from the outer layer side (left side), the following laminate structures.
(1) Substrate/printed layer/adhesive layer/sealant (2) Substrate/printed layer/adhesive layer/intermediate substrate/adhesive layer/sealant (3) Substrate/printed layer/adhesive layer/first intermediate substrate/adhesive layer/second intermediate substrate/adhesive layer/sealant

The packaging material contains a polyolefin resin in an amount of 80% by mass or more based on the total mass of the packaging material. The content is more preferably 85% by mass or more, and even more preferably 90% by mass or more. By containing the polyolefin resin in the above range, a molding material having a high ease of separation process and recyclability, good moldability, and usable for various applications can be obtained.
From the viewpoint of recyclability and easy tearing, the substrate, the sealant, and the intermediate substrate used as needed are preferably made of the same material. The substrate, the sealant, and the intermediate substrate used as needed preferably contain a polyolefin resin.
Furthermore, of the total mass of the substrate and sealant, and the intermediate substrate used as needed, the polyolefin resin is preferably 50 mass% or more, more preferably 60 mass% or more, even more preferably 70 mass% or more, even more preferably 80 mass% or more, and particularly preferably 90 mass% or more.
Moreover, the polyolefin resin is more preferably a polypropylene-based resin and/or a polyethylene-based resin, further preferably a polypropylene-based resin, and particularly preferably a polypropylene-based resin that is a copolymer with ethylene and/or butene.

<Chlorine content in packaging materials>
Due to halogen elements that may be contained in the packaging material, halogen gas or hydrogen chloride, an acidic gas, may be generated during pellet production, which may damage equipment or endanger human health. In addition, if bubbles are generated during pellet production, when the pellets are used to produce a molded product, the surface is likely to become uneven, which may deteriorate the surface condition of the molded product. Therefore, the chlorine content in the packaging material is preferably 0.4% by mass or less, more preferably 0.2% by mass or less, even more preferably 0.1% by mass or less, and particularly preferably 0.05% by mass or less, based on the total mass of the packaging material.

(Method for measuring chlorine content in packaging materials)
The chlorine content of the packaging material can be measured by known methods such as ion chromatography (IC) and ICP mass spectrometry (ICP-MS). Specifically, it can be determined by a method similar to the analytical method for the chlorine content described below.

<Base material>
The substrate is preferably in the form of a film or sheet for use as a packaging material, and preferably contains a polyolefin resin.
Furthermore, in the total mass of the base material, the polyolefin resin is preferably 50 mass% or more, more preferably 60 mass% or more, even more preferably 70 mass% or more, even more preferably 80 mass% or more, and particularly preferably 90 mass% or more.
Moreover, the polyolefin resin is more preferably a polypropylene-based resin and/or a polyethylene-based resin, further preferably a polypropylene-based resin, and particularly preferably a polypropylene-based resin that is a copolymer with ethylene and/or butene.

The substrate containing polyolefin resin may be simply a laminate of substrates made of polyolefin resin, or a substrate made of polyolefin resin may be laminated via adhesion or the like. The "substrate made of polyolefin resin" may be a film having properties different from the substrate made of polyolefin resin, and may be of any type. In addition, in the case of a laminated substrate, it may be in a form including an adhesive layer. The method for laminating the substrates is not particularly limited, and may be a conventionally known method such as coextrusion, heat fusion, or pressure bonding via an adhesive layer.

The above-mentioned substrate made of polyolefin resin has high resistance to alkaline aqueous solutions and heat during the molding process compared to ester-based substrates, and is less susceptible to thermal decomposition and hydrolysis, so that the molecular weight can be maintained high during recycling. Furthermore, from the viewpoint of ease of recovery after recycling, examples of the polyolefin substrate include polyethylene such as biaxially oriented polypropylene (OPP), non-oriented polypropylene (CPP), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), acid-modified polyethylene, acid-modified polypropylene, copolymer polypropylene, and films laminated with these. The thickness of the substrate is not particularly limited, and considering the processability into packaging containers, it is preferably 5 μm or more and 150 μm or less, more preferably 10 μm or more and 70 μm or less. Among them, films having heat sealability are preferably used, and CPP and heat-sealable OPP correspond to them.

The substrate is preferably a gas barrier substrate, for example, a plastic substrate having an inorganic vapor deposition layer such as aluminum, silica, or alumina; or a plastic substrate having an organic layer such as an ethylene-vinyl alcohol copolymer or polyvinyl alcohol.

The substrate is preferably in a form that contains additives such as antistatic agents, antifogging agents, and ultraviolet protection agents (coated or kneaded), has an easily adhesive coating layer (e.g., a layer containing polyvinyl alcohol and its derivatives), or has a surface that has been corona-treated or low-temperature plasma-treated. The above-mentioned additions and processing are also carried out for the purpose of improving the wettability of printing inks and other coating agents, or for the purpose of imparting specific functionality to the film. For example, it is also suitably used to provide a packaging material with excellent visibility of the contents by preventing fogging of the packaging material due to moisture.

<Printing layer>
The printed layer in the packaging material is a layer for displaying any design, pattern, character, symbol, etc. for the purpose of providing decoration or aesthetics; displaying the contents, expiration date, and manufacturer or seller, and is not particularly limited. The printed layer may be a solid printed layer. The method for forming the printed layer is not particularly limited, and the printed layer is formed using a printing ink containing a pigment and a binder resin. The printed layer may be a single layer or a multi-layer structure, and may be formed on the surface layer. The thickness of the printed layer is preferably 0.1 to 8 μm, more preferably 0.5 to 4 μm, and particularly preferably 0.8 to 2.5 μm.

(Pigment)
The printed layer in the packaging material preferably contains a pigment and is formed using a printing ink containing the pigment. Considering quality deterioration due to coloring after recycling, the content of the colorant containing the pigment is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 23% by mass or less, based on the total mass of the printed layer. The pigment may be any of organic pigments, inorganic pigments, and extender pigments, but inorganic pigments containing titanium oxide are preferred, and extender pigments such as silica, barium sulfate, kaolin, clay, calcium carbonate, and magnesium carbonate are preferred. Organic pigments made of organic compounds and organometallic complexes are preferred. Colorants such as pigments may be used alone or in combination. Any pigment with a C.I. pigment number may be used.

[Organic pigments]
Examples of the organic pigment include, but are not limited to, soluble azo pigments, insoluble azo pigments, azo pigments, phthalocyanine pigments, halogenated phthalocyanine pigments, anthraquinone pigments, anthanthrone pigments, dianthraquinonyl pigments, anthrapyrimidine pigments, perylene pigments, perinone pigments, quinacridone pigments, thioindigo pigments, dioxazine pigments, isoindolinone pigments, quinophthalone pigments, azomethine azo pigments, flavanthrone pigments, diketopyrrolopyrrole pigments, isoindoline pigments, indanthrone pigments, and carbon black pigments. Further examples include carmine 6B, lake red C, permanent red 2B, disazo yellow, pyrazolone orange, carmine FB, chromophthalic yellow, chromophthalic red, phthalocyanine blue, phthalocyanine green, dioxazine violet, quinacridone magenta, quinacridone red, indanthrone blue, pyrimidine yellow, thioindigo bordeaux, thioindigo magenta, perylene red, perinone orange, isoindolinone yellow, aniline black, diketopyrrolopyrrole red, and daylight fluorescent pigments.

The hue of the organic pigment is preferably at least one selected from the group consisting of black pigments, cyan pigments, green pigments, red pigments, purple pigments, yellow pigments, orange pigments, and brown pigments.More preferably, at least one selected from the group consisting of black pigments, cyan pigments, red pigments, and yellow pigments.Specific examples of organic pigments are shown by C.I. numbers of the Color Index International (abbreviated as C.I.).
Preferably, C.I. Pigment Red 57:1, C.I. Pigment Red 48:1, C.I. Pigment Red 48:2, C.I. Pigment Red 48:3, C.I. Pigment Red 146, C.I. Pigment Red 242, C.I. Pigment Yellow 83, C.I. Pigment Yellow 14, C.I. Pigment Orange 38, C.I. Pigment Orange 13, C.I. Pigment Yellow 180, C.I. Pigment Yellow 139, C.I. Pigment Red 185, C.I. Pigment Red 122, C.I. Pigment Red 178, C.I. Pigment Red 149, C.I. Pigment Red 144, C.I. C.I. Pigment Red 166, C.I. Pigment Violet 23, C.I. Pigment Violet 37, C.I. Pigment Blue 15, C.I. Pigment Blue 15:1, C.I. Pigment Blue 15:2, C.I. Pigment Blue 15:3, C.I. Pigment Blue 15:4, C.I. Pigment Blue 15:6, C.I. Pigment Green 7, C.I. Pigment Orange 34, C.I. Pigment Orange 64, C.I. Pigment Black 7.

[Inorganic pigments]
Examples of inorganic pigments include titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, silica, aluminum particles, mica, bronze powder, chrome vermilion, yellow lead, cadmium yellow, cadmium red, ultramarine, Prussian blue, red iron oxide, yellow iron oxide, iron black, titanium oxide, and zinc oxide. Aluminum can be of leafing or non-leafing type, with the non-leafing type being preferred.

(Binder resin)
The binder resin refers to the binding resin in the printing layer of the packaging material, and as described below, the chlorine content in the total binder resin is preferably 5 mass % or less, more preferably 3 mass % or less, and even more preferably 1 mass % or less.

The binder resin is preferably a thermoplastic resin that is soluble in an organic solvent. It is preferable to use a resin having a glass transition temperature of -60°C or more and less than 40°C in combination with a resin having a glass transition temperature of 40°C or more and 200°C or less. It is more preferable to use a resin having a glass transition temperature of -50°C or more and 0°C or less in combination with a resin having a glass transition temperature of 50°C or more and 190°C or less. In this specification, the glass transition temperature is a value measured by a differential scanning calorimeter (DSC). The resin is mainly a urethane resin. The resin may be a polyvinyl acetal resin, a cellulose ester resin, a rosin resin, or the like, with polyvinyl acetal resin being preferred.

Examples of binder resins include, but are not limited to, polyether-based urethane resins, polyester-based urethane resins, cellulose-based resins, polyamide resins, rosin-based resins, ethylene-vinyl acetate copolymer resins, vinyl chloride-vinyl acetate copolymer resins, vinyl acetate resins, acrylic resins, styrene resins, dammar resins, styrene-maleic acid copolymer resins, polyester resins, alkyd resins, terpene resins, phenol-modified terpene resins, ketone resins, cyclized rubbers, polyvinyl acetal resins, petroleum resins, and modified resins thereof. These resins can be used alone or in combination of two or more. Among the above, it is preferable that the binder resin does not substantially contain vinyl chloride-vinyl acetate copolymer resins, more preferably contains a urethane resin, and even more preferably contains a polyester-based urethane resin (B).

[Polyester-based urethane resin (B)]
The polyester-based urethane resin (B) used in the present invention refers to a urethane resin having structural units derived from polyester, preferably having a urea bond.
It is preferable that the polyester-based urethane resin (B) contains polyester-derived structural units in an amount of 40 mass% or more, more preferably 50 mass% or more, even more preferably 60 mass% or more, and particularly preferably 65 mass% or more, of the total mass of the polyester-based urethane resin (B).
The polyester-based urethane resin (B) is not limited to the following, but examples thereof include a polyester-based urethane resin obtained by reacting a urethane prepolymer obtained by reacting a polyisocyanate with a polyol including a polyester polyol, and then reacting the urethane prepolymer with a polyamine (chain extender) and, if necessary, a reaction terminator. In order to obtain a urethane resin having a polyester-derived structural unit, for example, a method of using a polyester polyol as the polyol in the above-mentioned urethane resin synthesis method can be used, but is not particularly limited.

<Polyester polyol>
The number average molecular weight of the polyester polyol is preferably 500 to 10,000, more preferably 1,000 to 5,000. Here, the number average molecular weight is calculated from the hydroxyl value, and the hydroxyl value is a value calculated by esterifying or acetylating the hydroxyl groups in the resin, back titrating the remaining acid with an alkali, and converting the amount of hydroxyl groups in 1 g of resin into mg of potassium hydroxide, measured according to JIS K0070. When the number average molecular weight of the polyester polyol is 10,000 or less, the printing layer has excellent blocking resistance to the plastic film. In addition, when the number average molecular weight of the polyester polyol is 500 or more, the flexibility of the printing layer is improved, and the adhesion to the plastic film is excellent.

The polyester polyol is preferably a polyester diol, which is a condensation product of a diol and a dicarboxylic acid (also called a dibasic acid). The polyester polyol may be used alone or in a mixture of two or more kinds.

Suitable examples of the dicarboxylic acid include adipic acid, phthalic anhydride, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, pimelic acid, azelaic acid, sebacic acid, suberic acid, glutaric acid, 1,4-cyclohexyldicarboxylic acid, dimer acid, and hydrogenated dimer acid, with adipic acid, succinic acid, and sebacic acid being preferred. Furthermore, a polyol having three or more hydroxyl groups and a polycarboxylic acid having three or more carboxyl groups can also be used in combination as raw materials for the polyester polyol.

Suitable examples of the diol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-methyl-1,3-propanediol, 3,3,5-trimethylpentanediol, 2,4-diethyl-1,5-pentanediol, 1,12-octadecanediol, 1,2-alkanediol, 1,3-alkanediol, 1-monoglyceride, 2-monoglyceride, 1-monoglycerin ether, 2-monoglycerin ether, dimer diol, and hydrogenated dimer diol. Among these, polyester diols, which are condensates of diols containing branched diols and dicarboxylic acids, are preferred. It may also be a polyester diol obtained by a ring-opening reaction of a cyclic ester (such as a lactone).

The diols can be classified into linear diols and branched diols.
The linear diol is a diol having two or more atoms, such as alkylene glycol, dialkylene glycol, trialkylene glycol, etc. The branched diol is a diol in which at least one hydrogen atom of the hydrocarbon group of an alkylene glycol is substituted with an atom other than a hydrogen atom.

Since the linear diol imparts crystallinity and the branched diol imparts flexibility, the polyurethane resin as a binder resin, by achieving a balance between these, makes the ink film tough and can impart high lamination strength and easy tearability to the ink film. It is believed that the polyurethane resin containing a branched diol structure and/or a linear diol structure is also effective in improving the efficiency of recycling packaging materials. As described below, it is more preferable that the polyurethane resin contains both a branched diol structure and a linear diol structure.

The branched diols include 2-butyl-2-ethyl-1,3-propanediol (hereinafter also referred to as BEPG), 2-methyl-1,3-propanediol (hereinafter also referred to as MPO), 3-methyl-1,5-pentanediol (hereinafter also referred to as MPD), neopentyl glycol (hereinafter also referred to as NPG), 1,2-propylene glycol (hereinafter also referred to as PG), 2,4-diethyl-1,5-pentanediol, 1,3-butanediol, dipropylene glycol, etc., and at least one branched diol selected from NPG and PG is particularly preferred.

The linear diol is preferably an alkylene glycol, and examples thereof include ethylene glycol (also described as EG), diethylene glycol, 1,3-propanediol (also described as 1,3PD), 1,4-butanediol (also described as 1,4BD), 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,4-butynediol, 1,4-butylenediol, diethylene glycol, and triethylene glycol.
Among these, preferred are linear diols having 8 or less carbon atoms, preferably 6 or less carbon atoms, such as EG, 1,3PD, 1,4BD, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, etc. Furthermore, from the viewpoint of physical properties, 1,3PD is particularly preferred.

When the polyester polyol contains a branched diol and a linear diol, from the viewpoint of laminate strength, the mass ratio of the branched diol and the linear diol in the total diols of the polyester polyol (branched diol: linear diol) is preferably 10:90 to 90:10, more preferably 20:80 to 80:20, and even more preferably 30:70 to 70:30.

The branched diol units and linear diol units may each be present in one polyester polyol, or a polyester polyol containing only branched diol units and a polyester polyol containing only linear diol units may be used as a mixture raw material to produce a biomass urethane resin. Approximately the same effect can be obtained.

Among these, preferred examples of polyester polyols include those containing adipic acid, succinic acid, sebacic acid or other dibasic acid, and both branched and linear diols. This improves the laminate strength of the packaging material.

Other polyols
The polyol may include polyols other than polyester polyols. For example, polyether polyols, polycarbonate polyols, and polyolefin polyols can be used.

<Polyisocyanate>
The polyisocyanate is preferably a diisocyanate, and various known aromatic, aliphatic, or alicyclic diisocyanates can be used, such as 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2,2,4-trimethylsilyl diisocyanate, 1,3-diphenylmethane diisocyanate, 1,4-diphenyldimethylmethane ... Representative examples include methylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, lysine diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanatemethyl)cyclohexane, methylcyclohexane diisocyanate, m-tetramethylxylylene diisocyanate, and dimer diisocyanate in which the carboxyl group of a dimer acid is converted to an isocyanate group. These can be used alone or in combination of two or more. Among them, isophorone diisocyanate, tolylene diisocyanate, and 4,4'-diphenylmethane diisocyanate are preferred, and isophorone diisocyanate is more preferred from the viewpoint of solubility.

Chain extender
The chain extender is preferably a polyamine. The polyamine is preferably an organic diamine, and examples thereof include, but are not limited to, ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, and dicyclohexylmethane-4,4'-diamine. In addition, amines having a hydroxyl group in the molecule, such as 2-hydroxyethylethylenediamine, 2-hydroxyethylpropyldiamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine, can also be used. These organic diamines can be used alone or in combination of two or more, with isophoronediamine being preferred. Furthermore, polyfunctional amines having three or more amino groups, such as diethylenetriamine, iminobispropylamine (IBPA, 3,3'-diaminodipropylamine), N-(3-aminopropyl)butane-1,4-diamine (spermidine), 6,6-iminodihexylamine, 3,7-diazanonane-1,9-diamine, and N,N'-bis(3-aminopropyl)ethylenediamine, can also be used in combination with the above organic diamines.

<Reaction stopper>
In the case of a urethane resin that can be produced only by the urethanization step, it is preferable to use a monoalcohol or a monoamine as the reaction terminator, and in the case of a urethane resin that is produced by carrying out a urethanization reaction step in addition to the urethanization step, it is preferable to use a monoamine.
The monoalcohol is preferably a substituted or unsubstituted alcohol, and suitable examples thereof include methanol, ethanol, n-propanol, isopropyl alcohol, 1-butanol, etc. The monoamine is preferably a substituted or unsubstituted monoamine, and suitable examples thereof include n-butylamine, n-dibutylamine, octylamine, diethylamine, monoethanolamine, monopropanolamine, diethanolamine, dipropanolamine, etc. In addition, the compounds listed as the chain extenders can also be used as the reaction terminator, and at least one of them may be used, or two or more of them may be used in combination.

In the above-mentioned production of a urethane prepolymer having isocyanate groups at its terminals obtained by reacting a polyisocyanate with a polyol, the molar equivalent ratio of NCO of the polyisocyanate to OH of the polyol (molar equivalent of NCO of the polyisocyanate/molar equivalent of OH of the polyol compound) is preferably 1.3 to 3, and more preferably 1.5 to 2.

The polyester-based urethane resin (B) and other urethane resins preferably have active hydrogen groups such as hydroxyl groups and/or amino groups. When the resin has a hydroxyl group, the hydroxyl value is preferably 0.5 to 30 mgKOH/g, more preferably 1 to 20 mgKOH/g, and even more preferably 2 to 15 mgKOH/g. When the resin has an amino group, the amine value is preferably 0.1 to 15 mgKOH/g, and even more preferably 1 to 12 mgKOH/g. On the other hand, the acid value of the urethane resin is preferably 5 mgKOH/g or less, and even more preferably 3 mgKOH/g or less. This is because the acid value does not contribute to the reaction with the isocyanate-based curing agent described later.

The weight average molecular weight of the polyester-based urethane resin (B) and other urethane resins is preferably 20,000 to 100,000, more preferably 25,000 to 90,000, and even more preferably 30,000 to 80,000. This is to make the printed layer into a strong film by crosslinking with the isocyanate-based curing agent described below, and to impart easy tearability.
In the present invention, the weight average molecular weight and the molecular weight distribution (Mw/Mn) described later can be measured by gel permeation chromatography (GPC). As an example, Water2690 (manufactured by Waters Corporation) or HLC-8220 (manufactured by Tosoh Corporation) can be used as a GPC device, and PLgel, 5 μm, MIXED-D (manufactured by Polymer Laboratories), TSKgelSuperAW series (manufactured by Tosoh Corporation), TSKgelSuperH series (manufactured by Tosoh Corporation), or the like can be used as a column. Tetrahydrofuran, 1,2,4-trichlorobenzene, N,N-dimethylformamide (with 0.01N lithium bromide added), or the like can be used as a developing solvent, and the flow rate is preferably 0.5 to 1.5 milliliters/minute. An RI detector or the like can be used for detection, and measurement can be performed under conditions such as a sample injection concentration of 0.5 to 1.5 milligrams/milliliter, an injection amount of 0.1 to 1.0 microliter, etc. The weight average molecular weight can be calculated as a polystyrene equivalent value.

The molecular weight distribution (Mw/Mn) of the polyester urethane resin (B) and other urethane resins is preferably 2.0 to 8.0, more preferably 2.5 to 7.0, and even more preferably 3.0 to 6.0. Mw represents the weight average molecular weight, and Mn represents the number average molecular weight. When Mw/Mn is within the above range, it is believed that the cohesive force and adhesive force are strengthened by crosslinking with the isocyanate curing agent described below, resulting in easy tearing properties. Note that Mw, Mn, and Mw/Mn can be determined by gel permeation chromatography (GPC) as described above.

In order to make the molecular weight distribution (Mw/Mn) of the polyester-based urethane resin (B) and other urethane resins fall within the above range, a method can be selected in which the selection of urethane synthesis raw materials, the solid content mass ratio, the dripping speed of reactive raw materials such as polyisocyanate in the synthesis reaction, the stirring speed and the shape of the stirring blade, and the reaction temperature are appropriately set in the synthesis of the urethane resin. In addition, when a chain extension reaction is performed, it is effective to set the dripping speed and temperature range control in a certain range when reacting polyamine with urethane prepolymer in order to make the molecular weight distribution fall within a predetermined range. Reaction temperature control is important, and it is preferable to control it between 50 and 130°C in the synthesis of urethane prepolymer, and it is preferable to control it to the range of 10 to 50°C when reacting polyamine with urethane prepolymer.
In addition, setting the charging ratio of the reaction raw materials to an appropriate ratio is also effective in keeping the molecular weight distribution within a predetermined range. Examples of the charging ratio include the NCO/OH ratio, which is the ratio of the hydroxyl groups of the polyol and hydroxy acid, and the isocyanate groups of the polyisocyanate, and the amino group/NCO ratio, which is the ratio of the amino group of the polyamine and the isocyanate group of the urethane prepolymer. In order to control the molecular weight distribution, it is preferable to use a reaction terminator such as the above for the purpose of preventing excessive polymerization reaction.

[Resin L]
When the binder resin contains a urethane resin, the binder resin preferably further contains a resin other than the urethane resin (referred to as resin L). The resin L is preferably at least one resin selected from the group consisting of polyvinyl acetal resin, cellulose-based resin, rosin-based resin, and acrylic resin. More preferably, it is a resin having a ring structure, even more preferably, it is a resin having at least one ring structure selected from the group consisting of an acetal ring structure, an aromatic ring structure, an alicyclic ring structure, and a pyranose ring structure, and particularly preferably, it is a resin having an acetal ring structure. These ring structures may have a double bond, or may have an alkyl group or other substituent.

Resin L preferably contains 40 to 95% by mass, and more preferably 50 to 90% by mass, of structural units having a ring structure based on the mass of resin L.
When the resin L contains a structural unit having a ring structure in the above range, the pigment dispersion in the printing ink is promoted, the lamination strength of the packaging material is excellent, deterioration over time can be suppressed, and blocking resistance is also excellent.
In this specification, the mass of the monomer having a ring structure includes groups substituted or adjacent to the ring structure, such as a methyl group or a nitro group. For example, when resin L is a styrene-acrylic resin and contains 50% by mass of structural units derived from α-methylstyrene and 50% by mass of structural units derived from butyl methacrylate, an acrylic monomer, the content of the ring structure is 50% by mass.

The content of the structural unit having a ring structure may be calculated according to the following formula.
Formula: Content of structural units having a ring structure (% by mass)
= Mass of monomer having a ring structure × 100 / Total mass of all monomers constituting resin L

Examples of resins having a ring structure include polyvinyl acetal resin, cellulose ester resin, rosin resin, polystyrene resin, polyester resin having a ring structure, acrylic resin having a ring structure, and copolymer resins thereof. More preferably, the resin contains at least one selected from the group consisting of polyvinyl acetal resin, cellulose ester resin, rosin resin, and acrylic resin having a ring structure. Even more preferably, the resin contains polyvinyl acetal resin.

<Polyvinyl acetal resin>
The polyvinyl acetal resin is an acetal cyclized product of reacting polyvinyl alcohol with an aldehyde such as butyraldehyde and/or formaldehyde, and preferably contains vinyl alcohol units, vinyl acetate units, and an acetal ring group. The polyvinyl acetal resin preferably contains 60 to 90% by mass of acetal rings, 5 to 30% by mass of vinyl alcohol units, and 0.5 to 10% by mass of vinyl acetate units, and is more preferably a polyvinyl butyral resin having a butyral ring as the acetal ring.
The weight average molecular weight of the polyvinyl acetal resin is preferably 10,000 to 100,000, and more preferably 10,000 to 80,000. The glass transition point of the polyvinyl acetal resin is preferably 50 to 80°C, and more preferably 60 to 75°C.

<Cellulose ester resin>
The cellulose ester resin is preferably a cellulose acetate alkylate resin, and for example, cellulose acetate propionate and cellulose acetate butyrate are suitably used.
The cellulose ester resin preferably has an alkyl group. The alkyl group is preferably an alkyl group having 10 or less carbon atoms, and for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a pentyl group, or a hexyl group is preferably used. The alkyl group may have a substituent.
The weight average molecular weight of the cellulose ester resin is preferably 5,000 to 200,000, more preferably 10,000 to 10,000, and further preferably 15,000 to 80,000. The glass transition point of the cellulose ester resin is preferably 120° C. to 180° C., and more preferably 130° C. to 170° C.
The combined use of urethane resin and cellulose ester resin improves printability, blocking resistance, and the like.

<Rosin resin>
The rosin resin refers to a resin having a structural unit derived from a rosin acid (e.g., abietic acid, neoabietic acid, palustric acid, pimaric acid, isopimaric acid, dehydroabietic acid) as a main component. Here, the main component means 50% by mass or more. The rosin acid or rosin resin may be hydrogenated.
The rosin resin is preferably at least one selected from the group consisting of rosin-modified phenolic resins, rosin ester resins, rosin-modified maleic acid resins, and polymerized rosin resins.
The acid value of the rosin resin is preferably 350 mgKOH/g or less, more preferably 250 mgKOH/g or less, and further preferably 150 mgKOH/g or less.
In one embodiment, the acid value is preferably 100 mgKOH/g or less, and more preferably 50 mgKOH/g or less.
The softening point of the rosin resin is preferably 60 to 180° C., and more preferably 70 to 150° C. In this specification, the softening point is a value measured by the ring and ball method, and can be measured in accordance with JIS K2207.

<Rosin ester>
The rosin resin is preferably a rosin ester, which is an ester condensation resin of a low molecular weight polyol having a molecular weight of 1,000 or less and a rosin acid. The low molecular weight polyol preferably has 2 to 4 hydroxyl groups in one molecule (hereinafter sometimes abbreviated as bifunctional to tetrafunctional) and a molecular weight of 50 to 500. As such a low molecular weight polyol, for example, bifunctional low molecular weight polyols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,10-decanediol, etc.; trifunctional low molecular weight polyols such as glycerin and trimethylolpropane; and tetrafunctional low molecular weight polyols such as erythritol and pentaerythritol are preferably used. Among them, trifunctional and/or tetrafunctional low molecular weight polyols are preferred.
The weight average molecular weight of the rosin ester is preferably 500 to 2,000, and more preferably 500 to 1,500.

<Acrylic resin>
As the acrylic resin, an acrylic resin having a glass transition temperature of 40 to 100° C. is preferably used.

In this specification, "acrylic resin" refers to a polymer having an acrylic monomer as a constituent unit. Furthermore, "acrylic monomer" refers to a monomer having an acrylic group or a methacryloyl group, and "methacrylic and acrylic" are sometimes collectively abbreviated as "(meth)acrylic". Furthermore, "methacrylate and acrylate" are sometimes collectively abbreviated as "(meth)acrylate".

The acrylic monomers constituting the acrylic resin are listed below, but these are examples of the embodiment and are not particularly limited. The acrylic monomers may be used alone or in combination of two or more types.

Examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, methylcyclohexyl (meth)acrylate, bornyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, tetradecyl (meth)acrylate, hexadecyl (meth)acrylate, and octadecyl (meth)acrylate. Of these, methyl (meth)acrylate is preferred.

For example, an aromatic ring-containing acrylic monomer can be used to obtain an acrylic resin having the above ring structure. Examples of aromatic ring-containing acrylic monomers include phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxymethyl (meth)acrylate, phenoxyethyl (meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate.

The glass transition temperature (Tg) of the acrylic resin is in the range of 40 to 100°C, preferably 40 to 90°C, and more preferably 40 to 80°C.

The weight average molecular weight (Mw) of the acrylic resin is preferably 20,000 to 300,000.

[Chlorine content of binder resin]
The chlorine content of the binder resin in the present invention is preferably 5% by mass or less, including the case where it is 0. The chlorine content is more preferably 4% by mass or less, further preferably 3% by mass or less, and particularly preferably 2% by mass or less. In addition, an embodiment in which it is 1% by mass or less or 0.5% by mass or less is particularly preferred. The chlorine content is the content (% by mass) of chlorine atoms based on the mass of the binder resin.
If the chlorine content is 5 mass % or less, the composition is excellent in environmental safety and is less likely to generate free chlorine.

The chlorine content can be measured by known methods such as ion chromatography (IC) and ICP mass spectrometry (ICP-MS). Examples of measuring instruments include LC-20ADsp manufactured by Shimadzu Corporation for IC and Agilent 7700x manufactured by Agilent Technologies for ICP-MS. The chlorine content of the printed layer can be calculated simply from the chlorine content of each raw material constituting the printed layer using the following formula. The same applies to each of the other layers.
Formula: Chlorine content (%) in total mass of binder resin solid content = mass of chlorine in total mass of binder resin solid content / total mass (%) of binder resin solid content
Formula: Chlorine content (%) in the total mass of solids in the printed layer = mass of chlorine in the total mass of solids in the printed layer / total mass of solids in the printed layer (%)

In the present invention, the chlorine content is preferably measured in accordance with JIS K0127 (2013). In this measurement method, a sample pretreated by the combustion method is quantified by ion chromatography.

[Degree of nitrification of binder resin]
The binder resin in the present invention preferably has a degree of nitration of 1 mass % or less, including the case where it is 0. By having a degree of nitration of 1 mass % or less, NOx gas generation can be suppressed, and a safer recycled material can be provided.
The degree of nitrification is the degree of esterification of nitric acid esters expressed as the nitrogen content (mass %). For example, commercially available nitrocellulose usually has a nitrogen content of 10 to 12 mass %.
The degree of nitration of the binder resin is more preferably 0.6% by mass or less, further preferably 0.4% by mass or less, and particularly preferably 0.2% by mass or less.
The nitrification degree of the urethane resin is preferably 0.3% by mass or less, more preferably 0.2% by mass or less, and even more preferably 0.1% by mass or less. The nitrification degree of the resin L is preferably 0.8% by mass or less, more preferably 0.6% by mass or less, and even more preferably 0.4% by mass.

(Isocyanate-based hardener)
In the packaging material of the present invention, in order to improve the laminate properties and tearability, the printing ink used to form the printed layer preferably contains an isocyanate-based curing agent. When the binder resin has a hydroxyl group, an amino group, or other active hydrogen group, the isocyanate-based curing agent crosslinks with the active hydrogen group, and when the binder resin does not have the active hydrogen group, the isocyanate-based curing agent crosslinks with itself only with the isocyanate-based curing agent, which is considered to improve the laminate strength, tearability, etc.

The following are preferred embodiments of the isocyanate-based curing agent. The weight average molecular weight of the isocyanate-based curing agent is preferably 800 to 8000, more preferably 1000 to 4500, and even more preferably 1500 to 4000. The molecular weight distribution (Mw/Mn) of the isocyanate-based curing agent is preferably 2.0 to 5.0, more preferably 2.2 to 4.5, and even more preferably 2.5 to 4.0. When the weight average molecular weight and furthermore Mw/Mn are within the above ranges, it is believed that the cohesive force and adhesive force of the printing ink are strengthened by the action with the urethane resin, resulting in good laminate strength and easy tearability.

Suitable isocyanate-based curing agents include polyisocyanates including adduct-type polyisocyanates (adduct bodies), biuret-type polyisocyanates (biuret bodies), isocyanurate-type polyisocyanates (isocyanurate bodies), and bifunctional polyisocyanates. Examples of adduct bodies, biuret bodies, and isocyanurate bodies include adduct bodies obtained by reacting trimethylolpropane or other polyols with diisocyanates, biuret bodies in which diisocyanates are dimerized and linked by biuret bonds, and isocyanurates obtained by the cyclic trimerization reaction of diisocyanates. The diisocyanate may be selected from the above diisocyanates, and among them, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hydrogenated diphenylmethane diisocyanate (hydrogenated MDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate, xylylene diisocyanate (XDI), hydrogenated xylylene diisocyanate (hydrogenated XDI), etc. may be preferably used. Adduct type polyisocyanate, biuret type polyisocyanate, and isocyanurate type polyisocyanate may be used in combination, and may also be used in combination with other polyisocyanates.

In order to set the weight average molecular weight and molecular weight distribution (Mw/Mn) of the isocyanate-based curing agent within the above range, it is possible to set the range by appropriately selecting diisocyanate, polyol, etc., the solid content mass ratio, the dripping speed of reactive raw materials such as polyisocyanate in the synthesis reaction, the stirring speed, the shape of the stirring blade, and the reaction temperature in the synthesis reaction. It is also effective to set the dripping speed and temperature range in a certain range when reacting polyamine with polyisocyanate in order to set the molecular weight distribution within the specified range.
In addition, it is effective to set the molecular weight distribution within a predetermined range by setting the charging ratio of the reaction raw materials to an appropriate ratio. Examples of the charging ratio include the NCO/OH ratio, which is the ratio of the isocyanate groups of the polyol and the polyisocyanate, and the amino group/NCO ratio, which is the ratio of the amino group of the polyamine and the isocyanate group of the polyisocyanate. Reaction temperature control is important, and in synthesis using a polyol and a polyisocyanate, it is preferable to control it between 50 and 130°C, and in the reaction of a polyamine and a polyisocyanate, it is preferable to control it within the range of 10 to 50°C. In addition, the solid content is also important, and it is preferable to set the solid content during the reaction to 40 to 80 mass%. The reaction solvent is also important, and it is preferable to use ethyl acetate, normal propyl acetate, or other ester-based organic solvents.

When the binder resin contains a urethane resin, the mass ratio of the urethane resin to the isocyanate-based curing agent (urethane resin:isocyanate-based curing agent) is preferably 99:1 to 60:40, more preferably 98:2 to 65:35, and even more preferably 95:5 to 70:30. When the binder resin contains resin L in addition to the urethane resin, the mass ratio of the total amount of the urethane resin and resin L to the isocyanate-based curing agent is preferably 99:1 to 60:40, and even more preferably 95:5 to 70:30. This is because it is believed that within this range, the effects of the crosslinking and substrate adhesion are good, and good laminate properties and easy tearing properties are exhibited.

(Organic Solvent)
The printing ink used to form the printing layer preferably contains an organic solvent as a liquid medium. The organic solvent used in the ink is preferably used as a mixed solvent, and known organic solvents such as aromatic organic solvents such as toluene and xylene, ketone organic solvents such as methyl ethyl ketone and methyl isobutyl ketone, ethyl acetate, n-propyl acetate, isopropyl acetate, isobutyl acetate, ester organic solvents, and alcohol organic solvents such as methanol, ethanol, n-propanol, isopropanol, and n-butanol can be used. Among them, organic solvents that do not contain aromatic organic solvents such as toluene and xylene (non-toluene organic solvents) are more preferred. More preferred are organic solvents that do not contain aromatic organic solvents and/or ketone organic solvents such as methyl ethyl ketone (hereinafter referred to as "MEK"), and preferably contain an ester organic solvent as the main component (50% or more) in the organic solvent. In particular, those containing an ester organic solvent and an alcohol organic solvent are preferred.

(Additives)
The printing ink used to form the printed layer may further contain any additives as necessary, such as a leveling agent, an antifoaming agent, a wax, a silane coupling agent, a filler, a stabilizer, a plasticizer, an antioxidant, a light stabilizer such as an ultraviolet absorber, a dispersant, a thickener, a drying agent, a lubricant, an antistatic agent, and a crosslinking agent.

(gravure printing)
The printing ink used to form the printed layer is preferably a gravure ink or a flexographic ink, more preferably a gravure ink. The printed layer is preferably formed by a gravure printing method or a flexographic printing method, more preferably by a gravure printing method.

(Photogravure version)
In the gravure printing method, the gravure plate is a cylindrical metal plate, and recesses for each color are created by engraving, etching, or laser. There are no restrictions on the use of engraving and laser, and they can be set arbitrarily according to the pattern. Lines per page are appropriately set to 100 to 300 lines, and the higher the line number, the finer the printing. The thickness of the printing layer is preferably 0.1 μm to 100 μm.

(Gravure printing machine)
In the gravure printing method, one printing unit in the gravure printing machine is equipped with the gravure plate and doctor blade. There are many printing units, and printing units corresponding to organic solvent-based printing inks and picture inks can be set, and each unit has an oven drying unit. Printing is performed by rotary printing, and a roll-up printing method is used. The type of plate and the type of doctor blade are appropriately selected according to the specifications.

<Adhesive layer>
The adhesive layer in the present invention comprises a cured product of a reactive adhesive containing a polyol compound (D) and an isocyanate compound (I).

(Polyol Compound (D))
The polyol compound (D) is not particularly limited, and examples thereof include polyester polyols, polyether polyols, polyurethane polyols, polyesteramide polyols, acrylic polyols, polycarbonate polyols, polycaprolactone polyols, polyvalerolactone polyols, polyolefin polyols, polyhydroxyalkanes, 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 butyl 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. These may be used alone or in combination of two or more kinds.

The polyol compound (D) preferably contains a structural unit derived from a polyester polyol or a structural unit derived from a polyether polyol. It may also be a polyester polyol or a polyether polyol itself. Of these, it is preferable that the polyol compound (D) is a urethane polyol containing a urethane structure.

The polyester polyols include dibasic acids such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, phthalic anhydride, adipic acid, azelaic acid, sebacic acid, succinic acid, glutaric acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, maleic anhydride, itaconic anhydride, or their dialkyl esters or mixtures thereof (hereinafter also referred to as carboxyl group components), and ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, butylene glycol, neopentyl glycol, dineopentyl glycol, trimethylolpropane, glycerin, 1,6-hexanediol, 1,4-butanediol, 1,5-dimethylphenylsilyl, 1,6-dimethylphenylsilyl, 1,7-dimethylphenylsilyl, 1,8-dimethylphenylsilyl, 1,9-dimethylphenylsilyl, 1,10-dimethylphenylsilyl, 1,2-dimethylphenylsilyl, 1,2-dimethylphenylsilyl, 1,3-dimethylphenylsilyl, 1,4-dimethylphenylsilyl, 1,5-dimethylphenylsilyl, 1,6 ... , 4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, 3,3'-dimethylolheptane, 1,9-nonanediol, polyoxyethylene glycol, polyoxypropylene glycol, polytetramethylene ether glycol, polyether polyol, polycarbonate polyol, polyolefin polyol, acrylic polyol, polyurethane polyol, or a mixture thereof (hereinafter also referred to as a hydroxyl group component) is subjected to an esterification reaction; polyester polyol obtained by ring-opening polymerization of lactones such as polycaprolactone, polyvalerolactone, and poly(β-methyl-γ-valerolactone); and the like. The above carboxyl group component and hydroxyl group component may be used in combination of two or more kinds.

The polyether polyols include polyether diols and polyether triols, such as polyether diols obtained by polymerizing oxirane compounds such as ethylene oxide, propylene oxide, butylene oxide, and tetrahydrofuran with bifunctional low molecular weight polyols such as water, ethylene glycol, and propylene glycol as an initiator; and polyether triols obtained by polymerizing oxirane compounds such as ethylene oxide, propylene oxide, butylene oxide, and tetrahydrofuran with low molecular weight triols such as trimethylolpropane and glycerin as an initiator.

The polyol compound (D) containing a structural unit derived from a polyester polyol or a structural unit derived from a polyether polyol may be a polyester urethane polyol or a polyether urethane polyol obtained by further reacting the polyester polyol or the polyether polyol with a diisocyanate, or may be a polyol obtained by further reacting the polyester polyol or the polyether polyol with an acid anhydride.
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.
Examples of the acid anhydride include pyromellitic anhydride, mellitic anhydride, trimellitic anhydride, and trimellitic ester anhydride. Examples of the trimellitic ester anhydride include ethylene glycol bisanhydrotrimellitate and propylene glycol bisanhydrotrimellitate.

The weight average molecular weight (Mw) of the polyol compound (D) is preferably from 2,000 to 80,000, more preferably from 5,000 to 60,000, and further preferably from 10,000 to 60,0000.
Furthermore, by using a polyol compound (D) having a molecular weight distribution (Mw/Mn) of 1.5 to 10, the leveling property during adhesive application and the adhesion between layers can be improved. In particular, when the polyol compound contains a structural unit derived from a polyether polyol, the molecular weight distribution (Mw/Mn) is preferably 3.0 to 10.0, more preferably 3.0 to 8.0. When the polyol compound contains a structural unit derived from a polyester polyol, the molecular weight distribution (Mw/Mn) is preferably 1.5 to 5.0, more preferably 2.0 to 4.0.

The acid value of the polyol compound (D) is not particularly limited, but is preferably 0 to 50 mgKOH/g, more preferably 0 to 40 mgKOH/g. The hydroxyl value of the polyol compound (D) is not particularly limited, but is preferably 1 to 200 mgKOH/g, more preferably 3 to 150 mgKOH/g.

(Isocyanate Compound (I))
The isocyanate compound (I) functions as a curing agent in the reactive adhesive, and can be used without any limitation as long as it is for use in a normal two-liquid reactive adhesive and contains a functional group reactive with a hydroxyl group. By having an isocyanate group, the adhesive strength and cohesive force are increased, and the adhesive can be cured at a low temperature around room temperature.

As the isocyanate compound (I), diisocyanates or urethane prepolymers which are reaction products of diisocyanates and polyols are preferred, and as such diisocyanates, various known aromatic, aliphatic or alicyclic diisocyanates can be used. For example, 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2,2,4-trimethylsilyl diisocyanate, 1,5-naphthylene ... Representative examples include methylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, lysine diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanatemethyl)cyclohexane, methylcyclohexane diisocyanate, m-tetramethylxylylene diisocyanate, and dimer diisocyanate in which the carboxyl group of a dimer acid is converted to an isocyanate group. These can be used alone or in combination of two or more kinds.
Among these, from the viewpoints of preventing yellowing and imparting flexibility for improving adhesion, it is preferable to use aliphatic diisocyanates such as hexamethylene diisocyanate and xylylene diisocyanate, and alicyclic diisocyanates such as isophorone diisocyanate, and from the viewpoints of compatibility with retort resistance, it is preferable to use an adduct such as trimethylolpropane, an isocyanurate, a biuret, or another polyisocyanate compound having three or more functional groups.

In one embodiment, the polyol compound (D) and the isocyanate compound (I) are preferably used so that the functional group equivalent ratio NCO/OH of the hydroxyl group derived from the polyol and the isocyanate group derived from the isocyanate is 1.5 to 8.0, and more preferably 2.0 to 5.0.
In the reactive adhesive, other components known for use in adhesives can be blended in the base agent or curing agent.

(Reaction accelerator)
The reactive adhesive may contain, for example, a reaction accelerator. Examples of reaction accelerators 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; reactive tertiary amines such as triethanolamine; titanium-based, zinc-based, and bismuth-based. These may be used alone or in any combination of two or more. Among them, titanium, zinc-based, and bismuth-based are preferred because they provide excellent aging effects and content resistance of the adhesive.

(Silane coupling agent)
The reactive adhesive may contain a silane coupling agent from the viewpoint of improving the adhesive strength to metal-based materials such as inorganic vapor deposition layers and metal foils. Examples of the silane coupling agent include trialkoxysilanes having a vinyl group, such as vinyltriethoxysilane and vinyltriethoxysilane; trialkoxysilanes having an amino group, such as 3-aminopropyltriethoxysilane and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane; and trialkoxysilanes having a glycidyl group, such as 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane. These may be used alone or in any combination of two or more.
The content of the silane coupling agent is preferably 0.01 to 5% by mass, more preferably 0.02 to 3% by mass, based on the total polyol component. By setting the content within the above range, the adhesive strength to the inorganic vapor deposition layer or metal foil can be improved.

(Phosphoric acid or phosphoric acid derivative)
The reactive adhesive may contain phosphoric acid or a phosphoric acid derivative from the viewpoint of improving the adhesive strength to metal-based materials such as metal foil. The phosphoric acid may be any one having at least one free oxygen acid, and examples thereof 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-mentioned 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. These may be used alone or in any combination of two or more.
The content of phosphoric acid or a derivative thereof is preferably 0.01 to 10 mass %, more preferably 0.05 to 5 mass %, and even more preferably 0.05 to 1 mass %, based on the solid content of the reactive adhesive.

(Leveling agent, defoamer)
The reactive adhesive may contain a known leveling agent or defoaming agent for the purpose of improving 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 resins, silicone solutions, and copolymers of alkyl vinyl ethers, alkyl acrylates, and alkyl methacrylates. These can be used alone or in any combination of two or more.
The content of the leveling agent and the defoaming agent is preferably 0.001 to 1 mass %, more preferably 0.005 to 0.5 mass %, based on the solid content of the reactive adhesive.

(Other additives)
Various additives may be blended into the reactive adhesive as long as they do 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.

(Organic Solvent)
The reactive adhesive may be diluted with a solvent to adjust the viscosity to an appropriate level. As the organic solvent used in the reactive adhesive, those that are inactive against the polyisocyanate component, such as esters such as ethyl acetate, ketones such as methyl ethyl ketone, and aromatic hydrocarbons such as toluene and xylene, are preferably used, and can be appropriately selected and used.

<Intermediate substrate>
The packaging material of the present invention may further comprise an intermediate substrate layer.
The intermediate substrate preferably comprises a polyolefin resin.
Furthermore, of the total mass of the intermediate substrate, the polyolefin resin is preferably 50 mass% or more, more preferably 60 mass% or more, even more preferably 70 mass% or more, even more preferably 80 mass% or more, and particularly preferably 90 mass% or more.
Moreover, the polyolefin resin is more preferably a polypropylene-based resin and/or a polyethylene-based resin, further preferably a polypropylene-based resin, and particularly preferably a polypropylene-based resin that is a copolymer with ethylene and/or butene.
Examples of intermediate substrates include polyolefin resins such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), ethylene-vinyl acetate copolymer, propylene homopolymer, and ethylene-propylene copolymer. Gas barrier substrates, for example, plastic substrates having an inorganic vapor deposition layer of aluminum, silica, alumina, or the like, and plastic substrates having a layer of a mixture of organic and inorganic components, are preferred.

<Sealant>
The inner layer of the sealant comes into direct contact with the packaged item and serves to protect the packaged item. In order to form the laminate into a bag, it is preferable that the innermost layer of the sealant has heat sealability.
The sealant preferably contains a polyolefin resin.
Furthermore, in the total mass of the sealant, the polyolefin resin is preferably 50 mass% or more, more preferably 60 mass% or more, even more preferably 70 mass% or more, even more preferably 80 mass% or more, and particularly preferably 90 mass% or more.
Moreover, the polyolefin resin is more preferably a polypropylene-based resin and/or a polyethylene-based resin, further preferably a polypropylene-based resin, and particularly preferably a polypropylene-based resin that is a copolymer with ethylene and/or butene.
Examples of materials constituting the sealant include polyolefin resins such as low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), ethylene-vinyl acetate copolymer, propylene homopolymer, and ethylene-propylene copolymer, and one or more of these resins can be used. The sealant may be composed of a single layer or may be composed of two or more layers. Note that the sealant is preferably a non-stretched film made of the above-mentioned resin in order to suppress shrinkage during heat sealing.

The thickness of the sealant is not particularly limited and is set appropriately depending on the application of the laminate and the type and properties of the packaged goods, but is usually preferably 10 to 200 μm. In addition, in the case of pouches (especially retort pouches), the thickness of the sealant is preferably 20 to 150 μm, more preferably 25 to 130 μm.

The sealant may be, for example, a sealant having an inorganic vapor deposition layer such as aluminum, silica, and alumina, or an organic layer such as ethylene-vinyl alcohol copolymer or polyvinyl alcohol. It may also be a kneaded opalescent substrate such as a pigment, or a composite substrate by coextrusion.

<Manufacturing method of packaging material>
The method for producing a packaging material of the present invention preferably includes a step of printing a gravure ink containing a polyester-based urethane resin (B) on a substrate to form a printed layer, and a step of applying a reactive adhesive containing a polyol compound (D) and an isocyanate compound (I) to form an adhesive layer. The adhesive layer may be formed by applying it on the printed layer or may be formed by applying it to a sealant.

A suitable embodiment is, for example, a mode in which an adhesive is applied onto the printed layer, and then a sealant is attached. If the packaging material further has an intermediate substrate layer, a preferred embodiment includes a step in which the printed layer and the intermediate substrate are first attached to each other with an adhesive, and then the intermediate substrate and the sealant are attached to each other. The above configuration is optional and is not particularly limited.

The method for applying the adhesive is not particularly limited, and examples of devices for applying the adhesive composition include a comma coater, a dry laminator, a roll knife coater, a die coater, a roll coater, a bar coater, a gravure roll coater, a reverse roll coater, a blade coater, a gravure coater, and a microgravure coater.
The coating amount of the solid content of the adhesive composition is not particularly limited and can be appropriately selected depending on the application, and is usually in the range of 0.5 to 6.0 g/m ^2. When the adhesive composition is a solventless type, the range of 1.0 to 3.0 g/m ² is preferably used, and when it is a solvent type, the range of 1.0 to 5.0 g/m ² is preferably used.

The packaging material thus obtained is cut to a predetermined size, and the edges are heat-sealed with the sealants joined together to form a bag. The heat-sealing temperature is preferably 50 to 250°C, and more preferably 80 to 180°C. The heat-sealing pressure may be, for example, 1 to 5 kg/ ^cm2 . One sheet of packaging material may be folded and the edges heat-sealed, or two or more sheets of packaging material may be heat-sealed. Moreover, the bag made of the packaging material may be one in which all openings are heat-sealed after the contents are packaged.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Note that parts and percentages in the present invention represent parts by mass and percentages by mass unless otherwise noted.

<Method for measuring amine value>
The amine value was determined in terms of the number of milligrams of potassium hydroxide equivalent to the amount of hydrochloric acid required to neutralize the amino groups contained in 1 g of resin, according to the following method in accordance with JIS K0070.
0.5 to 2 g of sample was precisely weighed out (sample solid content: Sg). 50 mL of a mixed solution of methanol/methyl ethyl ketone = 60/40 (mass ratio) was added to the precisely weighed sample to dissolve it. Bromophenol blue was added as an indicator to the resulting solution, and the resulting solution was titrated with 0.2 mol/L ethanolic hydrochloric acid solution (titer: f). The point at which the color of the solution changed from green to yellow was set as the end point, and the titration amount (A mL) at this time was used to calculate the amine value according to the following (Equation 1).
(Formula 1) Amine value = (A x f x 0.2 x 56.108) / S [mg KOH / g]

<Weight average molecular weight Mw, number average molecular weight Mn and molecular weight distribution Mw/Mn>
The weight average molecular weight Mw, number average molecular weight Mn and molecular weight distribution Mw/Mn were determined by measuring the molecular weight distribution using a GPC (gel permeation chromatography) device (HLC-8220 manufactured by Tosoh Corporation) and calculating the molecular weight converted using polystyrene as a standard substance. The measurement conditions are shown below.
Columns: The following columns were used in series connection:
Tosoh Corporation TSKgel Super HM-L
Tosoh Corporation TSKgel Super HM-L
Tosoh Corporation TSKgel Super HM-M
Tosoh Corporation TSK gelguard column Super H-H
Detector: RI (differential refractometer)
Measurement conditions: column temperature 40°C
Eluent: tetrahydrofuran Flow rate: 1.0 mL/min

<Method for measuring hydroxyl value>
It was determined according to the method described in JIS K0070.

<Method of measuring acid value>
It was determined according to the method described in JIS K0070.

[Synthesis Example 1-1] (Synthesis of polyester polyol A1)
26 parts of 1,3-propanediol (hereinafter also abbreviated as 1,3-PD), 26 parts of neopentyl glycol (hereinafter also abbreviated as NPG), 48 parts of sebacic acid, and 0.002 parts of tetrabutyl titanate were charged into a round-bottom flask equipped with a stirrer, a thermometer, a water divider, and a nitrogen gas inlet tube, and esterification was carried out for 8 hours at 230° C. under a nitrogen stream while removing water generated by condensation. After confirming that the acid value of the polyester was 15 or less, the degree of vacuum was gradually increased with a vacuum pump to terminate the reaction. As a result, polyester polyol A1 having a number average molecular weight of 2000, a hydroxyl value of 56.1 mgKOH/g, and an acid value of 0.3 mgKOH/g was obtained.

[Synthesis Examples 1-2 and 1-3] (Synthesis of Polyester Polyols A2 and A3)
Polyester polyols A2 to A3 were obtained in the same manner as in Synthesis Example 1-1, except that the raw materials and charging ratios shown in Table 1 were used. The abbreviations shown in the table represent the following.
NPG: neopentyl glycol, PG: 1,2-propylene glycol, 1,3-PD: 1,3-propanediol

[Synthesis Example 2-1] (Synthesis of polyester-based urethane resin B1)
A four-neck flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube was charged with 23.6 parts of polyester polyol A1, 4.68 parts of isophorone diisocyanate (hereinafter also abbreviated as IPDI), 7.5 parts of ethyl acetate, and 0.003 parts of tin 2-ethylhexanoate, and reacted for 6 hours at 120 ° C. under a nitrogen stream, and 7.5 parts of propyl acetate were added and cooled to obtain a solution of terminal isocyanate prepolymer. Next, 1.60 parts of isophorone diamine (hereinafter also abbreviated as IPDA), 0.12 parts of dibutylamine (hereinafter also abbreviated as DBA), 34 parts of ethyl acetate and 21 parts of isopropyl alcohol (hereinafter also abbreviated as IPA) were mixed, and the resulting solution of terminal isocyanate prepolymer was gradually added at room temperature, and then reacted at 50 ° C. for 1 hour to obtain a polyester urethane resin B1 solution with a solid content of 30%, a mass average molecular weight of 70,000, and an amine value of 4 mgKOH / g. The molecular weight distribution is shown in Table 2.

[Synthesis Examples 2-2 to 2-5] (Synthesis of Polyester-Based Urethane Resins B2 to B5)
Solutions of polyester-based urethane resins B2 to B5 were obtained in the same manner as in Synthesis Example 2-1, except that the raw materials and their charging ratios shown in Table 2 were used. The molecular weight distributions are shown in the same table.
The abbreviations in the table stand for the following:
IBPA: iminobispropylamine

In the ink preparation examples, the following were used:
・Polyvinyl butyral resin solution: A 30% solids solution of polyvinyl butyral resin (glass transition point 70 ° C., weight average molecular weight 50,000, chlorine content 0 mass%, nitrification degree 0 mass%) having vinyl alcohol units, vinyl acetate units and vinyl butyral units and containing 73 mass% butyral ring groups in an ethyl acetate / isopropanol = 1 / 1 mixed solvent. ・Vinyl chloride-vinyl acetate copolymer resin solution: A 30% solids solution of vinyl chloride-vinyl acetate copolymer resin (Solvine TA3 manufactured by Nissin Chemical Co., Ltd., chlorine content 47.1 mass%, nitrification degree 0 mass%) in ethyl acetate. ・Cellulose-based resin solution: DLX5-8: Nitrocellulose manufactured by ICI Novel enterprises, weight average molecular weight 50000, nitrogen content 12.0%, glass transition temperature 150 ° C. (30% solids isopropanol solution)
Rosin resin solution: Hariestar P, manufactured by Harima Chemicals Co., Ltd., rosin modified pentaerythritol ester, ethyl acetate solution with 30% solids Acrylic resin solution: BR-105, manufactured by Mitsubishi Chemical Corporation, acrylic resin, weight average molecular weight 60,000, glass transition point 50°C, acid value 3.5 mgKOH/g, ethyl acetate solution with 30% solids C.I. Pigment Yellow 14: manufactured by Toyo Color Co., Ltd. (chlorine content 10.8% by mass, nitrification degree 0% by mass)

[Ink Preparation Example 3-1] (Preparation of Ink C1)
C.I. Pigment Blue 15:3 (manufactured by Toyo Color Co., Ltd., product name: LIONOL BLUE FG-7330 chlorine content 0 mass%, nitrification degree 0 mass%) 5 parts, polyester-based urethane resin B1 solution 10 parts, polyvinyl butyral resin (PVB) solution 15 parts, mixed solvent (propyl acetate / IPA = 70 / 30 (mass ratio)) 10 parts were stirred and mixed and milled with a sand mill, and then polyester-based urethane resin (B) 30 parts, mixed solvent (normal propyl acetate / isopropyl alcohol = 70 / 30 (mass ratio)) 30 parts were stirred and mixed to obtain ink C1.

[Ink Preparation Examples 3-2 to 3-11] (Preparation of Inks C2 to C11)
Inks C2 to C11 were obtained in the same manner as in Preparation Example 3-1, except that the raw materials and charging ratios shown in Table 3 were used.

[Isocyanate-based hardener synthesis example]
(Isocyanate-based curing agent F1)
In a nitrogen gas atmosphere, 15 parts of trimethylolpropane, 60.3 parts of toluene-2,4-diisocyanate, and 32.3 parts of ethyl acetate that had been dehydrated in advance were reacted in a reactor equipped with an agitator at 50° C. and a stirring speed of 150 rpm for 3 hours to obtain an isocyanate-based curing agent F1. F1 had a weight average molecular weight of 1200, Mw/Mn of 2.5, and a solid content of 70% by mass.

In the examples described below, in addition to the above isocyanate-based curing agent F1, the following F2 was also used.
(Isocyanate-based curing agent F2)
・E402-80B Asahi Kasei Corporation
Weight average molecular weight: 4100 Mw/Mn: 3.4 Solid content 70% by mass

[Adhesive Synthesis Example 4-1] (Synthesis of Polyol Compound D1)
A reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dripping tank and a nitrogen gas inlet tube was charged with 40 parts of a bifunctional polypropylene glycol having a number average molecular weight of about 2,000, 30 parts of a bifunctional polypropylene glycol having a number average molecular weight of about 400, 10 parts of a trifunctional polypropylene glycol having a number average molecular weight of about 400, 20 parts of a bifunctional polyether polyol ECOPROL 2000 having a number average molecular weight of about 2000, and 26 parts of tolylene diisocyanate, and the mixture was heated at 80 to 90 ° C. for 5 hours while stirring under a nitrogen gas stream to carry out a urethanization reaction. During the urethanization reaction, 0.1% of dibutyltin dilaurate (DBTDL) was added as a reaction catalyst to promote the reaction, and a polyether urethane polyol was obtained. 0.02 parts of phosphoric acid was added to the obtained polyether urethane polyol, and the solid content concentration was adjusted to 75% with ethyl acetate to obtain a polyol compound D1 solution. The weight average molecular weight of the polyol compound D1 was 36,000, and the molecular weight distribution (Mw/Mn) was 3.5.

[Adhesive Synthesis Example 4-2] (Synthesis of Polyol Compound D2)
A reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dripping tank and a nitrogen gas inlet tube was charged with 10 parts of a bifunctional polypropylene glycol having a number average molecular weight of about 2,000, 90 parts of a bifunctional polypropylene glycol having a number average molecular weight of about 400, and 35 parts of tolylene diisocyanate, and the reaction was carried out by heating at 80 to 90°C for 5 hours while stirring under a nitrogen gas stream. During the urethanization reaction, 0.1% of dibutyltin dilaurate (DBTDL) was added as a reaction catalyst to promote the reaction, and a polyether urethane polyol was obtained. 0.01 parts of phosphoric acid and 0.02 parts of DYNASYLAN GLYMO were added to the obtained polyether urethane polyol, and the solid content concentration was adjusted to 75% with ethyl acetate, to obtain a polyol compound D2 solution. The weight average molecular weight of the polyol compound D2 was 25,000, and the molecular weight distribution (Mw/Mn) was 1.9.

[Adhesive Synthesis Example 4-3] (Synthesis of Polyol Compound D3)
A reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping tank and a nitrogen gas inlet tube was charged with 15 parts of bifunctional polypropylene glycol having a number average molecular weight of about 2,000, 70 parts of bifunctional polypropylene glycol having a number average molecular weight of about 400, 15 parts of trifunctional polypropylene glycol having a number average molecular weight of about 400, and 35 parts of tolylene diisocyanate, and the reaction was carried out by heating at 80 to 90 ° C. for 5 hours while stirring under a nitrogen gas stream. During the urethanization reaction, 0.2% of Orgatix TC-100 was added as a reaction catalyst to promote the reaction, and a polyether urethane polyol was obtained. 0.01 parts of phosphoric acid and 0.02 parts of DYNASYLAN GLYMO were added to the obtained polyether urethane polyol, and the solid content concentration was adjusted to 75% with ethyl acetate, to obtain a polyol compound D3 solution. The weight average molecular weight of the polyol compound D3 was 58,000, and the molecular weight distribution (Mw / Mn) was 6.2.

[Comparative adhesive synthesis example 4-1] (Synthesis of polyol compound E1)
A reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping tank and a nitrogen gas inlet tube was charged with 15 parts of bifunctional polypropylene glycol having a number average molecular weight of about 2,000, 65 parts of bifunctional polypropylene glycol having a number average molecular weight of about 400, 20 parts of trifunctional polypropylene glycol having a number average molecular weight of about 400, and 36 parts of tolylene diisocyanate, and the reaction was carried out by heating at 80 to 90 ° C. for 5 hours while stirring under a nitrogen gas stream. During the urethanization reaction, 0.2% of Orgatix TC-100 was added as a reaction catalyst to promote the reaction, and a polyether urethane polyol was obtained. 0.01 parts of phosphoric acid and 0.02 parts of DYNASYLAN GLYMO were added to the obtained polyether urethane polyol, and the solid content concentration was adjusted to 75% with ethyl acetate, to obtain a polyol compound E1 solution. The weight average molecular weight of the polyol compound E1 was 80,000, and the molecular weight distribution (Mw / Mn) was 10.2.

[Adhesive Synthesis Example 5-1] (Synthesis of Polyol Compound D4)
A reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping tank and a nitrogen gas inlet tube was charged with 20 parts of 1,6-hexanediol (1,6HG), 20 parts of neopentyl glycol (NPG), 30 parts of isophthalic acid and 30 parts of sebacic acid, and an esterification reaction was carried out at 240°C. After a predetermined amount of water was distilled off, the pressure was gradually reduced to 1 mmHg or less and a deglycolization reaction was carried out at 250°C for 5 hours to obtain a polyester polyol. Then, 1 part of isophorone diisocyanate was added and the reaction was carried out at 150°C for 2 hours to obtain a polyester polyurethane polyol. 1 part of trimellitic anhydride (TMA) was added to this polyester polyol and the reaction was carried out at 180°C for 2 hours, after which 0.2 parts of DYNASYLAN GLYMO was added and the mixture was diluted with ethyl acetate to a non-volatile content of 60%, to obtain a polyol compound D4 solution. The weight average molecular weight of the polyol compound D4 was 26,000, and the molecular weight distribution (Mw/Mn) was 2.8.

[Adhesive Synthesis Example 5-2] (Synthesis of Polyol Compound D5)
A reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping tank and a nitrogen gas inlet tube was charged with 15 parts of ethylene glycol (EG), 10 parts of 1,6-hexanediol, 20 parts of neopentyl glycol, 0.5 parts of trimethylolpropane (TMP), 32 parts of isophthalic acid and 20 parts of succinic acid, and an esterification reaction was carried out at 240 ° C. After a predetermined amount of water was distilled off, the pressure was gradually reduced to 1 mmHg or less and a deglycolization reaction was carried out at 250 ° C. for 4.5 hours to obtain a polyester polyol. Then, 2 parts of isophorone diisocyanate were added, and the reaction was carried out at 150 ° C. for 2 hours to obtain a polyester polyurethane polyol. 1 part of trimellitic anhydride was added to this polyester polyol, and the reaction was carried out at 180 ° C. for 2 hours, and then 0.2 parts of DYNASYLAN GLYMO was added, and the mixture was diluted with ethyl acetate to a non-volatile content of 60%, to obtain a polyol compound D5 solution. The weight average molecular weight of polyol compound D5 was 24,000, and the molecular weight distribution (Mw/Mn) was 4.2.

[Adhesive Synthesis Example 5-3] (Synthesis of Polyol Compound D6)
In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping tank and a nitrogen gas inlet tube, 20 parts of 1,6-hexanediol, 20 parts of neopentyl glycol, 30 parts of isophthalic acid and 30 parts of sebacic acid were charged and esterification reaction was carried out at 240°C. After a predetermined amount of water was distilled off, the pressure was gradually reduced to 1 mmHg or less and a deglycolization reaction was carried out at 250°C for 5 hours to obtain a polyester polyol. Then, 1 part of tolylene diisocyanate was added and the reaction was carried out at 150°C for 2 hours to obtain a polyester polyurethane polyol. 1 part of trimellitic anhydride was added to this polyester polyol and reacted at 180°C for 2 hours, 0.2 parts of DYNASYLAN GLYMO was added to this polyester polyurethane polyol, and then the mixture was diluted with ethyl acetate to a non-volatile content of 60%, to obtain a polyol compound D6 solution. The weight average molecular weight of the polyol compound D6 was 26,000 and the molecular weight distribution (Mw/Mn) was 2.2.

[Adhesive Synthesis Example 5-4] (Synthesis of Polyol Compound D7)
In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping tank and a nitrogen gas inlet tube, 20 parts of ethylene glycol, 30 parts of diethylene glycol (DEG), 35 parts of isophthalic acid and 15 parts of sebacic acid were charged and esterification reaction was carried out at 240 ° C. After a predetermined amount of water was distilled off, the pressure was gradually reduced to 1 mmHg or less and a deglycolization reaction was carried out at 250 ° C. for 5 hours to obtain a polyester polyol. 0.5 parts of DYNASYLAN AMEO was added to this polyester polyol, and then diluted with ethyl acetate to a non-volatile content of 60%, to obtain a polyol compound D7 solution. The weight average molecular weight of the polyol compound D7 was 22000 and the molecular weight distribution (Mw / Mn) was 1.9.

[Isocyanate compound]
(Isocyanate Compound I1)
23 parts of bifunctional polypropylene glycol having a number average molecular weight of about 2,000, 18 parts of bifunctional polypropylene glycol having a number average molecular weight of about 400, 2 parts of trifunctional polypropylene glycol having a number average molecular weight of about 400, and 30 parts of 4,4'-diphenylmethane diisocyanate were charged into a reaction vessel, and the mixture was heated at 70 to 80°C for 7 hours while stirring under a nitrogen gas stream to carry out a urethane reaction. After completion of the reaction, 7 parts of a trimethylolpropane adduct of tolylene diisocyanate were mixed. The mixture was diluted with ethyl acetate to a solid content concentration of 75%, to obtain a polyisocyanate solution containing polyether urethane polyisocyanate. 80 parts of the polyisocyanate solution and 20 parts of Desmodur L75 (manufactured by Sumika Covestro Urethane Co., Ltd., trimethylolpropane adduct of toluene diisocyanate, NCO group content of 13%, solid content concentration of 75%) were mixed to obtain an isocyanate compound I1 solution.

(Isocyanate Compound I2)
A 95% by mass (ethyl acetate) nonvolatile solution of hexamethylene diisocyanate biuret was used as an isocyanate compound I2 solution.

[Example 1] (Preparation of packaging material G1)
Ink C1 was diluted with a propyl acetate/IPA mixed solvent (mass ratio 70/30) so that the viscosity in a Zahn cup #3 (manufactured by Rigo Co., Ltd.) was 15 seconds (at 25°C), and printed on the corona-treated side of a single-sided corona-treated polypropylene film using a gravure printing machine equipped with a 35 μm deep gravure plate, followed by drying at 50°C to obtain a printed matter (OPP). The coating amount of the printed layer after drying was 2.5 g/ ^m2 .
On the printed layer of the above printed matter, a solution prepared by adding 1 part of polyol compound D1 solution, 1 part of isocyanate compound F3 solution, and ethyl acetate to adjust the non-volatile content to 30% was applied using a gravure roll coater, and the solvent was dried in an oven to form an adhesive layer of 2.5 g/ ^m2. This was then bonded to an unstretched polypropylene (CPP) film (thickness 30 μm, surface corona discharge treated) using a laminator, and the film was kept warm at 40° C. for 3 days to produce packaging material G1.
Composition: Biaxially oriented polypropylene (OPP) film (thickness 20 μm) / printing layer / adhesive layer / unoriented polypropylene (CPP) film (thickness 30 μm, surface corona discharge treatment)

In the following examples and comparative examples, the following were used.
NY: Surface corona discharge treated biaxially oriented nylon film (thickness 15 μm)
LLDPE 30μm: Surface corona discharge treatment Linear low density polyethylene film (thickness 30μm)
LLDPE150μm: Surface corona discharge treatment Linear low density polyethylene film (thickness 150μm)

[Examples 2 to 21] (Preparation of packaging materials G2 to 21)
In the same manner as in Example 1, packaging materials G2 to G21 were obtained according to the compositions shown in Table 6.
In Examples 18 and 19, the viscosity of the ink was adjusted with a propyl acetate/IPA mixed solvent (mass ratio 70/30), and then 3 parts each of isocyanate-based hardeners F1 and F2 were added per 100 parts of ink.

[Comparative Examples 1 to 3] (Preparation of Packaging Materials H1 to H3)
In the same manner as in Example 1, packaging materials H1 to H3 were obtained according to the compositions shown in Table 6.

The following characteristics were evaluated using the above packaging material. The results are shown in Table 6.

(Laminate strength)
The packaging materials obtained in the above Examples and Comparative Examples were cut into pieces 150 mm long and 15 mm wide, opened at the ink/OPP film or ink/NY film interface, and the laminate strength in the 90° direction was measured using a tensile tester.
[Evaluation Criteria]
A (Excellent): 1.5 N/15 mm or more B (Good): 1.0 N/15 mm or more but less than 1.5 N/15 mm C (Acceptable): 0.8 N/15 mm or more but less than 1.0 N/15 mm D (Unacceptable): 0.5 N/15 mm or more but less than 0.8 N/15 mm E (Poor): Less than 0.5 N/15 mm A to C are ratings for practical use.

(Easy tearability)
Samples were prepared from the packaging materials obtained in the above Examples and Comparative Examples in accordance with JIS K7128-1:1998, and evaluated for tear resistance using an Intesco 201 universal tensile tester.
[Evaluation Criteria]
A (Excellent): Less than 0.5N B (Good): 0.5N or more but less than 1.0N C (Acceptable): 1.0N or more but less than 1.5N D (Unacceptable): 1.5N or more but less than 2.0N E (Poor): 2.0N or more Furthermore, A to C are ratings for practical use.

(Recyclability evaluation)
The packaging material obtained in the above examples and comparative examples was cut into a size of 4 cm x 4 cm, washed with water and dried. The pieces of packaging material were fed into a single-screw extruder, melted and kneaded at a screw speed of 250 rpm and 220 ° C, and extruded from the discharge part of the extrusion device using a 150 mesh filter at a pressure of 4 MPa. Then, it was immediately cut with a pelletizer and cooled by immersing it in cold water. In this way, pellets of recycled plastic recycled from the packaging material were obtained. Then, the pellets of recycled plastic were extruded at 220 ° C using a T-die extruder to produce a film-shaped molded body with a thickness of 50 μm. The number of foreign matter and bubbles that could be visually identified per 0.5 m ² of the obtained film was counted and evaluated according to the following criteria.
[Evaluation Criteria]
A (Excellent): The number of foreign objects and bubbles is less than 40. B (Good): The number of foreign objects and bubbles is between 40 and 80. C (Fair): The number of foreign objects and bubbles is between 80 and 120.
D (Not acceptable): Foreign matter, number of bubbles: 120 or more but less than 200,
E (poor): The number of foreign bodies or bubbles is 200 or more.
The evaluation of practical use is A to C.

Claims (15)

A packaging material having a substrate, a printing layer, an adhesive layer, and a sealant,
The packaging material contains 80% by mass or more of polyolefin resin in the total mass of the packaging material,
the printing layer contains a pigment and a binder resin, the binder resin contains a polyester-based urethane resin (B) and a polyvinyl acetal resin,
The molecular weight distribution (Mw/Mn) of the polyester-based urethane resin (B) is 2.0 to 8.0,
A packaging material, in which the adhesive layer is made of a cured product of a reactive adhesive containing a polyol compound (D) and an isocyanate compound (I), and the molecular weight distribution (Mw/Mn) of the polyol compound (D) is 1.5 to 10.0 (however, excluding a packaging material having a configuration in which at least a first substrate, a printed layer, a polyurethane-based adhesive layer and a second substrate are laminated in this order from the outer layer side, the polyurethane-based adhesive layer is provided in contact with the second substrate, and the polyurethane-based adhesive layer is used to remove the second substrate). The packaging material of claim 1, wherein the reactive adhesive comprises phosphoric acid and/or a phosphoric acid derivative. The packaging material according to claim 1, wherein the reactive adhesive comprises a silane coupling agent. The packaging material according to any one of claims 1 to 3, wherein the polyol compound (D) contains structural units derived from a polyester polyol and/or a polyether polyol, and structural units derived from an acid anhydride. The packaging material according to any one of claims 1 to 4, wherein the polyol compound (D) contains a structural unit derived from a polyether polyol, and the molecular weight distribution (Mw/Mn) of the polyol compound (D) is 3.0 to 10.0. The packaging material according to any one of claims 1 to 4, wherein the polyol compound (D) contains a structural unit derived from a polyester polyol, and the molecular weight distribution (Mw/Mn) of the polyol compound (D) is 1.5 to 5.0. The packaging material according to any one of claims 1 to 6, wherein the chlorine content of the binder resin is 5% by mass or less. 2. The packaging material according to claim 1 , wherein the polyester-based urethane resin (B) contains a structural unit derived from a polyester that is a condensation product of a dibasic acid and a diol, and the dibasic acid includes sebacic acid and/or succinic acid. 9. The packaging material of claim 8 , wherein the diol comprises a branched diol and a linear diol. The packaging material according to any one of claims 1 to 9 , wherein the content of the pigment is 30 mass % or less based on the total mass of the printed layer. The packaging material according to any one of claims 1 to 10 , wherein the printed layer further contains an isocyanate-based curing agent having a weight average molecular weight of 800 to 8,000. The packaging material according to any one of claims 1 to 11 , wherein the substrate and sealant comprise a polyolefin resin. The packaging material according to claim 12 , wherein the polyolefin resin is a polypropylene-based resin. The packaging material according to any one of claims 1 to 13 , wherein the chlorine content is 0.4 mass% or less based on the total mass of the packaging material. A method for producing a packaging material having a substrate, a printing layer, an adhesive layer, and a sealant, and containing 80% by mass or more of an olefin resin in the total mass (excluding packaging materials having a configuration in which at least a first substrate, a printing layer, a polyurethane-based adhesive layer, and a second substrate are laminated in this order from the outer layer side, the polyurethane-based adhesive layer is provided in contact with the second substrate, and the polyurethane-based adhesive layer is used to remove the second substrate), comprising:
The method includes the steps of: printing a gravure ink containing a polyester-based urethane resin (B) and a polyvinyl acetal resin on the substrate to form the printed layer; and applying a reactive adhesive containing a polyol compound (D) and an isocyanate compound (I) to form the adhesive layer,
The molecular weight distribution (Mw/Mn) of the polyester-based urethane resin (B) is 2.0 to 8.0,
The polyol compound (D) has a molecular weight distribution (Mw/Mn) of 1.5 to 10.0.