JP7354827B2 - Packaging material and recycled base material manufacturing method - Google Patents

Description

The present invention relates to a packaging material including a recyclable base material and a method for producing a recycled base material.

In recent years, packages made from plastic film, plastic bottles, and other plastic products have been discarded or dumped as garbage in the ocean, causing environmental pollution. These plastic products decompose in seawater and become submicron-sized fragments (microplastics), which float in seawater. If such plastics are ingested by marine organisms such as fish, they become concentrated within the organisms. There are concerns that this could affect the health of seabirds and humans who consume the marine organisms as food. In order to improve these problems, various efforts have been launched to reduce microplastics.

The above-mentioned plastic products mainly include food packaging packages using plastic base materials. In this package, various plastic base materials are used as film base materials, such as a polyester (PET) base material, a nylon (NY) base material, and a polypropylene (PP) base material. These plastic base materials are coated with a printing layer using gravure ink, flexo ink, or other printing ink, and then bonded to a hot melt resin base material via an adhesive or the like to form a laminate. It is cut and heat-sealed to form a package.

Attempts to reduce the amount of microplastics mentioned above include (1) replacing the plastic base material with paper, and (2) simplifying recycling by limiting the use of plastic base materials to only the same type (known as monomaterialization). , (3) Recycling plastics by removing impurities.

Although (1) above is promising in terms of safety and recyclability, it has many performance disadvantages such as gas barrier properties, water vapor barrier properties, and water resistance compared to conventional plastic base materials.
Regarding (2) above, technology is being developed to cover the weaknesses of polyolefins with functional coating agents such as barrier coating agents, but this is because they are inferior in performance compared to conventional plastic base materials, such as retortability and light blocking properties. , it is not easy to replace them with polyolefins. Furthermore, ink, functional coating agents, adhesives, etc. between polyolefin base materials can become impurities when recycling polyolefins.

As for (3) above, attempts have been made to remove the printed layer on the outer surface of the package, which becomes an impurity in the recycling process, using a basic aqueous solution.
For example, Cited Document 1 discloses a technique in which an undercoat layer made of an acrylic resin or a styrene-maleic acid resin is provided on a plastic base material, and a printed layer placed on the undercoat layer is removed using a basic aqueous solution. Further, Patent Document 2 discloses a technique in which surface printing is performed using an ink using a polyurethane resin or acrylic resin having an acidic group as a binder resin, and the printed layer is similarly removed using a basic aqueous solution. However, these techniques only remove the surface printing ink on the outside of the package, and do not reach the level of removing the ink layer in the laminate and separating the base materials from each other.

In addition to removing the surface printing ink layer for plastic recycling, the technology for removing the ink layer from laminates is an important technology that can be used industrially for environmental conservation and for promoting plastic recycling. However, no technology has yet been reported that can accomplish both of these tasks.

Japanese Patent Application Publication No. 2001-131484 Japanese Patent Application Publication No. 11-209677

Therefore, an object of the present invention is to have excellent adhesion to the base material necessary for a packaging material, to be able to remove not only the outer printed layer of the package but also the inner printed layer, and to be able to remove both of the two types of base materials constituting the packaging material. An object of the present invention is to provide a packaging material suitable for plastic recycling and a method for producing a recycled base material, which has excellent removability.

The present invention includes a first base material, a first desorption layer for desorbing the first base material and recycling the first base material, and
A packaging material comprising a second base material and a second release layer for desorbing the second base material and recycling the second base material,
The first release layer is formed from a first release layer forming composition (A),
The second release layer is formed from a second release layer forming composition (B),
The first release layer forming composition (A) contains a resin (a) and a solvent, and the resin (a) has an acid value of 15 mgKOH/g or more,
The second release layer forming composition (B) is an adhesive composition containing a polyol component and a polyisocyanate component, and the polyisocyanate component is composed of an aliphatic polyisocyanate and an araliphatic polyisocyanate. The present invention relates to a packaging material containing at least one polyisocyanate component selected from the group consisting of at least one polyisocyanate component, and having an acid value of a reaction product of a polyol component and a polyisocyanate component of 5 mgKOH/g or more.

The present invention also relates to the above packaging material, wherein the resin (a) has a hydroxyl value of 1 to 250 mgKOH/g.

The present invention also relates to the above packaging material, wherein the resin (a) has an acid value of 15 to 70 mgKOH/g and a hydroxyl value of 1 to 45 mgKOH/g.

The present invention also relates to the above-mentioned packaging material, wherein the resin (a) contains a urethane resin.

The present invention also relates to the above packaging material, wherein the urethane resin contained in the resin (a) contains a structural unit derived from a polyester polyol.

The present invention also provides a method for producing a recycled base material, which includes the step of immersing the above-mentioned packaging material in a basic aqueous solution,
The basic aqueous solution contains a basic compound in an amount of 0.5 to 10% by mass of the total basic aqueous solution, and the water temperature of the basic aqueous solution during immersion is 30 to 120°C.

The present invention has excellent adhesion to the base material necessary for packaging materials, and it is possible to remove not only the outer printed layer of the package but also the inner printed layer, allowing the removal of both types of base materials that make up the packaging material. It is possible to provide a packaging material with excellent properties and suitable for plastic recycling, and a method for producing a recycled base material.

The embodiments of the present invention will be described in detail below, but the embodiments or description of requirements described below are examples of the embodiments of the present invention, and the present invention does not exceed the gist thereof. Not limited.

The packaging material of the present invention includes at least a first base material, a first release layer for removing the first base material and recycling the first base material, and
It is characterized by comprising a second base material and a second release layer (hereinafter also referred to as an adhesive layer) for removing the second base material and recycling the second base material.
In the present invention, "detachment" refers to the detachment of the first base material and the second base material from the packaging material by neutralizing or dissolving the detachment layer with a basic aqueous solution and peeling it off. ,
- When the release layer dissolves and the base material detaches, (2) Even if the release layer does not dissolve, it peels off due to neutralization, swelling, etc., and the base material detaches. include.
In this case, the desorption behavior of the first desorption layer and the desorption behavior of the second desorption layer may be different.
That is, for example, the time it takes for the first base material to peel off and the time it takes for the second base material to peel off may be the same or different.
In addition, in the packaging material of the present invention, there may be a layer on the outside of the first base material (on the opposite side to the first release layer), as long as it does not hinder the recycling of the base material, There may be a layer on the outside of the substrate (on the side opposite the second release layer).
Further, the first desorption layer and the second desorption layer may have the same composition. Moreover, the first release layer and the second release layer may be integrated.
Additionally, there may be a layer between the first release layer and the second release layer. In this case, as long as both base materials are peeled off, the first release layer and the second release layer may be integrated with each other via a layer after peeling.
Further, there may be a third base material to be recycled outside of base material 1 or base material 2, or between base material 1 and base material 2.
Details of the specific layer structure of the packaging material of the present invention will be described later.

In the packaging material, when both release layers are dissolved and peeled off using a basic aqueous solution or the like, both base materials are released, and both base materials can be separated and recovered. Therefore, the packaging material of the present invention corresponds to a packaging material used for separating and recovering both base materials.
The present invention will be described in detail below, but these are just examples of embodiments of the present invention, and the present invention is not limited to these contents unless the gist thereof is exceeded.

<First release layer for releasing the first base material, first release layer forming composition (A), primer composition>
The first release layer in the present invention is formed from the first release layer forming composition (A), is placed in contact with the first base material, and is dissolved and peeled off using a basic aqueous solution. This is a layer for detaching the first base material.
Hereinafter, when a printing layer (also referred to as a pattern layer or solid layer) may be present separately from the first release layer, the first release layer may be referred to as a primer layer.
Of course, the first release layer itself may be a printed layer. Further, the first release layer forming composition (A) may be referred to as a primer composition.

<Resin (a)>
The first release layer contains resin (a) as a binder resin.
The resin (a) is preferably a resin (a) that acts with the basic aqueous solution in order to contact the basic aqueous solution and detach the first base material. For desorption in a basic aqueous solution, the acid value of the resin (a) is 5 mgKOH/g or more, preferably 15 mgKOH/g or more, more preferably 20 mgKOH/g or more, and even more preferably 25 mgKOH/g or more. preferable. Further, it is also preferable to include a resin having an ester structure that is easily decomposed in a basic aqueous solution. Alternatively, it is also preferable to include a resin that easily swells in a basic aqueous solution.
Further, the hydroxyl value of the resin (a) is preferably 1 to 250 mgKOH/g, more preferably 10 to 45 mgKOH/g. It is preferable that the content is 1 mgKOH/g or more because the removability with a basic aqueous solution becomes good, and it is preferable that the content is 250 mgKOH/g or less because the adhesion to the substrate becomes good.
Both the hydroxyl value and the acid value are values measured according to JIS K0070.

The resin (a) preferably contains 60% by weight or more, more preferably 80% by weight or more of the total amount of resin components constituting the first release layer.
Examples of the resin skeleton of the resin (a) include urethane resins, acrylic resins, cellulose resins, polyamide resins, vinyl chloride resins such as vinyl chloride-vinyl acetate copolymer resins or vinyl chloride-acrylic copolymer resins, and rosin resins. , ethylene-vinyl acetate copolymer resin, vinyl acetate resin, styrene resin, dammar resin, styrene-maleic acid copolymer resin, styrene-acrylic copolymer resin, polyester resin, alkyd resin, terpene resin, phenol-modified terpene resin, ketone Examples include resin, cyclized rubber, chlorinated rubber, butyral, polyacetal resin, petroleum resin, amino resin, polylactic acid, and modified resins thereof. These resins may be used alone or in combination of two or more.
Among these, the first release layer preferably contains at least one resin selected from the group consisting of urethane resin, acrylic resin, cellulose resin, vinyl chloride resin, rosin resin, and styrene-maleic acid copolymer resin. .

[Urethane resin]
The acid value of the urethane resin is preferably 15 mgKOH/g or more, more preferably 15 to 70 mgKOH/g, and still more preferably 20 to 50 mgKOH/g. If it is 15 mgKOH/g or more, the molecular weight of the resin tends to decrease in a basic aqueous solution, and the desorption property with a basic aqueous solution becomes good, so it is preferable. This is preferable because the properties are improved.

The weight average molecular weight of the urethane resin is preferably 10,000 to 100,000, more preferably 15,000 to 70,000, and even more preferably 15,000 to 50,000.
The molecular weight distribution (Mw/Mn) of the urethane resin is preferably 6 or less. Mw represents weight average molecular weight, and Mn represents number average molecular weight. When the molecular weight distribution is 6 or less, effects caused by excessive high molecular weight components, unreacted components, side reaction components, and other low molecular weight components can be avoided, and the desorption property and the formation of the first desorption layer are improved. Composition (A) has good drying properties and retort resistance.

In addition, the smaller the molecular weight distribution, that is, the sharper the molecular weight distribution, the more uniform the dissolution and peeling action by the basic aqueous solution will be, and the better the releasability of the first base material will be improved. The molecular weight distribution is more preferably 5 or less, still more preferably 4 or less. Furthermore, the molecular weight distribution is preferably 1.5 or more, more preferably 1.2 or more.
Mw, Mn, and molecular weight distribution (Mw/Mn) are polystyrene equivalent values determined by gel permeation chromatography (GPC).
When the molecular weight distribution and acid value are within the above ranges, not only the releasability with a basic aqueous solution but also the drying properties, substrate adhesion, and retort resistance of the first release layer forming composition (A) are improved. This is preferable because it gives good results.

The urethane resin may have an amine value. When the urethane resin has an amine value, the amine value is preferably 0.1 to 20 mgKOH/g, more preferably 1 to 10 mgKOH/g. It is preferable that it is within the above range because the adhesion to the base material will be good.

The urethane resin is not particularly limited, and is preferably a resin obtained by reacting a polyol, a hydroxy acid, and a polyisocyanate. By using a hydroxy acid, an acid value can be imparted to the urethane resin, and the removability can be improved. More preferably, it is a resin formed by reacting a polyol, a hydroxy acid, and a polyisocyanate with a polyamine.

(polyol)
Polyol is a general term for compounds having at least two hydroxyl groups in one molecule, and does not include hydroxy acids described below.
The number average molecular weight of the polyol is preferably 500 to 10,000, more preferably 1,000 to 5,000. The number average molecular weight here is calculated from the hydroxyl value of the polyol, and the hydroxyl value is a value measured according to JIS K0070. When the number average molecular weight of the polyol is 500 or more, the first release layer has excellent flexibility and improves adhesion to the first base material. When the number average molecular weight is 10,000 or less, the blocking resistance against the first base material is excellent when there is a winding step after forming the first release layer.

The polyol is not particularly limited, and at least one polyol selected from the group consisting of polyester polyols, polyether polyols, and polycarbonate polyols is more preferably used. Furthermore, the polyol may also include other dimer diols, hydrogenated dimer diols, castor oil-modified polyols, and the like.
The urethane resin in the present invention more preferably contains a structural unit derived from at least one polyol selected from the group consisting of polyester polyols and polycarbonate polyols, and since the molecular weight easily decreases in a basic aqueous solution, the urethane resin has low removability. improves.
The content of the structural unit derived from the polyol is preferably 10 to 75% by mass, more preferably 15 to 70% by mass, and even more preferably 20 to 65% by mass, based on the total amount of the urethane resin.

[Polyester polyol]
Examples of the polyester polyol include polyester polyols made of a condensate of a dibasic acid and a diol; polyester polyols made of a polylactone polyol that is a ring-opening polymer of a cyclic ester compound; polyester diols are preferred. Polyester polyols can be used alone or in combination of two or more.
Dibasic acids 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, , 4-cyclohexyldicarboxylic acid, dimer acid, hydrogenated dimer acid, etc., among which adipic acid or succinic acid is preferred.

Examples of diols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol (hereinafter referred to as 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-trimethyl Pentanediol, 2,4-diethyl-1,5-pentanediol, 1,12-octadecanediol, 1,2-alkanediol, 1,3-alkanediol, 1-monoglyceride, 2-monoglyceride, 1-monoglycerin ether , 2-monoglycerol ether, dimer diol, hydrogenated dimer diol, and the like.

As the polyester diol, a condensate of a dibasic acid and a diol having a branched structure may be used. It is preferable to use a diol having a branched structure because it can improve adhesion to the plastic base material and retort resistance.
Preferably, the diol having a branched structure is a diol having a structure in which at least one hydrogen atom of alkylene glycol is substituted with an alkyl group, such as 1,2-propanediol, 1,3-butanediol, 2-methyl -1,3-propanediol, neopentyl glycol, 1,4-pentanediol, 3-methyl-1,5-pentanediol, 2,5-hexanediol, 2-methyl-1,4-pentanediol, 2, 4-diethyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-methyl-1,8-octanediol, 2,2,4-trimethyl-1,3-pentane diol, 2,2,4-trimethyl-1,6-hexanediol. Among them, at least one selected from the group consisting of 1,2-propanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, and 2-butyl-2-ethyl-1,3-propanediol 1,2-propanediol or 3-methyl-1,5-pentanediol is preferably used.

As a raw material for the polyester polyol, a polyol having three or more hydroxyl groups and a polyhydric carboxylic acid having three or more carboxyl groups may be used in combination.
Preferred examples of the cyclic ester compound include α-acetolactone, β-propiolactone, γ-butyrolactone, δ-valerolactone, and ε-caprolactone.

[Polycarbonate polyol]
The polycarbonate polyol preferably includes an aliphatic polycarbonate polyol. The number average molecular weight of the polycarbonate polyol is preferably 500 to 5,000, more preferably 800 to 4,000, and even more preferably 1,000 to 3,000.

The aliphatic polycarbonate polyol preferably contains a structural unit derived from an aliphatic diol such as a substituted or unsubstituted alkylene glycol, and the method for producing it is not limited, but the method is not limited to the following: A polycondensate obtained by transesterification is preferred.

The aliphatic diol preferably has 4 to 10 carbon atoms, and includes, for example, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2-Methyl-1,3-propanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl -1,8-octanediol, 1,10-decanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-butynediol, 2,2,4-trimethyl-1,3-pentane Examples include diol, 1,4-cyclohexanedimethanol, diethylene glycol, polypropylene glycol, dipropylene glycol and the like. The substituent of the aliphatic diol is preferably an alkyl group having 10 or less carbon atoms. These aliphatic diols can be used alone or in combination of two or more.

The carbonate compound is not particularly limited, and examples thereof include dialkyl carbonates such as dimethyl carbonate, diethyl carbonate, and dibutyl carbonate; diaryl carbonates such as diphenyl carbonate; and alkylene carbonates such as ethylene carbonate. Since the carbonate compound becomes a polycondensate in the transesterification reaction with an aliphatic diol and is substituted, the structure of the carbonate compound is not limited, and one with good reactivity may be appropriately selected.

It is preferable that the polycarbonate polyol is liquid at 25°C. By using liquid polycarbonate polyol as a raw material for the polyurethane resin, flexibility and elasticity are imparted to the first release layer, and adhesion to the substrate is improved, and retort suitability and blocking resistance are improved.
Such liquid polycarbonate polyols include, as aliphatic diol components, alkylene glycols with an odd number of carbon atoms and a linear structure, and alkylene glycols with an even number of carbon atoms and a linear structure (linear diols). Preferred examples include aliphatic polycarbonate diols using and, or aliphatic polycarbonate polyols using alkylene glycol (branched diol) having an alkyl substituent.

It is preferable for the aliphatic polycarbonate polyol to contain a structural unit derived from a branched diol having tertiary carbon as the aliphatic diol component, since this will improve the removability and blocking resistance.
Examples of branched diols having a tertiary carbon include 1,2-propanediol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, and 2-methyl-1,8-octane. Diols include 2,2,4-trimethyl-1,3-pentanediol, preferably 3-methyl-1,5-pentanediol.
More preferably, a linear diol and a branched diol having tertiary carbon are used together, and an aliphatic polycarbonate polyol using 1,6-hexanediol and 3-methyl-1,5-pentanediol is more preferable. Particularly preferred.
The mass ratio (linear diol:branched diol having tertiary carbon) in the total mass of the aliphatic polycarbonate polyol is preferably 70:30 to 5:95, more preferably 50:50 to 10:90.

(Hydroxy acid)
The hydroxy acid in the present invention refers to a compound having both a hydroxyl group, which is an active hydrogen group, and an acidic functional group in one molecule.
The acidic functional group refers to a functional group that can be neutralized with potassium hydroxide when measuring an acid value, and specifically includes a carboxyl group and a sulfonic acid group, with a carboxyl group being preferred. Since the probability of the acidic group reacting with an isocyanate group is low, the acid value can be maintained even when a urethane resin containing a hydroxyl group is used.
The hydroxy acid is not particularly limited, and dimethylolalkanoic acids such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, and 2,2-dimethylolvaleric acid are preferably used. These can be used alone or in combination of two or more.

(Polyisocyanate)
The polyisocyanate is not particularly limited and can be selected from conventionally known polyisocyanates, such as aliphatic polyisocyanates and aromatic polyisocyanates. These may be used alone or in combination of two or more.

As the aliphatic polyisocyanate, well-known aliphatic diisocyanates, cycloaliphatic diisocyanates, araliphatic diisocyanates, or derivatives thereof can be used.
For example, 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzylisocyanate, dimethyldiphenylmethane diisocyanate, tetramethyldiphenylmethane diisocyanate, 1,3- Aromatic diisocyanates such as phenylene diisocyanate, 1,4-phenylene diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, o-xylylene diisocyanate and 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate;
Methylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or Aliphatic diisocyanates such as 2,2,4-trimethylhexamethylene diisocyanate and 2,6-diisocyanate methyl caproate;
1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), methyl-2,4-cyclohexane diisocyanate, Methyl-2,6-cyclohexane diisocyanate, 1,4-bis(isocyanatomethyl)cyclohexane, 1,3-bis(isocyanatemethyl)cyclohexane, hydrogenated xylylene diisocyanate, lysine diisocyanate, m-tetramethylxylylene diisocyanate and dimer acid Alicyclic diisocyanates such as dimer diisocyanate in which the carboxyl group of is converted into an isocyanate group;
1,3- or 1,4-xylylene diisocyanate or mixtures thereof, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanate-1-methylethyl)benzene Aroaliphatic diisocyanates such as or mixtures thereof;
Examples include polyisocyanates derived from the above diisocyanates, such as allophanate type, nurate type, biuret type, adduct type derivatives, bifunctional type prepolymers, or complexes thereof.

As the aromatic polyisocyanate, well-known aromatic diisocyanates or derivatives thereof can be used.
Examples of the aromatic diisocyanate include toluene diisocyanate, diphenylmethane diisocyanate, allophanate-type, nurate-type, biuret-type, and adduct-type derivatives derived from the above diisocyanates, bifunctional prepolymers, and complexes thereof.

Among them, from the viewpoint of reactivity, preferred are isophorone diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane-4,4'-diisocyanate. At least one type selected from the group consisting of: It is also preferable that the diisocyanate is a triisocyanate having a trimeric structure such as an isocyanurate structure.

These polyisocyanates include bifunctional types and trifunctional or higher functional types, and the type, kind, and amount added are selected depending on the balance of required characteristics. It is preferable to use a bifunctional type to improve the deinking property, and a trifunctional or higher functional type to improve the image quality of the printing layer. Furthermore, when the amount of polyisocyanate added is less than the hydroxyl equivalent of the polyol, the deinking properties tend to improve, and when the amount added is larger, the image quality tends to improve.

(Polyamine)
The polyamine in the present invention is not particularly limited, and is preferably a diamine compound.
Examples of the diamine compound include ethylene diamine, propylene diamine, hexamethylene diamine, isophorone diamine, dicyclohexylmethane-4,4'-diamine, and dimer diamine obtained by converting the carboxyl group of dimer acid into an amino group. These can be used alone or in combination of two or more.
More preferably, hydroxyl groups such as 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, etc. It is a diamine with By using a diamine having a hydroxyl group, a certain amount of the hydroxyl group can remain unreacted, and a hydroxyl value can be introduced into the urethane resin.

Amino acids can be used as diamine compounds. Amino acid refers to a compound having both an amino group and an acidic functional group in one molecule, and includes, for example, glutamine, asparagine, lysine, diaminopropionic acid, ornithine, diaminobenzoic acid, and diaminobenzenesulfonic acid. Since the acidic group has a low probability of reacting with an isocyanate group, the acid value can be maintained in the polyurethane resin.

When reacting the polyamine, a polymerization terminator may be used in combination. Examples of the polymerization terminator include dialkylamine compounds such as di-n-dibutylamine; monoethanolamine, diethanolamine, butanolamine, 2-amino-2-methyl-1-propanol, tri(hydroxymethyl)aminomethane, Hydroxyl groups such as 2-amino-2-ethyl-1,3-propanediol, N-di-2-hydroxyethylethylenediamine, N-di-2-hydroxyethylpropylenediamine, and N-di-2-hydroxypropylethylenediamine. Monoamine-type amino acid compounds such as glycine, alanine, glutamic acid, taurine, aspartic acid, aminobutyric acid, valine, aminocaproic acid, aminobenzoic acid, aminoisophthalic acid, and sulfamic acid; In order to introduce a hydroxyl value into the polyurethane resin, it is preferable to use an amine compound having a hydroxyl group.
When a hydroxyl group-containing urethane resin is included, the mass ratio of the hydroxyl group-containing urethane resin to the other resin in the release layer forming composition (hydroxyl group-containing urethane resin: the other resin in the release layer forming composition) is: Preferably the ratio is 95:5 to 50:50. If it is within the above range, when the printed layer is peeled off together with the first release layer in a basic aqueous solution, the printed layer will be peeled off in a thin film state and recovery will be easy, which is preferable.

[Manufacture of urethane resin]
As mentioned above, a more preferable urethane resin is a resin obtained by reacting a polyol, a hydroxy acid, and a polyisocyanate to a urethane prepolymer having an isocyanate group at the end, and further reacting a polyamine to extend the chain. In this case, in the reaction of the polyol, hydroxy acid, and polyisocyanate (hereinafter referred to as urethanization step), the functional group molar ratio (NCO/OH) of the polyisocyanate, polyol, and hydroxy acid is preferably 1.05 to 3. .0, more preferably 1.1 to 2.8. Further, the functional group molar ratio (amino group/NCO) between the isocyanate group of the urethane prepolymer and the amino group of the polyamine is preferably 0.7 to 1.3.

The number of urethane bonds in the polyurethane resin is preferably 1 to 3 mmol/g, more preferably 1.5 to 2 mmol/g. The number of urea bonds in the polyurethane resin is preferably 0 to 3 mmol/g, more preferably 0.2 to 1 mmol/g. Further, the total number of urethane bonds and the number of urea bonds is preferably 1 to 6 mmol/g, more preferably 1.7 to 3 mmol/g.
It is preferable to set the number of urethane bonds and the number of urea bonds within the appropriate ranges because desorption and adhesion to the base material become good.

In the urethanization reaction step, the number of urethane bonds is a value expressed by the following formula (1) when (number of NCO moles/number of OH moles)>1, and when (number of NCO moles/number of OH moles)≦1. In this case, the value is expressed by the following formula (2).
Formula (1): Number of urethane bonds (mmol/g) = Total number of moles of hydroxyl groups (mmol)/Total solid mass (g)
Formula (2): Number of urethane bonds (mmol/g) = Total number of moles of isocyanate groups (mmol) / Total solid mass (g)
In formulas (1) and (2), the total number of moles of hydroxyl groups represents the total number of moles of hydroxyl groups possessed by the polyol and hydroxy acid used in the urethanization process, and the total solid mass represents the total number of nonvolatile components of the polyurethane resin. It represents the mass, and the total number of moles of isocyanate groups represents the total number of moles of isocyanate groups that the polyisocyanate has.

The number of urea bonds is a value applied to those subjected to the urethanization reaction under the condition of (number of moles of NCO/number of moles of OH)>1.
The number of urea bonds is a value expressed by the following formula (3) when (number of moles of amino groups/number of moles of NCO) > 1 in the ureation reaction step, and (number of moles of amino groups/number of moles of NCO) ≦1. In the case of , the value is expressed by the following formula (4).
Formula (3): Number of urea bonds (mmol/g) = [Total number of moles of isocyanate groups (mmol) - Total number of moles of hydroxyl groups (mmol)] / Total solid mass (g)
Formula (4): Number of urea bonds (mmol/g) = total number of moles of amino groups (mmol)/total mass of solid content (g)
In formulas (3) and (4), the total number of moles of isocyanate groups represents the total number of moles of isocyanate groups possessed by the polyisocyanate used in the urethanization step, and the total number of moles of hydroxyl groups represents the number of moles of isocyanate groups possessed by the polyol used in the urethanization step. The total number of moles of amino groups represents the total number of moles of primary and/or secondary amino groups possessed by the polyamine used in the ureation reaction step. The mass represents the total mass of non-volatile components of the polyurethane resin.

[acrylic resin]
Acrylic resin is a resin formed by polymerizing (meth)acrylic monomers. When an acrylic resin is used as the sole binder resin, the acrylic resin must have a carboxyl group, and for example, a monomer containing a (meth)acrylic monomer having a carboxyl group such as (meth)acrylic acid or maleic acid is polymerized. It is preferable to use a acrylic resin.
Alternatively, a monomer containing a (meth)acrylic monomer having a functional group such as 2-hydroxyethyl (meth)acrylate or glycidyl (meth)acrylate is polymerized, and after polymerization, the functional group has a carboxyl group and the functional group It is also possible to make the acrylic resin have a carboxyl group by reacting a compound (such as maleic anhydride) that reacts with the acrylic resin.
Monomers other than (meth)acrylic monomers having a carboxyl group include:
(meth)acrylic monomers such as methyl (meth)acrylate and butyl (meth)acrylate;
Examples include vinyl monomers such as maleic acid, maleic anhydride, styrene, vinyl acetate, butadiene, and acrylonitrile.
When an acrylic resin is used as the sole binder resin, the acid value of the acrylic resin is 50 mgKOH/g or more, preferably 100 mgKOH/g or more.
The acrylic resin may be used as an aqueous resin after undergoing a neutralization reaction. The aqueous resin may be in an emulsion form or a dissolved form.

[Cellulose resin]
Examples of cellulose resins include nitrocellulose, cellulose acetate propionate, cellulose acetate butyrate, hydroxyalkylcellulose, and carboxyalkylcellulose. Examples of the alkyl group optionally included in the cellulose resin include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, pentyl group, and hexyl group. The alkyl group may have a substituent. Among these, cellulose acetate propionate, cellulose acetate butyrate, and nitrocellulose are preferred. The weight average molecular weight is preferably 5,000 to 1,000,000, more preferably 10,000 to 200,000.

[Other ingredients]
The first release layer may further contain components other than the resin.
The first release layer preferably contains an extender pigment from the viewpoint of improving film strength, improving optical properties, and improving fluidity of the release layer forming composition.
Extender pigments include metal oxides such as silica, barium sulfate, kaolin, clay, calcium carbonate, magnesium carbonate, zinc oxide, and zirconium oxide. Among these, silica is preferred, and hydrophilic silica is more preferred.
The average particle diameter of the extender pigment is preferably 0.5 to 10 μm, more preferably 1 to 8 μm. The content of the extender pigment in the first release layer is preferably 0.5 to 10% by mass, more preferably 1 to 5% by mass. It is preferable that the average particle diameter and the content of the extender pigment are within the above ranges because the wettability of the printing layer is improved and the image quality is improved.
Furthermore, known additives may be added. Known additives include dispersants, wetting agents, adhesion aids, leveling agents, antifoaming agents, antistatic agents, viscosity modifiers, curing agents, metal chelates, trapping agents, antiblocking agents, and wax components other than those listed above. , silane coupling agents, and the like.
Other components may be blended with the resin (a) in advance, or may be added when blending the resin (a).

<Production of first release layer forming composition (A)>
The first release layer forming composition (A) can be produced by dissolving and/or dispersing at least the resin (a) in a solvent, and may contain the other components described above as necessary. Good too.
Examples of solvents include water; aromatic organic solvents such as toluene and xylene; ketone organic solvents such as methyl ethyl ketone and methyl isobutyl ketone; ester organic solvents such as ethyl acetate, n-propyl acetate, isopropyl acetate, and isobutyl acetate. Solvents; Alcohol-based organic solvents such as methanol, ethanol, n-propanol, isopropanol, and n-butanol; Glycol ether-based solvents such as ethylene glycol monopropyl ether and propylene glycol monomethyl ether; Known organic solvents such as; They can be used alone or in combination of two or more.

The solid content concentration in the first release layer forming composition (A) is preferably 5 to 50% by mass, more preferably 10 to 40% by mass. Further, the content of the resin (a) in the first release layer forming composition (A) is preferably 0.5 to 50% by mass, more preferably 5 to 30% by mass. By being within the above range, optimum printability can be obtained.
The viscosity of the first release layer forming composition (A) is preferably 20 to 500 mPa·s, more preferably 30 to 300 mPa·s, since appropriate printability can be obtained in the printing process. The viscosity of the first release layer forming composition (A) can be adjusted as appropriate by the content of the resin (a), the content of other components described below, and the like.
The first release layer can be formed by forming the first release layer forming composition (A) on the first base material using a known printing device or coating device. The viscosity of the first release layer-forming composition (A) depends on the printing device or coating device used, and can be adjusted using the organic solvent or the like.

<First base material>
The first base material is a recyclable base material, and examples thereof include film-like or sheet-like plastic base materials commonly used for packaging materials, and may be a laminate in which these are laminated.
Examples of the plastic base material include films of thermoplastic resin and thermosetting resin, and preferably a film of thermoplastic resin. Examples of the thermoplastic resin include polyolefin resin, polyester resin, polyamide resin, polystyrene resin, vinyl chloride resin, vinyl acetate resin, ABS resin, acrylic resin, acetal resin, polycarbonate resin, and cellulose plastic.

More specifically, polyolefin resin films such as polyethylene (PE) and biaxially oriented polypropylene (OPP); polyester resin films such as polyethylene terephthalate, polyethylene naphthalate (PEN), and polylactic acid (PLA); restyrene resin films; Polyamide resin films such as nylon 6, poly-p-xylylene adipamide (MXD6 nylon); polycarbonate resin films; polyacrylonitrile resin films; polyimide resin films; composites of these (for example, nylon 6/MXD6/ Nylon 6, nylon 6/ethylene-vinyl alcohol copolymer/nylon 6) and mixtures are used. Among these, those having mechanical strength and dimensional stability are preferred.
The thickness of the plastic film is preferably 5 μm or more and 200 μm or less, more preferably 10 μm or more and 100 μm or less, and still more preferably 10 μm or more and 50 μm or less.

The first base material may be a gas barrier base material, for example, a plastic base material having an inorganic vapor deposited layer such as aluminum, silica, alumina, etc.; a plastic base material having an organic layer such as polyvinyl alcohol; etc.
Examples of commercially available plastic substrates having an inorganic vapor deposited layer include "GL FILM" (manufactured by Toppan Printing Co., Ltd.) and IB-FILM (manufactured by Toppan Printing Co., Ltd.), in which an inorganic vapor deposited layer such as alumina is laminated on a plastic substrate. (manufactured by Nippon Printing Co., Ltd.). Note that since aluminum and alumina have solubility in a basic aqueous solution, they are dissolved in the desorption step described below, and only the plastic base material can be recycled.

From the viewpoint of reuse as a recycled base material, the first base material preferably contains a polyolefin resin film such as polyethylene or biaxially oriented polypropylene.

When the first base material is a laminate, the base materials are preferably laminated with an adhesive layer interposed therebetween. The method of forming the adhesive layer is not limited, and it can be formed by a known method using a known adhesive.
The first base material may contain additives such as an antistatic agent and an ultraviolet light inhibitor, if necessary, and the surface of the base material may be corona-treated or low-temperature plasma-treated.

<Print layer>
The printing layer in the present invention is provided in contact with the first release layer on the side opposite to the first base material of the first release layer, except when the first release layer also serves as the print layer. It is a layer that forms an arbitrary printed pattern for the purpose of decoration, imparting beauty, displaying contents, expiration date, manufacturer or seller, etc., and also includes a solid printing layer. The printing layer can be provided, for example, between the first release layer and the second release layer, and may be provided on the entire surface of the first release layer, or may be provided on a part of the first release layer. .
The printing layer can be formed using a conventionally known pigment or dye, or may be formed using a printing ink containing a pigment or dye, and the method for forming the layer is not particularly limited. The printing layer may be formed of a single layer or a plurality of layers.
The thickness of each printed layer is preferably 0.1 μm or more and 100 μm or less, more preferably 0.1 μm or more and 10 μm or less, and even more preferably 1 μm or more and 5 μm or less.

Examples of the printing ink for forming the printing layer include printing inks containing a medium such as a pigment, a binder resin, a solvent, or water. The binder resin for the printing ink is preferably one that prevents the printed layer from dissolving or finely dispersing in the basic aqueous solution and facilitates the removal of the printed layer. For example, fiber materials such as nitrocellulose, cellulose acetate propionate, chlorinated polypropylene, vinyl chloride-vinyl acetate copolymer, polyester, acrylic, polyurethane and acrylic urethane, polyamide, polybutyral, A cyclized rubber-based binder, a chlorinated rubber-based binder, or a combination thereof as appropriate can be used.

[Pigment]
The packaging material containing the printed layer used in the present invention is obtained by immersing a 2 cm x 2 cm cut piece in 50 ml of a 2% by mass sodium hydroxide aqueous solution at 70°C for 2 hours, and then immersing it in the visible light region (400 to 760 nm) of the aqueous solution. ) The transmittance at the maximum absorption wavelength is preferably 75% or more. A major factor that lowers the transmittance is that the pigment of the ink contained in the printing layer is eluted into the aqueous sodium hydroxide solution. Base materials made from recycled packaging materials are generally colored and are often used for applications where coloring is not a problem, but if uncolored recycled base materials can be obtained, the range of uses will expand. It is expected. It is significant that the specified transmittance, which is an indicator of whether the recycled base material is colored or not, satisfies the specified transmittance.
In order for the pigment to satisfy the transmittance specification, the pigment needs to have alkali resistance. The alkali resistance of pigments can generally be estimated based on the pigment skeleton/structure. Those derived from dyes that dissolve in alkaline aqueous solutions and those that decompose in alkaline aqueous solutions can be said to have no alkali resistance.
Further, even if the pigment itself has alkali resistance, the subcomponents contained in the pigment may lower the transmittance, which is also not preferable in applications where coloring is a problem.
For example, alkali-resistant pigments include inorganic pigments, P. B. 15, P. Y. 83 etc. are mentioned.

The coating method for printing ink is not particularly limited, and can be applied by methods such as gravure coating, flexo coating, roll coating, bar coating, die coating, curtain coating, spin coating, and inkjet coating. . A printed layer can be formed by leaving this as it is, or by blowing air, heating, drying under reduced pressure, irradiating ultraviolet rays, etc. as necessary.

<Second base material>
In the packaging material of the present invention, when the first base material is the lower side, the second base material is located at the uppermost side of the packaging material. A protective layer or the like may be provided on the upper side.
The second base material may be, for example, the base material mentioned above for the first base material or a sealant base material, and may be a laminate in which these are laminated. The second base material is preferably a sealant base material containing polyolefin. The second base material may have a deposited film of silica, alumina, or the like.
Examples of the sealant base material include polyethylene such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE), acid-modified polyethylene, unstretched polypropylene (CPP), acid-modified polypropylene, Examples include copolypropylene, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid ester copolymer, ethylene-(meth)acrylic acid copolymer, and ionomer.
From the viewpoint of recyclability, the second base material is made of the first base material low-density polyethylene, polyethylene such as linear low-density polyethylene or high-density polyethylene, acid-modified polyethylene, unstretched polypropylene, acid-modified polypropylene, or copolymerized polyethylene. Polyolefins such as polypropylene are preferred.
From the viewpoint of retort resistance, polypropylene is preferred, and from the viewpoint of heat sealability, unstretched polypropylene is preferred.

The thickness of the second base material is not particularly limited, and in consideration of processability into packaging containers, heat sealability, etc., it is preferably 10 μm or more and 150 μm or less, more preferably 20 μm or more and 70 μm or less. By providing the second base material with unevenness having a height difference of about several μm, it is possible to impart slipperiness and tearability to the packaging material.
The method of laminating the second base material is not particularly limited, and for example, the printing surface of the laminated film having the first base material, the first release layer, and the printing layer and the second base material may be laminated. A method of bonding using an adhesive (second release layer forming composition (B)); a method of melting the resin constituting the second base material, extruding it onto the printing layer, cooling and solidifying it; etc. Can be mentioned.

An example of the structure of the packaging material of the present invention is shown below, but the present invention is not limited thereto. As described above, the first base material and the second base material may be a laminate in which a plurality of base materials are laminated.
- First base material / first release layer / second release layer / second base material - first base material (laminate) / first release layer / printed layer / second Release layer/second base material/first base material/first release layer/printed layer/second release layer/second base material/first base material/first release layer Layer/Printed layer/Second release layer/Second base material (laminate)

<Second release layer forming composition (B)>
The second release layer in the present invention is formed from the second release layer forming composition (B), is placed in contact with the second base material, and is dissolved and peeled off using a basic aqueous solution. This is a layer for detaching the second base material.
The second release layer forming composition (B) is a two-component curable adhesive composition containing a polyol component and a polyisocyanate component, and the polyol component and the polyisocyanate component form a urethane bond. After curing, it becomes a reactant. The second release layer is also referred to as an adhesive layer.

[Polyol component]
The polyol component is not particularly limited, and can be selected from conventionally known polyol components, and may be used alone or in combination of two or more.
(Polyester polyol)
The polyol component preferably includes a polyester polyol, since the releasability will be improved if the polyol component has an ester bond that has a high affinity with a basic aqueous solution.
Examples of polyester polyols include, but are not limited to, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, phthalic anhydride, adipic acid, azelaic acid, sebacic acid, succinic acid, glutaric acid, tetrahydrophthalic anhydride, Dibasic acids such as hexahydrophthalic anhydride, maleic anhydride, itaconic anhydride, dialkyl esters thereof, or mixtures thereof (hereinafter also referred to as carboxyl group component),
For example, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, butylene glycol, neopentyl glycol, dineopentyl glycol, trimethylolpropane, glycerin, 1,6-hexanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, 3,3'-dimethylolheptane, 1,9-nonanediol, polyoxyethylene glycol, polyoxypropylene glycol, polytetramethylene ether glycol , diols such as polyether polyol, polycarbonate polyol, polyolefin polyol, acrylic polyol, polyurethane polyol, or mixtures thereof (hereinafter also referred to as hydroxyl group component),
or polyester polyols obtained by ring-opening polymerization of lactones such as polycaprolactone, polyvalerolactone, and poly(β-methyl-γ-valerolactone).
Two or more types of the above carboxyl group component and hydroxyl group component may be used in combination.

The polyester polyol preferably has a urethane bond, and may be, for example, a polyester polyurethane polyol further reacted with a diisocyanate. Moreover, the polyester polyol and the polyester polyurethane polyol may be further reacted 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, hydrogenated diphenylmethane diisocyanate, etc. can be mentioned.
Examples of the acid anhydride include pyromellitic anhydride, mellitic anhydride, trimellitic anhydride, trimellitic acid ester anhydride, and the like. Examples of the trimellitic acid ester anhydride include ethylene glycol bisanhydrotrimellitate, propylene glycol bisanhydrotrimellitate, and the like.

Among these, the polyester polyol preferably contains an acid anhydride modified polyester polyurethane polyol. Since the polyester polyol component has urethane bonds, it can exhibit excellent heat resistance and adhesive properties. It is preferable that the polyester polyol is an acid anhydride-modified product because the acid value can be precisely controlled and a polyester polyol having a suitable acid value range as described below can be easily obtained.

It is preferable that the adhesive composition has an acid value. When the adhesive composition has an acid value, the second base material can be easily peeled off with a basic aqueous solution due to the neutralization effect with the basic compound. Therefore, the polyol component preferably has an acid value, and the acid value of the polyester polyol is preferably 5 mgKOH/g or more, more preferably 10 mgKOH/g or more.

When the polyol component includes a plurality of polyols, the acid value of the polyol component can be determined from the acid value of each polyol and its mass ratio.

The number average molecular weight of the polyol component is a value calculated in terms of standard polystyrene using GPC (gel permeation chromatography) "Shodex GPCSystem-21" manufactured by Showa Denko, using tetrahydrofuran as a solvent.

The polyol component preferably contains a polyol with a number average molecular weight of 5,000 to 15,000, and further preferably contains a polyester polyol with a number average molecular weight of less than 3,000 in order to improve adhesion to the substrate.

(acrylic polyol)
As a polyol component, acrylic resins with hydroxy groups made by monopolymerizing (meth)acrylic monomers with hydroxy groups such as 2-hydroxyethyl (meth)acrylate or copolymerizing with other (meth)acrylic monomers or vinyl monomers are also used. It can be suitably used.

(Other polyols)
The adhesive composition of the present invention may contain polyols other than the above polyester polyol. Polyols that may be contained other than polyester polyols are not particularly limited, and examples include polycarbonate polyols, polycaprolactone polyols, polyether polyols, polyolefin polyols, acrylic polyols, silicone polyols, castor oil polyols, and fluorine polyols. . These may be used alone or in combination of two or more.

[Polyisocyanate component]
The polyisocyanate component is not particularly limited as long as it contains at least one polyisocyanate component selected from the group consisting of aliphatic polyisocyanates and araliphatic polyisocyanates. These may be used alone or in combination of two or more.

(Aliphatic polyisocyanate)
The aliphatic polyisocyanate is not limited to the following, but compounds derived from well-known aliphatic diisocyanates or alicyclic diisocyanates can be used.
Aliphatic polyisocyanates that can be used in the present invention include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, and 1,3-butylene diisocyanate. - aliphatic diisocyanates such as butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanate methyl caproate;
1,4-Cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), methyl 2,4-cyclohexane diisocyanate, methyl Alicyclic diisocyanates such as 2,6-cyclohexane diisocyanate, 1,4-bis(isocyanatomethyl)cyclohexane, 1,3-bis(isocyanatemethyl)cyclohexane;
Alternatively, polyisocyanates such as allophanate type, nurate type, biuret type, adduct type derivatives, or complexes thereof derived from the above aliphatic diisocyanates or alicyclic diisocyanates can be mentioned.
Preferred derivatives are nurate-type and adduct-type derivatives, and particularly preferred are adduct-type derivatives.
Preferably, the aliphatic polyisocyanate is a polyisocyanate derived from hexamethylene diisocyanate (hereinafter referred to as HDI), which can easily ensure a balance between removability and laminate physical properties.

(Aroaliphatic polyisocyanate)
The aromatic aliphatic polyisocyanate is not limited to the following as long as it is an aliphatic polyisocyanate having an aromatic ring, but compounds derived from well-known aromatic aliphatic diisocyanates can be used.
Aroaliphatic polyisocyanates that can be used in the present invention include 1,3- or 1,4-xylylene diisocyanate or mixtures thereof, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,3- or 1 , 4-bis(1-isocyanate-1-methylethyl)benzene or a mixture thereof;
Alternatively, polyisocyanates such as derivatives of the above-mentioned araliphatic diisocyanates or complexes thereof may be mentioned.

<Manufacture of adhesive composition>
The adhesive composition may further contain other components. Other components may be blended with either the polyol component or the polyisocyanate component, or may be added when blending the polyol component and the polyisocyanate component.

[Other ingredients]
(Silane coupling agent)
The adhesive composition can further contain a silane coupling agent to improve hot water resistance. Examples of the silane coupling agent include trialkoxysilane having a vinyl group such as vinyltrimethoxysilane and vinyltriethoxysilane, 3-aminopropyltriethoxysilane, and N-(2-aminoethyl)3-aminopropyltrimethoxysilane. trialkoxysilane having an amino group such as, 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 3-glycidoxypropyltriethoxysilane having a glycidyl group. Examples include trialkoxysilane. The amount of the silane coupling agent added is preferably 0.1 to 5% by mass, more preferably 0.5 to 3% by mass, based on the solid content of the adhesive composition.

(Phosphorous oxygen acid or its derivative)
The adhesive composition may further contain a phosphorus oxyacid or a derivative thereof to increase acid resistance. Among the phosphorus oxyacids and their derivatives, the phosphorus oxyacids may be those containing at least one free oxyacid, such as hypophosphorous acid, phosphorous acid, orthophosphoric acid, hypophosphorous acid, orthophosphoric acid. Examples include phosphoric acids such as phosphoric acid, and condensed phosphoric acids such as metaphosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, polyphosphoric acid, and ultraphosphoric acid. Examples of derivatives of phosphorus oxyacids include those obtained by partially esterifying the above phosphorus oxyacids with alcohols with at least one free oxyacid remaining. Examples of these alcohols include aliphatic alcohols such as methanol, ethanol, ethylene glycol, and glycerin, and aromatic alcohols such as phenol, xylenol, hydroquinone, catechol, and phloroglycinol. Two or more types of phosphorus oxygen acids or derivatives thereof may be used in combination. The amount of the phosphorus oxygen acid or its derivative added is preferably 0.01 to 10% by mass, more preferably 0.05 to 5% by mass, based on the solid content of the adhesive composition. A content of .1 to 1% by weight is particularly preferred.

(Leveling agent or antifoaming agent)
The adhesive composition may further contain a leveling agent or an antifoaming agent to improve the appearance of the laminate. Leveling agents include polyether-modified polydimethylsiloxane, polyester-modified polydimethylsiloxane, aralkyl-modified polymethylalkylsiloxane, polyester-modified hydroxyl-containing polydimethylsiloxane, polyetherester-modified hydroxyl-containing polydimethylsiloxane, acrylic copolymers, and methacryl. Examples thereof include polyether-modified polymethylalkylsiloxane, acrylic acid alkyl ester copolymer, methacrylic acid alkyl ester copolymer, and lecithin.
Examples of antifoaming agents include known ones such as silicone resins, silicone solutions, and copolymers of alkyl vinyl ethers, acrylic acid alkyl esters, and methacrylic acid alkyl esters.

(reaction accelerator)
The adhesive composition may further contain a reaction accelerator to promote the urethanization reaction. As a reaction accelerator, metal catalysts such as dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin dimalate; 1,8-diaza-bicyclo(5,4,0)undecene-7,1,5-diazabicyclo Tertiary amines such as (4,3,0) nonene-5,6-dibutylamino-1,8-diazabicyclo(5,4,0) undecene-7; reactive tertiary amines such as triethanolamine, etc. One or more reaction accelerators selected from these groups can be used.

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

The adhesive composition can be used in a solvent-free form if its viscosity is 100 to 10,000 mPa·s, preferably 100 to 5,000 mPa·s at room temperature to 150°C, preferably room temperature to 100°C. If the viscosity of the adhesive composition is higher than the above range, it may be diluted with an organic solvent. As the organic solvent, those inert to the polyisocyanate component are preferably used, such as esters such as ethyl acetate, ketones such as methyl ethyl ketone, and aromatic hydrocarbons such as toluene and xylene, and are appropriately selected. It can be used as

The acid value after curing of the adhesive composition for forming the urethane bond-containing resin layer for detaching the second base material is preferably 5 mgKOH/g or more, more preferably 7 mgKOH/g or more, More preferably, it is 10 mgKOH/g or more, particularly preferably 20 mgKOH/g or more.
When the acid value is 5 mgKOH/g or more, the second base material can be easily peeled off with a basic aqueous solution.

When blending the polyol component and the polyisocyanate component, they are blended so that the equivalent ratio (NCO/OH) of the isocyanate groups in the polyisocyanate to the hydroxyl groups in the polyol is 0.3 to 5.0. It is more preferably 0.3 to 2.0, particularly preferably 0.5 to 1.5.

Generally, when there is a printed layer, the method for forming the second release layer is to form the printed layer on the first base material, apply the above-mentioned adhesive composition on the printed layer, After volatilizing the organic solvent through a drying process if necessary, the second release layer is formed by laminating it with a second base material using a laminator and curing it at room temperature or under heating. It will be done.
The coating amount of the adhesive composition after drying is not limited and is usually in the range of 0.001 to 6 g/m ² , preferably 1 to 2.5 g/m ² for a solvent-free type and 1 to 6 g for a solvent type. / ^m2 range.
Further, the thickness of the adhesive layer is not limited and is usually in the range of 0.001 to 5 μm, preferably 1 to 2 μm/m ² for a solvent-free type and 1 to 5 μm for a solvent type.

<Packaging container>
The packaging material of the present invention can be used alone and processed into a bag shape, a cylinder shape, etc., but it can also be used as a packaging container in combination with other packaging materials.
Since at least a portion of the packaging container is formed of the packaging material, a packaging container whose base material can be recycled can be obtained from the packaging material portion.
Although the type and use of the packaging material of the present invention and the packaging container are not particularly limited, they can be suitably used, for example, as food containers, detergent containers, cosmetic containers, pharmaceutical containers, and the like. The shape of the packaging container is not limited, and can be formed into a shape depending on the contents, and is suitably used for pouches and the like.

<Recycled base material manufacturing method>
The recycled base material manufacturing method of the present invention includes:
At least a first base material, a first release layer for releasing the first base material, a second base material, a second release layer for releasing the second base material. By the step of immersing the provided packaging material in a basic aqueous solution, the first base material and the second base material are detached from the packaging material, and the first base material and the second base material can be recycled. .

Since the present invention aims to obtain each base material after desorption as a recycled base material or recycled base material, it is preferable to remove as much of each desorption layer as possible from each base material. It is. Specifically, out of 100% by mass of each desorption layer, it is preferable that at least 50% by mass or more is desorbed in the area and film thickness direction. More preferably, 60% by mass or more, still more preferably 80% by mass or more, particularly preferably 90% by mass or more is desorbed.

The basic compound used in the basic aqueous solution is not particularly limited, and examples include sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH) ₂ ), ammonia, barium hydroxide (Ba( OH) ₂ ) and sodium carbonate (Na ₂ CO ₃ ) are preferably used, but are not limited thereto. More preferably, it is at least one selected from the group consisting of sodium hydroxide and potassium hydroxide.
The basic aqueous solution preferably contains a basic compound in an amount of 0.5 to 20% by weight, more preferably 1 to 15% by weight, particularly preferably 3 to 10% by weight based on the total basic aqueous solution. When the concentration is within the above range, the basic aqueous solution can maintain sufficient basicity to peel off each release layer by dissolving or swelling and release each base material.

The basic aqueous solution permeates through the end portion of the packaging material or packaging container, contacts each release layer, dissolves or swells, and thereby releases each base material and each release layer. Therefore, in order to proceed with the desorption process efficiently, when the packaging material or packaging container is cut or crushed and immersed in a basic aqueous solution, each desorption layer must be exposed in the cross section. preferable. In such a case, each base material layer can be detached in a shorter time.

The temperature of the basic aqueous solution when the packaging material is immersed is preferably 25 to 120°C, more preferably 30 to 120°C, particularly preferably 30 to 80°C. The immersion time in the basic aqueous solution is preferably 1 minute to 24 hours, more preferably 1 minute to 12 hours, and preferably 1 minute to 6 hours. The amount of the basic aqueous solution used is preferably 1,000,000 to 1,000,000 times the weight of the packaging material, and in order to improve the desorption efficiency, it is preferable to stir or circulate the basic aqueous solution. The rotation speed is preferably 80 to 250 rpm, more preferably 80 to 200 rpm.

After separating and recovering each base material from the packaging material, each recycled base material can be obtained through a process of washing and drying each base material. The removal rate of the printed layer on the surface of each base material is preferably 70% or more, more preferably 80% or more, particularly preferably 90% or more, based on the area of the packaging material before detachment.

Therefore, according to the present invention, preferably, the step of immersing the packaging material or the packaging container in a basic aqueous solution, and dissolving or peeling off the respective release layer from the packaging material or the packaging container to release the respective base material. A recycled base material of each base material can be obtained by going through the steps of collecting each base material, and washing and drying each base material with water. Further, the obtained recycled base material can be processed into pellets using an extruder or the like and reused as recycled resin.

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples. Note that "parts" and "%" in the present invention mean "parts by mass" and "% by mass" unless otherwise specified.

(Molecular weight and molecular weight distribution)
The weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw/Mn) were measured by GPC (gel permeation chromatography) and determined as a converted molecular weight using polystyrene as a standard substance. The measurement conditions are shown below.
GPC device: Showa Denko Shodex GPC-104
Column: The following columns were connected in series and used.
Showa Denko Shodex LF-404 2 pieces Showa Denko Shodex LF-G
Detector: RI (differential refractometer)
Measurement conditions: Column temperature 40℃
Eluent: Tetrahydrofuran Flow rate: 0.3 mL/min

(Acid value, hydroxyl value)
Acid value and hydroxyl value were measured according to the method described in JIS K0070 (1992).

<Production of resin (a) for first release layer forming composition>
[Synthesis Example 1] (Oil-based polyurethane resin P1)
In a reactor equipped with a reflux condenser, a dropping funnel, a gas inlet tube, a stirrer, and a thermometer, while introducing nitrogen gas, the molar ratio of PPBS (1,3-propanediol to butylethylpropanediol to succinic acid) (polyester polyol with a number average molecular weight of 2,000, consisting of a polycondensate of 2/1/3), 147.9 parts, PPG (polyether polyol with a number average molecular weight of 2,000, consisting of polypropylene glycol) 14.8 parts , 25.2 parts of DMPA (2,2-dimethylolpropanoic acid), 96.8 parts of IPDI (isophorone diisocyanate), and 200 parts of NPAC (n-propyl acetate) were reacted at 90°C for 5 hours to form isocyanate at the terminal. A urethane prepolymer solution having groups was obtained.
Next, a mixture of 15.4 parts of AEA (2-(2-aminoethylamino)ethanol) and 350 parts of IPA (isopropyl alcohol) was added dropwise at room temperature over 60 minutes, and then reacted at 70°C for 3 hours. An oil-based polyurethane resin solution was obtained.
NPAC was added to the obtained polyurethane resin solution to adjust the solid content, and the solid content concentration was 30%, the mass average molecular weight was 28,000, Mw/Mn = 3.2, the acid value was 35.1 mgKOH/g, and the hydroxyl value was 27. A solution of oil-based polyurethane resin P1 of .7 mgKOH/g was obtained.

[Synthesis Examples 2 to 6] (Oil-based polyurethane resins P2 to P6)
Solutions of oil-based polyurethane resins P2 to P6 were obtained in the same manner as in Synthesis Example 1 except that the raw materials and amounts listed in Table 1 were used. The resin properties such as Mw and acid value are shown in Table 1.

[Synthesis Example 7] (Aqueous polyurethane resin P7)
PPA (consisting of a polycondensate of propylene glycol and adipic acid, number average molecular weight 2, 000 polyester polyol), 41.1 parts of PEG (polyether polyol with a number average molecular weight of 2,000, consisting of polyethylene glycol), 36.7 parts of DMPA, 103.5 parts of IPDI, NPAC. 200 parts of were charged and reacted at 90°C for 5 hours to obtain a prepolymer solution having isocyanate groups at the ends.
Next, a mixture of 9.3 parts of AEA and 150 parts of IPA was added dropwise at room temperature over 60 minutes, and then 10.0 parts of 28% ammonia water and 690 parts of ion-exchanged water were gradually added to the resin. It was made water-soluble by neutralizing the carboxyl group of.
Next, NPAC and IPA were distilled off under reduced pressure to obtain an aqueous solution having a solid content concentration of 30%, a mass average molecular weight of 34,000, Mw/Mn=3.4, an acid value of 51.2 mgKOH/g, and a hydroxyl value of 16.6 mgKOH/g. An aqueous solution of polyurethane resin P7 was obtained. However, the acid value at P7 is the value before neutralization.

[Synthesis Example 8] (Aqueous polyurethane resin P8)
A solution of aqueous polyurethane resin P8 was obtained in the same manner as in Synthesis Example 7 except that the raw materials and amounts listed in Table 1 were used. The resin properties such as Mw and acid value are shown in Table 1.

The abbreviations in Tables 1 and 2 are shown below.
・PPBS: Polyester polyol with a number average molecular weight of 2,000, consisting of a polycondensate of 1,3-propanediol, butylethylpropanediol, and succinic acid in a molar ratio of 2/1/3. ・PPA: Propylene glycol and adipic acid PMPA: A polyester polyol with a number average molecular weight of 2,000, consisting of a polycondensate of 3-methyl-1,5-pentanediol and adipic acid. - PC : Polycarbonate polyol with a number average molecular weight of 2,000, consisting of a polycondensate of 3-methyl-1,5-pentanediol, 1,6-hexanediol, and dimethyl carbonate in a molar ratio of 9/1/10. PPG: Polypropylene Polyether polyol consisting of glycol and having a number average molecular weight of 2,000 ・PEG: Polyether polyol consisting of polyethylene glycol and having a number average molecular weight of 2,000 ・DMPA: 2,2-dimethylolpropanoic acid ・IPDI: Isophorone diisocyanate ・NPAC : normal propyl acetate ・AEA: 2-(2-aminoethylamino)ethanol ・IPA: isopropyl alcohol In addition, in the above Synthesis Examples 2 to 8, dropwise addition was performed so that the Mw and Mw/Mn as shown in Table 1 were obtained. Synthesis conditions such as volume, dropping rate, temperature control, and stirring rate were adjusted.

[Synthesis Example 9] (Oil-based acrylic resin P9)
In a reactor equipped with a reflux condenser, a dropping funnel, a gas inlet tube, a stirrer, and a thermometer, while introducing nitrogen gas, 65 parts of benzyl methacrylate, 30 parts of acrylic acid, 5 parts of 2-hydroxyethyl methacrylate, 40 parts of ethyl acetate (EA) and 40 parts of isopropanol (IPA) were charged, the temperature was raised to 90°C, 1 part of azobisisobutyronitrile (AIBN) and 15 parts of EA were added, and a polymerization reaction was carried out for 4 hours. 0.1 part of AIBN and 3 parts of EA were added and reacted for 2 hours to obtain an oil-based acrylic resin solution.
IPA was added to the obtained oil-based acrylic resin solution to adjust the solid content, and an oil-based acrylic resin solution P9 with a solid content concentration of 30%, a mass average molecular weight of 28,000, an acid value of 234 mgKOH/g, and a hydroxyl value of 22 mgKOH/g was prepared. Obtained.

[Synthesis Example 10] (Oil-based acrylic resin P10)
40 parts of butyl methacrylate, 10 parts of methacrylic acid, 50 parts of 2-hydroxyethyl methacrylate while introducing nitrogen gas into a reactor equipped with a reflux condenser, a dropping funnel, a gas introduction pipe, a stirrer, and a thermometer. , 40 parts of EA and 40 parts of IPA were charged, the temperature was raised to 90°C, 1 part of AIBN and 15 parts of EA were added, a polymerization reaction was carried out for 4 hours, and 0.1 part of AIBN and 3 parts of EA were added. The mixture was reacted for 2 hours to obtain an oily acrylic resin solution.
IPA was added to the obtained oil-based acrylic resin solution to adjust the solid content, and an oil-based acrylic resin solution P10 with a solid content concentration of 30%, a mass average molecular weight of 30,000, an acid value of 65 mgKOH/g, and a hydroxyl value of 216 mgKOH/g was prepared. Obtained.

[Synthesis Example 11] (Oil-based acrylic resin P11)
84 parts of styrene, 8 parts of acrylic acid, 8 parts of 2-hydroxyethyl methacrylate, EA while introducing nitrogen gas in a reactor equipped with a reflux condenser, a dropping funnel, a gas introduction pipe, a stirrer, and a thermometer. 40 parts of AIBN and 40 parts of IPA were heated to 90°C, 1 part of AIBN and 15 parts of EA were added, and a polymerization reaction was carried out for 4 hours. The mixture was reacted for a period of time to obtain an oil-based acrylic resin solution.
IPA was added to the obtained oil-based acrylic resin solution to adjust the solid content, and an oil-based acrylic resin solution P11 with a solid content concentration of 30%, a mass average molecular weight of 29,000, an acid value of 62 mgKOH/g, and a hydroxyl value of 35 mgKOH/g was prepared. Obtained.

[Synthesis Example 12] (Aqueous acrylic resin P12)
40 parts of styrene, 35 parts of methacrylic acid, 15 parts of 2-hydroxyethyl methacrylate, acrylic while introducing nitrogen gas into a reactor equipped with a reflux condenser, a dropping funnel, a gas introduction pipe, a stirrer, and a thermometer. 10 parts of butyl acid, 40 parts of methyl ethyl ketone (MEK), and 40 parts of IPA were charged, the temperature was raised to 90°C, 1 part of AIBN and 15 parts of MEK were added, a polymerization reaction was carried out for 4 hours, and further 0.1 part of AIBN was added. and 3 parts of MEK were added and reacted for 2 hours. Thereafter, 25 parts of 28% ammonia water and 200 parts of ion-exchanged water were gradually added to neutralize the carboxyl groups in the resin, thereby making it water-soluble.
Next, MEK and IPA were distilled off under reduced pressure, and ion-exchanged water was added to adjust the solid content to give a solid content concentration of 30%, mass average molecular weight of 32,000, acid value of 228 mgKOH/g, and hydroxyl value of 65 mgKOH/g. Aqueous acrylic resin solution P12 was obtained. However, the acid value at P12 is the value before neutralization.

[Synthesis Example 13] (Aqueous acrylic resin P13)
In a reactor equipped with a reflux condenser, a dropping funnel, a gas inlet tube, a stirrer, and a thermometer, while introducing nitrogen gas, 40 parts of ion-exchanged water and Adekaria Soap SR-10 (Co., Ltd.) as a surfactant were added. Separately, add 0.2 parts of ADEKA), 42 parts of styrene, 8 parts of acrylic acid, 10 parts of 2-hydroxyethyl methacrylate, 40 parts of 2-ethylhexyl acrylate, 1.8 parts of SR-10, and ion-exchanged water. An additional 1% of the pre-mixed 53 parts pre-emulsion was added. After raising the internal temperature to 70° C. and thoroughly purging with nitrogen, 10% of 10 parts of a 5% aqueous solution of potassium persulfate was added to initiate polymerization. After holding the inside of the reaction system at 70°C for 5 minutes, the remainder of the pre-emulsion and the remainder of the 5% aqueous solution of potassium persulfate were added dropwise over 3 hours while maintaining the internal temperature at 70°C, and stirring was continued for an additional 2 hours. . Thereafter, the temperature was cooled to 30° C., and the pH was adjusted to 8.5 with 18% ammonia water to obtain an aqueous acrylic resin emulsion.
Ion-exchanged water was added to the resulting aqueous acrylic resin emulsion to adjust the solid content, resulting in an aqueous acrylic resin emulsion with a solid content concentration of 30%, a mass average molecular weight of 35,000, an acid value of 62 mgKOH/g, and a hydroxyl value of 43 mgKOH/g. P13 was obtained. However, the acid value in P13 is the value before neutralization.

<First release layer forming composition (A)>
[Manufacture example 1] (separable ink S1)
Stir 87 parts of polyurethane resin P1 solution, 5 parts of EA (ethyl acetate), 5 parts of IPA, and 3 parts of silica particles (manufactured by Mizusawa Chemical Co., Ltd. P-73: hydrophilic silica particles with an average particle size of 3.8 μm) using a disper. By mixing, release ink S1 was obtained.

[Production Examples 2 to 20, Comparative Production Example 1] (Releasable inks S2 to S20, SS1)
Release inks S2 to S20 and SS1 were obtained in the same manner as in Production Example 1, except that the raw materials and blending ratios shown in Table 2 were used.

[Production Example 21] (Detachable ink S21)
10 parts of copper phthalocyanine indigo (phthalocyanine LIONOL BLUE FG-7358-G manufactured by Toyo Color Co., Ltd.), 40 parts of polyurethane resin (P2), 3 parts of EA, and 3 parts of IPA were stirred and mixed, and the pigment was further dispersed in a sand mill for 20 minutes, followed by polyurethane resin. 40 parts of resin solution (P2), 2 parts of EA, and 2 parts of IPA were stirred and mixed to obtain a blue release ink (S21). Note that for each component shown in Table 2, the total value is shown.

[Production Example 22] (Detachable ink S22)
Detachable ink S22 was obtained in the same manner as in Production Example 21, except that the raw materials and blending ratios shown in Table 2 were used.

The abbreviations in Table 2 are shown below.
- P14 resin: maleated rosin aqueous solution (Arakawa Chemical Marquid No. 32, solid content 30% by weight, acid value 130mgKOH/g)
・ PP1 resin: Vinyl chloride-vinyl acetate copolymer resin (vinyl chloride/vinyl acetate/vinyl alcohol = 88/1/11 (mass ratio), solid content concentration 30%, acid value 0 mgKOH/g)
- Curing agent A: HDI bifunctional prepolymer (Asahi Kasei Duranate D101 solution diluted with ethyl acetate to a solid content of 50% by weight)
- Hardening agent B: HDI-TMP adduct (Asahi Kasei Duranate P301-75E solution diluted with ethyl acetate to a solid content of 50% by weight)
- Hardening agent C: HDI biuret (Asahi Kasei Duranate 22A-75E solution diluted with ethyl acetate to a solid content of 50% by weight)
- Hardening agent D: HDI Nurate (Asahi Kasei Duranate TPA100 solution diluted with ethyl acetate to a solid content of 50% by weight)
- Curing agent E: XDI-TMP adduct (Mitsui Chemicals Takenate D110NB solution diluted with ethyl acetate to a solid content of 50% by weight)
・Silica particles: P-73 manufactured by Mizusawa Chemical Co., Ltd. (hydrophilic silica particles with an average particle diameter of 3.8 μm)
・Polyethylene particles: Mitsui Chemicals Hiwax 220P (Mw2,000 low molecular weight polyethylene wax)
・Barium sulfate: Variace B30 manufactured by Sakai Chemical Industry Co., Ltd. (average particle size 0.3 μm)
・Copper phthalocyanine: Phthalocyanine LIONOL BLUE FG-7358-G manufactured by Toyocolor Co., Ltd.

<Manufacture of printing ink>
[Manufacturing example A] (Printing ink R1)
30 parts of PU (polyurethane resin solution, manufactured by Arakawa Chemical Co., Ltd. KL-593: polyester polyether combination polyurethane resin, solid content concentration 30%, mixed solution of ethyl acetate and isopropanol), PVC (vinyl chloride-vinyl acetate copolymer resin solution, Japan) 10 parts of Solvine TAO (manufactured by Shinkagaku Co., Ltd.: solid content concentration 30% ethyl acetate solution), 10 parts of indigo pigment (Lionol Blue FG7330, manufactured by Toyo Color Co., Ltd.), and 20 parts of a mixed solvent of NPAC and IPA were stirred and mixed, and the mixture was sand milled. Dispersion treatment was performed for 20 minutes using Thereafter, 30 parts of a mixed solvent of NPAC and IPA were stirred and mixed to obtain printing ink R1.

[Manufacturing examples B to E] (Printing inks R2 to R5)
Printing inks R2 to R5 were obtained in the same manner as in Production Example A, except that the raw materials and blending ratios shown in Table 3 were used.

The abbreviations in Table 3 are shown below.
・ PU: Polyurethane resin solution (manufactured by Arakawa Chemical Co., Ltd. KL-593: Polyester polyether combination polyurethane resin, solid content concentration 30%, mixed solution of ethyl acetate and isopropanol)
・PVC: Vinyl chloride-vinyl acetate copolymer resin solution (Nissin Chemical Co., Ltd. Solvain TAO: solid content concentration 30% ethyl acetate solution)
・NC: Nitrocellulose resin solution (nitrocellulose solution with nitrogen content of 11.5% and Mw of 50,000, solid content concentration of 30%)
・PAM: Polyamide resin solution (polyamide resin having a structure derived from dimer acid, solid content concentration 30% solution)
- AC: Acrylic resin solution (solid content concentration 30% solution of styrene-acrylic copolymer resin with Mw 40,000 and acid value 60 mgKOH/g)
・Indigo pigment: Lionor Blue FG7330 manufactured by Toyo Color Co., Ltd.

<Production of polyol of adhesive composition (B)>
(Synthesis Example 1) Polyester polyol (A-1)
124 parts of ethylene glycol, 212 parts of neopentyl glycol, 368 parts of 1,6-hexanediol, 645 parts of isophthalic acid, and adipic acid were placed in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping tank, and a nitrogen gas introduction tube. 36 parts of sebacic acid and 265 parts of sebacic acid were charged, and the temperature was raised to 250° C. with stirring under a nitrogen stream to perform an esterification reaction. After the reaction was continued until a predetermined amount of water was distilled out and the acid value became 5 or less, the pressure was gradually reduced and the deglycol reaction was performed at 1 mmHg or less for 5 hours to obtain a polyester polyol. Thereafter, 35 parts of isophorone diisocyanate was gradually added, and the reaction was carried out at 150° C. for about 2 hours to obtain a polyester polyurethane polyol. 12.0 parts of ethylene glycol bisanhydrotrimellitate was added to 100 parts of this polyester polyurethane polyol, reacted at 180°C for about 2 hours, and then diluted with ethyl acetate until the nonvolatile content was 50%. A solution of a partially acid-modified polyester polyol (A-1) having a molecular weight of 9,000 and an acid value of 30.3 mgKOH/g was obtained.

(Synthesis Example 2) Polyester polyol (A-2)
A reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping tank, and a nitrogen gas introduction tube was charged with 58 parts of ethylene glycol, 412 parts of diethylene glycol, 343 parts of neopentyl glycol, 517 parts of isophthalic acid, and 393 parts of adipic acid. The temperature was raised to 250° C. while stirring under a nitrogen stream to perform an esterification reaction. After continuing the reaction until a predetermined amount of water was distilled out and the acid value became 5 or less, the pressure was gradually reduced and the deglycol reaction was carried out for 5 hours at 1 mmHg or less to obtain a polyester polyol. 4.0 parts of trimellitic anhydride was added to 100 parts of this polyester polyol, reacted at 180°C for about 2 hours, and then diluted with ethyl acetate until the nonvolatile content was 50%, resulting in a number average molecular weight of 2,000, A solution of partially acid-modified polyester polyol (A-2) with an acid value of 23.5 mgKOH/g was obtained.

(Synthesis Example 3) Polyester polyol (A-3)
95 parts of ethylene glycol, 632 parts of neopentyl glycol, 498 parts of isophthalic acid, and 474 parts of adipic acid were charged into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping tank, and a nitrogen gas introduction pipe, and the mixture was heated under a nitrogen stream. The temperature was raised to 250° C. while stirring to perform an esterification reaction. After continuing the reaction until a predetermined amount of water was distilled out and the acid value became 5 or less, the pressure was gradually reduced and the deglycol reaction was carried out for 5 hours at 1 mmHg or less to obtain a polyester polyol. Thereafter, 4.0 parts of isophorone diisocyanate was gradually added, and the reaction was carried out at 150° C. for about 2 hours to obtain a polyester polyurethane polyol. Thereafter, the solution was diluted with ethyl acetate until the nonvolatile content became 50%, thereby obtaining a solution of polyester polyol (A-3) having a number average molecular weight of 12,000 and an acid value of 0.5 mgKOH/g.

(Synthesis Example 4) Acrylic polyol (A-4)
180 parts of ethyl acetate was charged into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping tank, and a nitrogen gas introduction tube, and the temperature was raised to 70° C. while stirring while introducing nitrogen gas.
Next, 120 parts of ethyl acrylate, 36 parts of butyl acrylate, 30 parts of methyl methacrylate, 4 parts of 2-hydroxyethyl methacrylate, 10 parts of methacrylic acid, and 20 parts of ethyl acetate were charged into dropping tank 1, and then into dropping tank 2. A solution of 4.0 parts of benzoyl peroxide in 40 parts of ethyl acetate was charged and added dropwise to each reactor simultaneously over 2 hours while stirring while maintaining the temperature inside the reaction vessel at 70°C.
After the reaction was completed, the mixture was diluted with ethyl acetate so that the nonvolatile content was 50%, thereby obtaining an acrylic polyol (A-4) having a number average molecular weight of 14,000 and an acid value of 32.6.

<Adjustment of polyisocyanate>
(Preparation example 1) Polyisocyanate (C-1)
Coronate 2785 (biuret type polyisocyanate derived from hexamethylene diisocyanate, manufactured by Tosoh Corporation) was diluted with ethyl acetate to adjust the non-volatile content to 50% and NCO% = 9.6%, and polyisocyanate (C-1) was prepared. A solution of was obtained.

(Preparation Example 2) Polyisocyanate (C-2)
Takenate D-110NB (trimethylolpropane adduct polyisocyanate derived from xylylene diisocyanate (hereinafter referred to as XDI), manufactured by Mitsui Chemicals) was diluted with ethyl acetate, nonvolatile content 50%, NCO% = 7.9%. A solution of polyisocyanate (C-2) was obtained.

(Preparation Example 3) Polyisocyanate (C-3)
Coronate L (trimethylolpropane adduct type polyisocyanate derived from toluene diisocyanate (hereinafter referred to as TDI), manufactured by Tosoh Corporation) was diluted with ethyl acetate to adjust the nonvolatile content to 50% and NCO% to 8.8%, A solution of polyisocyanate (C-3) was obtained.

<Production of adhesive composition (B)>
(Adhesive compositions T1 to T3, TT1, TT2)
The polyol solutions obtained in Synthesis Examples 1 to 4 above and the polyisocyanate solutions obtained in Preparation Examples 1 to 3 above were blended in the proportions (mass ratio) shown in Table 5, and ethyl acetate was added to reduce the nonvolatile content to 30. A mass percent adhesive composition solution was prepared.

<Manufacture of packaging materials>
In the production of the following packaging materials, a gravure plate with a laser beam of 175 lines/inch and a 25 μm solid area was used for printing the release ink and the printing ink. The printing speed was 70 m/min. Further, the thickness of both the release ink layer and the printing layer was 0.8 μm.

[Example 1] (Packaging material L1)
Separation ink S1 was diluted using a mixed solvent of EA/IPA (mass ratio 70/30) in a Zahn cup #3 at 25° C. for 15 seconds.
The diluted primer composition S1 was printed on an OPP film with a thickness of 20 μm using a gravure printing machine equipped with a gravure plate, and dried at 50° C. to form a first base layer (OPP)/first base layer (OPP). A laminate having a desorption layer structure was obtained.
Next, on the release layer of the obtained laminate, release adhesive T1 was applied using a dry laminating machine so that the coating amount after drying was 2 g/m ² , and after drying, a CPP film with a thickness of 30 μm was applied. A packaging material L1 having a configuration of first base layer (OPP)/first release layer/second release layer/second base layer (CPP) was obtained.

[Example 2, 29, 30] (Packaging materials L2, L29, L30)
Packaging materials L2, L29, and L30 were obtained by the same method as packaging material L1 except that the materials listed in Table 6 were used. For packaging material L2, diluted release ink was printed on the PET surface of a 12 μm thick alumina/PET film.

[Example 3] (Packaging material L3)
Separation ink S1 and printing ink R1 were each diluted using a mixed solvent of EA/IPA (mass ratio 70/30) in a Zahn cup #3 at 25° C. for 15 seconds.
On an OPP film with a thickness of 20 μm, diluted release ink S1 and printing ink R1 were printed in this order using a two-color gravure printing machine equipped with a gravure plate, dried at 50 ° C. A laminate having a structure of material layer (OPP)/first release layer/printing layer was obtained.
Next, release adhesive T1 was applied onto the printed layer of the obtained laminate using a dry laminating machine so that the coating amount after drying was 2 g/m ² , and after drying, a CPP film with a thickness of 30 μm was applied. By laminating them together, a packaging material L3 having a configuration of first base layer (OPP)/first release layer/printed layer/second release layer/second base layer (CPP) was obtained. .

[Examples 4-28, 31-33, Comparative Examples 3-5] (Packaging materials L4-L28, L31-L33, LL3-LL5)
Packaging materials L4 to L28, L31 to L33, and LL3 to LL5 were obtained in the same manner as packaging material L3 except that the materials listed in Table 6 were used. For packaging material L31, a diluted primer composition was printed on the PET surface of a 12 μm thick alumina/PET film. For packaging material L32, a diluted primer composition was printed on the alumina-deposited surface of an alumina/PET film having a thickness of 12 μm. In the packaging material L33, the vapor-deposited surface of a 12 μm thick VM/PET film was bonded onto the adhesive layer.

[Example 34] (Packaging material L34)
Separation ink S1 and printing ink R1 were each diluted using a mixed solvent of EA/IPA (mass ratio 70/30) in a Zahn cup #3 at 25° C. for 15 seconds.
A PET film with a thickness of 12 μm is printed with diluted release ink S1 and printing ink R1 in this order using a two-color gravure printing machine equipped with a gravure plate, dried at 50 ° C. A laminate having a structure of material layer (PET)/first release layer/printing layer was obtained.
Next, a releasable adhesive T1 was applied onto the PET film of the obtained laminate using a dry laminating machine so that the coating amount after drying was 2 g/m ² , and after drying, a PE film with a thickness of 50 μm was formed. By laminating them together, a packaging material L34 having a configuration of printed layer/first release layer/first base layer (PET)/second release layer/second base layer (PE) was obtained. .

[Example 35] (Manufacture of packaging material L35)
Each of the release inks S1 was diluted using a mixed solvent of EA/IPA (mass ratio 70/30) in a Zahn cup #3 at 25° C. for 15 seconds.
The diluted release ink S1 was printed on a 12 μm thick PET film using a gravure printing machine equipped with a gravure plate, and dried at 50°C to form a first base layer (PET)/first base layer (PET). A laminate having a desorption layer structure was obtained.
Next, release adhesive T1 was applied onto the release layer of the obtained laminate using a dry laminating machine so that the coating amount after drying was 2 g/m ² , and after drying, an aluminum foil with a thickness of 7 μm was applied. (hereinafter referred to as AL).
Next, a releasable adhesive T1 was applied and dried on the AL so that the coating amount after drying was 2 g/ ^m2 , and then laminated with a 30 μm thick CPP film to form the first base layer (PET)/ A packaging material L35 having a configuration of first release layer/adhesive layer/third base layer/second release layer/second base layer (CPP) was obtained.

[Example 36] (Manufacture of packaging material L36)
The release ink S1 and the printing ink R1 were each diluted using a mixed solvent of EA/IPA (mass ratio 70/30) in a Zahn cup #3 at 25° C. for 15 seconds.
A PET film with a thickness of 12 μm is printed with diluted release ink S1 and printing ink R1 in this order using a gravure two-color printing machine equipped with a gravure plate, and dried at 50° C. to form a first base material. A laminate having a structure of layer (PET)/first release layer/printing layer was obtained.
Next, release adhesive T1 was applied onto the printed layer of the obtained laminate using a dry laminating machine so that the coating amount after drying was 2 g/m ² , and after drying, it was pasted with AL having a thickness of 7 μm. Combined.
Next, a releasable adhesive T1 was applied and dried on the AL so that the coating amount after drying was 2 g/ ^m2 , and then laminated with a CPP film with a thickness of 30 μm to form the first base layer (PET)/ A packaging material L36 having a configuration of first release layer/printed layer/adhesive layer/third base layer/second release layer/second base layer (CPP) was obtained.

[Examples 37 to 41] (Packaging materials L37 to L41)
Packaging materials L37 to L41 were obtained in the same manner as packaging material L31 except that the materials listed in Table 6 were used. Packaging material L37 was obtained by bonding the printed layer and the vapor-deposited surface of a 12 μm thick VM/PET film with an adhesive, and further bonding the PET surface and a 30 μm thick CPP film with an adhesive. For packaging material L38, diluted release ink was printed on the alumina-deposited surface of an alumina/PET film having a thickness of 12 μm.

[Example 42] (Manufacture of packaging material L42)
The release ink S1 and the printing ink R1 were each diluted using a mixed solvent of EA/IPA (mass ratio 70/30) in a Zahn cup #3 at 25° C. for 15 seconds.
A PET film with a thickness of 12 μm is printed with diluted release ink S1 and printing ink R1 in this order using a gravure two-color printing machine equipped with a gravure plate, and dried at 50° C. to form a first base material. A laminate having a structure of layer (PET)/first release layer/printing layer was obtained.
Next, release adhesive T1 was applied onto the printed layer of the obtained laminate using a dry laminating machine so that the coating amount after drying was 2 g/m ² , and after drying, it was pasted with AL having a thickness of 7 μm. Combined.
Next, a releasable adhesive T1 was coated and dried on the AL so that the coated amount after drying was 2 g/m ² , and then a NY film having a thickness of 15 μm was bonded. Furthermore, a releasable adhesive T1 was coated and dried on the NY film so that the coating amount after drying was 2 g/ ^m2 , and then laminated with a CPP film with a thickness of 30 μm to form the first base layer (PET). /First release layer/Printed layer/Adhesive layer/Third base layer/Second release layer/Second base layer (NY)/Adhesive layer/Fourth base layer ( A packaging material L42 having a structure of CPP) was obtained.

[Comparative Example 1] (Packaging material LL1)
Each printing ink R1 was diluted using a mixed solvent of EA/IPA (mass ratio 70/30) in a Zahn cup #3 at 25° C. for 15 seconds.
The diluted printing ink R1 was printed on an OPP film with a thickness of 20 μm using a gravure printing machine equipped with a gravure plate, and dried at 50° C. to form the first base layer (OPP)/printing layer. A laminate was obtained.
Next, a releasable adhesive T1 was applied onto the printed layer of the obtained laminate using a dry laminating machine so that the coating amount after drying was 2 g/m ² , and after drying, a CPP film with a thickness of 30 μm was applied. By laminating them together, a packaging material LL1 having a configuration of first base layer (OPP)/printed layer/second release layer/second base layer (CPP) was obtained.

[Comparative Example 2] (Packaging material LL2)
Packaging material LL2 was obtained by the same method as packaging material LL1 except that the materials listed in Table 6 were used.

<Evaluation of packaging materials>
The following removability evaluation was performed on the obtained packaging material. The results are shown in Table 6.

(Yield of transparent base material)
100 samples cut out from the obtained packaging material into 1 cm x 1 cm sizes and 800 g of a 2% solids concentration aqueous solution of sodium hydroxide (hereinafter referred to as NaOH) were placed in a 1 L flask, and the mixture was heated at 70°C and a rotational speed of 200 rpm for 4 hours. Stirred. After washing and drying the sample, transparent films from which 80% or more of the printed layer had been visually removed were collected and counted. The yield was determined using the following formula. Note that since the AL foil is a metal layer, it is not counted in the number of base materials.
Yield=Number of transparent films recovered/Number of plastic base materials constituting the original packaging material The yield was evaluated based on the following criteria. ◯ and △ are within a range that causes no practical problems.
○: Yield is 80% or more △: Yield is 60% or more ×: Yield is less than 60%

(Removal rate of printed layer/adhesive layer of base material after detachment)
100 samples cut out from the obtained packaging material into 1 cm x 1 cm sizes and 800 g of a 2% solids concentration aqueous solution of sodium hydroxide (hereinafter referred to as NaOH) were placed in a 1 L flask, and the mixture was heated at 70°C and a rotational speed of 200 rpm for 4 hours. Stirred. After the samples were washed with water and dried, the removal rate of the printed layer was visually confirmed. A transparent film was collected from the obtained sample, and the presence or absence of an absorption peak of the adhesive composition was confirmed using FT-IR at five locations on the front and back sides of the film, and the removal rate of the adhesive composition was confirmed. The removal rates of the printed layer and adhesive layer were evaluated based on the following criteria. ◯ and △ are within a range that causes no practical problems.
○: Yield is 80% or more △: Yield is 60% or more ×: Yield is less than 60%

(Base material adhesion)
The obtained packaging material was cut to a width of 15 mm, and the peel strength (laminate strength) between base material 1 and base material 2 was measured using a 201 universal tensile tester manufactured by Intesco.
Adhesion to the base material was evaluated based on the following criteria. ◯ and △ are within a range that causes no practical problems.
○: Lamination strength is 1.0N/15mm or more △: Lamination strength is 0.5N/15mm or more and less than 1.0N/15mm ×: Lamination strength is less than 0.5N/15mm

The abbreviations in Table 6 are shown below.
・ OPP: Stretched polypropylene film thickness 20μm
・CPP: Unstretched polypropylene film thickness 30μm
・Al/PET: Alumina vapor-deposited polyethylene terephthalate film, thickness 12μm
・ VM/PET: Polyethylene terephthalate film with a vapor-deposited layer of amorphous aluminum, thickness 12 μm
・PET: Polyethylene terephthalate film thickness 12μm
・NY: Nylon film thickness 15μm
・PE: Linear low-density polyethylene film, thickness 50μm

According to the evaluation results, by having the first release layer and the second release layer, the packaging material of the present invention maintains adhesion to the base material while maintaining the printing layer and adhesion in a basic aqueous solution. The removability of the agent layer is improved, and the recyclability of the first base material and the second base material can be improved. The packaging material of the present invention and the packaging container using the packaging material are useful as packaging materials and packaging containers suitable for plastic recycling.

Claims (6)

a first base material; a first desorption layer for desorbing the first base material to separate and collect the first base material for recycling;
A packaging material comprising a second base material and a second detachment layer for detaching the second base material to separate, collect and recycle the second base material, the packaging material comprising:
the first release layer is placed in contact with the first base material,
the second release layer is placed in contact with the second base material,
The first release layer is formed from a first release layer forming composition (A),
The second release layer is formed from a second release layer forming composition (B),
The first release layer forming composition (A) contains a resin (a) and a solvent, and the resin (a) has an acid value of 15 mgKOH/g or more,
The second release layer forming composition (B) is an adhesive composition containing a polyol component and a polyisocyanate component, and the polyisocyanate component is composed of an aliphatic polyisocyanate and an araliphatic polyisocyanate. A packaging material containing at least one polyisocyanate component selected from the group consisting of at least one polyisocyanate component, and in which the acid value of the reaction product of the polyol component and the polyisocyanate component is 5 mgKOH/g or more. The packaging material according to claim 1, wherein the resin (a) has a hydroxyl value of 1 to 250 mgKOH/g. The packaging material according to claim 1 or 2, wherein the resin (a) has an acid value of 15 to 70 mgKOH/g and a hydroxyl value of 1 to 45 mgKOH/g. The packaging material according to any one of claims 1 to 3, wherein the resin (a) contains a urethane resin. The packaging material according to claim 4, wherein the urethane resin contained in the resin (a) contains a structural unit derived from a polyester polyol. A method for producing a recycled base material, comprising a step of immersing the packaging material according to any one of claims 1 to 5 in a basic aqueous solution,
The basic aqueous solution contains a basic compound in an amount of 0.5 to 10% by mass of the entire basic aqueous solution, and the water temperature of the basic aqueous solution during immersion is 30 to 120°C.