JP2023132208A - Printing laminate for packaging - Google Patents

Abstract

To provide a printing laminate for packaging which exhibits excellent oxygen barrier property even if heat treatment such as retort sterilization is performed while having a printing layer, having a high polyolefin percentage content and improving suitability for recycle.SOLUTION: A printing laminate for packaging includes a barrier film composed of a thermoplastic resin film, and an inorganic film formed on the surface of the film, a printing layer, and an adhesive layer, in this order, wherein the adhesive layer is formed of an epoxy-based adhesive, and a percentage content of polyolefin of the printing laminate for packaging is adjusted to be 80 mass% or more.SELECTED DRAWING: None

Description

The present invention relates to a printed laminate for packaging, and more particularly to a printed laminate for packaging that includes a printed layer and exhibits excellent oxygen barrier properties.

Resin films, typified by olefin resin films such as polypropylene film and polyethylene film, are inexpensive and have the advantage of being easily heat-sealed to form pouches, and have been used as packaging materials for a long time. Widely used.

Since such resin films have poor gas barrier properties, it is known that an inorganic film is formed on the surface of the resin film as a means to improve gas barrier properties. It is known to provide vapor-deposited films of materials, coatings mainly composed of silicon oxide, coatings formed by crosslinking reactions between carboxylic acids and metals, coatings in which metal oxides are dispersed, etc. . Furthermore, it is also known to provide the coating film on the vapor deposited film. A resin film having such an inorganic film on its surface exhibits high gas barrier properties and is therefore commercially available as a barrier film.

By the way, when producing a pouch using the above-mentioned barrier film, a heat-sealable resin layer is usually provided. Such a heat-sealable resin layer is attached to a barrier film using an adhesive.

For example, Patent Document 1 includes a base film having a vapor deposited film, and a heat-sealable resin layer provided on the vapor deposited film via an adhesive layer, and the adhesive layer includes polyester polyol, polyester polyol, A packaging laminate is disclosed that is formed of a cured product of a two-part curable adhesive containing an isocyanate compound and a phosphoric acid modified compound.
Note that the adhesive layer is provided to bond layers formed from different materials such as the base film and the heat-sealable resin layer, and the heat-sealable resin layer is provided to bond layers formed from different materials such as the base film and the heat-sealable resin layer. It is provided for bonding the heat-sealable resins together, and is different from the adhesive layer.

However, pouches obtained by making bags using this packaging laminate have sufficient oxygen barrier properties unless retort sterilization is performed; It will drop. Therefore, it is difficult to use such a packaging laminate as a pouch for retort food. It is believed that the decrease in oxygen barrier properties after retort sterilization is due to the base film expanding and contracting due to the heating during retort sterilization, which causes cracks in the deposited layer. Such a reduction in oxygen barrier properties due to heating occurs not only when a vapor-deposited film is formed, but also when other inorganic films are formed. Therefore, it is required to ensure excellent oxygen barrier properties by an inorganic film even after retort sterilization.

Furthermore, Patent Document 2 discloses a gas barrier polyolefin laminate film that includes a polyolefin film layer and a gas barrier layer. In this laminated film, the gas barrier layer is a film layer made by curing an epoxy resin containing aromatic rings in its molecules with an epoxy resin curing agent, and exhibits excellent oxygen barrier properties. Therefore, regardless of whether or not retort sterilization is performed, oxygen barrier properties as good as barrier films with inorganic films cannot be obtained.

Furthermore, in Japanese Patent Application No. 2020-153224, the applicant proposed a packaging laminate that exhibits excellent oxygen barrier properties even when subjected to heat treatment such as retort sterilization. This packaging laminate includes a barrier film in which an inorganic film is formed on the surface of a thermoplastic resin film, and an adhesive layer provided on the inorganic film. is characterized in that it is formed using an epoxy adhesive. That is, in this packaging laminate, other layers such as a heat-sealable resin layer (sealant film) are laminated on the inorganic film of the barrier film by an epoxy adhesive layer, and thereby the inorganic The crack resistance of the barrier film (inorganic-based This means that the properties of the film can be fully demonstrated.

JP2020-37187A Patent No. 4117461

The present inventors have further advanced the technology of the above-mentioned prior application (Japanese Patent Application No. 2020-153224), and have discovered that the adhesive layer used to laminate other layers to the inorganic film of the barrier film has high storage elasticity. When the inorganic film has a high oxygen barrier property, even if a printed layer is interposed between the inorganic film and the adhesive layer, the excellent oxygen barrier properties of the inorganic film are ensured. The present inventors have discovered that the properties are not impaired even when the polyolefin content in the laminate is high, and have completed the present invention.

That is, the object of the present invention is to provide printing for packaging that has a printed layer and a high polyolefin content, improves recyclability, and exhibits excellent oxygen barrier properties even when subjected to heat treatment such as retort sterilization. The purpose is to provide a laminate.

According to the present invention, a printed laminate for packaging includes a barrier film made of a thermoplastic resin film and an inorganic film formed on the surface of the film, a printed layer, and an adhesive layer in this order,
The adhesive layer is formed of an epoxy adhesive,
There is provided a printed laminate for packaging, characterized in that the polyolefin content of the printed laminate for packaging is adjusted to 80% by mass or more.

In the printed laminate for packaging of the present invention, the following aspects are suitably applied.
(1) The printing layer provided between the inorganic film and the adhesive layer contains titanium oxide.
(2) An inner side film including a heat-sealable resin layer is laminated via the adhesive layer.
(3) The inorganic film is formed from a vapor deposited layer formed using the thermoplastic resin film as a base.
(4) The vapor deposition layer is formed of silicon oxide, aluminum oxide, or silica-alumina composite oxide.
(5) An inorganic coating layer is provided on the vapor deposition layer as a protective layer.
(6) The inorganic coating layer is formed from a metal alkoxide or a condensate thereof.
(7) The heat-sealable resin layer is formed from an olefin resin composition. It consists of an olefin resin composition, and the olefin resin composition is formed from polypropylene (A), linear low density polyethylene (B), or a mixture of A and B.
(8) The olefin resin composition is formed from polypropylene, linear low density polyethylene, or a mixture of polypropylene and linear low density polyethylene.
(9) The olefin resin composition has a mass ratio of impact polypropylene component (A) in which an ethylene-propylene copolymer is dispersed in polypropylene and linear low density polyethylene (B) A:B = 99:1 ~ Formed from a 50:50 ratio.
(10) The thermoplastic resin film is a stretched polypropylene film.

According to the present invention, there is also provided a pouch obtained by pasting the above printed packaging laminates together by heat sealing.

The printed laminate for packaging of the present invention includes, in this order, a barrier film consisting of a thermoplastic resin film and an inorganic film formed on the surface of the film, a printed layer, and an adhesive layer. It has a basic structure in which a layer is further laminated with another layer (for example, a layer with a heat-sealable resin layer), but broadly speaking, it has the following two characteristics. .
(a) The adhesive layer mentioned above shall be formed of an epoxy adhesive.
(b) The polyolefin content contained in the entire printing laminate for packaging, including the layers laminated by the above-mentioned adhesive layer, is 80% by mass or more.

That is, to explain the feature (a) above, by forming an adhesive layer using an epoxy adhesive, excellent barrier properties can be obtained even after retorting. This point has been confirmed as a phenomenon as a result of many experiments, and the exact reason has not yet been elucidated. However, the present inventors speculate that one reason is that the adhesive layer formed from the epoxy adhesive exhibits a large storage modulus at high temperatures, particularly at 120°C.
This storage modulus is a parameter measured by a dynamic viscoelasticity test (10Hz) at 120°C, and the fact that the storage modulus at 120°C shows a high value as above means that the storage modulus at around 120°C This means that this adhesive layer suppresses the expansion and contraction of the base film and inorganic coating during heat treatment such as retort sterilization, and as a result, pouches can be made using this printed packaging laminate. However, when heat treatment such as retort sterilization is performed, cracking and peeling of the inorganic film are effectively prevented, and excellent oxygen barrier properties are exhibited. A great advantage of the present invention is that such characteristics of the adhesive layer are exhibited even when a printing layer (i.e., a layer containing printing ink) is interposed between the adhesive layer and the inorganic film. .

Further, to explain the feature (b), the printed laminate for packaging of the present invention is provided with an adhesive layer that exhibits a high storage modulus at 120°C by forming the adhesive layer with an epoxy adhesive. The body exhibits high oxygen barrier properties even when heat-treated (characteristic (a) above); is also demonstrated. That is, polyolefin has lower oxygen barrier properties than gas barrier resins such as ethylene/vinyl alcohol resins and aromatic polyamides. However, in the present invention, by forming a laminated structure on the inorganic film of the barrier film using the adhesive layer described above, excellent oxygen barrier properties can be achieved without using a gas barrier resin and using almost only polyolefin. It is possible to secure it. This means that the printed laminate for packaging of the present invention also has the great advantage of improving the recyclability of the pouch.

The printed laminate for packaging of the present invention exhibits excellent oxygen barrier properties not only before retorting but also after retorting, and is suitably used as a pouch for retort foods.

<Basic layer structure of printed laminate for packaging>
In the present invention, the inorganic film is formed using a thermoplastic resin film as a base, and usually the thermoplastic resin film on which the inorganic film is formed on the surface is treated as an integral film as a barrier film. .
The printed laminate for packaging of the present invention having such a barrier film has the basic layer structure shown below.
Barrier film/Print layer/Adhesive layer/Inner side film (1)

In the above basic layer structure (1), as understood from the position of the printed layer, the thermoplastic resin film becomes the outer surface. Therefore, the above basic layer structure (1) can also be expressed as follows.
Barrier film (inorganic film) / Printed layer / Adhesive layer / Inner side film In addition, a reinforcing film can be provided between the barrier film and the inner side film, and such a basic layer structure is as follows. .
Barrier film (inorganic film) / Printing layer / Adhesive layer / Reinforcement film / Adhesive layer / Inner side film
(2)
Furthermore, an adhesive layer can be provided on both sides of the barrier film, such a basic layer structure is as follows.
Reinforcement film / adhesive layer / printing layer / (inorganic film) barrier film / adhesive layer / inner side film
(3)

In addition, the printed layer must naturally be visible from the outside, and for this reason, the outer surface of the printed layer needs to have transparency to the extent that the printed layer can be seen, for example, The materials of the thermoplastic resin film and the inorganic film are selected so that the degree of haze is about 5% or less.

Furthermore, in the above basic structures (1) to (3), the inner side film faces the substance to be packaged, and may be a single-layer film or a multi-layer film, and is used after being made into a pouch. In this case, the innermost surface of this inner side film becomes a heat-sealable olefin resin layer (sometimes referred to as a sealant).

<Barrier film>
Thermoplastic resin film;
In the barrier film, the thermoplastic resin film that serves as the base for the inorganic film is produced by known means such as extrusion or coextrusion.

Such thermoplastic resin is not limited in principle and various thermoplastic resins can be used, such as low density polyethylene, high density polyethylene, medium density polyethylene, polypropylene, poly 1-butene, Olefin systems such as polyolefins such as random or block copolymers of α-olefins such as poly4-methyl-1-pentene or ethylene, propylene, 1-butene, 4-methyl-1-pentene, and cyclic olefin copolymers Resin is a typical example.

Since the printed laminate for packaging of the present invention contains at least 80% by mass or more, preferably 90% by mass or more of polyolefin in order to improve the recyclability of polyolefin, as long as such a high content of polyolefin is not impaired, In addition to the olefin resins mentioned above, the following resins can be used to form the thermoplastic resin film.

Ethylene/vinyl compound copolymers, such as ethylene/vinyl acetate copolymers, ethylene/vinyl alcohol copolymers, ethylene/vinyl chloride copolymers;
Styrenic resins, such as polystyrene, acrylonitrile/styrene copolymer, ABS, α-methylstyrene/styrene copolymer;
Polyvinyl resins, such as polyvinyl chloride, polyvinylidene chloride, vinyl chloride/vinylidene chloride copolymer, polymethyl acrylate, polymethyl methacrylate;
Polyamides, such as nylon 6, nylon 6-6, nylon 6-10, nylon 11, nylon 12;
Thermoplastic polyesters, such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate (PEN);
Other resins, such as polycarbonate, polyphenylene oxide, polyimide resin, polyamideimide resin, polyetherimide resin, fluororesin, allyl resin, polyurethane resin, cellulose resin, polysulfone resin, polyethersulfone resin, ketone resin, amino resin , polylactic acid, etc.;
Furthermore, a blend of the resins exemplified above or a resin modified by appropriate copolymerization (for example, an acid-modified olefin resin) may also be used.

Moreover, a multilayer film may be used in which a layer of olefin resin and a layer of resin other than olefin resin are laminated using a known adhesive resin such as an acid-modified olefin resin.

In the printed laminate for packaging of the present invention, the thermoplastic resin film is preferably an olefin resin film from the viewpoint of being used to form a retort pouch with high recyclability. From this point of view, polypropylene is more preferred.
Furthermore, it is preferable that the thermoplastic resin film is stretched in one or two axial directions since it has heat resistance that can withstand retort sterilization. The stretching ratio may be such that the film does not break due to overstretching, and is usually 2 times or more.

The above-mentioned thermoplastic resin film may have an appropriate thickness depending on the capacity of the pouch to be finally manufactured, but if it is too thin, it may be difficult to form the inorganic film described below. Since there is a possibility that strength may be lowered due to loss of orientation, etc., it is preferable that the thickness is at least 10 μm or more.

Inorganic film;
The inorganic film provided on the surface of the thermoplastic resin film mentioned above is provided to ensure oxygen barrier properties, and may be a vapor-deposited film of various metals or metal oxides, or a coating mainly made of silicon oxide. There are films, coating films of condensates of metal alkoxides, coating films formed by crosslinking reactions between carboxylic acids and metals, coating films in which metal oxides are dispersed, and the like. Moreover, it is suitable to provide the above-mentioned coating film as a protective film (so-called top coat layer) on the above-described vapor-deposited film.

The above-mentioned vapor deposited film is an inorganic vapor deposited film formed by physical vapor deposition represented by sputtering, vacuum vapor deposition, ion plating, etc., or chemical vapor deposition represented by plasma CVD. This is a film formed by Since such a deposited film is formed of an inorganic substance, it exhibits higher oxygen barrier properties than gas barrier resins such as ethylene-vinyl alcohol copolymers.

The above-mentioned vapor deposition film formation may be performed directly on the surface of the thermoplastic resin film described above, but in order to improve the smoothness of the vapor deposition film and the adhesion to the film surface, polyester, polyethyleneimine, etc. It is preferable to coat with a hydrophilic resin such as acrylic resin, polyamide, or polyurethane, and form a vapor deposited film on the coating film (so-called anchor coat layer).

In the present invention, from the viewpoint of ensuring that the formed film is dense and has particularly high oxygen barrier properties, an inorganic film is formed using a vapor-deposited film made of silicon oxide, aluminum oxide, silica-alumina composite oxide, etc. It is preferable that an inorganic film is formed by a vapor-deposited film of silicon oxide, since transparency is particularly ensured (haze of 5% or less) and good visibility is shown for the printed layer described later. Most preferably, it is formed.

Moreover, it is preferable that the above-mentioned inorganic coating film is provided as a protective film layer (top coat layer) on the above-mentioned vapor deposited film. Such a coating film functions as a protective film that penetrates into the minute defects (cracks) generated in the above-mentioned vapor deposited film, prevents the growth of the defects, and prevents the generation of new defects. Suitable coating films include those containing metal alkoxides such as alkoxysilane and alkoxytitanium, and those in which a portion is condensed are preferred from the viewpoint of adhesion to the deposited film.

The thickness of the above-mentioned inorganic film varies depending on the level of oxygen barrier properties required, but in the case of vapor-deposited films, it is possible to maintain the thickness of the inorganic film without impairing the properties of the thermoplastic resin film that serves as the base for vapor deposition, and before retort treatment. If so, it is preferable to set the thickness to such an extent that an oxygen permeability of 1 cc/m ² /day/atom or less can be ensured, and generally, the thickness should be about 1000 to 10 nm, particularly about 100 to 10 nm.

Also, what are the thickness and constituent elements of the inorganic coating? It can be identified by depth direction analysis using X-ray photoelectron spectroscopy (XPS) or Auger electron spectroscopy (AES), energy dispersive X-ray analysis (EDX), or the like.

<Print layer>
In the present invention, a printed layer is formed on the above-mentioned inorganic film.
Such a printing layer is formed on the surface of an inorganic film by a printing method known per se, such as inkjet printing, screen printing, or gravure printing. It is formed in the form of lines, letters, patterns, etc. using inks of various colors, and is formed by heating and drying as appropriate.

Ink resins (binder) used in such printing inks include polyurethane resins, polyurethane urea resins, acrylic modified urethane resins, acrylic modified urethane urea resins, vinyl chloride-vinyl acetate copolymer resins, and rosin resins ( Typical examples include rosin-modified maleic acid resin), polyamide resin, polyester resin, chlorinated polypropylene resin, acrylic resin, nitrocellulose resin, and rubber resin. In particular, from the viewpoint of bondability with the adhesive layer described below, urethane resins, vinyl chloride-vinyl acetate copolymer resins, and polyester resins are suitable.

Moreover, the above-mentioned printed layer may be a solid layer, or may be a local layer containing an image or a linear pattern formed with ink of each color. Further, it may be a solid layer in which a gradation-like pattern is formed using ink of each color, or it may be formed of a plurality of layers in which ink of each color is superimposed. Furthermore, if an ink image of a color other than white is formed in this printing layer, a white printing layer formed from white ink containing titanium oxide is formed as a background to cover such ink image. It is preferable that the This significantly improves the visibility of the ink image.

The total thickness of the printing layer described above is extremely thin at 5 μm or less. Therefore, it hardly affects the adhesiveness exhibited by the adhesive layer described later.

<Adhesive layer>
In any of the basic layer structures (1) to (3), the adhesive layer described above is formed directly or on the inorganic film with a printed layer interposed therebetween. This adhesive layer is formed of an epoxy adhesive and has a storage modulus of more than 1.5 MPa at 120°C. In other words, since it exhibits a large storage modulus at 120°C, it suppresses the expansion and contraction of the base film and inorganic coating when heat treatment is performed at around 100 to 120°C such as retort sterilization. The occurrence of defects such as cracks and peeling in the film can be effectively suppressed, and a decrease in oxygen barrier properties can be effectively avoided.

In the present invention, in order to form an adhesive layer exhibiting a large storage modulus as described above, it is preferable to use an epoxy adhesive known as a dry lamination adhesive.

Epoxy adhesive;
The above-mentioned epoxy adhesive is an adhesive that is bonded by curing a liquid epoxy resin with an epoxy curing agent.
Such epoxy resins are liquid resins that have epoxy groups in their molecules, and are obtained by reacting epichlorohydrin with phenolic compounds, amine compounds, carboxylic acids, etc., or by oxidizing unsaturated compounds such as butadiene with organic peroxides. A typical example is one obtained by doing this, and any type can be used.

Specific examples of epoxy adhesives include, but are not limited to, bisphenol A or bisphenol F epoxy resins, novolac epoxy resins, cycloaliphatic epoxy resins, long chain aliphatic epoxy resins, Examples include glycidyl ester type epoxy resins and glycidyl amine type epoxy resins.
In the present invention, glycidylamine type epoxy resin is particularly suitable in that it can form an adhesive layer with a high elastic modulus.

Furthermore, known epoxy curing agents such as amines, acid anhydrides, and polyamides can be used, but they form a coating film (adhesive layer) that has a particularly high elastic modulus and easily follows heat shrinkage. From the viewpoint that it can be used, amine curing agents, especially aromatic polyamines represented by metaphenylene diamine, are preferably used.

The ratio of the epoxy resin to the curing agent may be set according to the epoxy equivalent of the epoxy resin so that a sufficient cured film is formed.

In the present invention, the above-mentioned epoxy adhesive is applied to the inner surface film described later using a volatile organic solvent such as a hydrocarbon, alcohol, ketone, ester, or ether, and then dried. , forming an adhesive layer.
That is, by laminating the adhesive layer formed on the surface of the inner side film to the inorganic film on which the aforementioned printing ink image (furthermore, the white printing layer) is formed, the printed laminate for packaging of the present invention can be obtained. You get a body. The adhesive layer thus formed is usually cured by holding it at a temperature of about 30 to 50° C. for 24 hours or more.

<Reinforcement film>
The reinforcing film used in the patterns of basic layer structures (2) and (3) is an olefin-based stretched film that is also used as a base for the inorganic film in the barrier film described above, and by using such a film, it has a heat-resistant properties and mechanical strength are improved. Of course, in addition to olefin-based stretched films, polyamide stretched films can also be used as reinforcing films, but since there is a restriction that the polyolefin content must be kept at 80% by mass or more, in the present invention, polyolefin is usually used. , in particular a stretched film of polypropylene is used as reinforcing film.

<Inner side film>
The inner side film having the adhesive layer on its surface may have a single layer structure or a multilayer structure including a plurality of layers, but at least the surface opposite to the adhesive layer may have a single layer structure or a multilayer structure including a plurality of layers. must be a heat-sealable resin layer (hereinafter sometimes referred to as a sealant). That is, this sealant easily melts when heated and immediately solidifies when cooled, so it can be used to thermally bond this laminate to various objects, and furthermore, it can be used to bond laminates to each other. A pouch can be produced by thermal adhesion (heat sealing).

In the present invention, films made of various thermoplastic resins can be used as the film used to form the above-mentioned sealant, but in the present invention, in order to improve the recyclability of the pouch, polyolefin is used. It is necessary to set the content to 80% by mass or more. For this reason, films made of olefin resins such as homopolypropylene (homo-PP), random polypropylene (random PP), impact polypropylene (impact PP), and linear low-density polyethylene (LLDPE) are referred to as sealant films. When used to produce pouches that undergo retort processing, it is necessary to ensure heat resistance and impact resistance, so CPP film (unstretched polypropylene film, also called cast PP film) is preferably used. In particular, a CPP film made of impact PP is most preferably used since it can ensure excellent impact resistance and heat resistance.

The above CPP film using Impact PP is molded by melt extrusion of a propylene-based resin composition, but this propylene-based resin composition contains linear low-density polyethylene in addition to the Impact PP component (A). (B) may also be included.

Impact PP component (A);
The impact PP component (A) is made of impact polypropylene (impact PP), and the impact PP used in the present invention is particularly composed of homo or random polypropylene in which ethylene-propylene copolymer (EPR) is dispersed. It has a structure. That is, by dispersing EPR in polypropylene, impact resistance is imparted to polypropylene. In addition to EPR, styrene-butadiene copolymer (SBR) and ethylene-propylene-butene copolymer (EPBR) are known as rubber components dispersed in polypropylene. EPR is optimal in that it can improve impact resistance, especially impact resistance at low temperatures.

Impact PP as described above has an MFR (melt flow rate, 230° C.) of about 0.5 to 10 g/10 min from the viewpoint of film moldability (extrusion moldability) and the like.

In addition, the EPR content in the above impact PP can be expressed as the xylene soluble fraction when the CPP film used for forming the heat sealable resin layer is dissolved in boiling xylene, and this xylene soluble fraction is preferably 8% by mass or more, particularly in the range of 8 to 20% by mass. That is, if this xylene soluble fraction is smaller than the above range, the amount of EPR will be small, resulting in a decrease in the impact resistance of the pouch. Furthermore, if the soluble fraction is too high, the pouch may have poor appearance.

Linear low density polyethylene (B);
When mixed with the above-mentioned impact PP, this linear low density polyethylene (LLDPE) functions as a compatibilizer for polypropylene (PP) and ethylene-propylene copolymer (EPR), improving the dispersibility of EPR in PP. It is a component for fully exhibiting the impact improving effect of EPR by greatly improving .

Such LLDPE is a linear low density polyethylene with a density in the range of 0.860 to 0.925 g/cm ³ , such as butene-1, hexene-1, 4-methylpentene-1, octene-1 It is a product obtained by copolymerizing α-olefins such as Extremely high.

In addition, since this LLDPE is used mixed with impact PP, one with an MFR (190°C) of 1.0 to 15 g/10 min is preferably used in order not to impair film formability. As the comonomer component, hexene-1 and 4-methylpentene-1 (methylpentene) are preferred, and methylpentene is most preferred.

Further, it is preferable that this LLDPE has a content of α-olefin as a comonomer of 10 mol % or less, and a number average molecular weight measured by GPC in terms of polystyrene of 10,000 or more. In other words, when the content of the comonomer α-olefin is high, or when the number average molecular weight is small and a large amount of low molecular weight components are contained, when used as a pouch, oil resistance and flavor properties of the contents may be affected. It will be inferior to.

The composition of the above-mentioned LLDPE (B) is preferably designed such that the amount of LLDPE in the CPP film (corresponding to the amount of LLDPE in the heat-sealable resin layer) is 20% by mass or less. That is, if LLDPE is contained excessively, the blocking resistance and heat resistance of the film may be impaired.

Incidentally, the propylene resin composition used for forming the CPP film may contain additives known per se in an amount within a range that does not impair recyclability.

The CPP film containing the above-mentioned impact PP components is produced by dry blending each component, putting it into an extruder, melt-kneading it, melt-extruding the blend into a film from a T-die, and extruding the extruded film-like melt. It is manufactured by contacting a cooling roll to solidify it and then winding it up.
The thickness of such a CPP film is not particularly limited, but in consideration of rigidity, unsealability, etc., it is usually preferably in the range of 20 to 100 μm, particularly 50 to 80 μm.

In the present invention, other resin layers may be laminated on the above sealant film to have a multilayer structure, but such other resin layers may have an olefin content of 80% by mass or more based on the entire laminate. Other resins and adhesives other than olefin resins can be used as long as the properties (especially 90% by mass or more) are not impaired.

Typical examples of the other resins mentioned above include polyamide resins and ethylene/vinyl alcohol copolymers, and these resins are especially effective for further increasing oxygen barrier properties, and are It is also suitable for increasing puncture strength.
Further, the adhesive used as appropriate to form the multilayer structure in which the inner side films are laminated is not particularly limited, but the epoxy adhesive used to form the adhesive layer described above is suitable. .

In the present invention, when forming a multilayer structure in which the above-mentioned inner side films are laminated, a stretched polypropylene film is suitable in order to maintain a high polyolefin content. This film is also used as a base film for the inorganic coating in the above-mentioned reinforcing film and barrier film.
The adhesive used to introduce such a stretched polypropylene film into the inner side film is preferably the epoxy adhesive used to form the adhesive layer described above.

<Usage form of printed laminate for packaging>
The above-described printed laminate for packaging of the present invention is made into a bag by heat-sealing and pasting with a heat-sealable resin layer, and is suitably used as a pouch (bag-like container).
Bag making is performed by known means. For example, an empty pouch is prepared by three-way sealing using two laminates, the contents are filled through the opening, and finally the opening is closed by heat sealing.
Moreover, an empty pouch can also be produced by folding back one layered body and heat-sealing both ends. In this case, there is no need to heat seal the bottom. Furthermore, empty pouches can also be manufactured using laminates dedicated to the sides or the bottom. Such a method is advantageous in increasing the volume of the pouch or imparting standing properties to the pouch.

The pouches made using the printed packaging laminate of the present invention and filled with contents not only have excellent oxygen barrier properties, but also excellent heat resistance and impact resistance. Even when sterilization treatment (retort treatment) is performed using heated steam at 100 to 130° C., deterioration in oxygen barrier properties is effectively avoided and excellent oxygen barrier properties are maintained. Such pouches are therefore particularly suitable for containing food products.
Further, in the above pouch, from the viewpoint of recyclability, the types of various materials and the thicknesses of various layers are adjusted so that the content of the olefin resin is 80% by mass or more.

The excellent effects of the present invention will be explained in the following examples.
In addition, the following materials were used in the following experiment.

<Barrier film>
Two types of transparent vapor-deposited stretched polypropylene films containing the following vapor-deposited layers were used.
Barrier film A:
Deposited film: silicon oxide (SiOx)
Thickness: 20μm
Barrier film B:
Deposited film: aluminum oxide (AlOx)
Thickness: 20μm

<Reinforcement film>
The following stretched polypropylene film was used.
Reinforcement film thickness: 20μm

<Inner side film>
Three types of sealant films shown below were used.
Unstretched polypropylene film A (PP(A))
Polypropylene species:
Mixture of impact PP and linear low density polyethylene (LLDPE)
Mass ratio Impact PP:LLDPE=80:20
Thickness: 70μm
Unstretched polypropylene film B (PP(B))
Polypropylene type: random PP
Thickness: 70μm
Unstretched polyethylene film (PE(A))
Polyethylene type: LLDPE
Thickness: 80μm

<Adhesive>
Epoxy adhesive Coating liquid Polyepoxy resin/polyamine resin/mixed solvent
=5.4/18.6/60 (mass ratio)
(Mixed solvent mass ratio: methanol/ethyl acetate = 9/1)
Urethane adhesive Coating liquid Polyol resin/Polyisocyanate resin/Ethyl acetate
=40/5/60 (mass ratio)

<Print layer>
Ink/mixed solvent = 1/1 (mass ratio)
Ink: Contains 20-30% by mass of titanium oxide Solvent: Propyl acetate/isopropyl alcohol/methyl ethyl ketone/propylene
glycol monomethyl ether
=60/20/15/5 (mass ratio)

<Formation of printing layer>
The printing layer was applied to one side of the outermost film using a bar coater.
In the case of a barrier film, it was applied to the vapor-deposited side, and in the case of a reinforcing film, it was applied to the corona-treated side.

<Formation of laminate>
The adhesive coating solution was applied to the film using a bar coater. The amount of the adhesive liquid applied was approximately 3 g/m ² in terms of solid content.
A laminate was created by laminating the following layer structure by dry lamination and curing at 50° C. for 4 days.
Outermost layer/Print layer/Adhesive layer/Middle layer/Adhesive layer/Sealant layer

<Calculation of polyolefin content in the laminate>
Content of polyolefin in laminate (mass%)
= Mass of polyolefin/mass of laminate Here, the mass of the laminate is the sum of the mass of polyolefin (total mass of the outermost layer, intermediate layer, and sealant layer) and the total mass of printing ink and adhesive. .
However, since the inorganic coating of the barrier film is very thin and has almost no mass, it will not be considered.

<Bag making>
Two sheets of 140 mm x 180 mm in size were cut out from the laminate.
Furthermore, seal the three sides other than the opening (filling part) using an impulse sealer manufactured by Fuji Impulse Co., Ltd., then fill the filling part with 200 g of water, and finally seal the filling part to create a pouch. did.
Sealing conditions: 195℃, 1.4sec
Seal width: 5mm

<Retort>
The pouch was subjected to retort treatment at 121° C. for 30 minutes using a shower method.

<Oxygen permeability measurement>
Sample Preparation A measurement sample was prepared by cutting out a film from the retorted pouch.
Oxygen permeability measurement method OX-TRAN2/22 manufactured by MOCON was used.
Measurement conditions: 23℃, 60%RH

<Example 1>
A laminate having the following layer structure was produced by a dry lamination method using an epoxy adhesive coating solution.
Barrier film A/Printing layer/Adhesive/Reinforcement film/Adhesive/PP(A)
(Polyolefin content: 91% by mass)
The above laminate was made into a bag, then subjected to retort treatment, and the film was cut out to measure the oxygen permeability. The evaluation results are shown in Table 1.

<Example 2>
The same operation as in Example 1 was performed except that PP(A) was replaced with PP(B). The evaluation results are shown in Table 1.

<Example 3>
The same operation as in Example 1 was performed except that PP (A) was replaced with PE (A). The evaluation results are shown in Table 1.

<Example 4>
The same operation as in Example 1 was performed except that barrier film A was replaced with barrier film B. The evaluation results are shown in Table 1.

<Comparative example 1>
A laminate having the following layer structure was produced by a dry lamination method using a urethane adhesive coating solution.
Barrier film A/Printing layer/Adhesive/Reinforcement film/Adhesive/PP(A)
(Polyolefin content: 91% by mass)
The above laminate was made into a bag, then subjected to retort treatment, and the film was cut out to measure the oxygen permeability. The evaluation results are shown in Table 1.

<Comparative example 2>
The same operation as in Comparative Example 1 was performed except that PP(A) was replaced with PP(B). The evaluation results are shown in Table 1.

<Comparative example 3>
The same operation as in Comparative Example 1 was performed except that PP (A) was replaced with PE (A). The evaluation results are shown in Table 1.

<Comparative example 4>
The same operation as in Comparative Example 1 was performed except that barrier film A was replaced with barrier film B. The evaluation results are shown in Table 1.

Claims (12)

A printed laminate for packaging comprising, in this order, a barrier film consisting of a thermoplastic resin film and an inorganic film formed on the surface of the film, a printed layer, and an adhesive layer,
The adhesive layer is formed of an epoxy adhesive,
A printed laminate for packaging, wherein the content of polyolefin in the printed laminate for packaging is adjusted to 80% by mass or more. The printed laminate for packaging according to claim 1, wherein the printed layer provided between the inorganic film and the adhesive layer contains titanium oxide. The printed laminate for packaging according to claim 1, wherein an inner side film including a heat-sealable resin layer is laminated via the adhesive layer. The printed laminate for packaging according to claim 1, wherein the inorganic film is formed from a vapor deposited layer formed using the thermoplastic resin film as a base. The printed laminate for packaging according to claim 4, wherein the vapor deposition layer is formed of silicon oxide, aluminum oxide, or silica-alumina composite oxide. The printed laminate for packaging according to claim 4, wherein an inorganic coating layer is provided as a protective layer on the vapor deposition layer. The printed laminate for packaging according to claim 6, wherein the inorganic coating layer is formed from a metal alkoxide or a condensate thereof. The printed laminate for packaging according to claim 3, wherein the heat-sealable resin layer is formed from an olefin resin composition. 9. The printed laminate for packaging according to claim 8, wherein the olefin resin composition is formed from polypropylene, linear low density polyethylene, or a mixture of polypropylene and linear low density polyethylene. The olefin resin composition has a mass ratio of impact polypropylene component (A) in which an ethylene/propylene copolymer is dispersed in polypropylene and linear low density polyethylene (B) A:B=99:1 to 50:50 The printed laminate for packaging according to claim 8, which is formed from the range of. The printed laminate for packaging according to claim 1, wherein the thermoplastic resin film is a stretched polypropylene film. A pouch obtained by attaching the printed packaging laminates according to claim 3 to each other by heat sealing.