JP2002338715A - Film for water-based ink printing and packaging film obtained using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film for water-based ink printing, which exhibits transferability of a water-based ink, adhesion and printing qualities in gravure printing equal to or more excellent than performances by an organic solvent type ink, is excellent in gas barrier properties and hardly leaves a residual solvent, and a packaging film obtained using the same. SOLUTION: The film for water-based ink printing comprises a resin substrate and, laminated thereon, a coating film layer composed of a resin composition comprising at least a water-soluble resin and an inorganic stratified compound. The packaging film is obtained by printing with a water-based ink on the film for water-based ink printing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film and packaging for aqueous ink printing, which are excellent in transferability and adhesion of water-based ink in gravure printing, excellent in printing quality, excellent in gas barrier properties, and have very few residual solvents. It relates to a film for use.

[0002]

2. Description of the Related Art Printing of packaging films for foods and medicines requires diversification of printing materials, good printing quality, freedom of ink selection, appropriate post-processing such as lamination, and automatic packaging using winding. From the point of machine suitability, gravure printing is the mainstream.

[0003] Printing inks used for gravure printing are organic solvent type inks in terms of transferability to a film, suitability for high-speed printing such as appearance quality (fogging, doctor streak, etc.), and optical characteristics such as ink aging stability and gloss. Printing inks are widely used. Organic solvents used for gravure printing ink include hydrocarbons such as n-hexane and toluene, esters such as ethyl acetate, ketones such as acetone and methyl ethyl ketone, alcohols such as methanol and isopropyl alcohol, methyl cellosolve and ethyl. Polyhydric alcohol derivatives such as cellosolve are often used.

On the other hand, as a packaging film to which gravure printing is applied, many kinds of plastic films such as polyolefin films have been put to practical use.
In the field of food packaging, in order to further improve the storage stability of foods, films having gas barrier properties capable of preventing entry of outside air such as oxygen and water vapor have been developed and put into practical use.

Polymer Engineering and Science, Vol. 20, No. 22, pp. 1543-1546 (1)
According to December 986), gas barrier films that have been conventionally developed include polyvinylidene chloride, polyacrylonitrile, polyvinyl alcohol, and ethylene-
Examples include a melt-extruded film such as a vinyl acetate copolymer, and a coating film obtained by coating them on a resin base film such as a polyolefin film or polyethylene terephthalate.

[0006]

The organic solvent is generally flammable and may explode if a large amount of vapor is generated. In addition, if such an organic solvent leaks to the outside air, it may lead to environmental destruction and is highly toxic to the human body. Therefore, in recent years, there has been a movement to strengthen laws and regulations such as the Fire Service Law, the Occupational Safety and Health Law, and the air pollution control. In response to this, interest in more environmentally friendly water-based inks in gravure printing has increased, and It is a fact that studies are being conducted toward.

Here, the definition of the water-based ink refers to a printing ink which belongs to "hazardous material class 4 and class 2 petroleum" according to the Fire Service Law and "has an organic solvent content of 30% by weight or less in use". By printing using the aqueous ink, the problem of the organic solvent in the packaging film remaining by printing can be solved.

However, the use of water-based inks in gravure printing has been promoted when the substrate to be printed is paper. However, in the case of plastic films, printability and print quality are inferior to organic solvent-based inks. The reality is that practical use has not progressed. In particular, a film having gas barrier properties, for example, a polyvinylidene chloride-coated film has a low surface energy, so the ink coatability, transferability and adhesion are inferior to those of the organic solvent type, and conversely hydrophilic polyvinyl alcohol. The film coated with was inferior in print quality and adhesion, and in particular, in precision multicolor gravure printing, there was a considerable difference in finish.

In view of the background of the prior art, the present invention
The transferability, adhesion and print quality of aqueous inks in gravure printing are superior to or better than those of organic solvent type inks.In addition to being excellent in gas barrier properties, for aqueous ink printing with very little residual solvent It is intended to provide a film and a packaging film using the same.

[0010]

The present invention employs the following means in order to solve the above-mentioned problems. That is, the film for aqueous ink printing of the present invention,
It is characterized in that a coating layer made of a resin composition containing at least a water-soluble resin and an inorganic layered compound is laminated on a resin substrate. Further, the packaging film of the present invention is characterized in that such a film for aqueous ink printing is printed with an aqueous ink.

[0011]

DETAILED DESCRIPTION OF THE INVENTION The present invention has been made to solve the above problems, namely, the transferability and adhesion of the aqueous ink in gravure printing and the printing quality are equal to or higher than the performance of the organic solvent type ink, and the gas barrier property. In addition to being excellent
The water-based ink printing film with very little residual solvent was studied diligently, and a layer composed of a resin composition in which a specific inorganic particle was combined with a water-soluble resin was laminated on a resin base film. The inventors of the present invention have sought to solve these problems at once, and have accomplished the present invention.

That is, in the water-based ink printing film of the present invention, it is essential that a coating layer composed of a resin composition containing at least a water-soluble resin and an inorganic layer compound is laminated on a resin substrate.

In the present invention, the term "inorganic layered compound" means an inorganic compound having a plate-like structure in which unit crystal layers are stacked on each other. As specific examples of such an inorganic layered compound, for example, graphite, a phosphate derivative-type compound (zirconium phosphate compound, etc.), a chalcogenide, a clay mineral, and the like can be preferably used.

The chalcogenide is a group IV (Ti,
Zr, Hf), dichalcogenides of group V (V, Nb, Ta) and group VI (Mo, W), having the chemical formula MX
₂ (wherein, M represents an element of the above-mentioned IV group and VI group, and X represents a chalcogen (S, Se, Te)).

Among these, clay minerals having swelling and cleavage properties in a solvent are particularly preferably used. As such clay minerals, (i) a type having a two-layer structure having an octahedral layer having a central metal of aluminum, magnesium, or the like above a tetrahedral layer of silica; and (ii) a tetrahedral layer of silica, It is classified into a type having a three-layer structure in which an octahedral layer having aluminum or magnesium as a central metal is narrowed from both sides. As the former (i) two-layer structure type, clay minerals such as kaolinite group and antigolite group are used. In the latter (ii) three-layer structure type, depending on the number of interlayer cations,
Clay minerals such as smectite, vermiculite and mica are used.

As these clay minerals, specifically,
Kaolinite, dickite, nacrite, halloysite, antigorite, chrysotile, pyrophyllite, montmorillonite, beidellite, nontronite, saponite, sauconite, stevensite hectorite, tetrasilyl mica, sodium teniolite, muscovite, margarite, Talc, vermiculite, phlogopite, zansophyllite, chlorite and the like are preferably used. In addition, those obtained by treating these clay minerals with an organic substance (see Asakura Shoten, "Encyclopedia of Clay"; hereinafter sometimes referred to as organically modified clay minerals) can also be used as the inorganic layered compound.

Among the above clay minerals, more preferably, clay minerals such as smectite group, vermiculite group and mica group, particularly preferably smectite group are used from the viewpoint of swelling or cleavage. Specific examples of the smectite group clay mineral include montmorillonite, beidellite, nontronite, saponite, sauconite, stevensite, and hectorite. In the present invention, montmorillonite is most preferably used.

Such montmorillonite is generally represented by S
a layer i ⁴⁺ constitute a coordinated and tetrahedral structure with respect to ^{O 2-, Al 3+, Mg 2+} , Fe 2+, Fe 3+, Li + and the like O ^2-
And OH ^- coordinated with the layer constituting the coordinated the octahedral structure, constitutes a plate-like structure stacked attached at 2 to 1, the water in the unit crystal layers very thin relative to the absorption It is a clay mineral formed as one plate-like particle with one or several plate-like ultra-thin unit crystal layers overlapping.

Montmorillonite has exchangeable cations accompanied by water molecules between the unit crystal layers (also referred to as cations between unit crystal layers). Such exchangeable cations are generally Mg ²⁺ , Ca 2 ²⁺ , Na ⁺ ,
K ⁺ , H ⁺ , etc., and in the case of natural montmorillonite, among such exchangeable cations, those containing a large amount of Na ions, that is, Na ion type montmorillonite,
Those containing a large amount of Ca ions, that is, Ca ion type montmorillonite are roughly classified.

The montmorillonite of the present invention is more preferably a montmorillonite containing at least an exchangeable cation other than Na ion. That is, Na as an exchangeable cation other than Na ion
An alkali metal ion other than the ion, a benzalkonium ion, an alkyldimethylammonium ion, a quaternary alkylammonium ion such as a quaternized aminosilane, or a complex ion surfactant is preferably used.

In the present invention, it is preferable to use a montmorillonite in which the Na ion is replaced by another, ie, exchangeable cation other than the Na ion, between the unit crystal layers of the montmorillonite. These are preferably used because they exhibit an oxygen gas barrier property under high humidity and an effect of increasing the adhesion between the coating layer and the resin substrate and between the coating layer and the ink.

That is, the montmorillonite of the present invention preferably does not contain Na ions, that is, the content of exchangeable cations other than Na ions in montmorillonite is preferably at least 10 meq. Is preferably 40 milliequivalents or more. In the case of montmorillonite having a content of exchangeable cations other than Na ions of less than 10 (meq / 100 g), the oxygen gas barrier property under high humidity and the adhesion between the coating layer and the ink and between the coating layer and the resin substrate are not improved. May be inferior.

The content of Na ion in the montmorillonite is preferably 50 (milli-equivalent / 100 g) or less, more preferably 30-milliequivalent to 0-milliequivalent.

Here, the content of the exchangeable cation is determined, for example, by the standard test method (JBAS-
106-77), the cation contained in the inorganic layered compound was measured with a cation exchange capacity measuring device (for example, manufactured by Fujiwara Seisakusho) based on the method for measuring the cation exchange capacity (CEC) of bentonite. Leaching in a 1N ammonium acetate solution for 4 to 24 hours using the solution, the amount of cation leaching in the leaching solution was measured by ion chromatography or atomic absorption analysis, and Na ion, K ion, contained in 100 g of dried montmorillonite, It is calculated by using various other cations as equivalents.

In the water-based ink printing film of the present invention, two or more kinds of montmorillonite having different exchangeable cations may be mixed. For example, when Na ion type montmorillonite and K ion type montmorillonite are used, the content of the K ion type montmorillonite in the montmorillonite is preferably adjusted to 10 to 100% by weight, more preferably 90 to 100% by weight. Good to use.

In the water-based ink printing film of the present invention, the content of the K element in the coating layer is from 0.1% by weight to 5% by weight, more preferably from 0.3% by weight to 1.2% by weight.
It is better to adjust to the following range. That is, by such adjustment, the oxygen gas barrier property and the adhesion between the coating layer and the resin substrate under high humidity can be increased.

The K element content in the coating film layer referred to herein is as follows.
It is the content of the K element with respect to all components of the coating layer containing montmorillonite and the water-soluble resin.

Further, in the laminated film of the present invention,
The oxygen gas barrier property and the adhesion between the coating layer and the resin substrate under high humidity are increased by making the content of Na element in the coating layer 0.6% by weight or less as little as possible. be able to. The Na element content in the coating layer is preferably 0.4% by weight or less, more preferably 0.2% by weight.
It is better to control it to be not more than weight%.

The element content in the coating layer is 23 ° C.
It can be determined by analyzing a sample left for one day in an environment of 65% RH using a known composition analysis technique such as an atomic absorption method or an ICP method.

The inorganic layered compound of the present invention has an average particle size of preferably 5 μm or less, more preferably 3 μm or less.
The use of a resin having a size of at most 1 μm, particularly preferably at most 1 μm, can satisfy the adhesion, transparency and further transparency. In particular, the transparency is preferably 1 μm or less.

From the viewpoint of gas barrier properties, as the inorganic layered compound, one having an aspect ratio in the range of preferably 50 to 5,000 and 100 to 3,000 is used. When the aspect ratio is less than 50, the gas barrier property is not sufficient, and when the aspect ratio is more than 5,000, it is technically difficult to form a coating layer, and it is economically expensive.

The average particle size of the inorganic stratiform compound is adjusted to 3 wt% by distillation water.
After stirring for an hour, the dispersion liquid further subjected to dispersion treatment with an ultrasonic disperser for 2 hours is subjected to particle size distribution measurement using a laser diffraction type particle size distribution analyzer or a laser Doppler type particle size distribution analyzer. The value of% diameter was determined as the average particle diameter.

As a measuring device used for such a particle size distribution measurement, a commercially available device can be used. Specifically, for example, a laser diffraction / light scattering particle size analyzer LS230, LS200, and LS100 manufactured by Coulter;
Shimadzu Laser Diffraction Particle Size Analyzer SALD
2000, SALD2000A, SALD300
0: Laser diffraction / scattering type particle size distribution analyzer LA910, LA700, LA500 manufactured by Horiba Seisakusho; Microtrack SPA, Microtrack FRA manufactured by Nikkiso Co., Ltd. are used.

Next, the aspect ratio (aspect ratio (Z)) of the inorganic layered compound is a ratio obtained from a relational expression expressed as Z = L / a. The aspect ratio of the inorganic layered compound is, for example, 100 mg / dispersed in pure water.
1 was dropped on a freshly cleaved surface of mica, and an atomic force microscope (AFM) photograph was taken.
It can be determined by measuring the thickness a of the inorganic layered compound and the size L in the layer surface direction.

Next, the water-soluble resin in the present invention means a polymer soluble in water. Specifically, a polyvinyl alcohol-based polymer or a derivative thereof,
Ethylene-vinyl alcohol copolymer, carboxymethyl cellulose, cellulose derivatives such as hydroxyethyl cellulose, oxidized starch, etherified starch, starches such as dextrin, polyvinylpyrrolidone,
Copolymer polyester containing a polar group such as sulfoisophthalic acid, vinyl polymer such as polyhydroxyethyl methacrylate or a copolymer thereof, acrylic polymer,
A urethane-based polymer, an ether-based polymer, or a functional group-modified polymer such as a carboxyl group, an amino group, or a methylol group of these various polymers is preferably used.

Among them, polyvinyl alcohol-based polymers and ethylene-vinyl alcohol copolymers are more preferable, and polyvinyl alcohol or ethylene-vinyl alcohol copolymer having a saponification degree of 80 mol% or more is particularly preferably used.

As the ethylene-vinyl alcohol polymer, a vinyl alcohol unit is preferably 60
Ethylene-vinyl copolymer containing at least 40 mol%, preferably at most 20 mol%, more preferably at most 10 mol% of ethylene units. Alcohol copolymers are preferably used.

The degree of polymerization of the polyvinyl alcohol-based polymer or ethylene-vinyl alcohol copolymer is not particularly limited, but is preferably from 100 to 5000, more preferably from 200 to 25.
00 is more preferable, and 400 to 1800 is particularly preferable. If the degree of polymerization is less than 100, the strength of the coating layer may be insufficient. If it exceeds 5,000, the viscosity of the coating agent when forming the coating layer becomes too high, and a uniform coating layer is formed. May not be possible.

These polyvinyl alcohol-based polymers or ethylene-vinyl alcohol copolymers may of course be used alone, but may be used in combination with other resin compounds which can be mixed unless the object of the present invention is hindered. Can be.

As such a resin, for example, an acrylic resin composed of polyacrylic acid or an ester thereof,
A polyester resin, a polyurethane resin, a polyamide resin, an epoxy resin, a melamine resin, or the like can be used.

The mixing ratio of the inorganic layered compound and the water-soluble resin in the resin composition of the present invention is not particularly limited, but the weight ratio of the inorganic layered compound to the water-soluble resin (inorganic ratio) (Layered compound / water-soluble resin) is preferably 1/100 to 100
/ 1, more preferably 1/20 to 10/1, particularly preferably 1/20 to 2/1. That is, the higher the weight ratio of the inorganic layered compound is, the more excellent the barrier property is, but considering the bending resistance, the weight ratio is 1
Those in the range of / 20 to 2/1 are preferably used.

For the purpose of improving the water resistance of the resin composition, a crosslinking agent capable of performing a crosslinking reaction with the water-soluble resin can be used. That is, it is more preferable that the coating film made of the resin composition has a crosslinked structure from the viewpoint of water resistance. Such a cross-linking agent is not particularly limited, but a metal organic compound is particularly preferably used because a high level of water resistance such as boiling and retort properties can be imparted to the coating layer. As such a metal organic compound, a coordination bond with the water-soluble resin,
Any compound capable of performing a cross-linking reaction by a hydrogen bond, an ionic bond, or the like may be used. The compound has high cross-linking reactivity with a water-soluble resin, and can improve cross-linking efficiency as compared with, for example, an inorganic metal salt.

Since the coating layer of the present invention is laminated by coating with a coating containing the above resin composition, if the reactivity is too high, a crosslinking reaction proceeds in the coating and becomes unsuitable for coating. However, organometallic compounds are
The reactivity can be easily controlled by changing the ligand, which is suitable for coating.

As such a metal organic compound, an organic titanium compound, an organic zirconium compound, an organic aluminum compound, an organic silicon compound and the like are preferably used. Among such metal organic compounds, chelate compounds,
For example, a metal organic compound having a chelating ligand such as acetylacetonate is preferable because the crosslinking reactivity is well balanced and appropriate.

Further, as long as the gas barrier properties and the transparency are not impaired, various additives may be contained in a weight ratio of 30% or less. As such various additives,
An antioxidant, a weathering agent, a heat stabilizer, a lubricant, a crystal nucleating agent, an ultraviolet absorber, a coloring agent and the like can be compounded and used. In addition, as long as transparency and gas barrier properties are not impaired, 20% or less by weight of inorganic or organic particles may be contained. Such particles include, for example, calcium carbonate, titanium oxide, silicon oxide, calcium fluoride,
Lithium fluoride, alumina, barium sulfate, zirconia, calcium phosphate, crosslinked polystyrene particles, and the like can be used.

In the present invention, the thickness of the coating layer comprising the above resin composition is from 0.01 to 1 from the viewpoint of gas barrier properties.
0 μm is preferable, and 0.1
More preferably, it is 5 μm.

Examples of the resin substrate used in the present invention include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene-2,6-naphthalate, polyamides such as nylon 6, nylon 12, and the like. Polyvinyl chloride, ethylene-vinyl acetate copolymer or saponified product thereof, polystyrene, polycarbonate, polysulfone, polyphenylene oxide, polyphenylene sulfide, aromatic polyamide, polyimide, polyamide imide, cellulose, cellulose acetate,
Films such as polyvinylidene chloride, polyacrylonitrile, polyvinyl alcohol, and copolymers thereof are preferably used, and a laminate of two or more resin substrates may be used. Among such base materials, polyesters such as polyethylene terephthalate and polyolefins such as polyethylene and polypropylene are preferably used from the viewpoints of transparency and gas barrier properties. In particular, because of its excellent water vapor barrier properties,
Polyolefins such as polyethylene and polypropylene are particularly preferably used.

Further, it is more preferable to perform a surface treatment such as a corona discharge treatment, a flame treatment, or a plasma treatment on at least the coating film layer forming surface side of the resin substrate before forming the coating film layer.

Such a resin substrate may be any of unstretched, uniaxially stretched and biaxially stretched, but from the viewpoint of dimensional stability and mechanical properties, biaxially stretched one is particularly preferred. Further, the resin base material may contain various additives. For example, antioxidants, weathering agents, heat stabilizers, lubricants, nucleating agents, ultraviolet absorbers, coloring agents and the like. Further, inorganic or organic particles may be contained as long as the transparency is not impaired. For example, talc, kaolinite, calcium carbonate, titanium oxide, silicon oxide, calcium fluoride, lithium fluoride, alumina, barium sulfate, zirconia,
Mica, calcium phosphate, crosslinked polystyrene particles, and the like. The average particle size is preferably 0.001.
10 μm, more preferably 0.003 to 5 μm. In addition, the average particle diameter is 1 using a transmission microscope or the like.
The particle diameter is obtained by taking a photograph of 0000 to 100000 times and obtaining the number average.

Further, these resin substrates are preferably transparent. The light transmittance is preferably 40% or more, more preferably 60% or more. Further, the resin substrate is preferably smooth. The thickness of the resin substrate is not particularly limited, but is preferably in the range of 2 to 1000 μm.

Further, in the present invention, a layer made of a metal and / or a metal oxide may be further formed on at least one surface of the resin base material, and the coating layer may be formed thereon. By doing so, the gas barrier properties and adhesion, especially the stretch barrier properties and printability are improved, so that it is more preferable. As such a metal and / or metal oxide, a metal and / or metal oxide such as aluminum, silicon, zinc, and magnesium are preferable. In particular, when transparency is required, a metal oxide is preferable, and among them, an aluminum or silicon oxide is preferable.
Particularly preferred effects are exhibited in terms of gas barrier properties, stretch barrier properties, and productivity. It is also preferable to form a layer made of a metal and / or a metal oxide on the coating film formed on the resin substrate from the viewpoint of improving the gas barrier properties of the film.

For the purpose of improving the adhesion between the coating layer and the resin substrate, an anchor layer is formed on the resin substrate using an anchoring agent, and the coating layer is formed on the anchor layer. More preferably, it is formed. Such an anchor treatment agent is not particularly limited, but a urethane resin, an epoxy resin,
Polyethyleneimine or the like is preferably used, and the solvent of the anchor treatment agent is further formed by forming the anchor layer using an aqueous type anchor treatment agent consisting mainly of water, because the residual solvent can be significantly reduced, It is preferably used. The thickness of the anchor layer is not particularly limited, but is preferably 0.1 to 0.3 μm.

Next, a typical method for producing the water-based ink printing film of the present invention will be described, but the present invention is not limited thereto.

The method of forming the coating layer on the resin base material is not particularly limited, but a coating agent in which the components of the coating layer are dispersed in various solvents is capable of performing high-speed thin film coating. The gravure coat, reverse coat, spray coat,
A kiss coat, comma coat, die coat, knife coat, air knife coat or metalling bar coat is preferred.

Before applying the resin composition to form a coating layer, such a resin base material is subjected to an adhesion promoting treatment, for example, in air, in nitrogen gas, a mixed gas of nitrogen / carbon dioxide gas,
It is more preferable to perform a treatment such as a corona discharge treatment under another atmosphere, a plasma treatment under reduced pressure, a flame treatment, and an ultraviolet treatment. Furthermore, urethane resin, epoxy resin,
It is more preferable to perform the anchor treatment using an anchor treatment agent such as polyethyleneimine.

When a biaxially stretched film of a polyester such as polyethylene terephthalate or a polyolefin such as polypropylene is used as such a resin substrate, an off-line coating for coating the resin composition after the biaxially stretched film forming process is performed. In the biaxially stretched film forming process, either method of in-line coating for coating the resin composition may be adopted. When an in-line coating is used, it is preferable to coat the resin composition before the film is heat-set. Here, the heat setting means that the stretched film is heated at a temperature higher than the stretching temperature, and at a temperature lower than the melting point of the film, and is heat-treated while holding the film to crystallize the film. . Therefore, before heat setting means before heat treatment, it is preferable to coat the film immediately after unstretching, immediately after uniaxial stretching in the longitudinal direction or transverse direction, and immediately after biaxial stretching. More preferably, it is a means for coating the film immediately after the uniaxial stretching with the resin composition, and it is particularly preferable that the film is further uniaxially stretched and thermally fixed.

As a method for drying a coating layer made of such a resin composition, a hot roll contact method, a heat medium (air, oil, etc.) contact method, an infrared heating method, a microwave heating method, and the like can be used. From the viewpoint of gas barrier properties, drying of the coating film layer is performed at 60 ° C. to 180 ° C. in the case of off-line coating.
In the case of in-line coating, it is preferably performed within the range of 80 to 250 ° C., and the drying time is 1 to 60.
Seconds, preferably 3 to 30 seconds.

The coating agent containing the components of the coating layer is as follows:
A solution in which the inorganic layered compound is uniformly dispersed or swelled in the solvent and the water-soluble polymer is uniformly dissolved is preferable. As the solvent, water or a mixed solution of water / lower alcohol is used, and a mixed solution of water / lower alcohol is more preferably used.

The concentration of the solid content of the coating composition is preferably 2.5% by weight or more from the viewpoint of productivity such as viscosity of the coating composition and drying efficiency. That is, when a low-concentration coating agent having a concentration of less than 2.5% by weight is used, a method of adding a low-boiling-point solvent having a high affinity for water to the solvent of the coating agent, and drying the coating layer with the boiling point of water The method performed at the above temperature is used.

In order to impart the coating property of the coating composition to the film, the mixed solvent may be used as a third component in the mixed solvent as long as the stability of the dispersed state of the coating composition is maintained. May be contained. Examples of the water-soluble organic compound include alcohols such as methanol, ethanol, n-propanol and isopropanol, glycols such as ethylene glycol and propylene glycol, methyl cellosolve, ethyl cellosolve, and the like.
Glycol derivatives such as n-butyl cellosolve, polyhydric alcohols such as glycerin and waxes, ethers such as dioxane, esters such as ethyl acetate, and ketones such as methyl ethyl ketone are preferably used. Further, it is preferable that the pH of the coating composition is controlled in the range of pH 2 to 11 from the viewpoint of solution stability.

The method of adjusting the coating agent is not particularly limited,
A method in which the inorganic layered compound is uniformly dispersed in a solvent, and then mixed with a solution in which the water-soluble polymer is uniformly dissolved in the solvent is effectively used. It is preferable that the water-soluble polymer and the inorganic stratiform compound are extremely uniformly dispersed in such a coating composition. In particular, since the inorganic layered compound may be secondary aggregated in the coating material, after dispersing the inorganic layered compound in a solvent, a homomixer, a jet agitator, a ball mill, which is subjected to shearing force and shear stress. A method of mechanically forcibly dispersing using a device such as a kneader, a sand mill, or a three-roll machine is preferably used. For example, a water-soluble polymer in which an inorganic layered compound is uniformly dispersed in water at a concentration of several percent by weight, and then dispersed using a homomixer or the like, and then uniformly dispersed in water at a concentration of several percent by weight. A method of mixing with an aqueous solution, then forcibly dispersing again, and then adding a lower alcohol and water to adjust the concentration is preferably used. Further, the coating agent may contain a crosslinking agent, particles and the like.

The packaging film of the present invention is printed on the coating layer side of the above-described aqueous ink printing film using an aqueous ink. Particularly, those printed with an aqueous ink by a gravure printing method are preferable.

In the present invention, it is preferable to perform a surface treatment on the coating layer side before the gravure printing of the aqueous ink in order to improve the transferability of the ink and the adhesion between the ink and the coating layer. Such surface treatment is not particularly limited as long as it does not improve the transferability of the ink, the adhesion between the ink and the coating layer, and does not deteriorate the film properties such as gas barrier properties, laminate peel strength, mechanical properties, and optical properties. Instead, existing surface treatments can be used, for example, corona discharge treatment in air, nitrogen gas, mixed gas of nitrogen / carbon dioxide gas, other atmosphere, plasma treatment under reduced pressure, flame Treatment, ozone treatment, ultraviolet treatment and the like are preferably employed. By performing gravure printing on such a surface-treated surface, it is possible to provide a packaging film having more excellent wettability, transferability, adhesion, and print quality of the aqueous ink.

The aqueous ink used in the present invention can be used without any limitation as long as the amount of the organic solvent in the ink at the time of use is 30% by weight or less. As the vehicle to be incorporated into the ink, any of a water-soluble type, a colloidal dispersion type, and an emulsion type may be used. As the resin, shellac, rosin-modified resin, styrene-maleic acid resin, styrene-acrylic resin Resins, acrylic resins, polyester resins, polyurethane resins and the like can be used alone or as a mixture. In addition, as a pigment, an organic or inorganic pigment can be used without any limitation, and various auxiliaries such as a dispersant can be added. In addition, as a solvent for such an ink,
In addition to water, ethanol, isopropyl alcohol, n-propyl alcohol, and the like can be used.

The method of gravure printing the aqueous ink printing film with the aqueous ink is not particularly limited, and a known method is used. The present invention is particularly effective when multicolor gravure printing is used.

Further, the packaging film of the present invention may be used alone or may be laminated with another material.
Other materials are not particularly limited as long as they are generally used materials, and examples thereof include paper, metals such as aluminum and silicon or oxides thereof, non-woven fabrics, resin films and the like.

As the resin film, non-stretched or biaxially stretched film, co-extrusion film, coating film, vapor-deposited film, melt-extrusion resin and the like are used. Polyesters such as terephthalate and polyethylene-2,6-naphthalate, polyamides such as nylon 6 and nylon 12, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate or saponified product thereof, ethylene vinyl acetate copolymer or saponified product thereof, polystyrene , Aromatic polyamide, ionomer resin, polycarbonate, polysulfone, polyphenylene oxide, polyphenylene sulfide, polyimide, polyamide imide, cellulose, cellulose acetate , Polyacrylonitrile, and their copolymers are used.

More preferably, the packaging film of the present invention is suitably used as a laminated film in which a heat sealing material is laminated. The heat sealing material is not particularly limited as long as it has a sufficient sealing strength by being thermally fused at the time of bag making, and a generally used heat sealing material is used. For example, low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), linear polyethylene (LLDPE), unstretched polypropylene (CPP), ethylene-vinyl acetate copolymer (EVA), ethylene -Ethyl acrylate copolymer (EEA), ethylene-acrylic acid copolymer (EAA), ionomer, polyethylene terephthalate (PET), polyvinyl chloride, vinyl acetate copolymer, acrylic resin, nitrocellulose, chlorinated polypropylene, Polyvinylidene chloride and the like,
In particular, low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), linear polyethylene (L
LDPE) and unstretched polypropylene (CPP) are preferably used.

The method of lamination with the heat sealing material is not particularly limited, and the lamination can be performed by using an existing method such as dry lamination, wet lamination, and extrusion lamination.

The water-based ink printing film of the present invention is excellent in print quality because of good wettability and transferability of the water-based ink, and has good peel strength because of good adhesion between the coating layer and the water-based ink. Are sufficiently large and have excellent gas barrier properties. Therefore, it is suitably used as a packaging film for foods and the like. In addition, compared to printing using conventional organic solvent-based inks, it is possible to improve the safety and environment, such as exposure to organic solvents to workers during printing and the danger of explosion and ignition, etc. When used as a film, a film having a very small amount of residual solvent can be obtained.

[0071]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples.

In the following Examples and Comparative Examples, the exchangeable cation content of montmorillonite, the content of K and Na elements in the coating layer, the gas barrier properties, the peel strength of the laminate film, and the transferability of the ink in the following Examples and Comparative Examples. ,
The adhesion between the ink and the coating layer was measured by the following method. (1) Exchangeable Cation Content of Montmorillonite A cation contained in 0.4 to 0.5 g of montmorillonite was added to 100 ml of a 1N ammonium acetate solution using a cation exchange capacity measuring device (manufactured by Fujiwara Seisakusho).
Leached for ~ 24 hours. The amount of cationic leaching in the leachate was measured by ion chromatography or atomic absorption analysis, and Na ion and K ion contained in 100 g of dried montmorillonite were calculated as equivalents. (2) Content of K element and Na element in coating film layer From the laminated film stored in a desiccator at 23 ° C. and 65% RH for one day, an amount necessary for the measurement is cut out and used as a measurement sample. After measuring the weight of the measurement sample, 100
The coating film layer was peeled from the resin substrate by immersion in water at ℃, and the amounts of the K element and the Na element were measured by atomic absorption analysis.
After drying the resin substrate from which the coating layer was peeled off, the resin substrate was dried at 23 ° C.
The weight of the sample stored in a desiccator at 5% RH for 1 day was measured, and the weight subtracted from the weight before peeling of the coating layer was defined as the weight of the coating layer in the sample. The amount was calculated. (3) Gas barrier property The oxygen permeability was measured using an oxygen permeability measuring device (manufactured by MOCON, OX-TRAN 2/20) according to ASTM D-3985. The measurement conditions are a temperature of 20 ° C. and a relative humidity of 80% RH. (4) Moisture Peel Strength of Laminated Film First, the printed surface of the film of the present invention and an unstretched polypropylene film (CPP, T35 manufactured by Toray Synthetic Film Co., Ltd.)
01, 50 μm) with a polyurethane adhesive (“Dick Dry” LX-401A, S manufactured by Dainippon Ink and Chemicals, Inc.)
P-60, compounding ratio LX-401A: SP-60 = 1
0: 1, diluent solvent: ethyl acetate, drying temperature: 70 ° C., drying time: 30 seconds, coating amount: 2.0 g / m ^{2 of the} coating active ingredient
Dry laminating is performed and aged at 40 ° C. for 48 hours. Next, the width 1 is set in the film width (TD) direction.
Sampling is performed at 5 mm and a length of 10 cm in the machine direction (MD), and humidification aging is performed at 40 ° C. and 90% RH for 48 hours in a thermo-hygrostat. Immediately after aging is completed, a tensile tester (Autograph IM-100, manufactured by Shimadzu Corporation)
, The peel strength between the CPP and the film at a peel angle of 90 degrees was measured. (5) Transferability of ink Water-based ink (trade name: Ecofine (805 black, 115 red, 407B medium yellow, 709, manufactured by Dainippon Ink and Chemicals, Incorporated)
White) was printed with a four-color printing gravure printing machine, and the printed surface was observed with a microscope to determine whether or not the transferability of the halftone morphology was good. The evaluation criteria are as follows.

5: The rate of occurrence of omission, repelling, and spreading is 10% or less, 4: 〃10 to 20%, 3: ２０20 to 5
0%, 2: 50% to 80%, 1: 80% or more (6) Adhesion between ink and coating layer Adhere the cellophane adhesive tape on the printed surface and rub it 5 times from above to completely adhere. I let it. Thereafter, the cellophane adhesive tape was peeled off from the printing surface at a stretch, and the adhesiveness of the ink was judged from the state of the ink remaining on the printing surface.

The evaluation criteria are as follows.

5: 95% or more of the remaining area of the ink 4: 90% to 95% 3: 70% to 90% 2: 50% to 70% 1: 50% or less Example 1 Average particle diameter of montmorillonite 1. 0 μm montmorillonite (Kunimine Kogyo, “Kunipia” -F) was dispersed in water to prepare an A1 solution having a solid content of 4% by weight. Here, the exchangeable cation content of Na ion and K ion of montmorillonite in the A1 solution was measured.
It was 0 meq / 100 g and 2.3 meq / 100 g.

Next, the liquid A1 was subjected to a mechanical dispersion treatment with a homomixer (3500 rpm) so as to further eliminate the aggregates of the particles, thereby preparing a liquid A2.

Using an ethylene-vinyl alcohol copolymer having a saponification degree of 98.0 mol% and an ethylene content of 10 mol% as a water-soluble polymer and water as a solvent, a B1 solution having a solid content concentration of 6.7% by weight was prepared. did.

The B1 solution was again subjected to a dispersion treatment by a homomixer to prepare a B2 solution.

The A2 solution and the B2 solution were mixed at a weight ratio of A2 solution: B2 solution = 42: 58, dispersed by a homomixer, and further mixed with isopropyl alcohol (hereinafter referred to as IPA) at 20% by weight based on the total solvent. A coating composition was prepared such that the solid content concentration was 4.5% by weight.

A gravure coater (coating speed: 15 μm) was used as the resin base material, using a biaxially stretched polypropylene film (“Torayfan” manufactured by Toray, thickness: 20 μm) subjected to corona discharge treatment.
0m / min) and a urethane-based adhesive (manufactured by Takeda Pharmaceutical Co., Ltd.)
The main agent “Takelac” A3210, the curing agent “Takenate” A3070) were diluted with ethyl acetate, applied to a thickness of 0.2 μm after drying, and introduced into a hot air drying dryer at 70 ° C. under low tension. After drying for 5 seconds, an anchor coat layer was provided.

Thereafter, the above coating agent was applied to the anchor coat surface of the resin base material so as to have a thickness of 0.5 μm after drying, and was introduced into a hot-air drying drier to obtain 120 μm under low tension.
C. for 10 seconds to form a laminated film.

The content of Na element in the coating layer was 0.7% by weight, and the content of K element was 0.03% by weight.

Next, a water-based ink (trade name: Ecofine (805 ink, 115, manufactured by Dainippon Ink and Chemicals, Inc.)) was applied to the coating layer surface of the obtained laminated film using a gravure printing machine.
Red, 407B medium yellow, 709 white, reducer: gravure printing of a mixed solvent of 75% by weight of water and 25% by weight of ethanol) to obtain gas barrier properties, ink transferability, adhesion between the coating layer and the ink, and laminate peel strength. Examined.

As shown in Table 1, gas barrier properties, ink transfer properties, and adhesion between the coating layer and the ink were excellent.

Example 2 In Example 1, after adding potassium chloride to the A1 solution so that the amount of K ions becomes one time the cation exchange capacity of montmorillonite, part of the Na ions between the layers was exchanged for K ions. To remove Na ions discharged into the aqueous solution in place of K ions, the solution was filtered using a filter paper, and the residue was washed with 1 liter of purified water with respect to 5 g of montmorillonite solid content to prepare K-type montmorillonite M1.

The K-type montmorillonite M1 was redispersed in water so as to have a solid concentration of 4% by weight to prepare an A3 liquid. Here, when the exchangeable cation content of Na ion and K ion of montmorillonite in the A3 solution was measured,
8.5 meq / 100 g each, 100.9 meq / 10
It was 0 g.

Next, the A3 solution was subjected to a dispersion treatment in the same manner as in Example 1 to prepare an A4 solution.

The B2 solution and the A4 solution prepared in Example 1 were mixed at a weight ratio of A4 solution: B2 solution = 42: 58, and subjected to dispersion treatment by a homomixer. Further, isopropyl alcohol (hereinafter referred to as IPA) was added to all solvents. To prepare a coating so that the solid content concentration becomes 4.5% by weight.

Thereafter, a laminated film was prepared in the same manner as in Example 1. The Na element content in the coating layer was 0.05% by weight, and the K element content was 0.9% by weight. Next, a water-based ink was printed on the coating layer surface using a gravure printing machine in the same manner as in Example 1. Table 1 shows the gas barrier properties, ink transfer properties, adhesion between the coating layer and the ink, and the lamination peel strength of the obtained film.

As is clear from Table 1, the lamination peel strength was further superior to that of Example 1.

Example 3 The coating film layer side of the laminated film prepared in Example 1 was subjected to a corona discharge treatment of 30 W · min / m 2 according to a conventional method. The aqueous ink was printed on the corona discharge treated surface of this laminated film using a gravure printer in the same manner as in Example 1.

Table 1 shows gas barrier properties, ink transfer properties, adhesion between the coating layer and the ink, and laminate peel strength of the obtained film.

As is apparent from Table 1, the transferability of the ink and the adhesion between the coating layer and the ink were further excellent as compared with those of Example 1.

Example 4 The coating layer side of the laminated film prepared in Example 2 was subjected to a corona discharge treatment of 30 W · min / m 2 according to a conventional method. The aqueous ink was printed on the corona discharge treated surface of this laminated film using a gravure printer in the same manner as in Example 1.

Table 1 shows the gas barrier properties, ink transfer properties, adhesion between the coating layer and the ink, and the lamination peel strength of the obtained film.

As is clear from Table 1, the transferability of the ink, the adhesion between the coating layer and the ink, and the peel strength of the laminate were very excellent.

Comparative Example 1 A water-based ink was printed on a coated surface of a commercially available biaxially oriented polypropylene film (K-OPP) coated with polyvinylidene chloride using a gravure printing machine in the same manner as in Example 1.

Table 1 shows gas barrier properties, ink transfer properties, adhesion between the coating layer and the ink, and laminate peel strength of the obtained film.

As is clear from Table 1, the transferability of the ink and the adhesion between the coating layer and the ink were poor, and a good printed film could not be obtained.

Comparative Example 2 The coating surface of Comparative Example 1 was applied at 30 W · min according to a conventional method.
/ M ² of corona discharge treatment. The aqueous ink was printed on the corona discharge treated surface of this laminated film using a gravure printer in the same manner as in Example 1.

Table 1 shows the gas barrier properties, ink transfer properties, adhesion between the coating film and the ink, and the lamination peel strength of the obtained film.

As is clear from Table 1, the transferability of the ink and the adhesion between the coating layer and the ink were poor, and peeling occurred at the interface between the coating surface and the ink in the lamination peeling test.

Comparative Example 3 In Example 1, B2 containing no montmorillonite was used.
A laminated film was prepared using a coating agent consisting of only the liquid, and an aqueous ink was printed using a gravure printing machine in the same manner as in Example 1.

Table 1 shows the gas barrier properties, ink transfer properties, adhesion between the coating layer and the ink, and the lamination peel strength of the obtained film.

As is clear from Table 1, the ink transferability was poor, and the print quality was not good.

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[Table 1]

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According to the present invention, not only the gas barrier properties are excellent, but also the transferability and adhesion of the aqueous ink in gravure printing and the print quality are excellent. The present invention can provide a packaging film that can be used for the above purpose.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) B65D 65/40 BSF B65D 65/40 BSF // C08L 101: 00 C08L 101: 00 F term (reference) 3E086 AA01 AB01 AC07 BA04 BA15 BA24 BA33 BB05 BB62 BB90 CA01 CA28 DA02 4F006 AA12 AB20 AB76 BA01 CA07 DA04 4F100 AA00A AA00H AC03A AC03H AK01A AK01B AK01C AK07B AK21A AK51G AK69A BA02 BA03 BA07 BA10A BA10B BA10C BA15 CB00 CC00A DE10A DE10H EJ05A EJ38B EJ54A EJ55A EJ61A EJ64A GB15 HB31A JB05A JD02 JL01 JL12C YY00A YY00H

Claims (12)

[Claims] 1. A water-based ink printing film comprising a coating layer comprising a resin composition containing at least a water-soluble resin and an inorganic layered compound laminated on a resin substrate. 2. The aqueous ink printing film according to claim 1, wherein the inorganic layered compound is montmorillonite. 3. The water-based ink printing film according to claim 2, wherein the montmorillonite contains at least 40 (milli-equivalents / 100 g) of potassium ions. 4. The coating layer according to claim 1, wherein said coating layer contains 0.1% to 5% by weight of potassium element.
4. The water-based ink printing film according to any one of 3. 5. The aqueous ink printing film according to claim 1, wherein the coating layer has a sodium element content of 0.6% by weight or less. 6. The aqueous ink printing film according to claim 1, wherein the water-soluble resin is at least one of polyvinyl alcohol and an ethylene-vinyl alcohol copolymer. 7. The aqueous ink printing film according to claim 7, wherein the water-soluble resin is cross-linked. 8. The aqueous ink printing film according to claim 1, wherein the aqueous ink printing film has an anchor coat layer between the resin substrate and the coating layer. 9. The coating layer having been subjected to at least one kind of surface treatment selected from a corona discharge treatment, a plasma treatment, a flame treatment, an ozone treatment, and an ultraviolet treatment. Water-based ink printing film according to any one of 1 to 8. 10. A film for packaging, wherein the film according to claim 1 is printed using an aqueous ink. 11. The packaging film according to claim 10, wherein the aqueous ink is for gravure printing. 12. The packaging film according to claim 10, wherein the packaging film is laminated with a heat sealing material on a printing surface.