JP2020007395A - Ink and printed matter - Google Patents

Abstract

To provide ink which simultaneously imparts gas barrier when ink is printed on a base material such as a packaging film and a packaging sheet for the purpose of a design, thereby can achieve the design and the gas barrier with less number of steps, and is excellent in adhesion and laminate strength; and a printed matter having a barrier function using the ink.SOLUTION: Ink contains a colorant, a resin and lithium part fixing type smectite.SELECTED DRAWING: None

Description

  The present invention relates to an ink having a gas barrier function, and a printed matter obtained by printing the ink.

Packaging materials used for packaging foods and the like are required to have functions such as protection of contents, retort resistance, heat resistance, transparency, and workability. In order to maintain the quality of the contents, a gas barrier function is particularly important.

  In order to provide a gas barrier function, a film provided with a vapor deposited layer of a metal such as aluminum as a gas barrier layer or a film provided with a vapor deposited layer of a metal oxide such as silica or alumina as a gas barrier layer is widely used. However, it is generally unavoidable to increase the price of these films by vapor deposition. In addition, it is necessary to provide a separate print layer for design and display, and a printing process using ink is indispensable. If a gas barrier function can be provided by a printing process using ink, the gas barrier function can be provided without using a barrier film.

  As means for solving the above problems, Patent Document 1 discloses that an ink layer contains a vinylidene chloride-based copolymer resin (PVDC) having a barrier function against oxygen and water vapor and a plate-like filler (barium sulfate in the example). An ink composition having an oxygen / water vapor barrier function by being used in combination is exemplified.

  In Patent Literature 1, a gas barrier is provided by using a resin having a barrier improving function and a plate-like filler in combination. It is necessary to satisfy the adhesiveness and lamination strength, which are essential physical properties of the ink.However, the use of materials that are not originally contained in the ink, such as resins and fillers, may impair the original required physical properties. Design may be difficult.

JP 2018-24798 A

  An object of the present invention is to provide a gas barrier at the same time as printing an ink on a base material such as a packaging film or a packaging sheet for the purpose of a design, etc., so that the design and the gas barrier can be compatible in a small number of steps, and furthermore, the adhesion And to provide an ink having excellent lamination strength. Another object of the present invention is to provide a printed material having a barrier function using the ink. Another object of the present invention is to provide a packaging material using the printed matter.

  The present invention has found that the above-mentioned problems can be solved by using an ink containing a colorant, a resin, and a lithium partially fixed smectite, and have completed the present invention.

  According to the present invention, it is possible to provide an ink having an excellent gas barrier.

  Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

  The ink according to the embodiment contains a colorant, a resin, and a lithium partially fixed smectite.

<Lithium fixed smectite>
Smectite is a type of phyllosilicate mineral (layered clay mineral) having a layered structure. As specific structures of smectite, structures such as montmorillonite, beidellite, saponite, hectorite, stevensite, and sauconite are known. Among these, the structure of the clay material is preferably at least one structure selected from the group consisting of montmorillonite and stephensite. In these structures, some of the metal elements of the octahedral sheet have isomorphous substitution with low-valent metal elements, defects, and the like. Therefore, the octahedral sheet is negatively charged. As a result, these structures have vacant sites in the octahedral sheet, and in smectites having these structures, lithium ions can stably exist after migration as described later.

  Smectite whose cation is a lithium ion is referred to as lithium-type smectite (however, in this specification, a lithium partially fixed smectite described later is excluded). As a method for exchanging cations of smectite for lithium ions, for example, a method of adding a lithium salt such as lithium hydroxide or lithium chloride to a natural sodium-type smectite dispersion (dispersion slurry) and exchanging cations is known. No. By adjusting the amount of lithium added to the dispersion, the amount of lithium ions in the amount of leached cations of the obtained lithium-type smectite can be appropriately adjusted. Further, lithium-type smectite can also be obtained by a column method or a batch method using a resin obtained by ion-exchanging a cation exchange resin with lithium ions.

  In the embodiment, the lithium partially fixed smectite means a smectite in which a part of lithium ions in the lithium type smectite is fixed to an empty site of an octahedral sheet. The lithium partially fixed smectite is obtained by, for example, heat treatment of lithium type smectite, whereby lithium ions between layers are fixed to empty sites of an octahedral sheet. The immobilization of lithium ions makes the smectite water resistant.

  The temperature condition of the heat treatment for partially fixing lithium is not particularly limited as long as lithium ions can be fixed. As will be described later, when the cation exchange capacity (CEC: Cation Exchange Capacity) is small, the water vapor barrier property and the oxygen barrier property of the ink containing the lithium partially fixed smectite are further improved. Therefore, from the viewpoint of fixing lithium ions efficiently and greatly reducing the cation exchange capacity, it is preferable to heat at 150 ° C. or higher. The temperature of the heat treatment is more preferably from 150 to 600C, further preferably from 180 to 600C, particularly preferably from 200 to 500C, and most preferably from 250 to 500C. By heating at the above temperature, the cation exchange capacity can be reduced more efficiently, and at the same time, the dehydration reaction of the hydroxyl group in the smectite can be suppressed. The heat treatment is preferably performed in an open electric furnace. In this case, the relative humidity during heating becomes 5% or less, and the pressure becomes normal pressure. The heat treatment time is not particularly limited as long as lithium can be partially fixed, but is preferably 0.5 to 48 hours, more preferably 1 to 24 hours, from the viewpoint of production efficiency. .

  Whether or not the lithium is partially fixed type smectite can be determined by X-ray Photoelectron Spectroscopy (XPS) analysis. Specifically, the peak position of the binding energy derived from Li ions in the XPS spectrum measured by the XPS analysis is confirmed. For example, when the smectite is montmorillonite, the lithium-type smectite is converted into a lithium partially fixed type smectite by heat treatment or the like, so that the peak position of the binding energy derived from Li ions in the XPS spectrum changes from 57.0 ev to 55.4 ev. shift. Therefore, when the smectite is montmorillonite, it can be determined whether or not it is a partially fixed type by determining whether or not it has a binding energy peak of 55.4 ev.

  The cation exchange capacity of the lithium partially fixed smectite is preferably 70 meq / 100 g or less, more preferably 60 meq / 100 g or less, from the viewpoint of more excellent steam barrier properties and oxygen barrier properties (eg, oxygen barrier properties under high humidity). 100 g or less. The cation exchange capacity of the lithium partially fixed type smectite is 1 meq / 100 g or more, more preferably 5 meq / 100 g or more, from the viewpoint of more excellent water vapor barrier properties and oxygen barrier properties (eg, oxygen barrier properties under high humidity). And more preferably 10 meq / 100 g or more. From these viewpoints, the cation exchange capacity of the lithium partially fixed smectite is 1 to 70 meq / 100 g, more preferably 5 to 70 meq / 100 g, and further preferably 10 to 60 meq / 100 g. For example, when the smectite is montmorillonite, the ion exchange capacity is usually about 80 to 150 meq / 100 g, but can be 5 to 70 meq / 100 g by performing a partial immobilization treatment. The cation exchange capacity of the lithium partially fixed smectite may be less than 60 meq / 100 g, and may be 50 meq / 100 g or less. For example, the cation exchange capacity of the lithium partially fixed smectite may be 1 meq / 100 g or more and less than 60 meq / 100 g, 5 meq / 100 g or more and less than 60 meq / 100 g, or 10 meq / 100 g or more and less than 60 meq / 100 g. May be.

  The cation exchange capacity of smectite can be measured by a method according to the Schollenberger method (Clay Handbook, 3rd edition, edited by The Clay Society of Japan, May 2009, p. 453-454). More specifically, it can be measured by the method described in Japan Bentonite Industry Association Standard Test Method JBAS-106-77.

  The amount of leaching cations of the smectite was determined by leaching the interlayer cations of the smectite with 0.5 g of smectite using 100 mL of 1 M ammonium acetate aqueous solution for 4 hours or more, and determining the concentration of various cations in the obtained solution. , ICP emission analysis, atomic absorption analysis and the like.

  The content of the lithium partially fixed smectite is preferably 1% by mass or more based on the total amount of nonvolatile components in the ink. When the content of the lithium partially fixed smectite is 1% by mass or more based on the total amount of the nonvolatile components, the water vapor barrier property and the oxygen barrier property (for example, the oxygen barrier property under high humidity) are further improved. From the same viewpoint, the content of the lithium partially fixed smectite is 5% by mass or more, 7% by mass or more, 9% by mass or more, 10% by mass or more, 15% by mass or more, It may be at least 25 mass%. The content of the lithium partially fixed smectite is preferably 30% by mass or less based on the total amount of nonvolatile components in the ink. When the content of the lithium partially fixed type smectite is 30% by mass or less, the adhesion of the ink to the printing substrate is further improved, and the lamination strength between the films when a multilayer film is formed is also improved. . The non-volatile content refers to the mass of the total mass of the ink excluding the mass of the diluting solvent and the mass of volatile components contained in the resin, the coloring material, and various additives.

(Colorant)
The ink of the present invention contains a colorant. The colorant generally includes a dye that is soluble in a resin or a solvent contained in the ink, and a pigment that is not soluble in the ink. The ink of the present invention may contain only one of the pigment and the dye, or may contain both.

  Known dyes can be used, for example, azo dyes, metal chain salt azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinone imine dyes, methine dyes, cyanine dyes And indigo dyes, quinoline dyes, nitro dyes, xanthene dyes, thiazine dyes, azine dyes, oxazine dyes, and squarylium dyes. These dyes can be used alone or in combination.

  Examples of the pigment include an inorganic pigment and an organic pigment. Inorganic pigments include titanium oxide, zinc oxide, barium sulfate, calcium carbonate, silica, iron oxide, chromium oxide, aluminum, mica, carbon black, red earth, loess, green earth, navy blue, zinc white, cobalt blue, emerald green, and bilian. Can be exemplified.

  Examples of the organic pigment include anthraquinone pigments, perylene pigments, disazo pigments, phthalocyanine pigments, isoindoline pigments, dioxazine pigments, quinacridone pigments, perinone pigments, triphenylmethane pigments, thioindigo pigments, and diketopyrrolopyrroles. Organic pigments such as system pigments are exemplified. These pigments can be used alone or as a mixture.

Examples of other special pigments include fluorescent pigments, metal powder pigments, pearl pigments, temperature pigments, and pigments for ceramics.

  In the present invention, from the viewpoint of the durability of the ink, the colorant is preferably an inorganic pigment, and particularly preferably titanium oxide, zinc oxide, barium sulfate, calcium carbonate, silica, iron oxide, chromium oxide, aluminum, mica, It is carbon black.

(resin)
In the embodiment, the resin is not particularly limited as long as the effects of the present invention are not impaired. Specifically, rosin resin, rosin modified phenol resin, rosin ester resin, maleic acid resin, styrene / maleic acid resin, styrene / acrylic resin, amino resin, melamine resin, acrylic resin, vinyl chloride / vinyl acetate copolymer resin , A polyester resin, a polyurethane resin, a polyurea resin, an epoxy resin, a terpene resin, an alkyd resin, a cyclized rubber, and a chlorinated polyolefin resin. The resin is preferably a resin capable of uniformly dispersing a coloring material contained in the ink and adhering to a printing material such as a film, a plate, or a molding material. Particularly preferred resins are vinyl chloride / vinyl acetate copolymer resins, polyurethane resins, polyester resins, polyurea resins, and acrylic resins, which are widely used in inks for flexible packaging.

(solvent)
The ink of the present invention may contain a solvent for the purpose of adjusting the viscosity for imparting coating suitability. Examples of the solvent include water, and examples of the hydrocarbon solvent include mineral spirit, petroleum naphtha, toluene, xylene, tetralin, and turpentine oil. Further, examples of the ester system include n-butyl acetate, methoxybutyl acetate, ethyl acetate, and propyl acetate. Also, as ketones, MIBK and MEK cyclohexanone, and as alcohols, isopropyl alcohol, butanol, ethanol, and methanol are polyhydric alcohol derivatives. Examples of the ethers include compounds such as tetrahydrofuran, dioxane, diethyl ether, methyl ethyl ether, and dimethyl ether. These may be used in combination of two or more.

(Auxiliary agent)
The ink may further contain various auxiliaries for improving the performance as the ink. Examples of the auxiliary agent include a modifying agent, a leveling agent, a dispersant, an antifoaming agent, an antiblocking material, and a tackifier. For example, examples of the modifying agent include a coupling agent. Examples of the coupling agent include a silane coupling agent, a titanium coupling agent, a zirconium coupling agent, an aluminum coupling agent, and the like, a silane compound, a silazane compound, an acid anhydride. And the like. When the ink contains these modifiers, the wettability with the ink resin is improved, and the dispersibility in the ink is improved. A single modifier may be used alone, or a plurality of modifiers may be used in combination.

  The compounding amount of the modifier is preferably 0.1 to 50% by mass based on the total amount of the partially fixed lithium smectite. When the amount of the modifier is 0.1% by mass or more, the dispersibility of the lithium partially fixed smectite in the ink becomes better. When the amount of the modifier is 50% by mass or less, the effect of the modifier on the mechanical properties of the ink can be further suppressed. The compounding amount of the modifier is preferably 0.3 to 30% by mass, more preferably 0.5 to 15% by mass.

(Additive)
The ink of the present invention may contain various additives in addition to the above-mentioned auxiliaries as long as the effects of the present invention are not impaired. Examples of the additives include various fillers, stabilizers (antioxidants, heat stabilizers, ultraviolet absorbers, etc.), antistatic agents, lubricants, antiblocking agents, coloring agents, crystal nucleating agents, oxygen scavengers (oxygen scavengers) Compound having a function) and a tackifier. In particular, another inorganic layered compound may be used in combination with the lithium partially fixed smectite for the purpose of enhancing the gas barrier function. Examples of the inorganic layered compound include hydrated silicates (phyllosilicate minerals, etc.), kaolinite group clay minerals (halloysite, kaolinite, enderite, dickite, nacrite, etc.), antigolite group clay minerals (antigolite, etc.) , Chrysotile, etc.), smectite group clay minerals (montmorillonite, beidellite, nontronite, saponite, hectorite, sauconite, stevensite, etc.), vermiculite group clay minerals (vermiculite, etc.), mica or mica group clay minerals (muscovite, gold) Mica such as mica, margarite, tetrasilyl mica, teniolite, etc.). These minerals may be natural clay minerals or synthetic clay minerals.

  When an oxygen scavenging function is added for the purpose of maintaining the freshness of the contents of the package, for example, it reacts with oxygen such as a hindered phenol compound, vitamin C, vitamin E, an organic phosphorus compound, gallic acid, and pyrogallol. A low molecular weight organic compound, a transition metal compound such as cobalt, manganese, nickel, iron, and copper may be added.

  Further, the present invention also includes a printed matter on which the above-described ink is printed. Examples of the substrate to be printed include various papers and various plastic films. Polyethylene terephthalate (PET) film, polystyrene film, polyamide film, polyacrylonitrile film, polyethylene film (LLDPE: low-density polyethylene film, HDPE: high-density polyethylene film) and polypropylene film (CPP: unstretched polypropylene film, OPP: biaxial stretching) Polyolefin film such as polypropylene film), polyvinyl alcohol film, ethylene-vinyl alcohol copolymer film and the like. These may be subjected to a stretching treatment. Further, a film which has been subjected to a vapor deposition treatment such as transparent vapor deposition or aluminum vapor deposition may be used for these films. Further, these films may be further multilayered by performing a laminating process or the like.

  The use of the printed matter is not particularly limited, but the printed matter obtained is excellent in gas barrier properties, so that it can be particularly suitably used as a packaging material. The use of the packaging material of the present invention has the effect of extending the storage period of the contents.

(Ink printing method)
The printing method of the ink of the present invention is not particularly limited. As the relief printing type, relief printing, flexo, dry offset, intaglio as gravure, gravure offset, pad, lithographic as offset, stencil as screen, in addition to these, inkjet can be exemplified, but are not limited thereto. .

(Method of fixing ink)
Examples of the ink fixing method include, but are not limited to, evaporative drying type, oxidation polymerization type, two-pack reaction type, ultraviolet curable type, electron beam curable type, and osmotic dry type.

  Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited thereto.

(Filler)
As the filler contained in the ink, a lithium partially fixed smectite, a non-lithium partially fixed smectite, and an organically modified smectite were used. As the lithium partially fixed smectite, a montmorillonite slurry (trade name: RCEC-W, cation exchange capacity: 39.0 meq / 100 g) manufactured by Kunimine Industry Co., Ltd. was used. The content (w / w%) of the lithium partially fixed smectite in this dispersion slurry was 20 w / w%. In addition, sodium-type montmorillonite (trade name: Knipia F, cation exchange capacity: 108 meq / 100 g) manufactured by Kunimine Kogyo Co., Ltd. was used as smectite that was not partially fixed to lithium. Further, as the organically modified smectite, an organically modified smectite (trade name: ESVEN N-400, cation exchange capacity: 100 meq / 100 g) manufactured by Hojun Co., Ltd., in which metal cations between layers were ion-exchanged with a quaternary ammonium salt, was used.

(Synthesis of polyurethane resin, preparation of resin solution)
Number average obtained by reacting a mixture of ethylene glycol and neopentyl glycol (molar ratio = 1/1) with adipic acid in a four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas inlet tube. 605.9 parts of a polyester diol having a molecular weight of 1,800 and 94 parts of isophorone diisocyanate were charged and reacted at 90 ° C. for 10 hours under a nitrogen stream to produce a prepolymer having a free isocyanate value of 1.02% by weight. 300 parts of ethyl were added to obtain a urethane prepolymer.
Subsequently, the urethane prepolymer solution was added to a mixture consisting of 18.1 parts of isophoronediamine, 873 parts of ethyl acetate and 503 parts of IPA, and the mixture was stirred and reacted at 45 ° C. for 8 hours to obtain a resin solids concentration of 30.5% by mass. A polyurethane resin solution (A) having a weight average molecular weight of 58,000 and an amine value of 5.3 (mg KOH / g) was obtained.

(Preparation of vinyl chloride-vinyl acetate copolymer resin solution V)
A vinyl chloride-vinyl acetate copolymer resin having a hydroxyl group (vinyl chloride / vinyl acetate / vinyl alcohol = 92/3/5, hydroxyl value (mgKOH) = 64 in a resin monomer composition in mass%) used in combination with a polyurethane resin is used as acetic acid. A 15% solution was prepared with n-propyl, and this was used as a polyvinyl chloride resin solution (B).

(Example 1)
25 parts of the polyurethane resin solution (A) (solid content 30%), 10 parts of vinyl chloride vinyl acetate copolymer resin (B) (solid content 15%), 35 titanium oxide pigment (R-780 manufactured by Ishihara Sangyo Co., Ltd.) 35 , A mixture consisting of 15 parts of ethyl acetate and 15 parts of isopropyl alcohol is kneaded using a Dynomill (manufactured by Willie & Bacco Phenon), and 12.5 parts of RECE-W is further added and uniformly dispersed. A white ink was produced. The content of the partially fixed lithium smectite in the ink was 5.3% by mass based on the total amount of the nonvolatile components.

(Example 2)
A white ink was prepared in the same manner as in Example 1 except that the amount of RECE-W added was 25 parts. In addition, the content of the partially fixed lithium smectite in the present ink was 10.2% by mass based on the total amount of the nonvolatile components.

(Example 3)
A white ink was prepared in the same manner as in Example 1 except that the amount of RECE-W added was changed to 50 parts. The content of the partially fixed lithium smectite in the present ink was 18.5% by mass based on the total amount of the nonvolatile components.

(Comparative Example 1)
A white ink was produced in the same manner as in Example 1 except that 5 g of sodium montmorillonite powder Kunipia F was used instead of the lithium partially fixed type smectite slurry RCEC-W. The content of sodium montmorillonite in this ink was 10.2% by mass based on the total amount of nonvolatile components.

(Comparative Example 2)
A white ink was prepared in the same manner as in Example 1, except that 5 g of S-Ben N-400 was used as the organically modified smectite ion-exchanged with a quaternary ammonium salt instead of the lithium partially fixed type smectite slurry RCEC-W. did. The content of sodium montmorillonite in this ink was 10.2% by mass based on the total amount of nonvolatile components.

(Reference example)
A white ink was prepared in the same manner as in Example 1 except that the lithium partially fixed smectite slurry RCEC-W in Example 1 was not added.

(Preparation of printed matter)
The viscosities of the white inks obtained in Examples 1 to 3, Comparative Examples 1 and 2, and Reference Examples were diluted with ethyl acetate and isopropyl alcohol (IPA), and the viscosity was adjusted to 12 to about 16 with Zahn Cup # 3 (manufactured by Rigosha). Adjusted to seconds. Using a bar coater # 4, print this white ink on a biaxially stretched polyester film (hereinafter referred to as PET film, manufactured by Toyobo Co., Ltd., E-5100, 12 μm thick) having a corona treatment on one surface, and print the white ink. Obtained.

(Production of multilayer film)
Dic Dry LX-401A / SP-60 (DIC Co., Ltd.), which is an ether-based dry laminating adhesive, is applied to the printed matter using a bar coater so that the coating amount becomes 2.5 g / m 2, and dried. Thereafter, a non-stretched polypropylene film (hereinafter referred to as CPP: P1128 20 μm manufactured by Toyobo Co., Ltd.) was laminated and aged at 40 ° C. for 3 days to obtain a laminate on which white ink was printed.

(Oxygen permeability)
The measurement of the oxygen permeability was carried out in an atmosphere of a temperature of 23 ° C. and a humidity of 50% RH using an oxygen permeability measuring device OX-TRAN1 / 50 manufactured by Mocon Inc. in accordance with JIS-K7126 (isobaric method). In addition, RH represents a relative humidity. The oxygen permeability of a 12 μm PET film is about 135 cc / m ² · day · atm.

(Adhesion of cellophane tape)
After leaving the printed matter of the white ink on the PET film obtained in the preparation of the printed matter for one day, a cellophane tape (Nichiban 12 mm width) was attached to the printed surface, and the printed film was rapidly peeled off. The appearance was visually determined in the following five stages.
5: The printed film was not peeled at all.
4: 70% or more to less than 90% of the printed film remained on the film.
3: 50% or more to less than 70% of the printed film remained on the film.
2: 30% or more to less than 50% of the printed film remained on the film.
1: Less than 30% of the print film remained.

(Lamination strength)
The aged multilayer film is cut to a width of 15 mm in parallel with the coating direction, and peeled between the PET film and the CPP film using an Orientec Tensilon universal testing machine at an ambient temperature of 25 ° C. The speed was set to 300 mm / min, and the tensile strength at the time of peeling by the 90 ° peeling method was defined as the adhesive strength. The unit of the adhesive strength was N / 15 mm.

The results of Examples are shown in Table 1 below, and the results of Comparative Examples and Reference Examples are shown in Table 2.

The ink of the present invention was excellent in gas barrier function, especially in oxygen barrier. Further, practically sufficient cellophane tape adhesion and lamination strength were exhibited. Therefore, it can be suitably used as a packaging material having a gas barrier function.

Claims (7)

  An ink containing a colorant, a resin, and a lithium partially fixed smectite.   The ink according to claim 1, wherein the colorant is an inorganic pigment.   The ink according to claim 2, wherein the inorganic pigment is at least one selected from titanium oxide, zinc oxide, barium sulfate, and carbon black.   The ink according to any one of claims 1 to 3, wherein the lithium partially fixed smectite has a cation exchange capacity of 1 to 70 meq / 100 g.   The ink according to any one of claims 1 to 3, wherein the content of the lithium partially fixed smectite is 1 to 30% by mass based on the total amount of nonvolatile components of the resin composition.   A printed matter obtained by printing the ink according to claim 1.   7. The printed matter according to claim 6, which is a packaging material.