JP6824460B1 - Press-through pack (PTP) liquid ink for packaging - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a press-through pack package having improved peel strength between a plastic sheet and a metal foil. The above problem can be solved by a liquid ink composition for a press-through pack (PTP) package containing a vinyl chloride / vinyl acetate copolymer, a urethane resin, and a melamine resin of the present invention. [Selection diagram] None

Description

The present invention relates to a liquid ink for a press-through pack (hereinafter, may be referred to as PTP) packaging. According to the present invention, it is possible to improve the heat seal strength between the plastic sheet of the press-through pack package and the metal foil.

Press-through pack packaging is used for packaging pharmaceutical products such as tablets and capsules. The PTP package includes a pocket (recess) of a plastic sheet such as vinyl chloride in which contents such as tablets are stored, and a lid material of a metal foil such as a hard aluminum foil covering the pocket (recess). The vinyl-coated (VC) surface (the surface that comes into contact with the contents) and / or the overprint (OP) surface on the opposite side of the VC surface of the metal leaf may have a printing layer on one surface for coloring, or the contents, etc. Information and patterns are printed. Further, the VC surface is coated with a heat sealant in order to bond the plastic sheet and the metal foil.
As the liquid ink for this metal foil, a vinyl chloride / vinyl acetate copolymer having excellent adhesion to the metal foil is used, and a liquid ink containing a melamine resin in order to further impart heat resistance is used. It is disclosed (Patent Document 1).

However, when the conventional liquid ink is used, the peel strength between the plastic sheet and the metal foil is lowered on the VC surface, and poor adhesion occurs.

Japanese Unexamined Patent Publication No. 2014-198391 JP-A-2018-188181

As one method for improving the peel strength between the plastic sheet and the metal foil, the temperature and pressure of the heat seal have been increased to extend the heat seal time. However, in this method, the OP surface of the metal leaf exceeds the heat resistance limit, causing problems such as blocking with the hot plate and deformation and discoloration of the plastic sheet. In order to solve these problems, Patent Document 2 discloses a heat-sealing agent capable of heat-sealing at a low temperature in a short time (Patent Document 2).
However, as described in Patent Document 2, when a low Tg acrylic resin having a glass transition temperature of less than −70 ° C. to 30 ° C. is used as the heat sealant, after the heat sealant is applied to the metal foil. At the time of winding, winding blocking in which the OP surface and the VC surface stick to each other occurred, and further, the heat during the blister processing sometimes caused blocking of the VC surface and the contents.
Therefore, an object of the present invention is to provide a press-through pack package having improved peel strength between a plastic sheet and a metal foil.

As a result of diligent research on a press-through pack (PTP) package having improved peeling strength between a plastic sheet and a metal foil, the present inventor surprisingly found vinyl chloride / vinyl acetate copolymer, urethane resin, and It has been found that a PTP package having improved heat seal strength can be obtained by using a metal foil printed with a liquid ink containing a melamine resin.
The present invention is based on these findings.
Therefore, the present invention
[1] Liquid ink composition for press-through pack (PTP) packaging containing vinyl chloride / vinyl acetate copolymer, urethane resin, and melamine resin,
[2] A liquid ink containing the liquid ink composition and pigment according to [1].
[3] A press-through pack containing the metal leaf having the liquid ink printing layer according to [2] and the metal leaf and the container body according to [4] and [3].
Regarding.

According to the liquid ink for PTP packaging of the present invention, the heat sealing strength between the plastic sheet of the PTP packaging and the metal foil can be improved. Further, according to the liquid ink for PTP packaging of the present invention, since heat sealing is possible at a low temperature, it is possible to prevent cracks in the metal foil and deformation or discoloration of the plastic sheet. Further, the filling speed at the time of filling the contents such as tablets can be increased, and the productivity of the PTP package can be improved.

It is a graph which showed the peel strength of the press-through pack by the heat seal of the vinyl chloride sheet and the hard aluminum foil obtained in Examples 1-7 and Comparative Example 1.

The liquid ink composition for a press-through pack package of the present invention contains a vinyl chloride / vinyl acetate copolymer, a urethane resin, and a melamine resin.

《Press-through pack packaging》
The press-through pack package is used as a package for pharmaceutical products such as tablets or capsules. For example, a plastic sheet having pockets (recesses) for containing contents such as tablets or capsules is heat-sealed with a metal leaf lid material such as hard aluminum foil. The pocket of the plastic sheet can be formed by vacuum forming, compressed air forming, or the like. Examples of the material of the plastic sheet include polyvinyl chloride resin and polypropylene resin. The metal foil as the lid material has a vinyl coated (VC) surface (a surface in contact with the contents) and an overprint (OP) surface on the opposite side of the VC surface. The VC and OP surfaces may have a solid print layer for coloring the metal leaf. Further, information such as contents such as tablets or capsules and a pattern may be printed. Further, the VC surface has a heat seal layer for laminating the plastic sheet and the metal foil, and is sealed to the flange portion of the plastic sheet.

《Vinyl chloride / vinyl acetate copolymer》
The liquid ink composition of the present invention contains a vinyl chloride / vinyl acetate copolymer. The composition of vinyl chloride and vinyl acetate in the vinyl chloride / vinyl acetate copolymer is not particularly limited, but is preferably 98: 2 to 60:40. The weight average molecular weight of the vinyl chloride / vinyl acetate copolymer is not particularly limited, but is, for example, 1000 to 30000 Mw, more preferably 2000 to 20000 Mw, and further preferably 2500 to 150,000 Mw. The acid value of the vinyl chloride / vinyl acetate copolymer is not particularly limited, but is, for example, 2 to 20 mgKOH / g, more preferably 4 to 10 mgKOH / g, and further preferably 5 to 9 mgKOH. / G. When the acid value is in the above range, the adhesion to the metal foil is particularly improved.

《Urethane resin》
The liquid ink composition of the present invention contains a urethane resin. The urethane resin is a polymer having a urethane bond obtained by polymerizing diisocyanate and a diol monomer (or triol monomer). The urethane resin used in the present invention is not particularly limited as long as the effects of the present invention can be obtained, and examples thereof include a thermoplastic urethane resin and a thermosetting urethane resin, and a thermoplastic urethane resin is preferable. .. It is presumed that the urethane resin can impart toughness and flexibility to the ink layer and improve the heat seal strength between the plastic sheet of the PTP package and the metal foil by having the urethane bond.

Examples of the thermoplastic urethane resin include ester-based urethane resin, ether-based urethane resin, and carbonate-based urethane resin, and ester-based urethane resin is preferable.
The number average molecular weight of the urethane resin is not particularly limited, but is, for example, 5000 to 250,000 Mn, preferably 1000 to 150,000 Mn, more preferably 1500 to 100,000 Mn, and further preferably 2000 to 60000 Mn. The weight average molecular weight of the urethane resin is not particularly limited, but is, for example, 1000 to 30000 Mw, preferably 20000 to 20000 Mw, more preferably 30,000 to 150,000 Mw, and further preferably 50,000 to 90,000 Mw. It is presumed that toughness is imparted by being in the molecular weight range (relatively high molecular weight). The 100% elongation stress of the urethane resin is not particularly limited, but is, for example, 1 to 30 MPa, preferably 3 to 25 MPa, and more preferably 5 to 15 MPa. The elongation at break of the urethane resin is not particularly limited, but is, for example, 100 to 1500%, preferably 300 to 1200%, and more preferably 500 to 1000%. The breaking strength of the urethane resin is not particularly limited, but is, for example, 10 to 50 MPa, preferably 20 to 40 MPa, and more preferably 25 to 35 MPa. The glass transition temperature (Tg) of the urethane resin is not particularly limited, but is, for example, −60 to 10 ° C., preferably −55 to −5 ° C., and more preferably −55 to −20 ° C. Yes, more preferably −50 to −30 ° C. In particular, it is presumed that flexibility is imparted by being in the range of the glass transition temperature (relatively low Tg).
By adding the urethane resin, flexibility can be imparted to the ink coating film, and the heat seal strength in the press-through pack package can be improved.

《Melamine resin》
The liquid ink composition of the present invention contains a melamine resin. The melamine resin is a thermosetting resin obtained by polycondensation of melamine and formaldehyde. For example, melamine and formaldehyde are condensed under alkaline conditions to obtain methylol melamine. By heating methylolmelamine, a thermosetting resin that is polycondensed and crosslinked in a network can be obtained.
The melamine resin used in the liquid ink composition of the present invention is not particularly limited as long as the effects of the present invention can be obtained, but for example, a butylated melamine resin (n-butylated melamine resin or i-butylated resin) is used. Melamine resin), methylated melamine resin, methylated butylated melamine resin, ethylened melamine resin, or propylated melamine resin.
The weight average molecular weight of the melamine resin is not particularly limited, but is 500 to 30,000 Mw, preferably 1000 to 200,000 Mw, more preferably 1500 to 100,000 Mw, and further preferably 2000 to 7000 Mw.
By containing the melamine resin, the liquid ink composition and the liquid ink of the present invention can improve the heat resistance.

The content ratio of the vinyl chloride / vinyl acetate copolymer to the urethane resin in the liquid ink composition of the present invention is not particularly limited as long as the effects of the present invention can be obtained, but for example, 100: 0. It is 5 to 100: 500, more preferably 100: 1 to 100: 400, further preferably 100: 2 to 100: 300, and most preferably 100: 3 to 100: 200. The content ratio of the vinyl chloride / vinyl acetate copolymer with the urethane resin is the same for the liquid ink of the present invention.
Within the above range, the heat seal strength of the press-through pack package can be improved.

The content ratio of the melamine resin to the mixture of the vinyl chloride / vinyl acetate copolymer and the urethane resin in the liquid ink composition of the present invention is not particularly limited as long as the effects of the present invention can be obtained, but for example, 100. : 2 to 100:30, preferably 100: 3 to 100:25, more preferably 100: 4 to 100:20, still more preferably 100: 5 to 100:15. The content ratio of the melamine resin to the mixture of the vinyl chloride / vinyl acetate copolymer and the urethane resin is the same in the liquid ink of the present invention.
Within the above range, the heat resistance of the liquid ink composition and the liquid ink can be particularly improved.

The contents of the vinyl chloride / vinyl acetate copolymer, urethane resin, and melamine resin in the liquid ink composition of the present invention are not particularly limited. However, the vinyl chloride / vinyl acetate copolymer is, for example, 10 to 99% by weight, preferably 15 to 97% by weight, based on the total amount of the vinyl chloride / vinyl acetate copolymer, the urethane resin, and the melamine resin. It is more preferably 20 to 95% by weight, further preferably 30 to 90% by weight, and most preferably 50 to 80% by weight. The urethane resin is, for example, 0.5 to 90% by weight, preferably 1 to 70% by weight, more preferably 2 to 60% by weight, still more preferably 3 to 50% by weight, and most preferably. It is 4 to 40% by weight. The melamine resin is, for example, 0.1 to 20% by weight, preferably 0.5 to 15% by weight, more preferably 1 to 10% by weight, still more preferably 1.5 to 5% by weight. ..

"solvent"
In the liquid ink composition of the present invention, the vinyl chloride / vinyl acetate copolymer, urethane resin, and melamine resin may be mixed as they are, or may be dissolved in a solvent. The solvent is not particularly limited as long as it can dissolve a vinyl chloride / vinyl acetate copolymer, a urethane resin, and a melamine resin, but for example, a ketone-based organic solvent such as acetone, methyl ethyl ketone, and methyl isobutyl ketone. Alcohol-based organic solvents such as methanol, ethanol, n-propanol, isopropanol and butanol, ester-based organic solvents such as methyl acetate, ethyl acetate, propyl acetate and butyl acetate, fats such as n-hexane, n-heptane and n-octane. Group hydrocarbon-based organic solvents, glycol ester-based solvents such as propylene glycol monomethyl ether acetate, glycol ether-based solvents such as propylene glycol monomethyl ether and dipropylene glycol methyl ether, and cyclohexane, methylcyclohexane, ethylcyclohexane, cycloheptane, cyclooctane. Examples thereof include alicyclic hydrocarbon-based organic solvents such as.
The content of the solvent in the liquid ink composition of the present invention is not particularly limited as long as it can dissolve the contained resin or the like, but is, for example, 40 to 95% by weight of the liquid ink composition, which is more preferable. Is 50 to 90% by weight, more preferably 60 to 80% by weight.

The liquid ink of the present invention includes the liquid ink composition for a press-through pack package of the present invention and a pigment.

《Pigment》
The pigment contained in the liquid ink of the present invention is not particularly limited, and an inorganic pigment or an organic pigment generally used for printing ink can be used. Examples of the inorganic pigment include carbon black, titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, silica, red iron oxide, aluminum, mica (mica) and the like. Examples of organic pigments include azo-based, phthalocyanine-based, anthraquinone-based, perylene-based, perinone-based, quinacridone-based, thioindigo-based, dioxazine-based, isoindolinone-based, quinophthalone-based, azomethine-azo-based, dictopyrrolopyrrole-based, and isoindoline-based. Pigments can be mentioned. The content of the pigment is not particularly limited as long as it is an amount sufficient to secure the density and coloring power of the ink, but is contained in, for example, 0.5 to 50% by weight in the total amount of the ink.
As the solvent used for the liquid ink, the same solvent as that of the liquid ink composition can be used. The content of the solvent is not particularly limited, but is, for example, 1 to 99% by weight, more preferably 10 to 90% by weight, and further preferably 15 to 80% by weight of the liquid ink composition.

The liquid ink of the present invention may exhibit good ink adhesion, ink aging stability, or color heat flow resistance, but not limited to.

《Metal leaf》
The metal leaf of the present invention has a printing layer of the liquid ink. The metal foil is not particularly limited, and examples thereof include an aluminum foil. The thickness of the metal foil is not particularly limited, but for example, a metal foil having a thickness of 5 to 50 μm can be used. In the case of aluminum foil, preferably aluminum having a purity of 98.0 to 99.9% by weight can be used.
The tempering (classification) of the aluminum foil includes a hard material, a semi-hard material, and a soft material, and any of them can be used, but the hard aluminum foil is particularly preferable.

《Print layer》
The metal leaf used has a VC surface that comes into contact with the contents and an OP surface that is opposite to the VC surface. Normally, the press-through pack has a printing surface on either the VC surface or the OP surface, or both sides, but the metal foil of the present invention has a printing layer on the VC surface. The printing layer may be solid printing on the entire surface, or may be printing on a part of the surface such as information about the contents or a pattern for identification. However, solid printing on the entire surface is preferable. Further, a part of a pattern or the like may be further printed on the solid printing (solid coloring). By having the printed layer, the heat seal strength between the plastic sheet of the PTP package and the metal foil can be improved.
The thickness of the print layer is not particularly limited, but is, for example, 0.1 to 5 μm, preferably 0.2 to 4 μm, more preferably 0.3 to 3 μm, and even more preferably 0. .5-2 μm.

As a method for printing the liquid ink of the present invention on a metal leaf, a known printing method and coating method can be used. Examples thereof include gravure printing, offset printing, flexographic printing, inkjet printing, printing by a heat-sensitive transfer method, and coating methods such as a gravure roll coater and a curtain flow coater, but gravure printing is preferable.

《Heat seal layer》
The metal leaf of the present invention may have a heat seal layer on the printing layer on the VC surface. On the other hand, the heat seal layer may be formed on the metal foil having the print layer before the heat seal is performed.
Examples of the heat sealant for forming the heat seal layer include thermoplastic resins such as polyethylene, polyvinyl acetate, acrylic resin, polyamide, polyester, polypropylene, polyolefin, epoxy resin, polyvinyl and polyurethane, and mixtures thereof. Be done. More specifically, low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear (linear) low-density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-acrylic acid copolymer, Acrylic polyolefin resins such as ethylene-ethyl acrylate copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-propylene copolymer, methylpentene polymer, polybutene polymer, polyethylene or polypropylene Acid-modified polyolefin resin modified with unsaturated carboxylic acids such as acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, and itaconic acid, polyvinyl acetate resin, poly (meth) acrylic resin, polyacrylonitrile resin, poly In addition to vinyl chloride-based resins and other heat-adhesive resins, blended resins thereof, copolymers containing a combination of monomers constituting these, modified resins, and the like can be mentioned.

The thickness of the heat seal layer is not particularly limited, but is, for example, 1 to 10 μm, preferably 2 to 5 μm. The heat seal layer can be applied to a desired thickness, for example by a bar coater. Further, as the coating method, a gravure coating method, a reverse roll coating method, a knife coating method, a kiss coating method and the like may be used.

The press-through pack of the present invention includes a metal foil having a printing layer of the liquid ink, and a container body. The metal foil has a heat-sealing layer and is sealed on the flange portion of the container body (plastic sheet). The container body of the PTP package (press-through package) is obtained by forming a pocket or the like by forming a transparent plastic film or a plastic sheet by hot vacuum forming, hot vacuum forming, hot vacuum forming, or the like. Then, the pocket is filled with a solid drug, food, etc., and the opening is sealed and packaged with the metal foil of the present invention.

《Plastic sheet》
The plastic sheet of the container body is not particularly limited, but is, for example, a polyvinyl chloride resin, a vinylidene chloride resin, or a polyolefin resin (for example, a polyethylene resin, a polypropylene resin, or an ethylene-vinyl alcohol copolymer resin). , Resin composed of cyclic olefin, etc.), polychlorotrifluoroethylene, polyester and other well-known synthetic resins can be used as raw materials. These synthetic resin materials preferably have a thermal deformation temperature of 50 to 110 ° C, more preferably 60 to 90 ° C. A sheet material made of a polyvinyl chloride resin is preferable from the viewpoints of a wide range of molding conditions for vacuum or compressed pocket molding, mechanical strength, transparency, and cost. The shape of the pocket is not particularly limited, and examples thereof include a rectangle (square, rectangle, triangle, etc.) and a circle (circle, ellipse, etc.).

《Heat seal processing》
The press-through pack of the present invention can be manufactured by superimposing a flange portion of a plastic sheet and a heat-sealing layer of a metal leaf and heat-sealing the pack. The bonding of metal foil and plastic sheet is also called blister processing.
The heat seal temperature in the blister processing is not particularly limited as long as the effect of the present invention can be obtained, but can be carried out, for example, at 100 to 300 ° C. However, in order to avoid the influence of heat on the contents, it is preferable to carry out at a relatively low temperature. When the liquid ink composition of the present invention or the liquid ink is used, high heat seal strength can be obtained at a relatively low temperature as shown in Examples. Therefore, the heat seal temperature is, for example, 130 to 250 ° C., preferably 130 to 230 ° C., more preferably 130 to 210 ° C., and even more preferably 130 to 190 ° C.

The heat seal processing machine is not particularly limited, and examples thereof include a roll seal molding machine having a heat seal roll and a roll under the seal, and a flat seal molding machine having heat plates on the upper and lower sides. Further, the heat seal may be performed using a grid-shaped hot plate of a blister filling machine having a built-in heat sealer.
The heat seal temperature in the heat seal using the blister filling machine is, for example, 130 to 250 ° C., preferably 130 to 230 ° C., more preferably 130 to 210 ° C., and further preferably 130 to 190 ° C. The heat seal pressure is, for example, 0.2 to 2.0 MPa, preferably 0.3 to 1.0 MPa. The heat seal time is, for example, 0.05 to 1 second, preferably 0.2 to 0.8 seconds, and more preferably 0.3 to 0.6 seconds.

In the blister processing, heat and pressure are applied to the OP surface of the metal foil by a grid-shaped hot plate. When printing with ink is performed on the OP surface, it is preferable to apply a thermosetting OP varnish having excellent heat resistance and abrasion resistance to the entire surface in order to protect the ink coating film.

《Heat seal strength》
The heat seal strength between the plastic sheet and the metal foil of the press-through pack of the present invention is not particularly limited, but is, for example, 4.5 N / 15 mm or more, preferably 5.0 N / 15 mm or more, and more. It is preferably 5.5 N / 15 mm or more, more preferably 6.0 N / 15 mm or more, even more preferably 6.5 N / 15 mm or more, and most preferably 7.0 N / 15 mm or more. In the present invention, the plastic sheet and the metal foil do not need to be peeled off when the contents are taken out. Therefore, the upper limit of the heat seal strength is not particularly limited, but is, for example, 10.0 N / 15 mm.
The peel strength can be measured using, for example, a peel strength tester under the conditions of 100 m / min and 180 ° peeling.

《Action》
The mechanism by which the heat seal strength between the plastic sheet of the press-through pack printed on the metal foil using the liquid ink composition of the present invention or the liquid ink and the metal foil is excellent has not been completely elucidated. It can be estimated as follows. However, the present invention is not limited by the following estimates.
It is considered that the liquid ink composition of the present invention or the printing layer printed on the metal leaf by the liquid ink exhibits excellent heat-sealing strength because it contains a urethane resin. Specifically, it is said that imparting toughness and flexibility to the printed layer by having the urethane resin having a urethane bond can improve the heat seal strength between the plastic sheet of the PTP package and the metal foil. Presumed. Further, it is presumed that the toughness is further improved by the relatively high molecular weight of the urethane resin, and the flexibility is further improved by the relatively low glass transition temperature of the urethane resin.

Hereinafter, the present invention will be specifically described with reference to Examples, but these do not limit the scope of the present invention.

<< Example 1 >>
In this example, a liquid ink composition containing thermoplastic urethane and a liquid ink were prepared.
20 parts by weight of vinyl chloride / vinyl acetate copolymer (vinyl chloride: vinyl acetate: others = 84: 15: 1; Mw = 50-60 × 10 ³ ; acid value = 7 ± 1.0 mgKOH / g) and 80 parts by weight of methyl ethyl ketone The parts were mixed in a sealable glass bottle and heated and dissolved in a heat insulating chamber having an internal temperature of 50 ° C. to prepare a vinyl chloride / vinyl acetate copolymer solution. Thermoplastic urethane resin (number average molecular weight 40,000 Mn; weight average about 70,000 Mw; 100% elongation stress 10 MPa; breaking elongation 700%; breaking strength 29 MPa; Tg-45-35) 20 parts by weight and 80 parts by weight of methyl ethyl ketone can be sealed. It was blended in a glass bottle and melted by heating in a heat insulating chamber having an internal temperature of 50 ° C. to prepare a thermoplastic urethane resin solution. The vinyl chloride / vinyl acetate copolymer solution and the thermoplastic urethane resin solution are placed in a sealable glass bottle so that the mixing ratio of the vinyl chloride / vinyl acetate copolymer and the thermoplastic urethane resin is 20.0: 0.6. The mixture was mixed and stirred sufficiently until the solution became uniform to obtain a mixed resin solution. Eight parts of the pigment was added to 89 parts of the mixed resin solution, and 100 parts of 1.8 mm titania beads were further added. These were vibrated and dispersed with a paint shaker for 1 hour to obtain a pigment dispersion liquid. The titania beads were filtered off with a mesh. 3 parts of a butylated melamine resin solution was added to 97 parts of the pigment dispersion and stirred sufficiently to obtain an ink solution. As the butylated melamine resin solution, a solution in which 60% by weight of the resin solid content was dissolved in butanol was used.
Tables 2 and 3 show the composition of the liquid ink.

The obtained ink was coated on a hard aluminum foil mat surface of 20 μm with a bar coater so that the ink film thickness after drying was about 1 μm. An ink-coated sample was prepared by baking for 10 seconds in an oven whose internal temperature was set to 170 ° C.
Further, a heat sealant having the composition described in the table below was applied on the ink coating film with a bar coater to provide a heat seal resin layer having a dry coating film of 3 μm. After the heat sealant was applied, the sample was baked in an oven set at 170 ° C. for 10 seconds to prepare a heat sealant-coated sample.

<< Example 2 >>
In this example, the vinyl chloride / vinyl acetate copolymer solution and the thermoplastic urethane resin solution are prepared so that the mixing ratio of the vinyl chloride / vinyl acetate copolymer and the thermoplastic urethane resin is 20.0: 1.0. The operation of Example 1 was repeated except for mixing.

<< Example 3 >>
In this example, the vinyl chloride / vinyl acetate copolymer solution and the thermoplastic urethane resin solution are prepared so that the mixing ratio of the vinyl chloride / vinyl acetate copolymer and the thermoplastic urethane resin is 20.0: 2.0. The operation of Example 1 was repeated except for mixing.

<< Example 4 >>
In this example, the vinyl chloride / vinyl acetate copolymer solution and the thermoplastic urethane resin solution are prepared so that the mixing ratio of the vinyl chloride / vinyl acetate copolymer and the thermoplastic urethane resin is 20.0: 5.0. The operation of Example 1 was repeated except for mixing.

<< Example 5 >>
In this example, the vinyl chloride / vinyl acetate copolymer solution and the thermoplastic urethane resin solution are prepared so that the mixing ratio of the vinyl chloride / vinyl acetate copolymer and the thermoplastic urethane resin is 20.0: 10.0. The operation of Example 1 was repeated except for mixing.

<< Example 6 >>
In this example, the vinyl chloride / vinyl acetate copolymer solution and the thermoplastic urethane resin solution are prepared so that the mixing ratio of the vinyl chloride / vinyl acetate copolymer and the thermoplastic urethane resin is 20.0: 20.0. The operation of Example 1 was repeated except for mixing.

<< Example 7 >>
In this example, the vinyl chloride / vinyl acetate copolymer solution and the thermoplastic urethane resin solution are prepared so that the mixing ratio of the vinyl chloride / vinyl acetate copolymer and the thermoplastic urethane resin is 20.0: 40.0. The operation of Example 1 was repeated except for mixing.

<< Comparative Example 1 >>
In this comparative example, the operation of Example 1 was repeated except that the thermoplastic urethane resin was not used.

《Adhesion test》
Adhesion tests of the ink-coated samples obtained in Examples 1 to 7 and Comparative Example 1 were performed. Ink coating A 12 mm wide cellophane tape (registered trademark) manufactured by Nichiban was carefully attached to the ink-coated surface of the sample, and then vigorously peeled off. The peeled surface was visually evaluated on a 5-point scale according to the following criteria.
1: Completely taken.
2: Large amount taken.
3: Somewhat taken.
4: Very little taken.
5: Not taken.
The results are shown in Table 3. In all of Examples 1 to 7, the adhesion of the ink to the 20 μm hard aluminum foil matte surface was good.

《Heat sealability test》
The heat sealability test of the heat sealant coated samples obtained in Examples 1 to 7 and Comparative Example 1 was performed. The VC surface of the heat sealant coated sample and the 250 μm vinyl chloride sheet are overlapped, and with the heat sealant coated sample facing up, on a flat plate, 2 MPa, 1 second, from 150 ° C to 250 ° C, 20 Heat sealing was performed in increments of ° C.
At this time, the width of the heat sealant-coated sample and the vinyl chloride sheet of 250 μm was 15 mm, and the width of the normal heat plate was 5 mm. After the heat seal, the sample was cooled to room temperature, and the heat seal strength at 180 ° peeling was measured at 100 m / min with a peel strength tester. The results are shown in Table 4 and FIG. As the amount of the thermoplastic urethane resin compounded increased, the heat seal strength increased. Further, even with a low temperature heat seal, sufficient heat seal strength was obtained.

The liquid ink of the present invention can be used as a printing ink for a PTP package, and can improve the heat seal strength between a plastic sheet and a metal foil.

Claims (4)

A liquid ink composition for a press-through pack (PTP) package containing a vinyl chloride / vinyl acetate copolymer, a urethane resin, and a melamine resin, wherein the content ratio of the urethane resin to the vinyl chloride / vinyl acetate copolymer is For press-through pack (PTP) packages, which are 100: 3 to 100: 200 and have a melamine resin content ratio of 100: 2 to 100:30 with respect to a mixture of vinyl chloride / vinyl acetate copolymer and urethane resin. Liquid ink composition . A liquid ink containing the liquid ink composition and pigment according to claim 1. A metal leaf having a printing layer of the liquid ink according to claim 2. A press-through pack including the metal leaf and the container body according to claim 3.