Printed matter

Abstract

An objective of the present invention is to provide shrinkable polyester film printed matter printed with printing ink that is capable of accommodating the rapid shrinkage of a shrinkable film composed of a crystalline polyester and that has excellent adhesive properties and blocking resistance. Printed matter according to the present invention is characterized by comprising a shrinkable polyester film and a printing ink layer provided on the shrinkable polyester film, the shrinkable polyester film being a crystalline polyester film, and the printing ink layer containing a polyurethane resin and an antiblocking agent.

Description

printed matter

[0001] The present invention relates to a printed matter, and more specifically to a printed matter in which a printing ink layer is provided on a shrinkable film using a crystalline polyester.

[0002] Shrink films have traditionally been widely used for label packaging and stack packaging that combine the protection of glass bottles, plastic bottles, etc. with product labeling. Among these, polyester-based shrink films, which have high heat resistance, are easily incinerated, and have excellent solvent resistance, are widely used. Typically, polyester resins containing a large amount of amorphous components are used as raw materials for shrink polyester films to impart heat shrinkability. Shrink films using glycol-modified polyethylene terephthalate (PET-G) as the amorphous polyester resin have gradual shrink characteristics with temperature, allowing for shrink processing over a wide temperature range and achieving a beautiful shrink finish.

[0003] Furthermore, in recent years, there has been active development of technologies for collecting PET bottles and recycling plastics from an environmental perspective, and there is a demand for shrink films that can be recycled together with PET bottles, etc. while still covering the bottles. However, the above-mentioned PET-G has problems, such as a decrease in the quality of the recycled material when recycled together with PET bottles, etc., because it is glycol-modified, and being amorphous, it is prone to mutual adhesion (agglomeration) of recycled pellets during the recycling process. Therefore, shrink films using crystalline polyester (C-PET) have been developed as highly recyclable shrink PET films (for example, Patent Documents 1 and 2).

[0004] German Patent Application Publication No. 112021003920 Patent No. 6802535

[0005] Shrink films are often printed with gravure inks or flexographic inks to impart aesthetic appeal and functionality. However, inks for shrink films must have ink properties suitable for printing on shrink films, such as the ability to adapt to shrinkage, in addition to the properties of ordinary printing inks. Furthermore, in order to improve the quality of recycled materials in the recycling process of PET bottles and the like, it is desirable for the printing ink to be able to be released from the shrink film. However, developing an ink that meets all of these requirements is difficult and presents many challenges. For example, shrink films made from the highly recyclable crystalline polyesters described above have a rapid shrinkage characteristic with respect to temperature (they shrink rapidly within a specific temperature range). Therefore, a printing ink that is optimal for shrink C-PET film and can adapt to such rapid shrinkage is needed; however, no printing ink for shrink C-PET film has been developed.

[0006] Therefore, an object of the present invention is to provide a shrinkable polyester film print printed with a printing ink that can follow the rapid shrinkage of a shrinkable film made of crystalline polyester and has excellent adhesion and blocking resistance.

[0007] That is, the present invention is as follows. [1] A printed matter comprising a shrunk polyester film and a printing ink layer provided on the shrunk polyester film, wherein the shrunk polyester film is a crystalline polyester film, and wherein the printing ink layer contains a polyurethane resin and an anti-blocking agent. [2] The printed matter according to [1], wherein the printing ink layer further contains one or more resins selected from the group consisting of vinyl chloride-vinyl acetate copolymer resin, cellulose-based resin, polyester resin, rosin-modified maleic acid resin, and polyvinyl butyral resin. [3] The printed matter according to [1] or [2], wherein the printing ink layer does not contain a chlorine-based resin. [4] The printed matter according to any of [1] to [3], wherein the printing ink layer is removable by treatment with an alkaline solution. [5] The printed matter according to any of [1] to [4], wherein the shrunk polyester film does not contain a polyester resin containing 1,4-cyclohexanedimethanol as a raw material. [6] The printed matter according to any of [1] to [5], wherein the printed matter is a label for a PET bottle.

[0008] According to the present invention, it is possible to provide a shrinkable polyester film print printed with a printing ink that can follow the rapid shrinkage of a shrinkable film made of a crystalline polyester and has excellent adhesion and blocking resistance.

[0009] The following describes in detail an embodiment of the present invention (referred to as the "present embodiment"); however, the present disclosure is not limited to the following description and can be implemented in various modifications within the scope of its gist.

[0010] <Printed Matter> The printed matter of this embodiment has a shrinkable polyester film and a printing ink layer provided on the shrinkable polyester film. The printed matter of this embodiment may have a two-layer structure consisting of a shrinkable polyester film and a printing ink layer, or may have a multilayer structure including other layers as needed. The other layer may be provided between the shrinkable polyester film and the printing ink layer, or on the surface of the printing ink layer opposite the shrinkable polyester film. Examples of other layers include an anchor coat layer, a primer layer, a varnish layer, and an overcoat layer. In the printing ink layer of the printed matter of this embodiment (the printing ink composition described below that constitutes the printing ink layer), the colorant (pigment) is an optional component as described below, and when no colorant (pigment) is included, the above-mentioned other layer may be provided.

[0011] [Shrinkable Polyester Film] The shrinkable polyester film constituting the printed matter of this embodiment is preferably a crystalline polyester film using a crystalline polyester (C-PET), and is a heat-shrinkable film that shrinks when heated to a temperature equal to or higher than the shrinkage initiation temperature. Because the shrinkable polyester film of this embodiment is a film using a crystalline polyester, it has higher recyclability than films using amorphous polyesters such as PET-G.

[0012] The crystalline polyester film is not particularly limited as long as the main component resin (the resin with the highest content) constituting the shrink film is a crystalline polyester, and conventionally known films for label packaging and integrated packaging of containers such as glass bottles and plastic bottles can be used, such as the crystalline polyester films described in Patent Documents 1 and 2. The method for producing the crystalline polyester film is not particularly limited, and the film can be produced by known methods such as those described in Patent Documents 1 and 2. Commercially available crystalline polyester films may also be used, such as "ReCrysta" manufactured by Toyobo Co., Ltd., "Bonpet Renew" manufactured by Bonpet America, Inc., and "TopGreen" manufactured by Far Eastern New Century Co., Ltd. Among the conventionally known shrink films using crystalline polyesters, films that can be recycled together with plastic containers such as PET bottles while still covering them (without peeling them off from the plastic container) are preferred, such as shrink films certified by the U.S. Association of Plastic Recycles (APR).

[0013] The crystalline polyester constituting the crystalline polyester film preferably contains a small amount of monomers that can become amorphous components among the raw material monomers used in its synthesis, and more preferably does not contain any monomers that can become amorphous components. Examples of monomers that can become amorphous components include isophthalic acid, neopentyl glycol, 1,4-cyclohexanedimethanol, 1,4-cyclohexanedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,2-diethyl-1,3-propanediol, 2-n-butyl-2-ethyl-1,3-propanediol, 2,2-isopropyl-1,3-propanediol, 2,2-di-n-butyl-1,3-propanediol, and hexanediol. Among these, it is preferable that 1,4-cyclohexanedimethanol is not included in the raw material monomers, i.e., the crystalline polyester film does not contain a polyester resin containing 1,4-cyclohexanedimethanol as a raw material.

[0014] The thickness of the shrinkable polyester film is not particularly limited and may be, for example, 1 to 500 μm, 5 to 250 μm, 10 to 100 μm, or 20 to 60 μm. When the thickness of the shrinkable polyester film is within the above range, the printed matter can be suitably used for label packaging or integrated packaging of containers such as glass bottles and plastic bottles, and printing tends to be performed well. Furthermore, as described below, when the printed ink layer is made removable from the shrinkable polyester film by alkaline solution treatment, i.e., when the printed matter is made deinkable (deinkable), the thickness of the shrinkable polyester film is particularly preferably 30 to 50 μm. If the thickness of the shrinkable polyester film is too thin, the film tends to curl during the peeling treatment with a high-temperature alkaline solution (or hot water), reducing the releasability of the printed ink layer. Furthermore, if the thickness is too thick, the amount of crystalline polyester used increases, resulting in a greater environmental impact.

[0015] [Printed Ink Layer] The printed ink layer constituting the printed matter of the present embodiment is a film made of a printing ink composition and formed by printing the printing ink composition on the surface of the shrinkable polyester film or on the surface of another layer formed on the shrinkable polyester film.

[0016] In order to improve the quality of recycled materials in the recycling process of plastic containers such as PET bottles, the printing ink layer is preferably detachable from the shrink polyester film by treatment with an alkaline solution. Examples of methods for detaching the printing ink layer from the shrink polyester film by treatment with an alkaline solution include a method in which the printing ink layer itself has a detachment function and the printing ink layer is detached from the shrink polyester film, and a method in which another layer having a detachment function (a primer layer, a varnish layer, etc.) is provided between the printing ink layer and the shrink polyester film, and the other layer is detached to detach the printing ink layer together from the shrink polyester film. Examples of methods for imparting the detachment function to the printing ink layer itself (making the printing ink layer itself more detachable) include a method in which the acid value of the solids in the printing ink composition forming the printing ink layer is adjusted to a specific range, as described below, and a method in which an acidic additive is added to the printing ink composition.

[0017] Furthermore, it is preferable that the printing ink layer does not contain a resin containing chlorine (a chlorine-based resin), i.e., as described below, the printing ink composition does not contain a chlorine-based resin. If a chlorine-based resin is contained, when a plastic container such as a PET bottle is recycled while the printed matter of this embodiment is still coated thereon (without peeling the printed matter of this embodiment from the plastic container) without removing the printing ink layer, hydrogen chloride is released during the thermal decomposition process to generate hydrochloric acid, which may cause corrosion of equipment and piping, and the emitted chlorine gas may degrade the quality of the recycled material. There is also the problem of the emission of environmental hormones such as dioxins. Therefore, from the viewpoints of equipment maintenance, improving the quality of recycled materials, and environmental considerations, it is preferable that the printing ink layer does not contain a chlorine-based resin.

[0018] The total thickness of the printing ink layer of this embodiment may be, for example, 0.3 to 7.0 μm, with a lower limit of, for example, 0.3 μm or more, 0.5 μm or more, 1.0 μm or more, 1.1 μm or more, or 1.5 μm or more. The upper limit may be, for example, 7.0 μm or less, 6.0 μm or less, 5.0 μm or less, 4.0 μm or less, 3.0 μm or less, 2.1 μm or less, 2.0 μm or less, 1.5 μm or less, 1.3 μm or less, 1.0 μm or less, or 0.7 μm or less. In particular, when the printing ink layer of this embodiment is a single layer (single color), the thickness may be, for example, 0.3 to 1.5 μm, with a lower limit of, for example, 0.3 μm or more, 0.4 μm or more, 0.5 μm or more, 0.6 μm or more, or 0.7 μm or more. The upper limit may be, for example, 1.5 μm or less, 1.4 μm or less, 1.3 μm or less, 1.2 μm or less, or 1.1 μm or less. In particular, when the printing ink layer of this embodiment is a multi-layer (overprinted) layer, the thickness may be, for example, 0.6 to 7.0 μm, and the lower limit may be, for example, 0.6 μm or more, 0.7 μm or more, 0.8 μm or more, 0.9 μm or more, or 1.0 μm or more. The upper limit may be, for example, 7.0 μm or less, 6.9 μm or less, 6.8 μm or less, 6.7 μm or less, or 6.6 μm or less. The thickness of the printing ink layer is a value obtained by observing the cross-sectional shape of the printed matter using a scanning electron microscope (SEM) and measuring the film thickness of the printing film.

[0019] [Printing Ink Composition] The printing ink composition forming the printing ink layer of this embodiment contains a polyurethane resin and an antiblocking agent, and may also contain an organic solvent and other components described below. Biomass-derived raw materials may be used for the printing ink composition. Due to issues such as the depletion of petroleum resources, petroleum-derived products are preferably replaced by those that use plants as alternative energy sources and / or those produced using microorganisms, etc. In this case, the printing ink composition can contribute to reducing the environmental impact by becoming carbon neutral.

[0020] (Polyurethane Resin) The polyurethane resin contained in the printing ink composition of this embodiment preferably uses polyester polyol and / or polyether polyol as a synthetic raw material.

[0021] The polyester polyol preferably has a number-average molecular weight of 1,000 to 7,000. When the polyester polyol has a number-average molecular weight of 1,000 or more, the printed ink layer tends to have appropriate hardness and good adhesion to shrinkable polyester film. When the number-average molecular weight is 7,000 or less, the printed ink layer tends to be less brittle and the blocking resistance of the printed ink layer tends to be better. On the other hand, the polyester polyol is preferably present in an amount of 1 to 80 parts by mass per 100 parts by mass of polyurethane resin. When the polyester polyol is present in an amount of 1 part by mass or more, the solubility of the polyurethane resin in ketone-based, ester-based, and alcohol-based solvents tends to be better. Furthermore, the resolubility of the printed ink layer in the above solvents tends to be good, and the tone reproducibility of the printed material tends to be less likely to decrease. Furthermore, when the polyester polyol is present in an amount of 80 parts by mass or less, the printed ink layer tends to be less soft and the blocking resistance of the printed ink layer tends to be better. The number average molecular weight of the polyester polyol can be measured by GPC, and more specifically, it can be measured by the same method as used to measure the number average molecular weight of the polyurethane resin described in the examples below.

[0022] As the polyester polyol, for example, one obtained by a known esterification reaction between a compound having two or more hydroxyl groups and a polybasic acid can be used.

[0023] The compound having two or more hydroxyl groups is used as a chain extender, and examples thereof include glycols such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol; 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol, Compounds having a number average molecular weight in the range of 50 to 400 can be used, such as glycols having a branched structure such as 2-isopropyl-1,4-butanediol, 2,4-dimethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-ethyl-1,6-hexanediol, 3,5-heptanediol, and 2-methyl-1,8-octanediol; aliphatic polyols such as trimethylolpropane, trimethylolethane, pentaerythritol, sucrose, methylene glycol, glycerin, and sorbitol; and aromatic polyols such as bisphenol A, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, hydrogenated bisphenol A, and hydroquinone. These compounds having two or more hydroxyl groups may be used alone or in combination of two or more.

[0024] Examples of the polybasic acid that can be used include succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic anhydride, fumaric acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, phthalic acid, and anhydrides of these acids. These polybasic acids may be used alone or in combination of two or more.

[0025] The polyether polyol preferably has a number-average molecular weight of 100 to 4000. When the number-average molecular weight of the polyether polyol is 100 or more, the hardness of the printed ink layer tends to be appropriate and the adhesion to the shrinkable polyester film tends to be good. When the number-average molecular weight is 4000 or less, the printed ink layer tends to be less brittle and the blocking resistance of the printed ink layer tends to be better. The number-average molecular weight of the polyether polyol can be measured by the GPC method, and more specifically, it can be measured by the same method as the number-average molecular weight measurement of the polyurethane resin described in the Examples below.

[0026] Examples of the polyether polyol include polyether polyols which are polymers or copolymers of ethylene oxide, propylene oxide, tetrahydrofuran, etc. Specifically, known general-purpose polyether polyols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol may be used, and among these, polyethylene glycol is preferred.

[0027] Examples of diisocyanate compounds used in the production of polyurethane resins include various known aromatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates that are generally used in the production of polyurethane resins. For example, 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dimeryl diisocyanate, isophorone diisocyanate Examples of the diisocyanate include 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 5-isocyanato-1-(isocyanomethyl)-1,3,3-trimethylcyclohexane, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, methylcyclohexane diisocyanate, norbornane diisocyanate, m-tetramethylxylylene diisocyanate, 4,4-diphenylmethane diisocyanate, tolylene diisocyanate, bis-chloromethyl-diphenylmethane-diisocyanate, 2,6-diisocyanate-benzyl chloride, and dimer diisocyanate in which the carboxyl group of a dimer acid is converted to an isocyanate group. These diisocyanate compounds may be used alone or in combination of two or more.

[0028] As the chain extender used in the production of polyurethane resin, in addition to the above-mentioned compounds having two or more hydroxyl groups, ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, etc., as well as amines having a hydroxyl group in the molecule such as 2-hydroxyethylethylenediamine, 2-hydroxyethylpropyldiamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, etc. These chain extenders may be used alone or in combination of two or more.

[0029] In producing the polyurethane resin, a primary or secondary amine compound such as monoethanolamine, diethanolamine, 2-amino-2-methyl-1-propanol, monoisopropanolamine, or diisopropanolamine may be used as an end-blocking agent.

[0030] Polyurethane resins can be obtained, for example, by reacting a polyol, a polyisocyanate, a chain extender and / or a terminal blocking agent, and optionally a monovalent active hydrogen compound. For example, a polyester polyol and, if necessary, a co-used polyol are reacted with a diisocyanate compound in a proportion such that the isocyanate group is in excess to obtain a prepolymer having terminal isocyanate groups, and the resulting prepolymer is reacted with a chain extender and / or a terminal blocking agent in a suitable solvent (such as an ester solvent commonly used as a liquid ink solvent, e.g., ethyl acetate, propyl acetate, or butyl acetate; a ketone solvent such as acetone, methyl ethyl ketone, or methyl isobutyl ketone; an alcohol solvent such as methanol, ethanol, isopropyl alcohol, or n-butanol; a hydrocarbon solvent such as toluene, xylene, methylcyclohexane, or ethylcyclohexane; or a mixed solvent thereof), in a two-stage method, or a polyester polyol and, if necessary, a co-used polyol, a diisocyanate compound, a chain extender, and / or a terminal blocking agent can be reacted at once in a suitable solvent selected from the above. Among these methods, the two-stage method is preferred because it allows the production of a uniform polyurethane resin. Furthermore, when producing a polyurethane resin by the two-stage method, it is preferable to carry out the reaction so that the total equivalent ratio of the amino groups in the chain extender and / or end-capping agent to one equivalent of the isocyanate groups in the prepolymer is 0.9 to 1.3. When the total equivalent ratio of the amino groups is 1.3 or less, the amount of the chain extender and / or end-capping agent remaining unreacted is reduced, which tends to suppress yellowing of the polyurethane resin and the generation of odors after printing.

[0031] The number-average molecular weight of the polyurethane resin is not particularly limited, but is preferably 10,000 or more in order to improve the releasability of the printed ink layer when treated with an alkaline solution. It is more preferably 15,000 or more in order to improve the blocking resistance, laminate strength, and chemical resistance of the printed ink layer. It is more preferably 20,000 or more in order to achieve a high level of both releasability of the printed ink layer when treated with an alkaline solution and adhesion to the shrinkable polyester film. The upper limit of the number-average molecular weight of the polyurethane resin is not particularly limited, but is preferably 100,000 or less, more preferably 75,000 or less, and even more preferably 50,000 or less, in order to prevent the viscosity of the printing ink composition from becoming too high and to easily achieve a predetermined printing density. The number-average molecular weight of the polyurethane resin can be measured by gel permeation chromatography (GPC), more specifically, under the conditions described in the Examples below.

[0032] Examples of methods for imparting an acid value to a polyurethane resin (methods for obtaining a urethane resin having an acid value) include a method using a raw material having a carboxy group in the above-mentioned two-stage method or one-stage method, and a specific example is a method using a diol having a carboxy group as a co-used polyol. Examples of diols having a carboxy group include 2,2-dimethylolpropionic acid and 2,2-dimethylolbutanoic acid.

[0033] The amine value of the polyurethane resin is preferably 10.00 mgKOH / g or less. When the amine value is 10.00 mgKOH / g or less, the blocking resistance of the printed ink layer and the two-component stability of the printing ink composition when a curing agent is used in combination tend to be good. From the viewpoint of maintaining the above-mentioned blocking resistance and two-component stability while maintaining the plate fogging resistance, adhesion to shrinkable polyester film, and extrusion lamination strength of the printing ink composition, the amine value is more preferably in the range of 0 to 5.00 mgKOH / g, even more preferably in the range of 1.00 to 5.00 KOH / g, and even more preferably in the range of 1.00 to 3.50 mgKOH / g.

[0034] The polyurethane resin may be a polyurethane resin having a urea bond (—NH—C(═O)—NH—), or a polyurethane resin having no urea bond. It is preferable to use a polyurethane resin having a urea bond and a polyurethane resin having no urea bond in combination. Examples of polyurethane resins having no urea bond include those represented by the following general formula (I): (In the above general formula (I), R ３ and R ４ each independently represents an aromatic group having 6 to 15 carbon atoms, and M represents a divalent organic group, preferably an aliphatic hydrocarbon group (alkylene group or alkenylene group) having 1 to 20 carbon atoms. Note that * in the above general formula (I) represents a bond to another atom. It is preferable to use a polyurethane resin having a partial structure represented by the following formula: When the polyurethane resin has a partial structure represented by the above general formula (I), an ink layer with better adhesion, blocking resistance, PEEL strength, and dry laminate strength can be formed. In the above general formula (I), R ３ and R ４ are each independently one to three hydrogen atoms that are unsubstituted or substituted by R ５ Preferably, the substituent R represents a phenyl group or a naphthyl group, which may be substituted by ５ represents an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or a halogen atom. In the above general formula (I), M is preferably an alkylene group having 3 to 12 carbon atoms, not including the number of carbon atoms of the substituent.

[0035] The polyurethane resin having the partial structure represented by the general formula (I) preferably has a number average molecular weight (Mn) of 1000 to 3000, more preferably 1200 to 3000. When the number average molecular weight (Mn) of the polyurethane resin is 1000 to 3000, this is preferred from the viewpoint of the blocking resistance of the printing ink composition, the strength and oil resistance of the printed ink layer, or the gloss of the printed ink layer.

[0036] The urethane bond concentration of the polyurethane resin having the partial structure represented by the general formula (I) is preferably 0.9 mmol / g or more, more preferably 1.0 mmol / g or more and 3.0 mmol / g or less, and even more preferably 1.1 mmol / g or more and 2.6 mmol / g or less. When the urethane bond concentration is 1.1 mmol / g or more, the laminate strength is particularly excellent. The urethane bond concentration can be calculated by the following formula (1). [Formula (1)]: Urethane bond concentration = {(W １ ×OH １ +W ２ ×OH ２ +...+W ｉ ×OH ｉ ) × 1000} / (56100 × S) In the above formula (1), W is as follows. １ OH: mass of polyol (a1) １ W: hydroxyl value of polyol (a1) ２ OH: mass of polyol (a2) ２ W: hydroxyl value of polyol (a2) ｉ OH: mass of polyol (ai) ｉ S: hydroxyl value of polyol (ai) １ : Mass of solid content of polyurethane resin In the above formula (1), when i types of polyols (a) are used as synthetic raw materials for polyurethane resin, the numerator of the formula (1) is the sum of the values ​​obtained by multiplying the blending amount of each of the i types of polyols (a) by the hydroxyl value of each polyol (a). The denominator of the formula (1) is S, which is the mass of solid content of the obtained polyurethane resin. １ is multiplied by 56,100.

[0037] The polyurethane resin having the partial structure represented by general formula (I) may be composed solely of a resin having the partial structure represented by general formula (I), or may be a mixture containing a resin having the partial structure represented by general formula (I). The polyurethane resin having the partial structure represented by general formula (I) is preferably used when preparing a printing ink composition that does not contain a chlorine-based resin. It is also preferably used in combination with a polyvinyl butyral resin. The content of the polyurethane resin having the partial structure represented by general formula (I) is preferably 5 to 25% by mass, more preferably 7 to 23% by mass, and even more preferably 9 to 21% by mass, calculated as solids, relative to the total polyurethane resin (100% by mass). When the content of the polyurethane resin having the partial structure represented by general formula (I) is within the above range, a strong printing ink layer, good adhesion, and peel strength tend to be obtained.

[0038]

[0013] When forming a printing ink layer by gravure printing, for example, the content of the polyurethane resin in the printing ink composition is preferably 3% by mass or more, more preferably 5% by mass or more, calculated as solids, from the viewpoint of ensuring sufficient adhesion of the printing ink composition to a shrinkable polyester film. Furthermore, from the viewpoint of appropriate viscosity of the printing ink composition and operational efficiency during production and printing of the printing ink composition, the content of the polyurethane resin is preferably 25% by mass or less, more preferably 15% by mass or less, calculated as solids. Furthermore, when forming a printing ink layer by flexographic printing, the content of the polyurethane resin is preferably 5% by mass or more, more preferably 10% by mass or more, and preferably 30% by mass or less, more preferably 25% by mass or less, calculated as solids.

[0039] (Anti-blocking Agent) Examples of anti-blocking agents contained in the printing ink composition of this embodiment include particulate anti-blocking agents such as silica, calcium carbonate, calcium phosphate, talc, urethane beads, acrylic beads, and silicone beads, and organic compound-based anti-blocking agents such as polyolefin waxes such as polyethylene wax, Fischer-Tropsch wax, fatty acid amides, fatty acid esters, and higher fatty acids. These anti-blocking agents may be used alone or in combination of two or more. Inorganic (compound) anti-blocking agents form irregularities on the surface of the printing ink layer, thereby preventing blocking by reducing the contact area between the printed surface and the surface in contact with the printed surface. On the other hand, organic compound-based anti-blocking agents prevent blocking by bleeding out onto the surface of the printing ink layer. Therefore, it is preferable to use a particulate anti-blocking agent and an organic compound-based anti-blocking agent in combination.

[0040] The inorganic antiblocking agent preferably has an average particle size of 3.0 to 20 μm, more preferably 3.0 to 18 μm, and even more preferably 3.0 to 15 μm, as measured by a laser method.

[0041] From the viewpoint of exhibiting a good anti-blocking effect, the content of the inorganic anti-blocking agent in the printing ink composition is preferably 0.5% by mass or more, more preferably 0.8% by mass or more, and even more preferably 1.0% by mass or more. Furthermore, from the viewpoint of preventing sedimentation, the content of the inorganic anti-blocking agent is preferably 7.0% by mass or less, more preferably 6.0% by mass or less, and even more preferably 5.0% by mass or less. From the viewpoint of exhibiting a good anti-blocking effect, the content of the organic compound-based anti-blocking agent in the printing ink composition is preferably 0.5% by mass or more, more preferably 0.8% by mass or more, and even more preferably 1.0% by mass or more. Furthermore, from the viewpoint of preventing sedimentation, the content of the organic compound-based anti-blocking agent is preferably 7.0% by mass or less, more preferably 6.0% by mass or less, and even more preferably 5.0% by mass or less.

[0042] (Organic Solvent) The printing ink composition of this embodiment may contain an organic solvent. The organic solvent is not particularly limited, and examples thereof include various organic solvents such as aromatic hydrocarbons such as toluene, xylene, Solvesso #100, and Solvesso #150, aliphatic hydrocarbons such as hexane, methylcyclohexane, heptane, octane, and decane, and esters such as methyl acetate, ethyl acetate, isopropyl acetate, normal propyl acetate, butyl acetate, amyl acetate, ethyl formate, and butyl propionate. Examples of water-miscible organic solvents include alcohols such as methanol, ethanol, propanol, butanol, and isopropyl alcohol, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, and glycol ethers such as ethylene glycol (mono, di)methyl ether, ethylene glycol (mono, di)ethyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, monobutyl ether, diethylene glycol (mono, di)methyl ether, diethylene glycol (mono, di)ethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, triethylene glycol (mono, di)methyl ether, propylene glycol (mono, di)methyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and dipropylene glycol (mono, di)methyl ether. These may be used alone or in combination of two or more.

[0043] The ester-based organic solvent preferably contains an ester-based organic solvent having 4 or more carbon atoms, from the viewpoint of preventing the printing ink composition of this embodiment from becoming semi-dried due to its high volatility. The ester-based organic solvent having 4 or more carbon atoms is not particularly limited, but ethyl acetate, isopropyl acetate, n-propyl acetate, and butyl acetate are more preferred. The content of the ester-based organic solvent in the printing ink composition of this embodiment is preferably 1% by mass or more, preferably 3% by mass or more, preferably 5% by mass or more, preferably 7% by mass or more, preferably 10% by mass or more, preferably 12% by mass or more, preferably 15% by mass or more, preferably 18% by mass or more, and preferably 20% by mass or more. Furthermore, the content of the ester-based organic solvent is preferably 60% by mass or less, preferably 55% by mass or less, preferably 50% by mass or less, preferably 45% by mass or less, preferably 40% by mass or less, and preferably 35% by mass or less. The content of the ester-based organic solvent in the printing ink composition of this embodiment is preferably 1 to 60% by mass, preferably 3 to 55% by mass, preferably 5 to 50% by mass, preferably 7 to 45% by mass, preferably 10 to 40% by mass, preferably 12 to 35% by mass, preferably 15 to 30% by mass, preferably 18 to 28% by mass, preferably 20 to 25% by mass, or preferably 20 to 23% by mass.

[0044] When forming a printing ink layer by gravure printing (for gravure ink applications), the printing ink composition of this embodiment preferably does not contain an aromatic hydrocarbon organic solvent and contains an alcohol having a specific evaporation rate of 100 or less, where the evaporation rate of butyl acetate is taken as 100. Containing an alcohol having a specific evaporation rate of 100 or less tends to maintain highlight transferability with a dot area of ​​10% or less and maintain highlight improvement. This mechanism is thought to be due to the following two points. First, 1) after the printing ink composition of this embodiment is transferred to the shrinkable polyester film, half of the printing ink composition of this embodiment remains in the cells of the gravure plate. 2) The solvent contained in the remaining printing ink composition of this embodiment evaporates until it comes into contact with the printing ink composition of this embodiment again in the ink pan, resulting in a semi-dry state. Furthermore, since the solvent with the faster evaporation rate evaporates first, the solvent with the slower evaporation rate remains in the ink pan. 3) If any solvent with high resin solubility remains during this process, the semi-dried composition will re-dissolve when it comes into contact with the printing ink composition of this embodiment, preventing the printing ink composition of this embodiment from solidifying in the cells. With commonly used alcohols, whose specific evaporation rate exceeds 100 (assuming the evaporation rate of butyl acetate is 100), the evaporation rate is so fast that the above-mentioned mechanism tends to be difficult to achieve. Secondly, alcohols whose specific evaporation rate is 100 or less (assuming the evaporation rate of butyl acetate is 100) tend to increase the solubility of polyurethane resins due to the low ratio of hydroxyl groups (alcohol groups) per alcohol molecule. From the perspectives of both operational hygiene during printing and the harmfulness of packaging materials, it is more preferable to use ethyl acetate, propyl acetate, isopropanol, normal propanol, etc., and to avoid aromatic solvents such as toluene and ketone solvents such as methyl ethyl ketone. Among these, a mixture of isopropyl alcohol / ethyl acetate / normal propyl acetate / methylcyclohexane is more preferable from the standpoint of solubility in polyurethane resins. Furthermore, for the purpose of adjusting dryness, glycol ethers may be added in an amount of less than 10% by mass of the total composition.

[0045] (Other Components) The printing ink composition of this embodiment may optionally contain other components such as other resins other than the polyurethane resin described above, and colorants.

[0046] -Other Resins- Examples of other resins other than polyurethane resins include cellulose-based resins (e.g., soluble nitrocellulose), polyamide resins, vinyl chloride-vinyl acetate copolymer resins, ketone resins, polyester resins, (meth)acrylic resins, chlorinated polypropylene resins, ethylene-vinyl acetate copolymer resins, vinyl acetate resins, alkyd resins, polyvinyl chloride resins, cyclized rubber, chlorinated rubber, polyvinyl butyral resins, and petroleum resins; and radical copolymers such as (meth)acrylic resins, styrene-(meth)acrylic resins, styrene-(meth)acrylic resins, styrene-(anhydride)maleic acid resins, and terpene-(anhydride)maleic acid resins copolymerized with polymerizable monomers such as polymerizable monomers having a carboxyl group such as itaconic acid, maleic acid, fumaric acid, cinnamic acid, or acid anhydrides thereof, polymerizable monomers having a sulfonic acid group such as sulfonated styrene, and polymerizable monomers having a sulfonamide group such as vinylbenzenesulfonamide; and acid-modified polyolefin resins (excluding the polyurethane resins described above). These may be contained alone or in combination of two or more. The printing ink composition of this embodiment preferably contains one or more resins selected from the group consisting of vinyl chloride-vinyl acetate copolymer resins, cellulose-based resins, polyester resins, rosin-modified maleic acid resins, and polyvinyl butyral resins. The rosin-modified maleic acid resins are acidic additives described below.

[0047] The content of the other resin in the printing ink composition of this embodiment is preferably 1.0% by mass or more, preferably 2.0% by mass or more, and preferably 3.0% by mass or more. Furthermore, the content of the other resin is preferably 10% by mass or less, preferably 9.0% by mass or less, and preferably 8.0% by mass or less. When the content of the other resin is equal to or greater than the lower limit, blocking resistance tends to be good, and when the content is equal to or less than the upper limit, adhesion after shrinkage tends to be good.

[0048] Furthermore, the printing ink composition of this embodiment preferably does not contain a chlorine-containing resin (chlorine-based resin), such as a vinyl chloride-vinyl acetate copolymer resin, a polyvinyl chloride resin, or chlorinated rubber. If a chlorine-based resin is contained, when a plastic container such as a PET bottle is recycled while still covered with the printed matter of this embodiment (without peeling the printed matter of this embodiment from the plastic container) without removing the printed ink layer, hydrogen chloride is released during the thermal decomposition process to generate hydrochloric acid, which may cause corrosion of equipment and piping, and the emitted chlorine gas may degrade the quality of the recycled material. Another problem is the emission of environmental hormones such as dioxins. Therefore, from the perspectives of equipment maintenance, improving the quality of recycled materials, and environmental considerations, it is preferable that the printing ink composition does not contain a chlorine-based resin.

[0049] From the viewpoint of suppressing the amount of chlorine gas generated during recycling as described above, the printing ink composition of this embodiment preferably has a chlorine content of 5% by mass or less in the total solids, more preferably 4% by mass or less, more preferably 3% by mass or less, more preferably 2% by mass or less, and particularly preferably 0% by mass. Although the lower limit of the chlorine content can be said to be 0% by mass, the chlorine content may exceed 0% by mass because unavoidable amounts of chlorine may be included during the resin production process. The chlorine content can be determined by measuring the amount of chlorine in the total solids of the printing ink composition using known methods such as ion chromatography (IC) or inductively coupled plasma mass spectrometry (ICP-MS). The chlorine content can also be simply calculated from the chlorine content of each raw material constituting the printing ink composition using the following formula: chlorine content (% by mass) in the total solids of the printing ink composition = mass of chlorine contained in the total solids of the printing ink composition × 100 / mass of the total solids of the printing ink composition

[0050] Colorant: Examples of the colorant include inorganic pigments, organic pigments, and dyes that are commonly used in inks, paints, and recording materials.

[0051] Examples of organic pigments include soluble azo pigments, insoluble azo pigments, azo pigments, phthalocyanine pigments, halogenated phthalocyanine pigments, anthraquinone pigments, anthanthrone pigments, dianthraquinonyl pigments, anthrapyrimidine pigments, perylene pigments, perinone pigments, quinacridone pigments, thioindigo pigments, dioxazine pigments, isoindolinone pigments, quinophthalone pigments, azomethine azo pigments, flavanthrone pigments, diketopyrrolopyrrole pigments, isoindoline pigments, indanthrone pigments, and carbon black pigments. Other examples include carmine 6B, lake red C, permanent red 2B, disazo yellow, pyrazolone orange, carmine FB, cromophtal yellow, cromophtal red, phthalocyanine blue, phthalocyanine green, dioxazine violet, quinacridone magenta, quinacridone red, indanthrone blue, pyrimidine yellow, thioindigo bordeaux, thioindigo magenta, perylene red, perinone orange, isoindolinone yellow, aniline black, diketopyrrolopyrrole red, and daylight fluorescent pigments. Both non-acid-treated pigments and acid-treated pigments can be used. Specific examples of preferred organic pigments are listed below.

[0052] Examples of black pigments include C.I. Pigment Black 1, C.I. Pigment Black 6, C.I. Pigment Black 7, C.I. Pigment Black 9, and C.I. Pigment Black 20. Examples of indigo pigments include C.I. Pigment Blue 15, C.I. Pigment Blue 15:1, C.I. Pigment Blue 15:2, C.I. Pigment Blue 15:3, C.I. Pigment Blue 15:4, C.I. Pigment Blue 15:5, C.I. Pigment Blue 15:6, C.I. Pigment Blue 16, C.I. Pigment Blue 17:1, C.I. Pigment Blue 22, C.I. Pigment Blue 24:1, and C.I. Examples of the pigment include C.I. Pigment Blue 25, C.I. Pigment Blue 26, C.I. Pigment Blue 60, C.I. Pigment Blue 61, C.I. Pigment Blue 62, C.I. Pigment Blue 63, C.I. Pigment Blue 64, C.I. Pigment Blue 75, C.I. Pigment Blue 79, and C.I. Pigment Blue 80. Examples of the green pigment include C.I. Pigment Green 1, C.I. Pigment Green 4, C.I. Pigment Green 7, C.I. Pigment Green 8, C.I. Pigment Green 10, and C.I. Pigment Green 36. Examples of the red pigment include C.I. Pigment Red 1, C.I. Pigment Red 2, and C.I. Pigment Red 3, C.I. Pigment Red 4, C.I. Pigment Red 5, C.I. Pigment Red 6, C.I. Pigment Red 7, C.I. Pigment Red 8, C.I. Pigment Red 9, C.I. Pigment Red 10, C.I. Pigment Red 11, C.I. Pigment Red 12, C.I. Pigment Red 15, C.I. Pigment Red 16, C.I. Pigment Red 17, C.I. Pigment Red 18, C.I. Pigment Red 19, C.I. Pigment Red 20, C.I. Pigment Red 21, C.I. Pigment Red 22, C.I. Pigment Red 23, C.I. Pigment Red 31, C.I. Pigment Red 32, C.I. Pigment Red 38, C.I. Pigment Red 41, C.I. Pigment Red 43, C.I. Pigment Red 46, C.I. Pigment Red 48,C.I. Pigment Red 48:1, C.I. Pigment Red 48:2, C.I. Pigment Red 48:3, C.I. Pigment Red 48:4, C.I. Pigment Red 48:5, C.I. Pigment Red 48:6, C.I. Pigment Red 49, C.I. Pigment Red 49:1, C.I. Pigment Red 49:2, C.I. Pigment Red 49:3, C.I. Pigment Red 52, C.I. Pigment Red 52:1, C.I. Pigment Red 52:2, C.I. Pigment Red 53, C.I. Pigment Red 53:1, C.I. Pigment Red 53:2, C.I. Pigment Red 53:3, C.I. Pigment Red 54, C.I. Pigment Red 57, C.I. Pigment Red 57:1, C.I. Pigment Red 58, C.I. Pigment Red 58:1, C.I. Pigment Red 58:2, C.I. Pigment Red 58:3, C.I. Pigment Red 58:4, C.I. Pigment Red 60:1, C.I. Pigment Red 63, C.I. Pigment Red 63:1, C.I. Pigment Red 63:2, C.I. Pigment Red 63:3, C.I. Pigment Red 64:1, C.I. Pigment Red 68, C.I. Pigment Red 68, C.I. Pigment Red 81:1, C.I. Pigment Red 83, C.I. Pigment Red 88, C.I. Pigment Red 89, C.I. Pigment Red 95, C.I. Pigment Red 112, C.I. Pigment Red 114, C.I. Pigment Red 119, C.I. Pigment Red 122, C.I. Pigment Red 123, C.I. Pigment Red 136, C.I. Pigment Red 144, C.I. Pigment Red 146, C.I. Pigment Red 147, C.I. Pigment Red 149, C.I. Pigment Red 150, C.I. Pigment Red 164, C.I. Pigment Red 166, C.I. C.I. Pigment Red 168, C.I. Pigment Red 169, C.I. Pigment Red 170, C.I. Pigment Red 171, C.I. Pigment Red 172, C.I. Pigment Red 175, C.I. Pigment Red 176, C.I. Pigment Red 177, C.I. Pigment Red 178, C.I. Pigment Red 179,C.I. Pigment Red 180, C.I. Pigment Red 181, C.I. Pigment Red 182, C.I. Pigment Red 183, C.I. Pigment Red 184, C.I. Pigment Red 185, C.I. Pigment Red 187, C.I. Pigment Red 188, C.I. Pigment Red 190, C.I. Pigment Red 192, C.I. Pigment Red 193, C.I. Pigment Red 194, C.I. Pigment Red 200, C.I. Pigment Red 202, C.I. Pigment Red 206, C.I. Pigment Red 207, C.I. Pigment Red 208, C.I. Pigment Red 209, C.I. Pigment Red 210, C.I. Pigment Red 211, C.I. Pigment Red 213, C.I. Pigment Red 214, C.I. Pigment Red 216, C.I. Pigment Red 215, C.I. Pigment Red 216, C.I. Pigment Red 220, C.I. Pigment Red 221, C.I. Pigment Red 223, C.I. Pigment Red 224, C.I. Pigment Red 226, C.I. Pigment Red 237, C.I. Pigment Red 238, C.I. Pigment Red 239, C.I. Pigment Red 240, C.I. Pigment Red 242, C.I. Pigment Red 245, C.I. Pigment Red 247, C.I. Pigment Red 248, C.I. Pigment Red 251, C.I. Pigment Red 253, C.I. Pigment Red 254, C.I. Pigment Red 255, C.I. Pigment Red 256, C.I. Pigment Red 257, C.I. Pigment Red 258, C.I. Pigment Red 260, C.I. Pigment Red 262, C.I. Pigment Red 263, C.I. Pigment Red 264, C.I. Pigment Red 266, C.I. Pigment Red 268, C.I. Examples of purple pigments include C.I. Pigment Red 269, C.I. Pigment Red 270, C.I. Pigment Red 271, C.I. Pigment Red 272, and C.I. Pigment Red 279. Examples of purple pigments include C.I. Pigment Violet 1, C.I. Pigment Violet 2, C.I. Pigment Violet 3, C.I. Pigment Violet 3:1,C.I. Pigment Violet 3:3, C.I. Pigment Violet 5:1, C.I. Pigment Violet 13, C.I. Pigment Violet 19 (γ type, β type), C.I. Pigment Violet 23, C.I. Pigment Violet 25, C.I. Pigment Violet 27, C.I. Pigment Violet 29, C.I. Pigment Violet 31, C.I. Pigment Violet 32, C.I. Pigment Violet 36, C.I. Pigment Violet 37, C.I. Pigment Violet 38, C.I. Pigment Violet 42, C.I. Pigment Violet 50, and the like can be mentioned as yellow pigments. Examples of yellow pigments include C.I. Pigment Yellow 1, C.I. Pigment Yellow 3, C.I. Pigment Yellow 12, C.I. Pigment Yellow 13, C.I. Pigment Yellow 14, Pigment Yellow 17, C.I. Pigment Yellow 24, C.I. Pigment Yellow 42, C.I. Pigment Yellow 55, C.I. Pigment Yellow 62, C.I. Pigment Yellow 65, C.I. Pigment Yellow 74, C.I. Pigment Yellow 83, C.I. Pigment Yellow 86, C.I. Pigment Yellow 93, C.I. Pigment Yellow 94, C.I. Pigment Yellow 95, C.I. Pigment Yellow 109, C.I. Pigment Yellow 110, C.I. Pigment Yellow 117, C.I. Pigment Yellow 120, Pigment Yellow 125, C.I. Pigment Yellow 128, C.I. Pigment Yellow 129, C.I. Pigment Yellow 137, C.I. Pigment Yellow 138, C.I. Pigment Yellow 139, C.I. Pigment Yellow 147, C.I. Pigment Yellow 148, C.I. Pigment Yellow 150, C.I. Pigment Yellow 151, C.I. Pigment Yellow 153, C.I. Pigment Yellow 154, C.I. Pigment Yellow 155, C.I. Pigment Yellow 166, C.I. Pigment Yellow 168, C.I. Pigment Yellow 174, C.I. Pigment Yellow 180, C.I. Examples of orange pigments include C.I. Pigment Yellow 185 and C.I. Pigment Yellow 213. Examples of orange pigments include C.I. Pigment Orange 5,Examples of suitable brown pigments include C.I. Pigment Orange 13, C.I. Pigment Orange 16, C.I. Pigment Orange 34, C.I. Pigment Orange 36, C.I. Pigment Orange 37, C.I. Pigment Orange 38, C.I. Pigment Orange 43, C.I. Pigment Orange 51, C.I. Pigment Range 55, C.I. Pigment Orange 59, C.I. Pigment Orange 61, C.I. Pigment Orange 64, C.I. Pigment Orange 71, and C.I. Pigment Orange 74. Examples of suitable brown pigments include C.I. Pigment Brown 23, C.I. Pigment Brown 25, and C.I. Pigment Brown 26. Among them, preferred pigments include C.I. Pigment Black 7 as a black pigment, C.I. Pigment Blue 15, C.I. Pigment Blue 15:1, C.I. Pigment Blue 15:2, C.I. Pigment Blue 15:3, C.I. Pigment Blue 15:4, C.I. Pigment Blue 15:6 as indigo pigments, C.I. Pigment Green 7 as a green pigment, and C.I. Pigment Red 57:1, C.I. Pigment Red 48:1, C.I. Pigment Red 48:2, C.I. Pigment Red 48:3, C.I. Pigment Red 146, C.I. Pigment Red 242, C.I. Pigment Red 185, C.I. Examples of pigments include C.I. Pigment Red 122, C.I. Pigment Red 178, C.I. Pigment Red 149, C.I. Pigment Red 144, C.I. Pigment Red 166, purple pigments include C.I. Pigment Violet 23 and C.I. Pigment Violet 37, yellow pigments include C.I. Pigment Yellow 83, C.I. Pigment Yellow 14, C.I. Pigment Yellow 180, and C.I. Pigment Yellow 139, and orange pigments include C.I. Pigment Orange 38, C.I. Pigment Orange 13, C.I. Pigment Orange 34, and C.I. Pigment Orange 64. It is preferable to use at least one pigment selected from the group consisting of these pigments.

[0053] Examples of inorganic pigments include carbon black, titanium oxide, red iron oxide, aluminum, mica, zinc oxide, and barium sulfate. Also usable are glittering pigments (such as Metashine manufactured by Nippon Sheet Glass Co., Ltd.) in which a metal or metal oxide is coated on a base material of glass flakes or aggregate flakes. From the standpoints of cost and coloring power, it is preferable to use carbon black for black ink, titanium oxide for white ink, aluminum for gold and silver ink, and mica for pearl ink. Calcium carbonate and silica are also examples of inorganic pigments, but in this specification, these are included in the anti-blocking agent.

[0054] From the viewpoint of ensuring the concentration and tinting strength of the printing ink composition of this embodiment, the total content of the colorants in the printing ink composition of this embodiment is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more, and the total content of the colorants is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less.

[0055] In addition to the above, the printing ink composition of this embodiment may contain water, a wetting agent, an adhesion aid, a leveling agent, an antistatic agent, a viscosity modifier, a metal chelate, a trapping agent, an isocyanate-based curing agent, a silane coupling agent, a lubricant, and the like, as necessary.

[0056] The viscosity of the printing ink composition of this embodiment, as measured at 25°C using a Zahn Cup #3 manufactured by Rigo Co., Ltd., is preferably 6 seconds or more, more preferably 10 seconds or more, and even more preferably 13 seconds or more. The viscosity is preferably 25 seconds or less, more preferably 20 seconds or less, and even more preferably 18 seconds or less.

[0057] The printing ink composition of this embodiment preferably has an acid value of 1 mgKOH / g or more, more preferably 3 mgKOH / g or more, and even more preferably 5 mgKOH / g or more. The acid value is preferably 100 mgKOH / g or less, more preferably 90 mgKOH / g or less, and even more preferably 80 mgKOH / g or less. When the acid value of the solids in the printing ink composition is within the above range, the printing ink layer tends to be easily detached by treatment with an alkaline solution, and the adhesion between the shrinkable polyester film and the printing ink layer tends to be better.

[0058] The printing ink composition of this embodiment may further contain an acidic additive. If the printing ink composition of this embodiment contains an acidic additive, the printing ink layer will be more easily detached by alkaline solution treatment, which is preferable from the standpoint of recyclability.

[0059] (Acidic Additive) As the acidic additive, for example, an organic acid or a resin having an acidic group can be used. The acid value of the acidic additive is preferably 1 mgKOH / g or more, more preferably 3 mgKOH / g or more, more preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g or more, more preferably 20 mgKOH / g or more, more preferably 30 mgKOH / g or more, more preferably 40 mgKOH / g or more, and more preferably 50 mgKOH / g or more. The acid value of the acidic additive is preferably 900 mgKOH / g or less, more preferably 850 mgKOH / g or less, more preferably 800 mgKOH / g or less, more preferably 750 mgKOH / g or less, more preferably 700 mgKOH / g or less, more preferably 650 mgKOH / g or less, more preferably 600 mgKOH / g or less, and more preferably 550 mgKOH / g or less. When the acid value of the acidic additive is within the above range, the printing ink layer becomes more easily detached by treatment with an alkaline solution, and the adhesion between the shrinkable polyester film and the printing ink layer tends to be better. When emphasis is placed on detachability in an alkaline solution, the acid value of the acidic additive is preferably 50 mgKOH / g or more, more preferably 100 mgKOH / g or more, more preferably 200 mgKOH / g or more, more preferably 300 mgKOH / g or more, more preferably 400 mgKOH / g or more, more preferably 500 mgKOH / g or more, and particularly preferably 550 mgKOH / g or more. When emphasis is placed on adhesion to the shrinkable polyester film, the acid value is preferably 550 mgKOH / g or less, more preferably 500 mgKOH / g or less, more preferably 400 mgKOH / g or less, more preferably 300 mgKOH / g or less, and more preferably 200 mgKOH / g or less. When importance is placed on both the releasability in an alkaline solution and the adhesion to a shrinkable polyester film, the acid value of the acidic additive is preferably in the range of 1 to 900 mgKOH / g, more preferably 3 to 850 mgKOH / g, more preferably 5 to 800 mgKOH / g, more preferably 10 to 750 mgKOH / g, more preferably 20 to 700 mgKOH / g, more preferably 30 to 650 mgKOH / g, more preferably 40 to 600 mgKOH / g, and more preferably 50 to 550 mgKOH / g.Furthermore, when emphasis is placed on releasability in an alkaline solution, the acid value of the acidic additive is preferably in the range of 50 to 900 mgKOH / g, more preferably 65 to 900 mgKOH / g, more preferably 80 to 900 mgKOH / g, more preferably 100 to 900 mgKOH / g, more preferably 200 to 900 mgKOH / g, more preferably 300 to 900 mgKOH / g, more preferably 400 to 900 mgKOH / g, more preferably 500 to 900 mgKOH / g, and more preferably 550 to 900 mgKOH / g. Furthermore, when emphasis is placed on adhesion to a shrinkable polyester film, the acid value of the acidic additive is preferably in the range of 1 to 550 mgKOH / g, more preferably 1 to 500 mgKOH / g, more preferably 1 to 400 mgKOH / g, more preferably 1 to 300 mgKOH / g, and more preferably 1 to 200 mgKOH / g.

[0060] When both releasability in an alkaline solution and adhesion to a shrinkable polyester film are to be achieved, the molecular weight of the acidic additive is preferably 50 or more, preferably 60 or more, preferably 80 or more, preferably 100 or more, preferably 150 or more, preferably 200 or more, preferably 250 or more, and preferably 300 or more. The molecular weight of the acidic additive is preferably 2000 or less, preferably 1800 or less, preferably 1500 or less, preferably 1200 or less, and preferably 1000 or less. The molecular weight range of the acidic additive is preferably 50 to 2000, preferably 50 to 1800, preferably 50 to 1500, preferably 60 to 1500, preferably 80 to 1500, preferably 100 to 1500, preferably 150 to 1500, preferably 200 to 1500, preferably 250 to 1500, preferably 300 to 1500, preferably 300 to 1200, and preferably 300 to 1000.

[0061] When the acidic additive is an organic acid, the organic acid preferably has 3 or more carbon atoms, preferably 4 or more, preferably 5 or more, preferably 6 or more, preferably 7 or more, and preferably 8 or more. By setting the number of carbon atoms of the organic acid within the above range, adhesion to the shrinkable polyester film can be improved. Furthermore, the number of carbon atoms of the organic acid is preferably 20 or less, preferably 18 or less, and preferably 16 or less. By setting the number of carbon atoms of the organic acid within the above range, dispersibility in an aqueous medium can be improved. The range of the number of carbon atoms of the organic acid is preferably 3 to 20, preferably 3 to 18, preferably 4 to 18, preferably 5 to 18, preferably 6 to 18, preferably 6 to 16, preferably 7 to 16, and preferably 8 to 16.

[0062] When emphasis is placed on releasability from the shrinkable polyester film and water resistance of the printing ink layer, the solubility of the organic acid in 100 g of water at 25°C is preferably less than 2 g, more preferably less than 1.8 g, even more preferably less than 1.5 g, and particularly preferably less than 1.2 g.

[0063] When the acidic additive is a resin having an acidic group, examples of the resin having an acidic group include rosin-modified maleic acid resin and rosin-modified fumaric acid resin. The acid value of the resin having an acidic group is preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g or more, and even more preferably 20 mgKOH / g or more. The acid value of the resin having an acidic group is preferably 300 mgKOH / g or less, more preferably 280 mgKOH / g or less, and even more preferably 260 mgKOH / g or less. By setting the acid value within the above range, both hot water or alkaline solution releasability and adhesion to a shrinkable polyester film can be achieved.

[0064] When the resin having an acid group is a resin having an acid value such as a rosin-modified maleic acid resin or a rosin-modified fumaric acid resin, the weight-average molecular weight of the resin having an acid group is preferably 500 or more, more preferably 700 or more, and even more preferably 1,000 or more. When the resin having an acid group is a resin having an acid value such as a rosin-modified maleic acid resin or a rosin-modified fumaric acid resin, the weight-average molecular weight of the resin having an acid group is preferably 50,000 or less, more preferably 30,000 or less, more preferably 10,000 or less, more preferably 5,000 or less, and even more preferably 2,000 or less. ... in the above range, the viscosity of the printing ink composition can be reduced, and the balance between the adhesion to a shrinkable polyester film and the releasability in an alkaline solution can be further improved. When the resin having an acidic group is a resin having an acid value such as a rosin-modified maleic acid resin or a rosin-modified fumaric acid resin, the range of the weight-average molecular weight of the resin having an acidic group is preferably 500 to 50,000, more preferably 700 to 520,000, more preferably 1,000 to 10,000, and even more preferably 1,000 to 5,000. By setting the weight-average molecular weight of the resin having an acidic group within the above range, printability can be improved.

[0065]

[0043] From the viewpoints of the resolubility of the printing ink composition of this embodiment, suppression of blocking in printed matter, improvement of print density, and adhesion to shrinkable polyester films, the content of the acidic additive in the printing ink composition of this embodiment is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, more preferably 1% by mass or more, more preferably 1.5% by mass or more, more preferably 2% by mass or more, preferably 60% by mass or less, more preferably 55% by mass or less, and more preferably 50% by mass or less, calculated as solids. The content of the acidic additive is preferably in the range of 0.1 to 60% by mass, more preferably 0.5 to 55% by mass, more preferably 1 to 50% by mass, more preferably 1.5 to 45% by mass, and more preferably 2 to 40% by mass, calculated as solids. When the acidic additive is an organic acid, the content of the organic acid in the printing ink composition of this embodiment is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, more preferably 0.3% by mass or more, more preferably 0.5% by mass or more, more preferably 1% by mass or more, more preferably 1.5% by mass or more, more preferably 2% by mass or more, and preferably 20% by mass or less, more preferably 18% by mass or less, more preferably 16% by mass or less, more preferably 14% by mass or less, more preferably 12% by mass or less, and more preferably 10% by mass or less, in terms of solid content. The content of the organic acid is preferably 0.1 to 20% by mass, more preferably 0.2 to 18% by mass, more preferably 0.3 to 16% by mass, more preferably 0.5 to 14% by mass, more preferably 1 to 12% by mass, more preferably 1.5 to 10% by mass, and more preferably 2 to 10% by mass. When the acidic additive is a resin having an acidic group, the content of the resin having an acidic group in the printing ink composition of this embodiment is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, more preferably 1% by mass or more, more preferably 1.5% by mass or more, more preferably 2% by mass or more, and preferably 60% by mass or less, more preferably 55% by mass or less, and more preferably 50% by mass or less, calculated as solids. The content of the resin having an acidic group is preferably 0.1 to 60% by mass, more preferably 0.5 to 55% by mass, more preferably 1 to 50% by mass, more preferably 1.5 to 45% by mass, and more preferably 2 to 40% by mass, calculated as solids.

[0066] Incidentally, resist ink is an example of a printing ink composition that is removed from a film, but the resist ink is intended to remove the printing ink layer from the film in advance, leaving a portion of it, and then process the film. The resist ink has a fundamentally different use and purpose from the printing ink composition of the present embodiment, which removes the entire printing ink layer and recycles the shrunk polyester film, and therefore does not fall under the well-known technology of the present invention.

[0067] [Method for producing printing ink composition] The printing ink composition of this embodiment can be produced using an Eiger mill, sand mill, gamma mill, attritor, or the like, which are commonly used in the production of gravure or flexographic inks. When preparing the printing ink composition of this embodiment, from the viewpoint of uniformity, a preliminary composition (milled base ink) may be prepared in advance by mixing at least a portion of the polyurethane resin, the antiblocking agent, other components such as a colorant, and at least a portion of the organic solvent.

[0068] <Method for producing printed matter> The printed matter of this embodiment can be produced by first adhering and transferring the printing ink composition to a printing plate or printing pattern, such as by gravure printing using a gravure printing plate made by electronic intaglio or the like, or by flexographic printing using a flexographic printing plate made by a resin plate or the like, and then adhering only the printing ink composition to a shrinkable polyester film and drying it as necessary. If the printing ink composition contains an acidic additive, it is preferable to thoroughly clean the equipment used immediately after use. As the cleaning agent, a cleaning agent commonly used for cleaning printing ink compositions can be used.

[0069] <Uses of Printed Material> The printed material of this embodiment can be suitably used for label packaging, integrated packaging, etc. of containers such as glass bottles and plastic bottles. In particular, since it uses a highly recyclable crystalline polyester, it can be suitably used for label packaging of recycled plastic containers, such as labels for PET bottles. In particular, an embodiment having a printed ink layer that can be removed by alkaline solution treatment is particularly suitable for label packaging of recycled plastic containers, such as labels for PET bottles, because the quality of the regenerating agent is not impaired even when the printed material is left covering the plastic container, such as a PET bottle, and recycled together with the plastic container (without peeling the printed material of this embodiment from the plastic container). Furthermore, an embodiment that does not contain a chlorine-based resin in the printed ink layer can also reduce the amount of chlorine gas generated when the printed material is left covering the plastic container, such as a PET bottle, and recycled together with the plastic container (without peeling the printed material of this embodiment from the plastic container), thereby improving equipment maintenance and the quality of the recycled material. Therefore, it is suitable for label packaging of recycled plastic containers, such as labels for PET bottles.

[0070] The present invention will be described in more detail below with reference to examples. The present invention is not limited to the following examples as long as it does not depart from the gist of the present invention. Hereinafter, "parts" and "%" are all based on mass unless otherwise specified.

[0071] The measurement and evaluation methods used in the examples and comparative examples are as follows.

[0072] [Number Average Molecular Weight of Polyurethane Resin] The number average molecular weight of the solid content (polyurethane resin) of the polyurethane resin solution was measured by GPC under the following conditions: Measurement apparatus: High-speed GPC apparatus ("HLC-8220GPC" manufactured by Tosoh Corporation) Separation columns: One TSKgel G5000 (7.8 mm I.D. x 30 cm), one TSKgel G4000 (7.8 mm I.D. x 30 cm), one TSKgel G3000 (7.8 mm I.D. x 30 cm), and one TSKgel G2000 (7.8 mm I.D. x 30 cm) connected in series. Detector: RI (differential refractometer) Column temperature: 40°C Eluent: tetrahydrofuran (THF) Flow rate: 1.0 mL / min Injection amount: 100 μL (tetrahydrofuran solution with a sample concentration of 0.4% by mass) Standard sample: A calibration curve was prepared using the following standard polystyrenes (all manufactured by Tosoh Corporation). (Standard polystyrene) TSKgel Standard polystyrene A-500 TSKgel Standard polystyrene A-1000 TSKgel Standard polystyrene A-2500 TSKgel Standard polystyrene A-5000 TSKgel Standard polystyrene F-1 TSKgel Standard polystyrene F-2 TSKgel Standard polystyrene F-4 TSKgel Standard polystyrene F-10 TSKgel Standard polystyrene F-20 TSKgel Standard polystyrene F-40 TSKgel Standard polystyrene F-80 TSKgel Standard polystyrene F-128 TSKgel Standard polystyrene F-288 TSKgel Standard polystyrene F-550

[0073] [Amine Value of Polyurethane Resin] The amine value of the solid content of a polyurethane resin solution (polyurethane resin) is the amount of potassium hydroxide (mg) equivalent to the amount of hydrochloric acid required to neutralize the amino groups contained in 1 g of sample. It was measured in accordance with JIS K 0070. Specifically, 0.5 to 2 g of sample was precisely weighed (sample solid content: S g) and dissolved in 50 mL of a 60 / 40 (mass ratio) methanol / methyl ethyl ketone mixed solution. Bromophenol blue was added to the resulting solution as an indicator, and titration was performed with a 0.2 mol / L ethanolic hydrochloric acid solution (titer: f). The point at which the solution color changed from green to yellow was defined as the endpoint, and the titration volume (A mL) at this point was used to calculate the amine value according to the following formula: Amine value = (A × f × 0.2 × 56.108) / S [mg KOH / g]

[0074] [Thickness of Printed Ink Layer] The cross-sectional shape of the produced printed matter was observed using a scanning electron microscope (SEM) (JEOL Ltd., "JSM-IT210"), and the thickness of the printed ink layer (film thickness of the printed film) (μm) was measured.

[0075] [Adhesion (Cellophane Tape)] (1) Before shrinkage: The printed matter prepared was left for one day, and then cellophane tape (12 mm wide, manufactured by Nichiban) was applied to the printed surface. The cellophane tape was quickly peeled off, and the appearance of the printed ink layer (printed film) was visually observed, and film adhesion was evaluated according to the following criteria. (Evaluation criteria) 5: The printed film did not peel off at all. 4: The printed film peeled off slightly, but 80% or more remained on the film. 3: 50% or more but less than 80% of the printed film remained on the film. 2: 30% or more but less than 50% of the printed film remained on the film. 1: Less than 30% of the printed film remained on the film. (2) After shrinkage: The printed matter prepared was partially fixed to a stainless steel plate and immersed in 90°C hot water for 20 seconds to shrink it, and then dried. In the same manner as before shrinkage, cellophane tape was applied to the printed surface and then quickly peeled off, and the appearance of the printed ink layer (printed film) was visually observed, and the film adhesion was evaluated according to the above criteria.

[0076] [Blocking Resistance] The printed surface and the non-printed surface of the produced printed matter were overlapped with each other, and the resulting film was subjected to a pressure of 10 kgf / cm２ A load of 1000 kJ / cm was applied and the film was left in an environment of 40°C for 12 hours. After removal, the film was peeled off by hand, and the presence or absence of peel resistance and the degree of transfer of the printed ink layer (printed film) were visually observed. The same test was also conducted when the films were overlapped so that the printed surfaces of the printed matter were in contact with each other, and the blocking resistance was evaluated according to the following criteria. (Evaluation criteria) 5: No transfer of the printed ink layer, no peel resistance. 4: No transfer of the printed ink layer, but peel resistance present. 3: The amount of transferred printed ink layer was less than 10% of the printed area, and peel resistance present. 2: The amount of transferred printed ink layer was 10% or more but less than 50% of the printed area, and peel resistance present. 1: The amount of transferred printed ink layer was 50% or more of the printed area, and peel resistance present.

[0077] [Deinking Property (Deinking Property)] (1) Peeling Test: Test pieces of the prepared printed matter cut to a size of 20 mm x 20 mm were immersed in an alkaline solution (1% by mass of sodium hydroxide, 0.3% nonionic surfactant, 85°C) and stirred with a stirrer for 15 minutes. After stirring, the state of detachment of the printed ink layer (printed film) was confirmed, and then the printed matter was rubbed with a finger to confirm whether rubbing would detach the printed ink layer. The removability of the printed ink layer was evaluated according to the following criteria. (Evaluation Criteria) 5: Desorption of the printed ink layer was confirmed within 5 minutes of stirring. Complete detachment with rubbing. 4: Desorption of the printed ink layer was confirmed after 15 minutes of stirring. Complete detachment with rubbing. 3: No detachment of the printed ink layer was confirmed after 15 minutes of stirring. Complete detachment with rubbing. 2: No detachment of the printed ink layer was confirmed after 15 minutes of stirring. Partial detachment with rubbing. 1: No detachment of the printed ink layer was confirmed after 15 minutes of stirring. Although a rating of 4 or higher is practically preferable, a rating of 3 is also considered to be a level that can contribute to recycling, and therefore a rating of 3 or higher is considered to be acceptable.

[0078] (2) Coloration Inhibition Test: Fifty test pieces were prepared by cutting the prepared printed matter into 20 mm x 20 mm pieces. These pieces were immersed in 500 mL of alkaline solution (1% by mass sodium hydroxide, 0.3% nonionic surfactant, 85°C) and stirred with a stirrer for 15 minutes. According to the method of JIS (Japanese Industrial Standards) K0102, the transparency of each alkaline solution after stirring was measured using a transparency meter. Specifically, the alkaline solution was filled into a transparency meter, which was a glass cylinder with a bottom opening graduated every 10 mm and equipped with a sign plate with a double cross on the bottom. The bottom was viewed from the top, and the sample was rapidly drained from the bottom opening until the double cross on the sign plate was clearly visible for the first time. The water level was read. This was repeated twice, and the average value was calculated and expressed as transparency in degrees (10 mm = 1 degree). The coloration of the alkaline solution (cleaning solution) was evaluated according to the following criteria. As blank samples, 50 test pieces were prepared by cutting unprinted film into 20 mm x 20 mm pieces. These were then immersed in 500 mL of alkaline solution and stirred with a stirrer. (Evaluation criteria) 5: Transparency greater than 80% (same as) the blank sample. 4: Transparency greater than 60% and equal to or less than 80% the blank sample. 3: Transparency greater than 40% and equal to or less than 60% the blank sample. 2: Transparency greater than 20% and equal to or less than 40% the blank sample. 1: Transparency equal to or less than 20% the blank sample. Note that for examples in which the printing ink layer did not detach in the above-mentioned "(1) Peel Test" (evaluation result was "1"), the coloration inhibition test was conducted only for examples in which coloration from the alkaline solution (cleaning solution) was clearly observed during the peel test. The other examples were not subjected to the coloration inhibition test, and the evaluation result was given as "-".

[0079] (3) Recycle Test: After carrying out the above-mentioned "(1) Peel Test," the test specimens were extruded at 200°C using a twin-screw extruder to produce recycled pellets. The pressure increase during extrusion and the adhesion of gel matter to the filter were observed, and the recyclability was evaluated according to the following criteria. (Evaluation Criteria) 5: No pressure increase was observed during extrusion, and no gel matter was deposited on the filter. 4: A slight pressure increase was observed during extrusion (up to 120% of the initial pressure), but there was almost no gel matter deposited on the filter. 3: A pressure increase was observed during extrusion (more than 120% and up to 150% of the initial pressure), and gel matter was visually confirmed to have deposited on the filter. 2: A significant pressure increase was observed during extrusion (more than 150% and up to 180% of the initial pressure), and a large amount of gel matter was deposited on the filter. 1: The pressure increase during extrusion made it difficult to continue the test (more than 180% of the initial pressure), and gel matter deposited on the filter, causing clogging.

[0080] The raw materials used in the examples and comparative examples are as follows.

[0081] [Film] Crystalline polyethylene terephthalate (C-PET) film: "Bonpet Renew" manufactured by Bonpet America, Inc., thickness 40 μm Glycol-modified polyethylene terephthalate (PETG) film: "Hishipet LX-18S" manufactured by Mitsubishi Chemical Corporation, thickness 40 μm

[0082] [Pigments] Phthalocyanine blue pigment: "FASTOGEN BLUE FA5380" manufactured by DIC Corporation Titanium oxide: "JR-809" manufactured by Teika Corporation

[0083] [Resins] Polyurethane resin solutions PU1 to PU3 (raw materials for polyurethane resin solutions) Polyester polyol (PES#2000): "TA22-981" manufactured by Resonac Co., Ltd. Polyester polyol (PES#3000): "Kuraray Polyol P-3010" manufactured by Kuraray Co., Ltd. Polyester polyol (PES#5000): "Kuraray Polyol P-5010" manufactured by Kuraray Co., Ltd. Polyether polyol (PEG#400): "PEG#400" manufactured by NOF Corporation Polyether polyol (PEG#1000): "PEG#1000" manufactured by NOF Corporation Isophorone diisocyanate (IPDI) Isophorone diamine (IPDA) Cyclohexylamine (CHA) Ethyl acetate-isopropyl alcohol (IPA) Preparation of Polyurethane Resin Solution PU1: 120.0 parts by weight of PES#2000, 30.0 parts by weight of PEG#400, and 45.0 parts by weight of IPDI were added to a four-neck flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, and the mixture was allowed to react at 85°C for 6 hours under a nitrogen stream to produce a urethane prepolymer. 48.8 parts by weight of ethyl acetate was added to this mixture to form a homogeneous solution, yielding a urethane prepolymer solution. The urethane prepolymer solution was then added to a mixed solution consisting of 12.0 parts by weight of IPDA, 0.3 parts by weight of CHA, 289.8 parts by weight of ethyl acetate, and 145.1 parts by weight of IPA, and the mixture was allowed to react at 40°C for 4 hours under a nitrogen stream to yield Polyurethane Resin Solution PU1. The nonvolatile content (solids concentration) of the resulting polyurethane resin solution PU1 was 30%, the amine value of the solids (polyurethane resin) was 2.5 mgKOH / g, and the number average molecular weight of the solids (polyurethane resin) was 35,000. Preparation of polyurethane resin solutions PU2 and PU3 Polyurethane resin solutions PU2 and PU3 were prepared in the same manner as polyurethane resin solution PU1, except that the blending compositions of the raw materials were changed as shown in Table 1. The compositions and physical properties of polyurethane resin solutions PU1 to PU3 are shown in Table 1.

[0084]

[0085] Acrylic resin solution: "Acrydic WCL-1419" manufactured by DIC Corporation, number average molecular weight 16,000, non-volatile content 50%, ethyl acetate / IPA solution. Cellulose acetate propionate (CAP) resin solution: Eastman "CAP-482-0.5" manufactured by Nippon Chem. Co., Ltd., 20% non-volatile content, ethyl acetate / IPA solution / polyvinyl butyral resin solution; "S-LEC BL-10" manufactured by Sekisui Chemical Co., Ltd., 15% non-volatile content, ethyl acetate / IPA solution / vinyl chloride-vinyl acetate copolymer resin solution; "Solvine A" manufactured by Nissin Chemical Industry Co., Ltd., 15% non-volatile content, ethyl acetate solution / nitrocellulose resin solution; "Nitrocellulose DLX5-8" manufactured by Nobel, 30% non-volatile content, ethyl acetate / IPA solution / maleic acid resin solution R1; "Marquid #31" manufactured by Arakawa Chemical Industries, Ltd., 50% non-volatile content, IPA solution, acid value 175 to 200 mgKOH / g Maleic acid resin solution R2: "Marquid #32" manufactured by Arakawa Chemical Industries, Ltd., non-volatile content 50%, IPA soluble, acid value 120 to 140 mg KOH / g

[0086] [Anti-blocking agent] Polyethylene wax: "LUWAX AF-31" manufactured by BASF Fischer-Tropsch wax: "SasolWax Spray 105" manufactured by Sasol Polyolefin wax: "CERETAN MX 9510" manufactured by MUSING Micro Technologies Silica S1: "Sylysia 350" manufactured by Fuji Silysia Chemical Ltd., average particle size 3.9 μm, specific surface area 300 m ２ / g, oil absorption 320 mL / 100 g Silica S2: "Sylysia 470" manufactured by Fuji Silysia Chemical Ltd., average particle size 14.1 μm, specific surface area 350 m ２ / g, oil absorption amount 200mL / 100g

[0087] [Others] Silicone varnish: Shin-Etsu Chemical Co., Ltd. "KF-96-100CS", non-volatile content 1%, soluble in ethyl acetate.

[0088] [Examples 1 to 58, Comparative Examples 1 to 48] (Preparation of printing ink compositions) Printing ink compositions were prepared according to the formulations shown in Tables 2 and 3. (Production of printed matter) The viscosity of the ink compositions prepared above was adjusted to 16 seconds (25°C) using ethyl acetate in a Zahn cup #3 (manufactured by Rigo Co., Ltd.), and the ink compositions were printed on film using a gravure proofing machine equipped with a gravure plate with a plate depth of 35 µm, followed by drying at 40 to 50°C to obtain printed matter.

[0089]

[0090]

[0091]

[0092]

[0093] As shown in Table 2, all of the Examples exhibited excellent adhesion before and after shrinkage. Furthermore, since the Examples contained an anti-blocking agent, they also exhibited excellent blocking resistance. From the perspective of recyclability, Examples that did not contain a chlorine-based resin (vinyl chloride-vinyl acetate copolymer) in the printed ink layer and Examples in which the printed ink layer was removable by alkaline solution treatment (peel test results of 3 or higher) were preferred. Furthermore, as shown in Table 3, Comparative Examples that did not contain a polyurethane resin in the printed ink layer exhibited poor adhesion before and after shrinkage. In particular, for Comparative Examples that did not contain a polyurethane resin in the printed ink layer, when a C-PET film was used, adhesion after shrinkage was worse than when a PET-G film was used. On the other hand, since the Examples contained a polyurethane resin in the printed ink layer, good adhesion after shrinkage was maintained even when a C-PET film was used.

[0094] The printed matter of the present invention is a shrinkable polyester film print printed with a printing ink having excellent adhesion and blocking resistance, and can adapt to the rapid shrinkage of shrinkable film made from a highly recyclable crystalline polyester. Therefore, the printed matter can be suitably used for label packaging, stack packaging, etc. of containers such as glass bottles and plastic bottles. In particular, because the printed matter uses a highly recyclable crystalline polyester, it can be suitably used for label packaging of recycled plastic containers, such as labels for PET bottles.

Claims

1. A printed matter comprising: a shrinkable polyester film; and a printing ink layer provided on the shrinkable polyester film, wherein the shrinkable polyester film is a crystalline polyester film, and the printing ink layer contains a polyurethane resin and an anti-blocking agent.

2. The printed matter according to claim 1, wherein the printing ink layer further contains one or more resins selected from the group consisting of vinyl chloride-vinyl acetate copolymer resin, cellulose-based resin, polyester resin, rosin-modified maleic acid resin, and polyvinyl butyral resin.

3. The printed material according to claim 1 or 2, wherein the printing ink layer does not contain a chlorine-based resin.

4. The printed material according to claim 1 or 2, wherein the printing ink layer is removable by treatment with an alkaline solution.

5. The printed matter according to claim 1 or 2, wherein the shrinkable polyester film does not contain a polyester resin containing 1,4-cyclohexanedimethanol as a raw material.

6. The printed material according to claim 1 or 2, which is a label for a PET bottle.

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