Printing ink composition for shrink packaging, method for manufacturing printed materials for shrink packaging, and printed materials for shrink packaging

Abstract

To provide a printing ink composition for shrink packaging which is excellent in content resistance suitability (surfactant resistance and alkali resistance) even when a biomass degree is set to be high, and has good other performances.SOLUTION: A printing ink composition for shrink packaging contains a pigment, a resin component and a solvent component, and contains a carboxyl group-containing acrylic resin, a cellulose resin, a rosin resin and a derivative thereof satisfying the following conditions 1 and 2 as resin components. Condition 1: A ratio of a solid content mass of the carboxyl group-containing acrylic resin to a solid content mass of the cellulose resin is 80 / 20 to 60 / 40. Condition 2: The rosin resin and the derivative thereof have acid values of 150 mgKOH / g or less, and are contained in an amount of 3.0-20.0 mass% in the solid content of the ink composition.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a printing ink composition for shrink packaging, a method for manufacturing a printed matter for shrink packaging, and a printed matter for shrink packaging.

Background Art

[0002] As various containers in the fields of beverages, cosmetics, detergents, etc., paper containers, steel cans, aluminum cans, glass containers, plastic containers, etc. are utilized while taking advantage of their respective characteristics. And, various prints for displaying the contents, etc. are applied to the surfaces of these various containers. Among the above various containers, in the case of paper containers, since they are formed after printing is performed in the form of a sheet or a roll of paper, the printing efficiency is extremely high. However, in the case of other containers, since they are pre-formed into a special shape, ordinary printing methods could not be applied. Therefore, a label print was attached, or printing was performed by transferring the ink on a screen or intaglio plate surface to an elastic body, or a special printing method for cans was used to directly print on the formed container. However, these methods had extremely poor working efficiency or were not suitable for small-lot production of multiple varieties. Therefore, a so-called shrink packaging is used, in which a heat-shrinkable film is used as the printing material, the printed matter after printing on this is made into a tube shape, the tube is placed on the container, and then it is attached to the surface by heat shrinkage for packaging. And generally, in shrink packaging printing, a binder resin using a combination of an organic solvent, an acrylic resin, and nitrocellulose (for example, see Patent Documents 1 and 2), or a binder resin using a combination of an acrylic resin and a cellulose resin (for example, Patent Document 3) is used for a gravure printing ink composition for shrink packaging suitable for various films such as a polystyrene film, a PET film, and a vinyl chloride film, which are the printing materials. However, in recent years, due to environmental concerns, there has been a demand for inks with a high biomass content in gravure printing ink compositions for shrink packaging. In particular, in applications requiring surfactant resistance and alkali resistance, the use of cellulose-based components is limited, making it difficult to achieve a high biomass content. Furthermore, in white inks, the proportion of pigments such as titanium dioxide in the solid content is high, and the acrylic resin used as the binder resin is petroleum-derived, making it even more difficult to achieve a high biomass content. Furthermore, when shrink wrapping is used for products such as household detergents, shampoos, body soaps, and alkaline cleaning agents, the contents may adhere to the surface of the container after it has been opened. In such cases, the shrink wrap must have resistance to the contents so as not to damage the printing. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2004-175858 [Patent Document 2] Japanese Patent Publication No. 2009-286974 [Patent Document 3] Patent No. 6732151 [Overview of the project] [Problems that the invention aims to solve]

[0004] The present invention In particular, containing specific amounts of cellulose resin, rosin resin and its derivatives, The objective is to provide a printing ink composition for shrink packaging that exhibits excellent resistance to contents (resistance to surfactants and alkalis) and good performance in other areas. [Means for solving the problem]

[0005] As a result of diligent research to solve the above problems, the inventors have completed the following invention. In other words, the present invention is as follows: 1. A printing ink composition for shrink packaging containing a pigment, a resin component, and a solvent component, wherein the resin component includes a carboxyl group-containing acrylic resin, a cellulose resin, a rosin resin, and a derivative thereof that satisfy the following conditions 1 and 2. Condition 1: The ratio of the solid content mass of the carboxyl group-containing acrylic resin to the solid content mass of the cellulose resin is 80 / 20 to 60 / 40. Condition 2: The rosin resin and its derivatives have an acid value of 150 mgKOH / g or less and are contained in the ink composition at a concentration of 3.0 to 20.0% by mass in the solid content. 2. The shrink packaging printing ink composition according to claim 1, wherein the carboxyl group-containing acrylic resin has an acid value of 2 to 20 mg KOH / g and a mass average quantity of 30,000 to 100,000. 3. The shrink packaging printing ink composition according to claim 1 or 2, wherein the cellulose resin is a cellulose acetate propionate resin and a cellulose acetate butyrate resin. 4. A printing ink composition for shrink packaging according to any one of 1 to 3, wherein the acid value of the rosin resin and its derivatives is 30 mg KOH / g or less. 5. A printing ink composition for shrink packaging according to any one of claims 1 to 4, wherein the solvent component contains an alcohol-based solvent and an ester-based solvent, and the mass ratio of the alcohol-based solvent to the ester-based solvent is alcohol-based solvent / ester-based solvent = 60 / 40 to 80 / 20. 6. A printing ink composition for shrink packaging according to any one of 1 to 5, containing a plasticizer. 7. The printing ink composition for shrink packaging according to 6, wherein the plasticizer is an epoxidized vegetable oil. 8. A printing ink composition for shrink packaging according to any one of 1 to 7, wherein the pigment is a white pigment. 9. The printing ink composition for shrink packaging according to 8, wherein the white pigment is rutile-type titanium oxide having a treatment layer made of silica and / or alumina. A method for producing a shrink-wrapped printed material by printing a shrinkable film with a shrink-wrapped printing ink composition described in any of sections 10.1 to 10.9. A printed material for shrink packaging obtained by printing a shrinkable film with any of the shrink packaging printing ink compositions described in 11.1 to 11.9. [Effects of the Invention]

[0006] According to the present invention, it is possible to increase the biomass content even when the pigment content of the ink composition, particularly the white ink composition, is high, and furthermore, it is possible to obtain a printing ink composition for shrink packaging that has excellent resistance to contents (resistance to surfactants and alkalis) (the printed area is not damaged when soap or toiletries, which are the contents of the container, adhere to the printed surface). [Modes for carrying out the invention]

[0007] The present invention relates to a printing ink composition for shrink packaging containing a pigment, a resin component, and a solvent component, wherein the resin component includes a carboxyl group-containing acrylic resin, a cellulose resin, a rosin resin, and a derivative thereof that satisfy the following conditions 1 and 2. Condition 1: The ratio of the solid content mass of the carboxyl group-containing acrylic resin to the solid content mass of the cellulose resin is: Solid content mass of carboxyl group-containing acrylic resin / Solid content mass of cellulose resin = 80 / 20 to 60 / 40 Condition 2: The acid value of rosin resin and its derivatives is 150 mgKOH / g or less. 3.0 to 10.0% by mass of the solid content of the ink composition Contains. The printing ink composition for shrink packaging according to the present invention will be described in detail below. The biomass content of the shrink packaging printing ink composition of the present invention is preferably 10 or higher. The biomass content is calculated by the following formula. Biomass content = Amount of biomass components / Total solids including pigment in the shrink packaging printing ink composition × 100 Biomass component: The total weight of biomass-derived components in the resin solids and additive solids. (Resin weight × biomass weight ratio + additive weight × biomass weight ratio)

[0008] <Acid value> In the present invention, the acid value is obtained by determining the theoretically necessary neutralization amount of potassium hydroxide (KOH) with respect to the amount of each monomer theoretically required to obtain 1 g of a carboxyl group-containing acrylic resin, rosin resin, etc., and taking the total mg number of the neutralization amounts as the acid value of the polymer.

[0009] <Mass average molecular weight> The mass average molecular weight of the resin in the present invention can be measured by gel permeation chromatography (GPC). As an example, using Water2690 (manufactured by Waters) as the GPC device, PLgel, 5 μm, MIXED-D (manufactured by Polymer Laboratories) as the column, tetrahydrofuran as the developing solvent, column temperature of 25 °C, flow rate of 1 milliliter / minute, RI detector, sample injection concentration of 10 milligrams / milliliter, and injection volume of 100 microliters, perform chromatography and obtain it as the mass average molecular weight in terms of polystyrene.

[0010] <Pigment> As the pigment, various inorganic pigments, organic pigments, etc. generally used in printing inks can be used. Specifically, as inorganic pigments, colored pigments such as titanium oxide, red iron oxide, antimony red, cadmium yellow, cobalt blue, ultramarine blue, carbon black, graphite, and extender pigments such as calcium carbonate, kaolin, clay, barium sulfate, aluminum hydroxide, talc, etc. can be mentioned. Furthermore, as organic pigments, soluble azo pigments, insoluble azo pigments, azo lake pigments, condensed azo pigments, copper phthalocyanine pigments, condensed polycyclic pigments, etc. can be mentioned. White pigments such as titanium oxide and rutile-type titanium oxide having a treatment layer composed of silica and / or alumina and other colored pigments may also be used. The content of the pigment is 1 to 50% by mass based on the total mass of the shrink packaging printing ink composition. The present invention is useful for titanium oxide which is an inorganic pigment.

[0011] <Resin component> As the resin component, it contains a carboxyl group-containing acrylic resin, a cellulose resin, a rosin resin and its derivatives. (Carboxyl group-containing acrylic resin) Examples of the carboxyl group-containing acrylic resin include copolymers of a radically polymerizable carboxylic acid monomer and a radically polymerizable acrylic monomer, and copolymers containing radically polymerizable monomers other than the radically polymerizable carboxylic acid monomer and the radically polymerizable acrylic monomer. Examples of the radically polymerizable carboxylic acid monomer include acrylic acid, methacrylic acid, crotonic acid; monoesters and monoamides of dicarboxylic acids such as maleic acid, fumaric acid, citraconic acid, and itaconic acid; maleic anhydride, citraconic anhydride, itaconic anhydride; esters of vinyl alcohol and saturated carboxylic acids having 2 to 18 carbon atoms such as acetic acid, propionic acid, lauric acid, and stearic acid. Examples of the radically polymerizable acrylic monomer include alcohol esters such as methyl, ethyl, propyl, butyl, and pentyl alcohol esters of acrylic acid and methacrylic acid, and diesters such as ethylene glycol and pyropylene glycol. Examples of the radically polymerizable monomer (c) other than the radically polymerizable carboxylic acid monomer and the radically polymerizable acrylic monomer include styrene and α-methylstyrene. Among these carboxyl group-containing acrylic resins, copolymers in which the origin of the carboxyl group is a methacrylic acid monomer are preferred, and further copolymers of methacrylic acid (MAA), methyl methacrylate (MMA) and butyl methacrylate (BMA) are preferred.

[0012] The acid value of the carboxyl group-containing acrylic resin obtained by copolymerizing the above monomers is preferably 2 to 20 mgKOH / g. More preferably, it is 3 mgKOH / g or more, more preferably <15 mgKOH / g, and even more preferably <10 mgKOH / g. If it is less than 2 mgKOH / g, problems are likely to occur in the compatibility with the cellulose resin, and if it is higher than 20 mgKOH / g, the suitability for the contents (surfactant resistance, alkalinity resistance) tends to be poor. Furthermore, the mass-average molecular weight of the carboxyl group-containing acrylic resin is preferably 30,000 to 100,000. Of these, 35,000 or more is more preferable, and 40,000 or more is even more preferable. Also, 90,000 or less is more preferable, and 80,000 or less is even more preferable. When the mass-average molecular weight is less than 30,000, blocking properties and adhesive properties tend to decrease, while when it exceeds 100,000, solubility and solubility with cellulose resin tend to decrease. The content of carboxyl group-containing acrylic resin in the solid content of the shrink packaging printing ink composition of the present invention is preferably 10.0% by mass or more, more preferably 13.0% by mass or more, and even more preferably 14.0% by mass or more. Furthermore, it is preferably 40.0% by mass or less, more preferably 35.0% by mass or less, and even more preferably 30.0% by mass or less.

[0013] (Cellulose resin) As the cellulose resin, conventionally used gravure inks such as cellulose acetate propionate resin, cellulose acetate butyrate resin, and nitrocellulose resin can be used. Cellulose acetate propionate resin and cellulose acetate butyrate resin are preferred from the viewpoint of improving surfactant resistance and alkali resistance. The cellulose resin in the shrink packaging printing ink composition of the present invention satisfies the following condition 1: In the printing ink composition for shrink packaging, the ratio of the solid content mass of carboxyl group-containing acrylic resin to the solid content mass of cellulose resin is 80 / 20 to 60 / 40. A ratio of 75 / 25 to 65 / 35 is preferred. If the proportion of cellulose resin solid content is greater than 40, the suitability for handling contents (surfactant resistance, alkali resistance) tends to decrease, while if it is less than 20, blocking properties tend to decrease. Furthermore, the total content of each cellulose resin in the solid content of the shrink packaging printing ink composition of the present invention is preferably 3.0% by mass or more, more preferably 5.0% by mass or more, and even more preferably 7.0% by mass or more. Also, it is preferably 20.0% by mass or less, more preferably 15.0% by mass or less, and even more preferably 11.0% by mass or less.

[0014] (Cellulose acetate propionate resin) As the cellulose acetate propionate resin, a known cellulose acetate propionate resin that has been conventionally used in gravure printing ink compositions can be used. Cellulose acetate propionate resin is obtained by triesterinating cellulose with acetic acid and propionic acid, followed by hydrolysis. Generally, commercially available cellulose acetate propionate resins have an acetyl group content of 0.6 to 2.5% by weight, a propionate group content of 42.0 to 46.0% by weight, and a hydroxyl group content of 1.8 to 5.0% by weight. Among these, it is preferable to use a low molecular weight resin in order to improve the biomass content. The content of cellulose acetate propionate resin in the solid content of the shrink packaging printing ink composition of the present invention is preferably 3.0% by mass or more, more preferably 5.0% by mass or more, and even more preferably 7.0% by mass or more. Furthermore, it is preferably 20.0% by mass or less, more preferably 15.0% by mass or less, and even more preferably 11.0% by mass or less.

[0015] (Cellulose acetate butyrate resin) As the cellulose acetate propionate resin, resins conventionally used in gravure printing ink compositions can be used. Cellulose acetate butyrate resin is obtained by triesterinating cellulose with acetic acid and butyric acid, followed by hydrolysis. Generally, resins with acetylation of 2-30% by weight, butyrylation of 17-53% by weight, and hydroxyl groups of 1-5% are commercially available. Among these, it is preferable to use a low molecular weight resin in order to improve the biomass content. The content of cellulose acetate butyrate resin in the solid content of the shrink packaging printing ink composition of the present invention is preferably 3.0% by mass or more, more preferably 5.0% by mass or more, and even more preferably 7.0% by mass or more. Furthermore, it is preferably 20.0% by mass or less, more preferably 15.0% by mass or less, and even more preferably 11.0% by mass or less.

[0016] (Nitrocellulose resin) As the nitrocellulose resin, nitrocellulose resins that have been conventionally used in gravure printing ink compositions can be used. Nitrocellulose resins are obtained by reacting natural cellulose with nitric acid, and replacing three hydroxyl groups in the six-membered ring of the anhydrous glucopyranose group in the natural cellulose with nitrate groups to form a nitrate ester. The nitrocellulose resin used in the present invention preferably has a nitrogen content of 10-13% and an average degree of polymerization of 35-90. Specific examples include SS1 / 2, SS1 / 4, SS1 / 8, TR1 / 16, NCRS-2 (manufactured by KOREA CNC LTD), etc. The nitrocellulose resin content in the solid content of the shrink packaging printing ink composition of the present invention is preferably 3.0% by mass or more, more preferably 5.0% by mass or more, and even more preferably 7.0% by mass or more. Furthermore, it is preferably 20.0% by mass or less, more preferably 15.0% by mass or less, and even more preferably 11.0% by mass or less.

[0017] (Rosin resin and its derivatives) Examples of rosin resins include gum rosin, tall oil rosin, and wood rosin. Generally, rosin is an amber-colored, amorphous resin obtained from pine trees. Although it is a mixture because it is obtained from natural sources, it may also be used by isolating each of its constituent components, such as abietic acid, neoabietic acid, palastic acid, pimaric acid, isopimaric acid, sandaracopimaric acid, and dehydroabietic acid. In this invention, these are also defined as rosin resins. Rosin resin derivatives are compounds obtained by modifying the above-mentioned rosin resin, and are specifically listed below. (1) Hydrogenated rosin: This is a type of rosin in which hydrogen is added to the conjugated double bond (hydrogenation) to improve weather resistance. (2) Disproportionated rosin: Disproportionation is a modification in which two molecules of rosin react, and two molecules of abietic acid with conjugated double bonds become one aromatic molecule and the other a molecule with a single double bond. Generally, it has lower weather resistance than hydrogenated rosin, but it has improved weather resistance compared to untreated rosin. (3) Rosin-modified phenolic resin: Rosin-modified phenolic resin is often used as the main binder in offset printing inks. Rosin-modified phenolic resin can be obtained by known manufacturing methods. (4) Rosin esters: These are ester resins derived from rosin and have long been used as tackifiers for adhesives and glues. (5) Rosin-modified maleic acid resin: This is produced by adding maleic anhydride to rosin, and may also include resins in which a hydroxyl group-containing compound such as glycerin is esterified with the anhydride group and grafted onto it, if necessary. (6) Polymerized rosin: A derivative containing dimerized resin acid derived from natural resin rosin. In addition, known rosins and rosin derivatives can also be used, and these can be used alone or in combination. The rosin resin in the printing ink composition for shrink packaging of the present invention satisfies the following condition 2: The acid value of rosin resin and its derivatives is 150 mgKOH / g or less. If it exceeds 150 mgKOH / g, the stability of the ink composition and its suitability for contents (alkali resistance and surfactant resistance) will decrease. Furthermore, from the viewpoint of superior suitability for contents, 100 mgKOH / g or less is preferred, 50 mgKOH / g or less is even more preferred, 30 mgKOH / g or less is even more preferred, 20 mgKOH / g or less is extremely preferred, and 10 mgKOH / g or less is most preferred. The content of rosin resin and its derivatives in the solid content of the shrink packaging printing ink composition of the present invention is 3.0 to 20.0% by mass. Preferably, it is 5.0% by mass or more, more preferably 7.0% by mass or more. Also, preferably 15.0% by mass or less, and more preferably 10.0% by mass or less.

[0018] (Other resins) The shrink-wrapping printing ink composition of the present invention may contain, as necessary and appropriate, other resins as resin components other than the carboxyl group-containing acrylic resin, cellulose resin, rosin resin, and their derivatives, provided that they do not impair the effects of the present invention. Other resins include polyurethane urea resin, polyurethane resin, vinyl chloride-vinyl acetate copolymer resin, polyamide resin, acrylic resin, ethylene-vinyl acetate copolymer resin, chlorinated olefin resin, alkyd resin, vinyl acetate resin, ketone resin, polybutyral resin, cycloplastic rubber resin, chlorinated rubber resin, petroleum resin, olefin resin, polyester resin, and polylactic acid resin. Furthermore, the material may or may not contain an acrylic resin having a phosphate group.

[0019] (Plasticizer) As plasticizers, dioctyl sebatate, fatty acid triglycerides, ethyltoluenesulfonamide, tributyl acetylcitrate, 2-ethylhexyl stearate, 2-ethylhexyl palmitate, etc., which have been conventionally used in gravure printing inks, and epoxidized vegetable oils can be used. Among these, epoxidized vegetable oils such as epoxidized soybean oil and epoxidized linseed oil are preferred in terms of suitability for contents resistance (surfactant resistance, alkali resistance) and biomass content. The content of the plasticizer is not particularly limited. For example, the plasticizer content in the shrink packaging printing ink composition is preferably 0.05% by mass or more, more preferably 0.5% by mass or more, preferably 5.0% by mass or less, and more preferably 3.0% by mass or less. By having a plasticizer content within the above range, the resulting shrink packaging printing ink composition will have improved resistance to contents (surfactant resistance, alkali resistance).

[0020] (Amide compounds) Furthermore, it is preferable to include amide compounds in the printing ink composition for shrink packaging in order to further improve scratch resistance, adhesion to the substrate, abrasion resistance, and suitability for contents (surfactant resistance and alkali resistance). Examples of amide compounds include palmitate amide, stearate amide, ethylenebisoleate amide, and hexamethylenebisoleate amide, which may be used individually or in mixtures of two or more. When adding amide compounds, it is preferable to include 0.1 to 5.0% by mass in the printing ink composition for shrink packaging. In particular, it is preferable to include 0.1 to 4.0% by mass, and more preferably 0.3 to 2.5% by mass, in order to achieve a balance of scratch resistance, adhesion to the substrate, abrasion resistance, surfactant resistance, and alkali resistance.

[0021] (Solvent component) The solvent components used in the shrink packaging printing ink composition of the present invention include alcohol-based solvents such as methanol, ethanol, isopropanol, n-propanol, butanol, isobutanol, and tert-butanol; aromatic hydrocarbon solvents such as toluene and xylene; aliphatic hydrocarbon solvents such as hexane, cyclohexane, methylcyclohexane, and ethylcyclohexane; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester-based solvents such as ethyl acetate, n-propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, sec-butyl acetate, and tert-butyl acetate; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol dimethyl ether. Examples include glycol-based solvents such as ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, and propylene glycol monobutyl ether, as well as their esterified products. As esterified products, acetate-forms are mainly selected, such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate. These can be used individually or in combination of two or more. Among these solvent components, from an environmental perspective, it is preferable to use alcohol-based solvents and / or ester-based solvents, and more preferably C1-C4 alcohol-based solvents and / or ester-based solvents. Furthermore, it is preferable to use C1-C4 alcohol-based solvents and ester-based solvents in a mass ratio of alcohol-based / ester-based solvent = 60 / 40 to 80 / 20, and more preferably 63 / 37 to 75 / 25. If the amount of ester-based solvent is greater than 40, there is a possibility of attacking shrinkable OPS (untreated shrinkable polystyrene film). Also, if the amount of ester-based solvent is less than 20, the solubility of the resin components tends to decrease.

[0022] (Other ingredients) The printing ink composition for shrink packaging of the present invention may also contain, as needed, friction-resistant enhancers, anti-blocking agents, pigment dispersants, antistatic agents, lubricants, crosslinking agents, defoaming agents, drying regulators, other plasticizers, tackifiers, adhesion enhancers, leveling agents, antioxidants, and the like. Among these, biomass-derived additives are even preferable. Preferred lubricants include polyethylene (PE) wax, polypropylene wax, PTFE-based wax, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, Montan wax, carnauba wax, shellac wax, amide wax, organic polymers, beeswax, and mixtures thereof, with polyethylene wax and polypropylene wax being more preferred.

[0023] (Method for producing the printing ink composition for shrink packaging according to the present invention) Next, an example of a method for manufacturing the ink composition described above will be explained. In this embodiment, the method for manufacturing the printing ink composition for shrink packaging involves stirring and mixing the pigment, binder resin, organic solvent, and optionally other components (pigment dispersant, surfactant, etc.), then kneading the mixture using various kneading machines, such as a bead mill, ball mill, sand mill, attritor, roll mill, pearl mill, etc., and finally adding and mixing the remaining materials, such as predetermined additives.

[0024] (Printed material for shrink wrapping) Next, a printed material for shrink packaging (hereinafter simply referred to as "printed material") according to one embodiment of the present invention will be described. The printed material of the present invention is a printed material in which the above-described ink composition is printed on a shrinkable film which is a substrate. The printed material is preferably obtained by printing the ink composition on a shrinkable film which is a substrate using a gravure printing machine or a flexographic printing machine. Known conditions are appropriately adopted for printing conditions. The printed material may be dried after printing to allow the organic solvent in the ink to evaporate. Known conditions are appropriately adopted for drying conditions. Preferably, the shrinkable film is a shrinkable polypropylene film, shrinkable polyvinyl chloride film, shrinkable polyethylene phthalate film, or shrinkable polystyrene film (especially a shrinkable untreated polystyrene film) obtained by stretching or the like. The resulting printed materials are used for various shrink packaging applications, such as shrink labels and printed film for wrapping. When used for shrink labels, the printed materials are tubed by means of heat sealing or other methods, attached to PET containers or glass containers, and then heat-shrunk by heating to a predetermined shrinkage temperature, ensuring a tight fit to the container. When used for printed film for wrapping, the printed materials are used for packaging irregularly shaped objects, bundling products, and guarantee packaging. [Examples]

[0025] The present invention will be described more specifically below with reference to examples. The present invention is not limited in any way to these examples. Unless otherwise specified, "%" means "mass%" and "parts" means "parts by mass" (the values ​​listed in the table are in parts by mass). The raw materials used and their preparation methods are shown below. (Carboxyl group-containing acrylic resin) Carboxyl group-containing acrylic resin 1: MAA / MMA / BMA Theoretical acid value: 3 mg KOH / g, mass-average molecular weight: 60,000 Carboxyl group-containing acrylic resin 2: MAA / MMA / BMA Theoretical acid value: 7 mg KOH / g, mass-average molecular weight: 60,000 Carboxyl group-containing acrylic resin 3: MAA / MMA / BMA Theoretical acid value 13 mg KOH / g, mass-average molecular weight 60,000 Carboxyl group-containing acrylic resin 4: MAA / MMA / BMA Theoretical acid value: 3 mg KOH / g, mass-average molecular weight: 40,000 Carboxyl group-containing acrylic resin 5: MAA / MMA / BMA Theoretical acid value: 3 mg KOH / g, mass-average molecular weight: 80,000

[0026] (Acrylic resin containing phosphate groups) Acrylic resin solution containing phosphate groups A 40% solids solution of a resin synthesized by a conventional method, containing 0.01% by mass of a (meth)acrylic acid ester having a phosphate group, 35% by mass of methyl methacrylate, and 64.99% by mass of butyl methacrylate, in a mixed solvent of isopropyl alcohol / ethyl acetate = 4 / 6, in a total weight-average molecular weight of 60,000 and an acid value of 0.1 mgKOH / g.

[0027] (Pigment) Titanium dioxide: Rutile-type titanium dioxide pigment surface-treated with silica alumina Pigment Blue 15:4 (PB15:4)

[0028] (Cellulose resin) Cellulose acetate butyrate (CAB-381-0.5, manufactured by Eastman, number average molecular weight 30,000) Cellulose acetate butyrate (CAB-381-0.1, manufactured by Eastman, number-average molecular weight 20,000) Cellulose acetate propionate (CAP-482-0.5, manufactured by Eastman, number average molecular weight 25,000) Nitrocellulose: (LIG1 / 8, manufactured by SNPE Japan Co., Ltd.)

[0029] (Rosin resin and its derivatives) Rosin ester (acid value 7 mg KOH / g) Rosin ester (acid value 15 mg KOH / g) Maleic acid-modified rosin resin (acid value 40 mg KOH / g) Dimerized rosin (140mgKOH / g) Maleic acid-modified rosin resin (acid value 300 mg KOH / g)

[0030] (Plasticizer) Epoxy soybean oil Epoxy linseed oil Dioctyl sebacate

[0031] (Amide compounds) Stearic acid amide (PE wax) Spray 30 (manufactured by Sasol) (Antifoaming agent) BYK-094 (manufactured by BYK)

[0032] <Examples 1-18 and Comparative Examples 2-5: Printable white ink compositions for shrink packaging> 45 parts by mass of pigment (titanium dioxide), 9 parts by mass of carboxyl group-containing acrylic resin (7.5 parts by mass in the case of Comparative Example 6), 10 parts by mass of isopropyl alcohol, and 15 parts by mass of ethyl acetate were kneaded using a paint conditioner. Further addition and mixing of carboxyl group-containing acrylic resin, rosin resin, plasticizer, remaining materials, and solvent was performed to prepare a white printing ink composition for shrink packaging, according to the formulations shown in Table 1. <Examples 19-28: Printing ink compositions for shrink packaging> Ten parts by mass of a color pigment other than white, nine parts by mass of carboxyl group-containing acrylic resin, ten parts by mass of isopropyl alcohol, and fifteen parts by mass of ethyl acetate were kneaded using a paint conditioner. Further addition and mixing of carboxyl group-containing acrylic resin, rosin resin, cellulose resin, plasticizer, remaining materials, and solvent were added and mixed to achieve the formulation shown in Table 1 to prepare a printing ink composition for shrink packaging. <Comparative Example 1: Printing white ink composition for shrink packaging> A white printing ink composition for shrink packaging was prepared by kneading 45 parts by mass of pigment (titanium dioxide), 22.5 parts by mass of phosphate-containing acrylic resin solution, 6.9 parts by mass of isopropyl alcohol, and 4.6 parts by mass of ethyl acetate using a paint conditioner. Further mixing was performed by adding and mixing the phosphate-containing acrylic resin solution, rosin resin, cellulose resin, plasticizer, remaining materials, and solvent to achieve the formulation shown in Table 1.

[0033] <Printing method> The shrink packaging printing ink compositions of Examples 1-28 and Comparative Examples 1-6 were diluted with a mixed solvent (isopropyl alcohol:ethyl acetate = 6:4) so ​​that the viscosity was 15 seconds using a Zahn Cup #3 manufactured by Rigosha Co., Ltd. These diluted compositions were printed onto untreated shrinkable polystyrene film (BS-55S, 50 μm thick, manufactured by Takiron CI Co., Ltd.) at a printing speed of 150 m / min using a gravure printing press (manufactured by Toshiba Corporation) equipped with an engraving plate (printing plate, Helio 175 lines / inch) to obtain each printed material. All printed materials evaluated for properties other than blocking resistance were obtained using this method.

[0034] <Print Evaluation> (Adhesiveness) The adhesion of each of the above printed materials was evaluated according to the following evaluation criteria based on the degree to which the printed film peeled off the film when cellophane tape (registered trademark) was applied to the printed surface and rapidly peeled off. <Evaluation Criteria> ○: It did not peel off at all. △: A small portion peeled off, but it was still usable. ×: Mostly or completely detached.

[0035] (Scratch resistance) Each of the above printed materials was rubbed firmly with the back of a fingernail, and the amount of ink removed was observed for evaluation. <Evaluation Criteria> ○: It wasn't scratched at all. △: Part of it has peeled off. ×: Mostly or completely detached.

[0036] (Resistance to rubbing) The state of cracking in the coating of each printed material after vigorously rubbing it with both hands 10 times was evaluated according to the following evaluation criteria. <Evaluation Criteria> ○: It didn't break at all. △: Partially cracked. ×: Cracked all over. Scratch resistance.

[0037] (Residual solvent) For each of the printed materials mentioned above, the amount of residual solvent was measured in accordance with the Flexible Packaging Hygiene Council method and evaluated according to the following evaluation criteria. <Evaluation Criteria> ○: The amount of residual solvent is 5 mg / m². 2 It was less than [amount missing]. △: The amount of residual solvent is 5-15 mg / m². 2 That was the case. ×: The amount of residual solvent is 15 mg / m². 2 There were more.

[0038] (Resistant to raw material attacks) The degree of cracking in each of the above printed materials was visually evaluated. The evaluation criteria for resistance to raw material attack are shown below. <Evaluation Criteria> ○: There are absolutely no cracks in the printed material. △: Slight cracking is observed in the printed material. ×: The printed material shows significant cracking, or is completely torn.

[0039] (Blocking resistance) The printing ink compositions for shrink packaging of Examples 1-28 and Comparative Examples 1-6 were spread using a 0.1 mm diameter wire bar, then dried with hot air to obtain printed materials. The printed and unprinted surfaces of the printed material together measured 29.4 × 10⁻⁶. 4 Pa(3kg / cm 2 After being left under the specified load at 40°C for 24 hours, the peel resistance and the degree of ink film peeling were evaluated by peeling by hand. The evaluation criteria for blocking resistance are shown below. <Evaluation Criteria> ○: There is absolutely no ink peeling, and no resistance to peeling is felt. △: There is slight ink peeling, and some resistance to peeling can be felt. ×: The ink peels off almost completely, and there is a strong resistance to peeling.

[0040] (Edge cracking) The film was sandwiched between each of the above printed materials, wrapped around a glass bottle, and immersed in 90°C hot water for 10 seconds. After drying, the degree of cracking at the edges was evaluated. <Evaluation Criteria> ○: There was absolutely no cracking of the ink. △: There were some cracks in the ink. ×: There were cracks in the ink throughout.

[0041] <Content resistance> Each of the above printed materials was immersed in the following contents and left at 40°C for 24 hours. After the immersion period, the contents were washed off with water, and the degree of ink loss was evaluated. Body soap (manufactured by Kracie Holdings Co., Ltd., Naive® Body Soap) Hand soap (manufactured by Kracie Holdings, Ltd., Naive® Hand Soap) Kitchen Hyter (manufactured by Kao Corporation) <Evaluation Criteria> ○: There was absolutely no ink fading. △: There was slight ink fading. ×: The ink has completely come off.

[0042] [Table 1] TIFF0007847951000002.tif188170TIFF0007847951000003.tif157170TIFF0007847951000004.tif213170

[0043] According to each example, in addition to achieving a sufficiently high biomass content, it is possible to achieve excellent adhesion, scratch resistance, kneading resistance, raw material attack resistance, blocking resistance, and content resistance, as well as low residual solvent. However, Comparative Example 1, which did not contain carboxyl group-containing acrylic resin but contained phosphate group-containing acrylic resin, Comparative Example 2, in which the acid value of the rosin resin was too high, and Comparative Example 4, in which the rosin resin content was too high, showed poor resistance to the contents. Furthermore, in Comparative Example 3, which contained less rosin resin, it was not possible to achieve a sufficiently high biomass content. In Comparative Example 5, where the ratio of solid content mass of carboxyl group-containing acrylic resin to solid content mass of cellulose resin was in excess, the more important blocking resistance was insufficient. Conversely, in Comparative Example 6, where the carboxyl group-containing acrylic resin was insufficient, the more important adhesion was insufficient, and residual solvent was present.

Claims

1. A printing ink composition for shrink packaging containing a pigment, a resin component, and a solvent component, wherein the resin component includes a carboxyl group-containing acrylic resin, a cellulose resin, a rosin resin, and its derivatives that satisfy the following conditions 1 and 2: Condition 1: The ink composition contains 3.0 to 20.0% by mass of cellulose resin in its solid content. The ratio of the solid content mass of the carboxyl group-containing acrylic resin to the solid content mass of the cellulose resin is such that solid content mass of carboxyl group-containing acrylic resin / solid content mass of cellulose resin = 80 / 20 to 60 / 40 Condition 2: The rosin resin and its derivatives have an acid value of 150 mgKOH / g or less and are contained in the ink composition in an amount of 3.0 to 10.0% by mass in the solid content.

2. The printing ink composition for shrink packaging according to claim 1, wherein the rosin resin and its derivatives are contained in an amount of 3.0 / 67.5 or more by mass relative to the solid content of the ink composition.

3. A printing ink composition for shrink packaging according to claim 1 or 2, wherein the carboxyl group-containing acrylic resin has an acid value of 2 to 20 mg KOH / g and a mass-average molecular weight of 30,000 to 100,000.

4. A printing ink composition for shrink packaging according to any one of claims 1 to 3, wherein the cellulose resin is a cellulose acetate propionate resin and a cellulose acetate butyrate resin.

5. A printing ink composition for shrink packaging according to any one of claims 1 to 4, wherein the acid value of the rosin resin and its derivatives is 30 mg KOH / g or less.

6. A printing ink composition for shrink packaging according to any one of claims 1 to 5, wherein the solvent component contains an alcohol-based solvent and an ester-based solvent, and the mass ratio of the alcohol-based solvent to the ester-based solvent is alcohol-based solvent / ester-based solvent = 60 / 40 to 80 / 20.

7. A printing ink composition for shrink packaging according to any one of claims 1 to 6, comprising a plasticizer.

8. The printing ink composition for shrink packaging according to claim 7, wherein the plasticizer is an epoxidized vegetable oil.

9. A printing ink composition for shrink packaging according to any one of claims 1 to 8, wherein the pigment is a white pigment.

10. The printing ink composition for shrink packaging according to claim 9, wherein the white pigment is rutile-type titanium oxide having a treatment layer made of silica and / or alumina.

11. A method for producing a printed material for shrink packaging, comprising printing a printing ink composition for shrink packaging described in any one of claims 1 to 10 onto a shrinkable film.

12. A printed material for shrink packaging obtained by printing the printing ink composition for shrink packaging described in any one of claims 1 to 10 onto a shrinkable film.

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