Gravure printing ink for surface printing, and printed materials using it.

Abstract

The present invention aims to provide a gravure printing ink for surface printing that exhibits good abrasion resistance, heat resistance, oil resistance, and printability, and in particular, excellent adhesion to the substrate immediately after printing, resistance to blocking on vinyl chloride sheets, and resistance to blocking on anti-fogging films when printed and wound up. [Solution] A gravure printing ink for surface printing containing a binder resin, a cyclized rubber, a fatty acid amide, and an organic solvent, or a gravure printing ink for surface printing characterized in that the binder resin contains one of the two combinations of resins shown in (1) to (4) below. (1) Polyurethane resin and vinyl chloride resin (2) Polyurethane resin and cellulose resin (3) Polyurethane resin and polyvinyl acetal resin (4) Polyamide resins and cellulose resins

Description

[Technical Field]

[0001] This invention relates to gravure printing ink for surface printing and the printed material thereof.

[0002] More specifically, this relates to gravure printing inks for surface printing that allow for long-term storage of the ink, have good adhesion to the substrate, blockage resistance to prevent adhesion between the substrate and the printed material, abrasion resistance, heat resistance, oil resistance, and printability, and are also environmentally friendly and hygienic. [Background technology]

[0003] In recent years, it has become common for product packaging and other wrapping materials to be printed for decoration and surface protection. Furthermore, the quality of the printing, including its design, aesthetic appeal, and sense of luxury, can stimulate consumer purchasing intent, and therefore has significant industrial value.

[0004] On the other hand, food manufacturers and printing and processing companies are increasingly demanding higher quality and performance from surface printing inks due to the diversification of packaging materials and the sophistication of packaging technology. Surface printing inks include flexographic inks, offset inks, gravure printing inks, and others, but gravure printing inks are widely used from a productivity standpoint because of their good printing speed.

[0005] Gravure printing inks for front-facing printing require various performance characteristics, including not only print quality but also adhesion to the substrate, blocking resistance to prevent ink from bleeding or adhering to the back of the substrate when printed and wound up, abrasion resistance to prevent damage to the printed surface, heat resistance during bag making, and oil resistance to oils and fats.

[0006] As gravure printing inks for surface printing that have excellent adhesion and various resistances, for example, a gravure ink containing a binder resin and hydrocarbon wax, with the hardness (penetration) and content of the hydrocarbon wax specified (Patent Document 1), a gravure ink for lamination containing a polyurethane resin, a terpene phenol resin, an organic solvent and a wax, with the content of the wax specified, and the wax being at least one selected from fatty acid amides and hydrocarbon waxes (Patent Document 2), and a gravure ink for surface printing containing a polyamide resin, a nitrocellulose resin, a cellosolve-type solvent and an organic solvent other than a cellosolve-type solvent, with the content of the polyamide resin, nitrocellulose resin and cellosolve-type solvent specified, and the type and viscosity symbol of the nitrocellulose viscosity measurement specified have been proposed (Patent Document 3).

[0007] However, conventional surface-printing inks have struggled to meet the required adhesion and blocking resistance requirements for substrates when printing on corona discharge-treated films (substrates) or substrates with surface treatments such as anti-fogging agents, due to the winding load of the printed film and environmental conditions (temperature and humidity). In particular, if the adhesion is poor immediately after printing, the ink may come into contact with the unprinted surface during winding before a stable coating is formed, potentially resulting in poor blocking resistance. Furthermore, if it takes time for the adhesion to develop, it also takes time to judge the quality of the printed material, leading to a decrease in printing productivity. In particular, higher resistance to blocking is required when printing on anti-fogging films with anti-fogging treatment on both sides and when winding them, and there is still room for improvement in resistance to blocking on flexible polyvinyl chloride sheets commonly used for tablecloths. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2018-123333 [Patent Document 2] Japanese Patent Publication No. 2021-187871 [Patent Document 3] Japanese Patent Publication No. 2023-095738 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The present invention aims to provide a gravure printing ink for surface printing that has good abrasion resistance, heat resistance, oil resistance, and printability, and moreover, excellent adhesion to the substrate immediately after printing, resistance to blocking on vinyl chloride sheets, and resistance to blocking on anti-fogging films when printed and wound up. [Means for solving the problem]

[0010] As a result of diligent research into the aforementioned problems, the inventors have found that the above problems can be solved by using the gravure printing ink for surface printing described below, and have thus come to present invention.

[0011] In other words, the present invention relates to a gravure printing ink for surface printing that contains a binder resin, a cyclized rubber, a fatty acid amide, and an organic solvent.

[0012] In other words, the present invention relates to a gravure printing ink for surface printing, characterized in that the binder resin contains one of the two resin combinations shown in (1) to (4) below. (1) Polyurethane resin and vinyl chloride resin (2) Polyurethane resin and cellulose resin (3) Polyurethane resin and polyvinyl acetal resin (4) Polyamide resins and cellulose resins

[0013] In other words, the present invention relates to a gravure printing ink for surface printing in which the solid content mass ratio of cyclized rubber and fatty acid amide is 1:20 to 20:1.

[0014] In other words, the present invention relates to a gravure printing ink for surface printing in which the cyclized rubber contains an aromatic ring structure.

[0015] That is, the present invention relates to the gravure printing ink for surface printing, wherein the weight average molecular weight of the cyclized rubber is 1,000 to 50,000.

[0016] That is, the present invention further relates to the gravure printing ink for surface printing, which contains a chelating agent.

[0017] That is, the present invention relates to the gravure printing ink for surface printing, wherein the chelating agent is an acetylacetone-based titanium chelate and / or an alkyl acetoacetate-based titanium chelate.

[0018] That is, the present invention further relates to the gravure printing ink for surface printing, which contains hydrocarbon wax particles.

[0019] That is, the present invention relates to a printed matter having a printing layer made of the gravure printing ink for surface printing on a substrate.

Advantages of the Invention

[0020] According to the present invention, it is possible to provide a gravure printing ink for surface printing, which has good friction resistance, heat resistance, oil resistance and printing suitability of the ink, and further particularly excellent adhesiveness to the substrate immediately after printing, blocking resistance to a vinyl chloride sheet, and blocking resistance to an anti-fog film when printed and wound up.

Embodiments for Carrying Out the Invention

[0021] Hereinafter, embodiments of the present invention will be described in detail. However, the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention is not limited to these contents unless it exceeds the gist thereof.

[0022] In the following description, "gravure printing ink for surface printing" may be simply abbreviated as "gravure printing ink" or "ink", but they are the same. Also, "part" means "part by mass" unless otherwise specified, and "%" means "% by mass". Also, "ratio" represents "mass ratio" unless otherwise specified.

[0023] In this invention, "surface printing" refers to a printing method in which, when printed on a plastic or paper substrate, the printed pattern or design can be seen from the printed layer side. In the case of a laminate or packaging bag, the outermost surface becomes the printed layer. The layer obtained by printing with surface-printing gravure ink may be referred to as the "printed layer," "ink layer," or "ink film," but these terms are synonymous.

[0024] <Gravure printing ink for surface printing> This is a gravure printing ink for surface printing containing a binder resin, cyclized rubber, fatty acid amide, and an organic solvent. In addition to the adhesion and film strength of the binder resin alone, the cyclized portion, which is a unique structure within the cyclized rubber molecule, improves the physical properties of the ink film. Furthermore, although uniform in the organic solvent, during the drying process after printing, the fatty acid amide, with its relatively small molecular weight, is more easily oriented on the ink film surface. Moreover, it quickly forms an ink film with the cyclized portion, which is a unique structure within the cyclized rubber molecule. Therefore, it is believed to have a unique effect of improving adhesion to the substrate immediately after printing, resistance to blocking on anti-fogging films and vinyl chloride sheets, abrasion resistance, heat resistance, and oil resistance.

[0025] <Binder resin> The binder resin in this invention can be any known resin used as an ink, and may be a single resin or a combination of multiple resins. This is because the combination of cyclized rubber, fatty acid amide, and binder resin described above is thought to be able to produce the effects necessary to solve the problem.

[0026] Furthermore, the binder resin is preferably present in an amount of 10 to 90% by mass, more preferably 20 to 80% by mass, and even more preferably 30 to 70% by mass, in the total mass of the ink of the present invention.

[0027] In one embodiment, it is preferable that the binder resin contains one of the two resin combinations shown in (1) to (4) below. (1) Polyurethane resin and vinyl chloride resin (2) Polyurethane resin and cellulose resin (3) Polyurethane resin and polyvinyl acetal resin (4) Polyamide resins and cellulose resins If any one of the above is included, it is preferable that the two resins together constitute 50 to 100% by mass of the total mass of the binder resin, and more preferably 60 to 95% by mass.

[0028] Polyurethane resins and polyamide resins primarily improve adhesion to the substrate, while vinyl chloride resins, cellulose resins, and polyvinyl acetal resins improve various resistances of the printing ink layer, such as blocking resistance, abrasion resistance, and heat resistance. Therefore, combinations of each of the above two types of resins tend to achieve both good adhesion to the substrate and various resistances. Furthermore, other resins can be used in combination as needed. For example, rosin resins (rosin-modified phenolic resin, rosin-modified maleic acid resin, rosin ester, polymerized rosin resin, etc.) can be used in combination, and their use tends to improve gloss, blocking resistance to vinyl chloride sheets, and oil resistance.

[0029] <Polyurethane resin> The polyurethane resin used in the present invention is a resin having urethane bonds, and examples include a polyurethane resin composed of a polyol and a polyisocyanate, or a polyurethane urea resin obtained by reacting a urethane polymer with a terminal isocyanate composed of a polyol and an isocyanate with a chain extender such as a polyamine. Examples of manufacturing methods include those described in Japanese Patent Application Publication No. 2013-256551 and Japanese Patent Application Publication No. 2016-043600. A preferred form of the urethane resin is a polyurethane resin having urethane bonds obtained by reacting a polyol component containing an aliphatic diol with a polyisocyanate. Furthermore, if necessary, the chain may be extended via urea bonds formed by the remaining isocyanate and polyamine.

[0030] (Polyol) The polyol preferably has an average of 1.7 to 2.3 hydroxyl groups per molecule, and more preferably an average of 2 hydroxyl groups. Examples of polyols include polyether polyols such as polymers or copolymers of ethylene oxide, propylene oxide, tetrahydrofuran, etc., polyester polyols which are dehydration condensates of diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentadiol, methylpentadiol, hexadiol, octanediol, nonanediol, methylnonanediol, diethylene glycol, triethylene glycol, dipropylene glycol, etc., with dibasic acids including aliphatic dibasic acids having 5 to 11 carbon atoms, polycarbonate polyols, polybutadiene glycols, polyols obtained by adding ethylene oxide or propylene oxide to bisphenol A, dimer diols, castor oil polyols, hydrogenated castor oil polyols, and various other known polyols, which may be used alone or in combination of two or more. Furthermore, the polyol may contain biomass-derived compounds or raw materials (biomass raw materials) as constituent elements.

[0031] The number-average molecular weight of the polyol is preferably 300 or more, more preferably 500 to 6000, and even more preferably 1000 to 3000, in order to maintain the solubility of the polyurethane resin.

[0032] In the present invention, polyester polyols are preferred among polyols from the viewpoint of adhesion to polyester films and polyolefin films that serve as substrates. Furthermore, when two or more polyols are used in combination, it is more preferable that the polyester polyol is present in an amount of 40% by mass or more of the total mass of polyols from the viewpoint of adhesion to the substrate.

[0033] Polyester polyols preferably contain polyester-derived structural units consisting of a dibasic acid, including an aliphatic dibasic acid having 5 to 11 carbon atoms, and a diol. More preferably, the aliphatic dibasic acid has 6 to 10 carbon atoms, resulting in good adhesion to the substrate. Furthermore, increasing the number of carbon atoms in the aliphatic dibasic acid improves alcohol resistance.

[0034] (Aliphatic diols) The polyol constituting the polyurethane resin preferably contains an aliphatic diol. Examples of aliphatic diols include linear diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, and 1,9-nonanediol; branched diols such as 1,2-propanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, butylethylpropanediol, and methylnonanediol; and alicyclic diols such as cyclohexanedimethanol and cyclohexanediol. Multiple types may be used in combination. Among these, aliphatic diols having an alkyl group with 1 to 6 carbon atoms as a substituent are preferred because they have excellent adhesion to polyolefin substrates, enhance the solubility of the polyurethane resin, and improve printability. More specifically, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, butylethylpropanediol, 2-methyl-1,3-propanediol, and neopentyl glycol are preferably used.

[0035] Structural units derived from aliphatic diols with a molecular weight of 180 or less enhance the density of urethane bonds, imparting crystallinity and cohesiveness, while structural units derived from polyols contribute to flexibility and adhesion. The content of aliphatic diol-derived structural units (excluding structural units contained in the polyol) in the total amount of polyol-derived structural units is preferably 10 to 60% by mass, and more preferably 20 to 40% by mass. If the content is 10% by mass or more, the cohesiveness of the urethane bonds obtained by reaction with isocyanate is improved, and excellent blocking resistance is achieved. If the content is 60% by mass or less, the solubility of the polyurethane resin in solvents can be well maintained.

[0036] Other polyol components include aromatic diols and aliphatic diols with a molecular weight exceeding 180, and these may be used in combination.

[0037] (Polyisocyanate) As the polyisocyanate, diisocyanates are preferred. For example, aromatic diisocyanates such as 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyli isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylenediisocyanate, 1,4-phenylenediisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropyl diisocyanate, methylene diisocyanate, and 2,2,4 Examples include aliphatic diisocyanates such as trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, lysine diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanate-methyl)cyclohexane, methylcyclohexane diisocyanate, norbornane diisocyanate, m-tetramethylxylylene diisocyanate, and dimer diisocyanates obtained by converting the carboxyl group of a dimer acid to an isocyanate group. Among these, isophorone diisocyanate and hexamethylene diisocyanate are preferred.

[0038] To obtain the polyurethane resin used in the present invention, the reaction is carried out such that the reaction molar ratio (molar equivalent of NCO / molar equivalent of OH) of polyols and aliphatic diols is 0.5 or more and 2 or less, preferably 1.05 or more and 3 or less, and then the chain can be extended with the polyamine described above as needed. Furthermore, a reaction stopper can be used to prevent overreaction.

[0039] The urethane formation reaction may be carried out in an organic solvent or without a solvent. When using an organic solvent, it is advisable to select it appropriately in terms of temperature, viscosity, and control of side reactions during the reaction. When carrying out the urethane formation reaction without a solvent, it is desirable to raise the temperature to a viscosity that allows for sufficient stirring in order to obtain a uniform polyurethane resin. The urethane formation reaction is preferably carried out for 10 minutes to 5 hours, and the endpoint of the reaction can be determined by viscosity measurement, NCO-derived peak measurement by IR measurement, or NCO% measurement by titration.

[0040] The polyamines used for chain extension are preferably aliphatic diamines such as ethylenediamine, 1,4-butanediamine, isophoronediamine, and aminoethylethanolamine. Glycols such as ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, and triethylene glycol can also be used as chain extenders. Other reaction stoppers include monoalcohols such as methanol and ethanol, alkylamines such as n-propylamine, n-butylamine, and di-n-butylamine, and alkanolamines such as monoethanolamine and diethanolamine.

[0041] The polyurethane resin is preferably contained in a solid content of 3 to 15% by mass per 100% by mass of the total ink mass, and more preferably 5 to 12% by mass. When the content is 3% by mass or more, adhesion to the substrate is improved, and when it is 15% by mass or less, the fluidity and leveling properties of the printing ink are improved, and storage stability and printability tend to be good.

[0042] The weight-average molecular weight of the polyurethane resin is preferably 8,000 to 80,000, and more preferably 10,000 to 60,000. The glass transition temperature is preferably 0°C or lower, more preferably -40°C to -5°C, and even more preferably -35°C to -10°C. It tends to have good affinity with vinyl chloride resins, cellulose resins, or polyvinyl acetal resins. Furthermore, the polyurethane resin is preferably one that has an amine value, more preferably 1 to 20 mgKOH / g, and even more preferably 5 to 15 mgKOH / g. It is believed that the adhesion to the substrate is improved when the amine value is within the above range.

[0043] Furthermore, the polyurethane resin may or may not have urea bonds. The manufacturing method when urea bonds are present is not particularly limited, but it is preferable that the total number of amino groups in the chain extender and reaction stopper, when the number of isocyanate groups in the prepolymer having isocyanate groups at the terminals, obtained by reacting an aliphatic diol, a polyol, and a polyisocyanate, is in the range of 0.5 to 1.3.

[0044] The polyurethane resin preferably has a urethane bond concentration of 1.6 mmol / g or higher, and more preferably 2.0 mmol / g or higher. When the urethane bond concentration is 1.6 mmol / g or higher, blocking resistance is improved. The urea bond concentration is preferably 1.6 mmol / g or lower, and more preferably 1.4 mmol / g or lower. By setting the urea bond concentration to 1.6 mmol / g or lower, solubility in organic solvents and adhesion to the substrate are improved. Furthermore, the sum of the urethane bond concentration and urea bond concentration is preferably 3.2 mmol / g to 4.4 mmol / g, and more preferably 3.6 mmol / g to 4.0 mmol / g. This is considered to achieve both adhesion to the substrate and blocking resistance.

[0045] (Urethane bonding concentration) In the above case, if (NCO molar equivalent / OH molar equivalent) > 1, it is expressed by the following formula (1). Formula (1) Urethane bond concentration (mmol / g) = Total number of moles of hydroxyl groups (mmol) / Total solids (g) Here, the total number of moles of hydroxyl groups refers to the total number of moles of hydroxyl groups present in the polymeric polyol, aliphatic diol, and other polyols used in the reaction to form urethane. The total solids content refers to the total mass of non-volatile components that make up the polyurethane resin. In the above case, if (NCO molar equivalent / OH molar equivalent) < 1, it is expressed by the following formula (2). Formula (2) Urethane bond concentration (mmol / g) = Total number of isocyanate groups (mmol) / Total solids (g) Here, the total number of isocyanate groups refers to the total number of moles of isocyanate groups in the polyisocyanate used in the reaction to form urethane.

[0046] (urea bond concentration) When a prepolymer having terminal isocyanate groups is synthesized under the above condition (NCO molar equivalent / OH molar equivalent) > 1, and then the chain is extended with a polyamine, resulting in a polyurethane resin with amino groups at its ends, it is represented by the following formula (3). Formula (3) Urea bond concentration (mmol / g) = [Total isocyanate group moles (mmol) - Total hydroxyl group moles (mmol)] / Total solids (g) When a prepolymer having terminal isocyanate groups is synthesized under the above condition (NCO molar equivalent / OH molar equivalent) > 1, and then the chain is extended with a polyamine, resulting in a polyurethane resin with isocyanate groups at the ends, it is represented by the following formula (4). Formula (4) Urea bond concentration (mmol / g) = (Total number of moles of amino groups (mmol)) / Total solids (g) Here, the total number of moles of amino groups refers to the total number of moles of amino groups in the polyamine used to generate urea bonds by reacting with a prepolymer having terminal isocyanate groups.

[0047] In this invention, the total number of moles of hydroxyl groups (mmol), the total number of moles of isocyanate groups (mmol), the total number of moles of amino groups (mmol), and the total solid content (g) were all calculated based on 100 parts by mass of the target polyurethane resin solution.

[0048] <Polyamide resin> The polyamide resin used in the present invention is not limited to the following, but is preferably a thermoplastic polyamide soluble in organic solvents that can be obtained by polycondensation of a polybasic acid and a polyhydric amine. In particular, it is more preferably a polyamide resin containing a reaction product of an acid component containing polymerized fatty acids and / or dimer acids and an aliphatic and / or aromatic polyamine, and even more preferably a polyamide resin that partially contains primary and secondary monoamines.

[0049] The polybasic acids used as raw materials for polyamide resins are not limited to the following, but include adipic acid, sebacic acid, azelaic acid, phthalic anhydride, isophthalic acid, suberic acid, glutaric acid, fumaric acid, pimelic acid, oxalic acid, malonic acid, succinic acid, maleic acid, terephthalic acid, 1,4-cyclohexyldicarboxylic acid, trimellitic acid, dimeric acid, hydrogenated dimeric acid, and polymerized fatty acids. Among these, polyamide resins containing structures derived from dimeric acid or polymerized fatty acids (50% by mass or more in the polyamide resin) are preferred. Here, polymerized fatty acids are obtained by cyclization reactions of unsaturated fatty acids, and include monobasic fatty acids, dimerized polymerized fatty acids (dimeric acid), and trimerized polymerized fatty acids. The fatty acids constituting polymerized fatty acids or dimeric acid are preferably derived from natural oils such as soybean oil, palm oil, and rice bran oil, and those obtained from oleic acid and linoleic acid are preferred. Monocarboxylic acids can also be used in combination with polybasic acids. Examples of monocarboxylic acids that can be used in combination include acetic acid, propionic acid, lauric acid, palmitic acid, benzoic acid, and cyclohexanecarboxylic acid.

[0050] Examples of polyhydric amines used as raw materials for polyamide resins include polyamines and primary or secondary monoamines. Examples of polyamines include aliphatic diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, and methylaminopropylamine; aliphatic polyamines such as diethylenetriamine and triethylenetetramine; alicyclic polyamines such as cyclohexylenediamine and isophoronediamine; aromatic aliphatic polyamines such as xylylenediamine; and aromatic polyamines such as phenylenediamine and diaminodiphenylmethane. Furthermore, examples of primary and secondary monoamines include n-butylamine, octylamine, diethylamine, monoethanolamine, monopropanolamine, diethanolamine, and dipropanolamine.

[0051] The polyamide resin used in the present invention preferably has a molecular weight distribution of 3,000 or less in the weight fraction measured by gel permeation chromatography (GPC) of the tetrahydrofuran-soluble portion, where the area ratio (area percentage) of the total peak area of ​​the molecular weight distribution curve is 10 to 50%, and more preferably 20 to 40%. In the low molecular weight range of 3,000 or less, polyamide resins melt at low temperatures, making them easier to wet and spread on the substrate, resulting in good adhesion to the substrate. By containing polyamide resins, cellulose resins, fatty acid amides, and chelating agents with a molecular weight of 3,000 or less and an area percentage of 10-50%, both adhesion to the substrate and resistance to blocking are achieved. The area ratio (%) is the area percentage (%) within the range of Log(3,000) or less and Log(50,000) or more, in a molecular weight distribution map where the vertical axis is the area percentage (%) of molecular weight M and the horizontal axis is the common logarithm LogM of molecular weight M.

[0052] The polyamide resin is preferably contained in an amount of 3 to 15% by mass, and more preferably 5 to 12% by mass, in solid content per 100% by mass of the total ink. When the amount is 3% by mass or more, adhesion to the substrate is improved, and when it is 15% by mass or less, the fluidity and leveling properties of the printing ink are improved, resulting in good storage stability and printability.

[0053] Furthermore, the polyamide resin preferably has a softening point of 80 to 140°C, and more preferably 90 to 130°C. In the above embodiment, the ink film becomes stronger. When the softening point is 80°C or higher, the surface tack breakage of the ink film on the printed material is good, preventing blocking. When the softening point is 140°C or lower, the ink film becomes flexible, improving adhesion to the substrate. Note that the softening point is the value measured according to JIS K2207 (ring-ball method). Preferred polyamide resins include the Rheomide series (manufactured by Kao Corporation) and the Polymide series (manufactured by Sanyo Chemical Industries, Ltd.).

[0054] <Vinyl chloride resin> The vinyl chloride resin used in the present invention is not particularly limited as long as it contains structural units derived from vinyl chloride and structural units derived from other monomers. Among these, vinyl chloride-vinyl acetate copolymer resins are preferred. In the present invention, the vinyl chloride resin is preferably present in a solid content of 0.5 to 10% by mass, and more preferably 0.7 to 5% by mass, per 100% by mass of the total mass of the ink.

[0055] (Vinyl chloride-vinyl acetate copolymer resin) Vinyl chloride-vinyl acetate copolymer resin is obtained by copolymerizing vinyl chloride monomer and vinyl acetate monomer. The molecular weight is preferably 5,000 to 100,000 by weight average, and more preferably 20,000 to 70,000. The structure derived from vinyl acetate monomer is preferably 1 to 30% by mass, more preferably 1 to 20% by mass, in the 100% by mass solid content of the vinyl chloride-vinyl acetate copolymer resin, and the structure derived from vinyl chloride monomer is preferably 70 to 99% by mass, more preferably 80 to 99% by mass. In this case, solubility in organic solvents is improved, and the adhesion to the substrate and the physical properties of the ink layer tend to be better. Furthermore, it is preferable that the material has hydroxyl groups, and this can be obtained by further using vinyl alcohol in copolymerization or by saponifying a portion of the vinyl acetate. The monomer ratios of vinyl chloride, vinyl acetate, and vinyl alcohol affect the properties of the resin film and the resin dissolution behavior. For example, vinyl chloride is thought to impart toughness and hardness to the resin film, vinyl acetate imparts adhesion and flexibility, and vinyl alcohol imparts good solubility in polar solvents.

[0056] The vinyl chloride-vinyl acetate copolymer resin is preferably contained in a solid content of 0.5 to 10% by mass per 100% by mass of the total ink mass, and more preferably 0.7 to 5% by mass. When the content is 0.5% by mass or more, various resistances of the printing ink layer, such as blocking resistance, abrasion resistance, and heat resistance, are improved, and when it is 10% by mass or less, the fluidity of the printing ink tends to improve, resulting in good storage stability. The hydroxyl value of the vinyl chloride-vinyl acetate copolymer resin is preferably 50 to 180 mgKOH / g, and more preferably 70 to 160 mgKOH / g. The glass transition temperature is preferably 50°C to 90°C, and more preferably 60 to 80°C.

[0057] The combination of the above polyurethane resin and the above vinyl chloride resin functions effectively as a binder resin. When other resins are used in combination, it is preferable that the total amount of polyurethane resin and vinyl chloride resin be 60% by mass or more, and more preferably 80% by mass or more, of the solid content of the binder resin. This is thought to result in good adhesion to the substrate. Furthermore, the solid content mass ratio (polyurethane resin:vinyl chloride resin) of the polyurethane resin and the vinyl chloride resin is preferably 95:5 to 50:50, and more preferably 90:10 to 60:40. With this combination and mixing ratio, the various resistances of the printing ink layer, such as adhesion to the substrate, blocking resistance, abrasion resistance, and heat resistance, tend to be good.

[0058] <Cellulose resin> Examples of cellulose-based resins include cellulose acetate propionate, cellulose acetate butyrate and other cellulose ester resins, nitrocellulose, hydroxyalkylcellulose, and carboxyalkylcellulose. Cellulose ester resins preferably have an alkyl group, and examples of such alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, and hexyl groups, and the alkyl group may also have substituents. As the cellulose-based resin, cellulose acetate propionate, cellulose acetate butyrate, and nitrocellulose are preferred among the above. Nitrocellulose is particularly preferred. In the present invention, the cellulose-based resin is preferably present in a solid content of 1 to 15% by mass, and more preferably 2 to 10% by mass, per 100% by mass of the total mass of the ink.

[0059] (Nitrocellulose) The above-mentioned nitrocellulose is preferably obtained as a nitrate ester by reacting natural cellulose with nitric acid, thereby substituting three hydroxyl groups in the six-membered ring of the anhydrous glucopyranose group in the natural cellulose with nitrate groups, and is preferably in the range of 20 to 200, and more preferably 30 to 150, with an average degree of polymerization in the range of 20 to 200. When the average degree of polymerization is 20 or higher, the strength of the ink layer and the abrasion resistance are improved. When the average degree of polymerization is 200 or lower, the solubility in solvents, the low-temperature stability of the ink, and the compatibility with the co-used resin are improved. The weight-average molecular weight is preferably 5,000 to 200,000, and more preferably 10,000 to 50,000. Furthermore, the glass transition temperature is preferably 120°C to 180°C, more preferably 140 to 180°C, and the nitrogen content is preferably 10.5 to 12.5% ​​by mass. When used in combination with polyurethane resin or polyamide resin, the physical properties of the ink film, such as blocking resistance, scratch resistance, and heat resistance, tend to be further improved. Nitrocellulose is preferably contained in a solid content of 1 to 15% by mass per 100% by mass of the total ink mass, and more preferably in a solid content of 2 to 10% by mass. When the content is 1% by mass or more, various resistances of the printing ink layer, such as blocking resistance, abrasion resistance, and heat resistance, are improved, and when it is 10% by mass or less, the fluidity of the printing ink tends to improve, resulting in good storage stability. Preferred nitrocellulose resins include the TR series (manufactured by TNC Industrial) and the DLX series (manufactured by Nobel Enterprises).

[0060] The solid content mass ratio of the polyurethane resin and the cellulose-based resin is preferably 90:10 to 40:60, and more preferably 80:20 to 50:50. This combination and mixing ratio results in good adhesion to the substrate, as well as good resistance to various aspects of the printing ink layer, such as blocking, abrasion, and heat. When other resins are used in combination, it is preferable that the binder resin contains a total of 60% or more by mass of polyurethane resin and cellulose-based resin, and more preferably 80% or more by mass, of the solid content of 100% by mass. This is thought to result in good adhesion to the substrate.

[0061] Furthermore, the solid content mass ratio of the polyamide resin and the cellulose-based resin is preferably 90:10 to 40:60, and more preferably 80:20 to 45:55. With this combination and blending ratio, the various resistances of the printing ink layer, such as adhesion to the substrate, blocking resistance, abrasion resistance, and heat resistance, tend to be good. When other resins are used in combination, it is preferable that the binder resin contains a total of 60% or more by mass of polyamide resin and cellulose-based resin, and more preferably 80% or more by mass, of the solid content of 100% by mass. This is thought to result in good adhesion to the substrate.

[0062] <Polyvinyl acetal resin> The polyvinyl acetal resin used in the present invention is obtained by reacting polyvinyl alcohol with an aldehyde. Among these, polyvinyl butyral resin is preferred. In the present invention, the polyvinyl acetal resin is preferably present in a solid content of 0.5 to 10% by mass, and more preferably 0.7 to 5% by mass, per 100% by mass of the total mass of the ink.

[0063] (Polyvinyl butyral resin) Polyvinyl butyral resin is obtained by reacting polyvinyl alcohol with butyraldehyde and is composed of units of butyral groups, aldehyde groups, and hydroxyl groups. The weight-average molecular weight is preferably 10,000 to 60,000, and more preferably 15,000 to 40,000. Within this weight-average molecular weight range, pigment dispersibility and viscosity are good, and ink storage stability is improved. The butyral group units in 100% by mass of the solids content of the polyvinyl butyral resin are preferably 65 to 95% by mass, and more preferably 75 to 85% by mass. When the solids content is 65% by mass or more, the ink film becomes stronger, and blocking resistance, abrasion resistance, and oil resistance are improved. When the solids content is 95% by mass or less, the solubility of the polyvinyl butyral resin increases, improving ink storage stability and printability. The aldehyde group unit is preferably 0.5 to 10% by mass, more preferably 1 to 7% by mass, to suppress ink viscosity increase. The hydroxyl group unit is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, as the OH group is thought to improve adhesion to the substrate. Furthermore, polyvinyl butyral resin is preferably contained in a solid content of 0.5 to 10% per 100% of the total mass of the ink, and more preferably 0.7 to 5% per 100% of the total mass. When the content is 0.5% or more, various resistances of the printing ink layer, such as blocking resistance, abrasion resistance, and heat resistance, are improved, and when it is 10% or less, the fluidity of the printing ink tends to improve, resulting in good storage stability. The glass transition temperature is preferably 50°C to 90°C, and more preferably 60°C to 80°C. A preferred polyvinyl butyral resin is the S-LEC B series (Sekisui Chemical Co., Ltd.). Examples include (manufactured by...).

[0064] The combination of the above polyurethane resin and the above polyvinyl acetal resin functions effectively as a binder resin. When other resins are used in combination, it is preferable that the total content of the polyurethane resin and polyvinyl acetal resin be 60% by mass or more, and more preferably 80% by mass or more, of the solid content of the binder resin. Adhesion to the substrate tends to be good. Furthermore, the solid content mass ratio (polyurethane resin:vinyl chloride resin) of the polyurethane resin and the polyvinyl acetal resin is preferably 95:5 to 50:50, and more preferably 90:10 to 60:40. This combination and mixing ratio result in good adhesion to the substrate, as well as good resistance to various aspects of the printing ink layer, such as blocking, abrasion, and heat.

[0065] <Ecogenic rubber> Cyclized rubber refers to conjugated diene rubbers such as natural rubber and synthetic isoprene rubber, in which some of the chain molecules in the rubber molecule are cyclized in the presence of a cyclization catalyst. Specifically, a conjugated diene monomer such as 1,3-butadiene or isoprene, or a conjugated diene monomer and monomers copolymerizable with a conjugated monomer, is polymerized using an organically activated metal catalyst such as an organolithium compound to obtain a conjugated diene polymer. Next, the conjugated diene polymer is subjected to a cyclization catalyst such as sulfuric acid, an organic sulfonic acid, or a metal halide to obtain a conjugated diene polymer cyclized product (cyclized rubber). The gravure ink for surface printing of the present invention is expected to have improved substrate adhesion, abrasion resistance, oil resistance, and heat resistance due to the inclusion of cyclized rubber.

[0066] The weight-average molecular weight of the cyclized rubber is preferably 1,000 to 50,000, and more preferably 3,000 to 30,000. When the weight-average molecular weight is 1,000 or higher, the ink film immediately after printing becomes stronger, improving blocking resistance, abrasion resistance, and oil resistance. When the molecular weight is 50,000 or lower, the solubility of the cyclized rubber increases, and the storage stability and printability of the ink tend to improve. Furthermore, the cyclized rubber is preferably contained in a solid content of 0.1 to 5% per 100% of the total mass of the ink, and more preferably in a solid content of 0.2 to 4%. When the content is 0.1% or more, blocking resistance, abrasion resistance, and oil resistance are improved, and when it is 5% or less, the storage stability and printability of the ink tend to improve.

[0067] The cyclized rubber preferably has a softening point of 90 to 150°C, and more preferably 100 to 140°C. The ink film becomes stronger within this range. When the softening point is 90°C or higher, the surface tack breakage of the ink film on the printed material is good, preventing blocking. When the softening point is 150°C or lower, the ink film becomes more flexible, and it is thought that the adhesion to the substrate is improved. In addition, to obtain similar effects, the glass transition temperature of the cyclized rubber is preferably 50 to 150°C, and more preferably 60 to 120°C.

[0068] Furthermore, among cyclized rubbers, cyclized rubber derivatives containing polar groups and / or aromatic ring structures are preferred. In particular, cyclized rubber derivatives to which polar groups such as anhydride groups, carboxyl groups, and hydroxyl groups are attached, and cyclized rubber derivatives having phenolic groups are preferred, with cyclized rubber derivatives having phenolic groups being especially preferred. It is believed that cyclized rubber derivatives having phenolic groups improve blocking resistance, abrasion resistance, and oil resistance by strengthening the ink film through hydrogen bonding between phenolic OH groups, and that adhesion is improved by the reaction between the phenolic OH groups and the substrate treated surface. Furthermore, it is believed that the presence of aromatic ring groups such as phenolic groups strengthens the ink film, further improving blocking resistance, abrasion resistance, and oil resistance. The aromatic ring groups (aromatic ring structures) are preferably contained in the cyclized rubber derivative at a concentration of 0.5 to 20% by mass, and more preferably at a concentration of 1 to 10% by mass.

[0069] <Fatty acid amide> The gravure printing ink for surface printing of the present invention contains a fatty acid amide. In the present application, the fatty acid amide refers to a compound having an amide group or an amide bond, and a monoamide having a total number of amide groups and amide bonds of 1 and a bisamide having a total number of amide groups and amide bonds of 2 are preferred. The fatty acid amide mainly has a function of improving blocking resistance, such as blocking resistance to a vinyl chloride sheet and blocking resistance to an anti-fogging film, and is particularly effective in blocking resistance to an anti-fogging film.

[0070] (Monoamide) The monoamide is represented by the following general formula (5) or general formula (6). General formula (5) R 1 -CONH General formula (6) R 2 -CONH-R 3 (In the formula, R 1 , R 2、 and R 3 represent aliphatic hydrocarbon groups having 10 to 25 carbon atoms, and may be the same or different.)

[0071] Examples of the monoamide include lauric acid amide, palmitic acid amide, stearic acid amide, hydroxystearic acid amide, behenic acid amide, oleic acid amide, erucic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, N-oleyl palmitic acid amide, N-oleyl oleic acid amide, etc. Among them, palmitic acid amide, oleic acid amide, and erucic acid amide are preferred, and oleic acid amide and erucic acid amide are more preferred.

[0072] (Bisamide) The bisamide is represented by the following general formula (7) or general formula (8). General formula (7) R 4 -CONH-R 5 -HNCO-R 6 General formula (8) R 7 -NHCO-R 8 -CONH-R 9 (In the formula, R 4 , R 6 , R 7 , and R 9 R represents an aliphatic hydrocarbon group having 10 to 25 carbon atoms, and may be the same or different. 5 and R 8 (This represents an alkylene group or an arylene group.)

[0073] Examples of bisamides include methylenebisstearate, ethylenebiscaprate, ethylenebislaurate, ethylenebisstearate, ethylenebishydroxystearate, ethylenebisbehenamide, hexamethylenebisstearate, hexamethylenebisbehenamide, hexamethylenebishydroxystearate, ethylenebisoleamide, ethylenebiserucamide, and hexamethylenebisoleamide. Examples include N,N'-distearyl adipic acid amide, N,N'-distearyl sebacin acid amide, N,N'-dioleyl adipic acid amide, and N,N'-dioleyl sebacin acid amide, with ethylenebisstearate amide, ethylenebisoleate amide, hexamethylenebisoleate amide, and N,N'-dioleyl adipic acid amide being preferred, and ethylenebisoleate amide, hexamethylenebisoleate amide, and N,N'-dioleyl adipic acid amide being more preferred.

[0074] The weight-average molecular weight of the fatty acid amide is preferably 200 to 1,500, and more preferably 250 to 1,000. When the weight-average molecular weight is 200 or higher, blocking resistance is improved. When the molecular weight is 1,500 or lower, it becomes easier to orient on the surface of the ink film after printing, resulting in tape peelability and slipperiness, and good adhesion and abrasion resistance to the substrate. By using the binder resin in combination with a fatty acid amide within the above weight-average molecular weight range, adhesion and blocking resistance to the substrate are further improved. Furthermore, the fatty acid amide is preferably contained in a solid content of 0.1 to 5% per 100% of the total ink mass, and more preferably 0.2 to 4% per 100% of the total ink mass. When the content is 0.1% or more, blocking resistance is improved, and when it is 5% or less, ink storage stability, printability, and oil resistance are improved.

[0075] The fatty acid amide preferably has a softening point of 80 to 150°C, more preferably 90 to 130°C. The ink film becomes stronger within this range. When the softening point is 80°C or higher, the surface tack breakage of the ink film on the printed material is good, preventing blocking. When the softening point is 140°C or lower, the ink film becomes flexible, improving adhesion to the substrate.

[0076] Furthermore, among the above fatty acid amides, bisamides are preferred. Bisamides have more amide groups per molecule than monoamides and have a relatively low weight-average molecular weight. Therefore, in the case of bisamides, there are more amide groups oriented on the surface of the ink film compared to monoamides, and it is thought that the blocking resistance is further improved through interaction with the substrate in contact with the ink film.

[0077] The fatty acids constituting the bisamide are preferably saturated fatty acids having 10 to 22 carbon atoms and / or unsaturated fatty acids having 16 to 25 carbon atoms, and more preferably saturated fatty acids having 12 to 18 carbon atoms and / or unsaturated fatty acids having 18 to 22 carbon atoms. Examples of saturated fatty acids include lauric acid, palmitic acid, stearic acid, behenic acid, and hydroxystearic acid, while examples of unsaturated fatty acids include oleic acid and erucic acid. Bisamides composed of unsaturated fatty acids are particularly preferred in terms of solubility in organic solvents and printability.

[0078] Furthermore, by using the above-mentioned cyclized rubber and fatty acid amide in combination, it is expected that the adhesion to the substrate immediately after printing will be improved. It is presumed that by using cyclized rubber and fatty acid amide in combination, the cyclized portion, which is a unique structure in the cyclized rubber molecule, quickly forms an ink film with the fatty acid amide, which is oriented on the surface of the coating film, thus improving adhesion to the substrate immediately after printing. In order to achieve both adhesion to the substrate immediately after printing and blocking resistance, the solid content mass ratio of cyclized rubber to fatty acid amide is preferably 1:20 to 20:1, more preferably 1:15 to 15:1, and even more preferably 1:10 to 10:1. If the solid content mass ratio of cyclized rubber to fatty acid amide is greater than 1:20, the ink film and adhesion will be stronger immediately after printing. If the weight ratio of cyclized rubber to fatty acid amide is greater than 20:1, the amount of amide groups oriented on the surface of the ink film will increase, improving blocking resistance, thus achieving both adhesion to the substrate immediately after printing and blocking resistance.

[0079] <Chelating agent> In addition to the above requirements, the gravure printing ink for surface printing of the present invention preferably further uses a chelating agent. The inclusion of a chelating agent improves the bonding strength with the substrate and the cohesive force in the ink film, thereby improving adhesion to the substrate, abrasion resistance, and heat resistance. Chelating agents include organotitanium compounds and organozirconium compounds, with titanium chelates having Ti-OC type bonds and zirconium chelates having Zr-OC type bonds in one molecule being preferred. Chelating agents generally require heating to complete the crosslinking reaction, but are less prone to hydrolysis at room temperature, have excellent stability, and are suitable for use in inks, and can be used appropriately. Specifically, examples include titanium alkoxides such as tetraisopropyl titanate, tetran-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, tetramethyl titanate, and tetrastearyl titanate; titanium chelates such as triethanolamine titanate, titanium acetylacetonate, titanium ethylacetoacetate, titanium lactate, octylene glycol titanate, and titanium tetraacetylacetonate; and zirconium chelates such as zirconium monoacetylacetonate, zirconium tetraacetylacetonate, and zirconium ethylacetoacetate.

[0080] In the present invention, in terms of improving adhesion to the substrate, abrasion resistance, and heat resistance, it is preferable to use acetylacetone-based titanium chelate and / or alkyl acetoacetate-based titanium chelate among the above chelating agents. Furthermore, the blocking resistance is further improved by using the fatty acid amide in combination with the acetylacetone-based titanium chelate and / or alkyl acetoacetate-based titanium chelate. To achieve both adhesion to the substrate and blocking resistance, the mass ratio of the fatty acid amide to the acetylacetone-based titanium chelate and / or alkyl acetoacetate-based titanium chelate is preferably 10:90 to 90:10, and more preferably 15:85 to 85:15.

[0081] The chelating agent is preferably contained in an amount of 0.1 to 5% by mass per 100% of the total mass of the ink. When the amount is 0.1% by mass or more, adhesion, abrasion resistance, and heat resistance are improved. Furthermore, when the amount is 5% by mass or less, the storage stability and printability of the ink are thought to be improved.

[0082] <Hydroxide wax particles> The gravure printing ink for surface printing of the present invention preferably further contains hydrocarbon wax particles. Examples of hydrocarbon wax particles include polyolefin wax and paraffin wax, and it is preferable that they be contained in an amount of 0.1 to 3% by mass, and more preferably 0.3 to 2.5% by mass, per 100% by mass of the total ink mass. When the amount is 0.1% by mass or more, abrasion resistance is improved. Furthermore, when the amount is 3% by mass or less, gloss, ink storage stability, and printability tend to improve.

[0083] The hardness (penetration) of hydrocarbon wax particles at 25°C, as defined in JIS K2207, is preferably 12 or less, more preferably 0.5 to 10, and more preferably 1 to 8. When within this range, friction resistance and slipperiness tend to be good. The melting point of hydrocarbon wax particles in DSC measurement is preferably 90 to 150°C, and more preferably 100 to 125°C. When within this range, the storage stability of the ink and the blocking resistance of the printed material tend to be good. Note that the melting point of hydrocarbon wax particles represents the melting point of the peak top (minimum value) of the endothermic peak in the DSC heating curve. The average particle diameter of hydrocarbon wax particles is preferably 0.5 to 12 μm, more preferably 1 to 10 μm, and more preferably 1.5 to 4 μm. Note that the average particle diameter of hydrocarbon wax particles represents the D50 value measured by dynamic light scattering.

[0084] <Colorants, Pigments> The gravure printing ink for surface printing of the present invention may contain a colorant. Examples of colorants include pigments. The pigments usable in the present invention are not particularly limited, and various inorganic pigments and organic pigments that can be used in printing inks and paints in general can be suitably used. Examples of inorganic pigments include colored pigments such as titanium dioxide, red iron oxide, Prussian blue, ultramarine, carbon black, and graphite, and extender pigments such as calcium carbonate, kaolin, clay, barium sulfate, aluminum hydroxide, and talc. Suitable organic pigments include soluble azo pigments, insoluble azo pigments, azo lake pigments, condensed azo pigments, copper phthalocyanine pigments, and condensed polycyclic pigments. However, the pigments are not limited to these, and those listed by their generic names in the color index can be used as appropriate. The content of these pigments is preferably 0.5 to 50% by mass per 100% by mass of the total ink mass.

[0085] <Additives> Various additives may be used in the gravure printing ink for surface printing of the present invention as needed. Examples include pigment dispersants, extender pigments, inorganic fine particles, leveling agents, and adhesion aids. Specifically, various additives can be used, such as pigment dispersants to improve the dispersibility of pigments, extender pigments to improve drying properties and film opacity, inorganic fine particles to provide anti-slip properties, leveling agents to improve leveling properties, defoaming agents to provide defoaming properties, and adhesion aids to improve adhesion to the substrate. The content of these additives is preferably 0.1 to 10% by mass in terms of solid content or active ingredients per 100% by mass of the total mass of the ink.

[0086] <Organic solvents> The solvents used in the ink of the present invention mainly include alcohol-based organic solvents such as methanol, ethanol, n-propanol, isopropanol, and butanol; ketone-based organic solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ester-based organic solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; aliphatic hydrocarbon-based organic solvents such as n-hexane, n-heptane, and n-octane; and alicyclic hydrocarbon-based organic solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, cycloheptane, and cyclooctane. It is preferable to use a mixture of these solvents, taking into consideration the solubility and drying properties of the binder resin and cyclized rubber. The amount of these organic solvents used is preferably 20% by mass or more per 100% by mass of the total ink mass. Furthermore, for odor control during printing and environmental considerations, it is preferable that the organic solvent mainly consists of a mixed solvent of ester-based organic solvent and alcohol-based organic solvent, with a mass ratio (ester-based organic solvent: alcohol-based organic solvent) of 50:50 to 90:10. Furthermore, in order to improve the solubility of the ink, it is preferable to include methylcyclohexane in an amount of 5 to 40% by mass per 100% by mass of the total ink mass.

[0087] <Manufacturing of gravure printing inks for surface printing> One method for producing the gravure printing ink for surface printing according to the present invention is to first uniformly stir and mix a composition containing pigment, binder resin, cycloadhesive rubber, fatty acid amide, chelating agent, organic solvent, and optionally hydrocarbon wax particles and other additives using a bladed agitator, then disperse it using various kneading machines such as bead mills, ball mills, sand mills, attritors, roll mills, pearl mills, etc., and further mix in other resins and additives. Among these, it is preferable to knead and disperse the composition containing pigment after stirring and mixing using a bead mill.

[0088] <Base material> The printing ink of the present invention is printed on a substrate to form a printed product. The substrate is not particularly limited, but is preferably a film substrate. Examples include polyolefin substrates such as polyethylene and polypropylene, polyester substrates such as polyethylene terephthalate, polycarbonate, and polylactic acid, polystyrene-based substrates such as polystyrene, AS resin, and ABS resin, film substrates such as nylon substrates, polyamide substrates, polyvinyl chloride substrates, polyvinylidene chloride substrates, and cellophane substrates, and film substrates made of composite materials thereof. The plastic substrate may have metals or metal oxides such as silica, alumina, and aluminum deposited on it, and the deposited surface may be further coated with a paint such as polyvinyl alcohol. Generally, the surface of the substrate to be printed is often subjected to surface treatment such as corona treatment. Furthermore, the substrate can also be an anti-fogging film or a matte film obtained by processing a plastic film in advance by coating or kneading in an anti-fogging agent, or by surface coating or kneading in a matting agent. Furthermore, the base material may be a single layer or a laminate (base material layer) in which two or more base materials are stacked. The base materials constituting the base material layer may be the same or different. In particular, a polyolefin substrate is preferred. The polyolefin substrate may or may not be surface-treated.

[0089] The anti-fogging agent is preferably a surfactant, and one or more ionic surfactants such as polyhydric alcohol fatty acid esters such as sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene fatty acid ester, and glycerin fatty acid ester, or ethylene oxide adducts are used.

[0090] <Printed material> Printed materials are formed by printing gravure printing ink for surface printing onto a substrate. After printing on the substrate using the gravure printing ink for surface printing of the present invention, the ink layer is formed by removing volatile components using a hot air oven or the like, thereby obtaining the printed material. The printing method is gravure printing, for example, the ink is diluted with a diluent solvent to a viscosity and concentration suitable for gravure printing, supplied to each printing unit either alone or in mixtures, and printed. The ink layer is then fixed by drying in an oven. Furthermore, inks that do not contain pigments or other colorants are also called overprint varnishes (OP varnishes) and can be used to form an OP layer. Specifically, after forming the above-mentioned ink layer containing a colorant, printing is performed to cover the ink layer, and the OP layer is formed by drying in an oven. [Examples]

[0091] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the present invention, parts and % refer to parts by mass and mass %, respectively, unless otherwise noted.

[0092] <Weight-average molecular weight and number-average molecular weight> The weight-average molecular weight (Mw) and number-average molecular weight (Mn) were determined by GPC (gel permeation chromatography). The molecular weight distribution was measured using Showa Denko's "Shodex GPC-104," and the polystyrene-equivalent molecular weight was determined. The measurement conditions are shown below. Columns: Use the following multiple columns linked in series. Two Shodex LF-404 tubes manufactured by Showa Denko. Showa Denko Shodex LF-G Detector: RI (Differential Refractometer), Column temperature: 40℃ Eluent: Tetrahydrofuran Flow rate: 0.3mL / min

[0093] <Preparation of polyurethane resin solution> In a four-necked flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, 103.2 parts of polyester polyol (condensation molar ratio 1:1), a condensate of 3-methyl-1,5-pentanediol and sebacic acid with a number average molecular weight of 2000, 35.2 parts of neopentyl glycol, 121.4 parts of isophorone diisocyanate, 0.03 parts of stannous 2-ethylhexylate, and 65.1 parts of ethyl acetate were charged. The mixture was reacted at 90°C for 2 hours under a nitrogen stream, and 165.3 parts of ethyl acetate was added and cooled to obtain 490.2 parts of a solvent solution of the terminal isocyanate prepolymer. Next, the obtained 490.2 parts of terminal isocyanate prepolymer was gradually added at room temperature to a mixture of 33.6 parts of isophorone diamine, 1.2 parts of di-n-butylamine, 237.5 parts of ethyl acetate, and 200.6 parts of isopropyl alcohol, and the mixture was then reacted at 50°C for 1 hour. Subsequently, 5.3 parts of isophorone diisocyanate were added to adjust the viscosity, and then the solid content was adjusted to 30% with a mixed solvent consisting of ethyl acetate and isopropyl alcohol in a ratio of 65:35 (by weight), yielding a polyurethane resin solution with Mw = 37,000 and Mn = 9,830.

[0094] <Preparation of polyamide resin solution> A polyamide resin with Mw=10,200 and Mn=1,470 was synthesized with reference to the examples in Japanese Patent Publication No. 6255123. Next, 30 parts of the polyamide resin were mixed and dissolved in 70 parts of a mixed solvent consisting of n-propyl acetate, ethyl acetate, isopropyl alcohol, and methylcyclohexane in a weight ratio of 20:20:20:40 to obtain a polyamide resin solution with a solid content of 30%. Polyamide resins are polyamide resins that have constituent units derived from polymerized fatty acids and / or dimer acids in the polyamide resin and have a softening point of 100 to 130°C.

[0095] <Preparation of vinyl chloride-vinyl acetate copolymer resin solution> 20 parts of vinyl chloride-vinyl acetate copolymer resin (manufactured by Nisshin Chemical Co., Ltd., product name Solvine TA5R) were mixed and dissolved in 80 parts of ethyl acetate to obtain a vinyl chloride-vinyl acetate copolymer resin solution with a solid content of 20%.

[0096] <Preparation of Nitrocellulose Solution> Twenty parts of nitrocellulose wetted with isopropyl alcohol (manufactured by TNC INDUSTRIAL, product name NC TR2) were mixed and dissolved in 80 parts of a mixed solvent consisting of n-propyl acetate, ethyl acetate, isopropyl alcohol, and methylcyclohexane in a weight ratio of 20:20:20:40 to obtain a nitrocellulose solution with a solid content of 20%.

[0097] <Preparation of polyvinyl butyral resin solution> Twenty parts of polyvinyl butyral resin (manufactured by Sekisui Chemical Co., Ltd., product name Esrec BL-1) were mixed and dissolved in ethyl acetate:isopropyl alcohol:ethyl alcohol = 30:40:30 (by weight) to obtain a polyvinyl butyral resin solution with a solid content of 20%.

[0098] <Preparation of cyclized rubber solution> The following cyclized rubber was synthesized with reference to the examples in Japanese Patent Publication No. 57-145103 or Japanese Patent No. 4207587. Cycloidal rubber (1): A cycloidal rubber derivative containing 3% by mass of a phenolic ring structure, Mw = 8,200 Cycloidal rubber (2): Cycloidal rubber derivative containing 5% by mass of a phenolic ring structure, Mw = 25,000 Cycloidal rubber (3): Cycloidal rubber, Mw=7,500, no aromatic ring structure. Cycloidal rubber (4): Cycloidal rubber derivative containing 18% by mass of a phenolic ring structure, Mw = 8,200 Cycloidal rubber (5): A cycloidal rubber derivative containing 25% by mass of a phenolic ring structure, Mw = 9,000 Cyclo-rubber (6): Cyclo-rubber derivative containing 3% by mass of a phenolic ring structure, Mw = 1,400 Cyclo-rubber (7): Cyclo-rubber derivative containing 3% by mass of a phenolic ring structure, Mw=900 Cyclo-rubber (8): Cyclo-rubber derivative containing 3% by mass of a phenolic ring structure, Mw = 47,000 Cyclo-rubber (9): Cyclo-rubber derivative containing 3% by mass of a phenolic ring structure, Mw = 55,000 Twenty parts of each cyclized rubber were mixed and dissolved in 80 parts of a mixed solvent consisting of ethyl acetate, isopropyl alcohol, and cyclohexane in a weight ratio of 20:40:40 to obtain a cyclized rubber solution with a solid content of 20%.

[0099] <Chelating agent> Titanium Chelate (1): Acetylacetone-based Titanium Chelate Titanium chelate (2): Alkyl acetoacetate-based titanium chelate Zirconium chelate: Acetylacetone-based zirconium chelate

[0100] <Fatty acid amide> Bisamide: Hexamethylenebisoleamide, Mw=650 Monoamide: Palmitic acid amide, Mw=260

[0101] <Hydroxide wax particles> Polyethylene wax (manufactured by Mitsui Chemicals, product name: High Wax 320MP)

[0102] <Example 1> A gravure printing ink for surface printing (ink S1) was prepared by kneading 10 parts of a phthalocyanine-based blue pigment (Toyo Color Co., Ltd. Lionol Blue FG-7400G (CI Pigment Blue 15:4)), 34 parts of polyurethane resin solution, 6 parts of vinyl chloride-vinyl acetate copolymer resin solution, 5 parts of cyclocompound rubber solution (1), 1 part of bisamide, 0.5 parts of monoamide, 1 part of titanium chelate (1), 1 part of titanium chelate (2), 1 part of polyethylene wax, and 40.5 parts of a mixed solvent (1) consisting of n-propyl acetate:ethyl acetate:isopropyl alcohol:methylcyclohexane = 30:25:30:15 (weight ratio) in a sand mill (Eiger mill).

[0103] <Examples 2-26> Gravure printing inks for surface printing (inks S2 to S26) were obtained in the same manner as in Example 1, except that the raw materials and mixing ratios listed in Tables 1-1 and 1-2 were used.

[0104] <Example 27> A gravure printing ink for surface printing (ink S27) was prepared by kneading 37.4 parts of a mixed solvent (1) consisting of 10 parts of a phthalocyanine-based blue pigment (Lionol Blue FG-7400G (CI Pigment Blue 15:4) manufactured by Toyo Color Co., Ltd.), 34 parts of polyurethane resin solution, 15 parts of nitrocellulose solution, 5 parts of cyclocompound rubber solution (1), 1 part of bisamide, 0.5 parts of monoamide, 1 part of titanium chelate (1), 1 part of titanium chelate (2), 1 part of paraffin wax, and n-propyl acetate:ethyl acetate:isopropyl alcohol:methylcyclohexane = 30:25:30:15 (by weight ratio) in a sand mill (Eiger mill).

[0105] <Examples 28-51> Gravure printing inks for surface printing (inks S28-S51) were obtained in the same manner as in Example 27, except that the raw materials and mixing ratios listed in Tables 2-1 and 2-2 were used.

[0106] <Example 52> A gravure printing ink for surface printing (Ink S52) was prepared by kneading 10 parts of a phthalocyanine-based blue pigment (Lionol Blue FG-7400G (CI Pigment Blue 15:4) manufactured by Toyo Color Co., Ltd.), 34 parts of polyurethane resin solution, 5 parts of polyvinyl butyral resin solution, 5 parts of cyclocompound rubber solution (1), 1 part of bisamide, 0.5 parts of monoamide, 1 part of titanium chelate (1), 1 part of titanium chelate (2), 1 part of paraffin wax, and 41.5 parts of a mixed solvent (1) consisting of n-propyl acetate:ethyl acetate:isopropyl alcohol:methylcyclohexane = 30:25:30:15 (by weight ratio) in a sand mill (Eiger mill).

[0107] <Examples 53-76> Gravure printing inks for surface printing (inks S53-S76) were obtained in the same manner as in Example 52, except that the raw materials and mixing ratios listed in Tables 3-1 and 3-2 were used.

[0108] <Example 77> Ten parts of phthalocyanine-based blue pigment (Lionol Blue FG-7400G (CI Pigment Blue 15:4) manufactured by Toyo Color Co., Ltd.), 32 parts of polyamide resin solution, 31 parts of nitrocellulose solution, 5 parts of cyclocompound rubber solution (1), 1 part of bisamide, 0.5 parts of monoamide, 1 part of titanium chelate (1), 1 part of titanium chelate (2), 1 part of paraffin wax, and 23.3 parts of mixed solvent (2) consisting of n-propyl acetate:ethyl acetate:isopropyl alcohol:methylcyclohexane = 20:20:20:40 (by weight) were kneaded in a sand mill (Eiger mill) to obtain gravure printing ink for surface printing (Ink S77).

[0109] <Examples 78-101> Gravure printing inks for surface printing (inks S78 to S101) were obtained in the same manner as in Example 77, except that the raw materials and mixing ratios listed in Tables 4-1 and 4-2 were used.

[0110] <Comparative Examples 1-9> Gravure printing inks for surface printing (inks T1 to T9) were obtained in the same manner as in Example 1, except that the raw materials and mixing ratios listed in Table 5 were used.

[0111] <Manufacturing (printing) of gravure printed materials for cover printing> The gravure printing ink for surface printing obtained in Example 1 was diluted with a diluent solvent (n-propyl acetate:ethyl acetate:isopropyl alcohol:methylcyclohexane = 30:25:30:15 (by weight)), adjusted to 15 seconds in a Zahn cup No. 3, and used as a diluted ink for printing. Next, printing was performed on the corona-treated surface of a corona-discharge weakly treated polypropylene film (D-SHNY01, single-sided treatment, 28 μm, manufactured by DIC Corporation) or on an anti-fog film (AF-642S, double-sided anti-fog treatment, 25 μm, manufactured by Futamura Chemical Co., Ltd.) using a gravure proofing press with an etching plate depth of 30 microns (drying temperature 50°C, printing speed 50 m / min) to obtain the respective printed materials.

[0112] Polypropylene film printed materials and anti-fog film printed materials were obtained in the same manner as described above, except that the gravure printing inks for surface printing obtained in Examples 2 to 76 were used.

[0113] Polypropylene film prints and anti-fog film prints were obtained in the same manner as described above, except that the gravure printing inks for surface printing obtained in Comparative Examples 1-6 and 9 were used.

[0114] The gravure printing ink for surface printing obtained in Example 77 was diluted with a diluent solvent (n-propyl acetate:ethyl acetate:isopropyl alcohol:methylcyclohexane = 20:20:20:40 (by weight)), adjusted to 15 seconds in a Zahn cup No. 3, and used as a diluted ink for printing. Next, printing was performed on the corona-treated surface of a corona-discharge weakly treated polypropylene film (D-SHNY01, single-sided treatment, 28 μm, manufactured by DIC Corporation) or on an anti-fog film (AF-642S, double-sided anti-fog treatment, 25 μm, manufactured by Futamura Chemical Co., Ltd.) using a gravure proofing press with an etching plate depth of 30 microns (drying temperature 50°C, printing speed 50 m / min) to obtain printed materials.

[0115] Polypropylene film printed materials and anti-fog film printed materials were obtained in the same manner as described above, except that the gravure printing inks for surface printing obtained in Examples 78 to 101 were used.

[0116] Polypropylene film printed materials and anti-fog film printed materials were obtained in the same manner as described above, except that the gravure printing inks for surface printing obtained in Comparative Examples 7 and 8 were used.

[0117] The gravure printing inks for surface printing and their printed materials obtained in Examples 1-101 and Comparative Examples 1-9 were evaluated as described below. The results are shown in Tables 1-5.

[0118] <Adhesiveness> Adhesion was evaluated by the degree to which the ink film peeled off the polypropylene film printed on Examples 1-101 and Comparative Examples 1-9 was peeled off rapidly after applying adhesive tape (product name: cellophane tape) to the ink film surface of the printed material. The evaluation was performed immediately after printing and again at 25°C after 1 hour of storage at 25°C. A. The ink layer is not removed from the film. B. Cases where the area peeled from the ink layer film is less than a few points. C. Cases where the area peeled from the ink layer film is several points or more but less than 5%. D. The area peeled from the ink layer film is 5% or more but less than 15%. E. Products in which 15% or more of the ink layer has been peeled off from the film. Note that immediately after printing, scores of A, B, and C are considered passing, and after one hour, a score of A is considered passing.

[0119] <PVC blocking resistance> The printed materials printed on the polypropylene films of Examples 1-101 and Comparative Examples 1-9 were cut into 4cm squares, and the ink-coated surface of the printed material was placed on top of an antibacterial-treated soft polyvinyl chloride sheet cut to the same size, and a load of 0.5kg / cm² was applied. 2 After applying a load and leaving it in a 50°C, 80%RH atmosphere for 24 hours, the printed surface and the vinyl chloride sheet were peeled apart, and the PVC blocking resistance was evaluated based on the degree of ink film peeling. A. The ink layer is not removed from the polypropylene film. B. Products in which less than 5% of the area peeled off from the polypropylene film of the ink layer. C. Products in which the area peeled from the polypropylene film of the ink layer is 5% or more but less than 15%. D. Products in which the area peeled from the polypropylene film of the ink layer is 15% or more but less than 50%. E. Products in which 50% or more of the area peeled off from the polypropylene film of the ink layer. Furthermore, A, B, and C are within a range that does not pose any practical problems.

[0120] <Anti-fog film blocking properties> The anti-fogging film prints of each of the surface-printed gravure inks in Examples 1-101 and Comparative Examples 1-9 were measured at 50 kg / cm². 2 The printed material was wound up to 100m under a load, left in a 60°C atmosphere for 24 hours, and then the printed and unprinted sides of the printed material were peeled off from the core to evaluate the blocking resistance based on the degree of ink peeling. A. The ink layer is not removed from the film. B. Products in which less than 5% of the ink layer has been peeled from the film. C. Products in which the area peeled from the ink layer film is 5% or more but less than 15%. D. Cases where the area peeled from the ink layer film is 15% or more but less than 50%. E. Products in which 50% or more of the ink layer has been peeled off from the film. Furthermore, A, B, and C are within a range that does not pose any practical problems.

[0121] <Abrasion resistance> The ink layer surface of each gravure print printed on polypropylene film in Examples 1-101 and Comparative Examples 1-9 was placed on high-quality paper and evaluated using a Japan Society for the Promotion of Science (JSPS) type friction resistance tester. The evaluation conditions were a load of 500g × 100 cycles of friction, and the degree to which the ink layer peeled off from the film after friction was evaluated to determine the friction resistance. A. The ink layer is not removed from the film. B. Products in which less than 5% of the ink layer has been peeled from the film. C. Products in which the area peeled from the ink layer film is 5% or more but less than 15%. D. Cases where the area peeled from the ink layer film is 15% or more but less than 50%. E. Products in which 50% or more of the ink layer has been peeled off from the film. Furthermore, A, B, and C are within a range that does not pose any practical problems.

[0122] <Heat resistance> For each gravure print printed on polypropylene film in Examples 1-101 and Comparative Examples 1-9, a glossy aluminum foil was placed on the ink layer surface. The prints were then pressed together using a heat seal tester at a temperature of 170°C and a load of 2 kg for 1 second. The heat resistance was evaluated based on the degree of adhesion of the ink layer to the aluminum foil after the aluminum foil was peeled off following the pressing. A. No ink layer adheres to the aluminum foil. B. The area of ​​the ink layer adhering to the aluminum foil is less than 5% of the total pressure-applied area. C. The area of ​​the ink layer attached to the aluminum foil is 5% or more but less than 15% of the total pressure-applied area. D. The area of ​​the ink layer attached to the aluminum foil is 15% or more but less than 50% of the pressure-applied area. E. The area of ​​the ink layer attached to the aluminum foil is 50% or more of the pressure-applied area. Furthermore, A, B, and C are within a range that does not pose any practical problems.

[0123] <Oil resistance> Each gravure print printed on polypropylene film from Examples 1-101 and Comparative Examples 1-9 was cut to a size of 2 cm x 20 cm. Melted commercially available butter (Snow Brand Hokkaido Butter, manufactured by Snow Brand Megmilk Co., Ltd.) was applied to the entire surface of the ink layer, and after standing for 12 hours at 25°C, a cloth (Kanakin No. 3) was applied and evaluated using a Japan Society for the Promotion of Science (JSPS) type friction resistance tester. The evaluation conditions were a load of 200 g x 100 cycles of friction, and oil resistance was evaluated from the degree to which the ink layer peeled off from the film after friction. A. The ink layer is not removed from the film. B. Products in which less than 5% of the ink layer has been peeled from the film. C. Products in which the area peeled from the ink layer film is 5% or more but less than 15%. D. Cases where the area peeled from the ink layer film is 15% or more but less than 50%. E. Products in which 50% or more of the ink layer has been peeled off from the film. Furthermore, A, B, and C are within a range that does not pose any practical problems.

[0124] <Printability> For the gravure printing inks for surface printing obtained in Examples 1-101 and Comparative Examples 1-6 and 9, the viscosity was adjusted to 15 seconds (25°C) using a Zahn cup No. 3 with a diluent (n-propyl acetate: ethyl acetate: isopropyl alcohol: methylcyclohexane = 30:25:30:15 (weight ratio)). For the gravure printing inks for surface printing obtained in Examples 77-101 and Comparative Examples 7-8, the viscosity was adjusted to 15 seconds (25°C) using a diluent (n-propyl acetate: ethyl acetate: isopropyl alcohol: methylcyclohexane = 20:20:20:40 (weight ratio)). The area of ​​the plate overprint was visually determined and evaluated after 90 minutes of plate idle on the printing press. A. The area of ​​the print cover cannot be visually confirmed. B. Those with a plate overlap area of ​​0% or more but less than 5% C. Those with a plate cover area of ​​5% or more but less than 10%. D. Those with a plate cover area of ​​10% or more but less than 20% E. Those with a plate overlap area of ​​20% or more. Furthermore, A, B, and C are within a range that does not pose any practical problems.

[0125] [Table 1-1]

[0126] [Table 1-2]

[0127] [Table 2-1]

[0128] [Table 2-2]

[0129] [Table 3-1]

[0130] [Table 3-2]

[0131] [Table 4-1]

[0132] [Table 4-2]

[0133] [Table 5]

[0134] In particular, the gravure printing ink for surface printing of the present invention exhibits a unique effect in that it maintains good adhesion to the substrate of the printed material, even under harsh conditions immediately after printing and one hour after printing.

[0135] The present invention provides a gravure printing ink for surface printing that exhibits good abrasion resistance, heat resistance, oil resistance, and printability, and in particular, excellent adhesion to the substrate immediately after printing, resistance to blocking on vinyl chloride sheets, and resistance to blocking on anti-fogging films when printed and wound up. Comparative Examples 1, 2, 5, and 7, which do not contain cyclized rubber, Comparative Examples 2, 4, 6, and 8, which do not contain fatty acid amide, and Comparative Example 9, which does not contain cyclized rubber or fatty acid amide, failed to meet the standards for adhesion, blocking resistance to vinyl chloride sheets, and blocking resistance to anti-fogging films.

Claims

1. A gravure printing ink for surface printing containing a binder resin, cyclic rubber, fatty acid amide, and an organic solvent.

2. The gravure printing ink for surface printing according to claim 1, characterized in that the binder resin contains one of the two resin combinations shown in (1) to (4) below. (1) Polyurethane resin and polyvinyl chloride resin (2) Polyurethane resins and cellulose resins (3) Polyurethane resin and polyvinyl acetal resin (4) Polyamide resins and cellulose resins

3. The gravure printing ink for surface printing according to claim 1, wherein the solid content mass ratio of cyclized rubber and fatty acid amide is 1:20 to 20:

1.

4. The gravure printing ink for surface printing according to claim 1, wherein the cyclized rubber includes an aromatic ring structure.

5. The gravure printing ink for surface printing according to claim 1, wherein the weight-average molecular weight of the cyclized rubber is 1,000 to 50,000.

6. Furthermore, the gravure printing ink for surface printing according to claim 1, further comprising a chelating agent.

7. The gravure printing ink for surface printing according to claim 6, wherein the chelating agent is an acetylacetone-based titanium chelate and / or an alkyl acetoacetate-based titanium chelate.

8. Furthermore, the gravure printing ink for surface printing according to claim 1, further containing hydrocarbon wax particles.

9. A printed article having a printed layer on a substrate made of a gravure printing ink for surface printing as described in any one of claims 1 to 8.

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