WO2014084307A1

WO2014084307A1 - Print-ink stacked body

Info

Publication number: WO2014084307A1
Application number: PCT/JP2013/082045
Authority: WO
Inventors: 倫弘野田; 安田　秀樹
Original assignee: 東洋インキＳｃホールディングス株式会社
Priority date: 2012-11-30
Filing date: 2013-11-28
Publication date: 2014-06-05
Also published as: CN104918785B; JP2014108534A; JP5487492B1; CN104918785A

Abstract

The present invention relates to a print-ink stacked body obtained by stacking, upon a transparent plastic film (1), a white ink film layer (2) formed using print ink including a polyurethane resin (A) and a white inorganic pigment, and a coloured ink film layer (3) formed using print ink including a polyamide resin (B) and an organic pigment, in that order, said print-ink stacked body wherein the polyurethane resin (A) is obtained by causing a reaction between an organic diamine and a urethane prepolymer having an isocyanate group at a terminal thereof, said urethane prepolymer being obtained by causing a reaction between a polymer polyol and polyisocyanate. According to the present invention, an ink stacking method can be used to produce an ink stacked body exhibiting, among other necessary properties, excellent white/colour-layer gloss, while reducing the usage amount of residual solvents.

Description

Printing ink laminate

The present invention relates to a printing ink laminate of coating ink for various plastic films, plastic sheets or synthetic resin products. More specifically, the present invention relates to an ink laminate that is excellent in white / color gloss, reduces residual solvent, and has other necessary physical properties by an ink lamination method.

In recent years, product packaging is generally printed for decoration and surface protection, and the consumer's willingness to purchase depends on the print quality such as the design of the printed matter. ing. Therefore, high design properties are required for printing inks.

In order to realize the design properties demanded by consumers, a polyamide resin having high pigment dispersibility is often used as a binder for printing ink for surface printing. When a polyamide resin is used, high gloss and high color development can be realized. However, when a polyamide resin is used, the residual solvent tends to increase, and there is a problem that the suitability for high-speed printing is insufficient.

On the other hand, in order to reduce the residual solvent, a urethane resin having suitability for high-speed printing may be used as a binder for printing ink for surface printing. However, since the pigment dispersibility is lower than that of the polyamide resin, there is a tendency that the glossiness of the ink coating surface tends to be low, and the design property is insufficient.

In addition, with the diversification of packaging and advancement of packaging technology, food manufacturers and converters are increasingly demanding high quality and performance for printing inks. Processability such as drying and drying, adhesion to the film substrate after printing, blocking resistance to prevent the ink from adhering to the back side of the film substrate or printed materials when printed and wound, scratches on the printed surface It has become necessary to combine various resistances such as friction resistance to prevent rusting, oil resistance to oils and fats, and heat resistance during bag making.

JP-A-9-296143 JP 2012-12597 A

The object of the present invention is to provide a printing ink laminate in which a white ink film layer and a color ink film layer are laminated on various plastic films, plastic sheets or synthetic resin-based products. It is an object of the present invention to provide a printing ink laminate that can realize a reduction in residual solvent when printing, and further has various physical properties such as white / color trapping.

The present invention is formed from a white ink film layer (2) formed from a printing ink containing polyurethane resin A and a white inorganic pigment on a transparent plastic film (1), and a printing ink containing polyamide resin B and an organic pigment. A printed ink laminate in which the colored ink film layer (3) is laminated in order, wherein the polyurethane resin A is a urethane prepolymer having an isocyanate group at the terminal obtained by reacting a polyisocyanate and a polymer polyol. The present invention relates to a printing ink laminate, which is a polyurethane resin obtained by reacting a polymer with an organic diamine.

Further, the present invention is characterized in that the above-mentioned polymer polyol comprises a polyester diol and a polyether diol, and the polyester diol is 0 to 50% by mass and the polyether diol is 50 to 100% by mass in the polymer polyol. It is related with the above-mentioned printing ink layered product.

Furthermore, the present invention relates to the printing ink laminate, wherein the polyamide resin B has a softening point in the range of 100 to 130 ° C.

Upon completion of the present invention, when a white ink film layer and a color ink film layer are laminated on various plastic films, plastic sheets, or synthetic resin products, the white / color overlap trapping and white / color overlap gloss are excellent, and the residual solvent In addition, it has become possible to provide an ink laminate having printability on the surface of white ink.

Hereinafter, the transparent plastic film (1) of the present invention will be described. Specific examples of the transparent plastic film include stretched and unstretched polyolefins such as polyethylene and polypropylene, polyester, nylon, cellophane, and vinylon.

Further, for these transparent plastic films (1), it is also possible to use a film obtained by processing a transparent plastic film in advance such as coating and kneading of an antifogging agent, surface coating of a matting agent, and kneading. .

The white ink film layer (2) formed from the printing ink containing the polyurethane resin A and the white inorganic pigment will be described.

The polyurethane resin A usable in the present invention can be produced by a known method, and the production method is not particularly limited. For example, a polymer polyol and a polyisocyanate compound are reacted in an excess ratio of the isocyanate group to prepare a prepolymer having an isocyanate group at the terminal of the polymer polyol, and then a chain extender in the solvent and the reaction stop A two-stage method in which an agent is reacted is mentioned. The two-stage method is preferable because a uniform polymer solution can be easily obtained. As the solvent, an ester solvent, a ketone solvent, and an alcohol solvent may be used alone or in combination of two or more.

Here, as the usable polymer polyol compound, polyether polyols such as polymers or copolymers such as ethylene oxide, propylene oxide, and tetrahydrofuran,
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 and other low molecular weight glycols, adipic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, glutar Polyester polyols obtained by dehydration condensation of dibasic acids such as acid, pimelic acid, azelaic acid, sebacic acid, dimer acid or their anhydrides,
Other known polyols include polycarbonate diols, polybutadiene glycols, glycols obtained by adding bisphenol A ethylene oxide or propylene oxide; dimer diols and the like.

These polyols may be used alone or in combination of two or more.

In the present invention, polyether diols and / or polyester diols are preferably used from the viewpoint of hygiene and inkability, and polyether polyols are more preferably used from the viewpoint of solvent detachability.

More specifically, it is preferable to use PEG (polyethylene glycol), PPG (polypropylene glycol), or PTMG (polyoxytetramethylene glycol) from the viewpoint of ease of synthesis and the like.

In the present invention, when the polyester diol and the polyether diol are used in combination, the polyester diol is used in an amount of 0 to 60% by mass, the polyether diol is used in an amount of 40 to 100% by mass, the polyester diol is 0 to 50% by mass, and the polyether diol. Is preferably 50 to 100% by mass. Within such a range, there is a tendency that the solvent removability is improved and the residual solvent amount is reduced.

The number average molecular weight of the polymer polyol is appropriately determined in consideration of the solubility, drying property, blocking resistance, etc. of the resulting polyurethane resin, but it is usually preferably 150 to 6000. When the molecular weight is 150 or more, printability tends to be improved with improvement in solubility, and when it is 6000 or less, drying property and blocking resistance are improved.

Next, the polyisocyanate used in the present invention is not particularly limited as long as it is a compound having two or more isocyanate groups, but an organic diisocyanate compound is preferably used. Examples of the organic diisocyanate compound include various known aromatic, aliphatic or alicyclic diisocyanates. For example, 1,5-naphthylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyldimethylmethane diisocyanate, 4,4′-dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3- Phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4- Diisocyanate, xylylene diisocyanate, isophorone diisocyanate, lysine diisocyanate, Cyclohexylmethane-4,4'-diisocyanate, 1,3-bis (isocyanatemethyl) cyclohexane, methylcyclohexane diisocyanate, norbornane diisocyanate, m-tetramethylxylylene diisocyanate, dimerisocyanate in which the carboxyl group of dimer acid is converted to an isocyanate group, etc. It is.

Next, the method for producing the polyurethane resin when the polymer polyol and polyisocyanate are reacted is not particularly limited. For example, the conditions for reacting the polymer polyol and the polyisocyanate are not particularly limited except that the polyisocyanate is excessive, but the equivalent ratio of isocyanate group / hydroxyl group is 1.5 / 1 to 3.0 / 1. It is desirable to be within the range. Since the polyurethane resin obtained when the equivalent ratio of isocyanate group / hydroxyl group is 1.5 / 1 or more is tough, polyvinyl chloride blocking hardly occurs when used in printing ink. On the other hand, if the equivalent ratio of isocyanate group / hydroxyl group is 3.0 / 1 or less, free isocyanate residues not used in the reaction are reduced, and the stability of the ink over time is improved.

The above polyurethane formation reaction may be performed in a solvent or in a solvent-free atmosphere. In the case of using a solvent, a solvent shown later may be appropriately selected and used from the viewpoints of temperature and viscosity during reaction and control of side reactions. In addition, when the polyurethane-forming reaction is performed in a solvent-free atmosphere, it is desirable to raise the temperature and lower the viscosity to such an extent that stirring is sufficient in order to obtain a uniform polyurethane resin. The urethanization reaction is preferably carried out for 10 minutes to 5 hours, and the end point of the reaction is judged by viscosity measurement, NCO peak by IR measurement, NCO% measurement by titration, and the like.

Further, after synthesizing a prepolymer having a terminal isocyanate group by reacting a polymer polyol and polyisocyanate, a urea bond (urea bond) is introduced into the polyurethane resin by using a chain extender and a reaction terminator. By using urea resin, the physical properties of the coating film are further improved.

The present invention includes a polyurethane-urea resin having a urea bond with the polyurethane resin.

Next, various known amines can be used as a chain extender that can be used when a urea bond is introduced. Examples thereof include ethylenediamine, propylenediamine, hexamethylenediamine, triethylenetetramine, diethylenetriamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine and the like. In addition, 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, etc. Representative examples thereof include diamines having a hydroxyl group and dimer diamine obtained by converting a carboxyl group of dimer acid into an amino group.

Examples of the reaction terminator include dialkylamines such as di-n-butylamine and alcohols such as ethanol and isopropyl alcohol.

The production method for introducing the urea bond into the polyurethane resin is not particularly limited, but the chain extender and the reaction terminator when the number of free isocyanate groups at both ends of the prepolymer is 1 are used. The total number of amino groups therein is preferably in the range of 0.5 to 1.3. When the total number of amino groups is in the range of 0.5 to 1.3, the drying property, blocking resistance and coating strength are good, and the chain extender and the reaction terminator hardly remain unreacted. Therefore, it is difficult for the odor to remain on the printed matter.

In the present invention, the printing ink containing the polyurethane resin A can be added with vinyl chloride / vinyl acetate copolymer and nitrified cotton in order to impart toughness and hardness of the resin film. When nitrified cotton is used, yellowing of the ink and the printing stock may occur due to the influence of NOx gas generated when the nitrified cotton is decomposed. Therefore, it is more preferable to use a vinyl chloride / vinyl acetate copolymer as the combined resin.

The vinyl chloride / vinyl acetate copolymer in the printing ink used in the present invention is obtained by copolymerizing a vinyl chloride monomer and a vinyl acetate monomer. The vinyl chloride / vinyl acetate copolymer having a hydroxyl group can further use vinyl alcohol in the copolymerization or saponify a part of vinyl acetate. In the vinyl chloride / vinyl acetate copolymer having a hydroxyl group, the properties of the resin film and the resin dissolution behavior are determined by the monomer ratio of vinyl chloride, vinyl acetate and vinyl alcohol. That is, vinyl chloride imparts toughness and hardness of the resin coating, vinyl acetate imparts adhesion and flexibility, and vinyl alcohol imparts good solubility in polar solvents. In the present invention, the vinyl chloride / vinyl acetate copolymer preferably has a hydroxyl group.

Next, the solvent used in the printing ink containing the polyurethane resin A in the present invention mainly includes alcohol organic solvents such as methanol, ethanol, n-propanol, isopropanol, and butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone. Ketone organic solvents such as methyl acetate, ethyl acetate, propyl acetate, butyl acetate and other ester organic solvents, n-hexane, n-heptane, n-octane and other aliphatic hydrocarbon organic solvents, and cyclohexane, Examples thereof include alicyclic hydrocarbon-based organic solvents such as methylcyclohexane, ethylcyclohexane, cycloheptane, and cyclooctane. In consideration of the solubility and drying property of the binder resin, it is preferable to use them by mixing. The amount of these organic solvents used is 30% by mass or more in ordinary ink.

As the white inorganic pigment used for the white ink film layer (2), a general titanium oxide pigment can be used. The content of these pigments is 5 to 50% by mass in the ink composition. Further, from the viewpoint of gloss, it is preferable to select those having no silica treatment, an average particle size of 0.2 to 0.3 μm, and an alumina treatment amount of 1.5 to 3.5%.

The white ink film layer (2) is a gravure printing method and is applied to an adherend such as various plastic films at a coating amount of 0 to 2.0 g / m ² of a dry film. Immediately after coating, dry with a dryer. If the drying is insufficient, the amount of residual solvent may increase and adhesion failure may occur due to whitening.

The color ink film layer (3) formed from the printing ink containing the polyamide resin B and the organic pigment will be described.

The polyamide resin B that can be used in the present invention is a thermoplastic polyamide that can be obtained by polycondensation of a polybasic acid and a polyvalent amine, and has a weight average molecular weight of 3,000 to 100,000, more preferably 5 50,000 to 50,000 are preferably used. When the molecular weight is 3,000 or more, the film strength is good, and when printed, the friction resistance and scratch strength are improved. When the molecular weight is 100,000 or less, the stability of the printing ink composition is preferably improved.

When the weight average molecular weight is 5,000 to 50,000, both the film strength and the stability of the ink composition can be achieved.

Further, the softening point of the polyamide resin may be 90 to 145 ° C., and is preferably in the range of 100 to 130 ° C. When the softening point is 100 ° C. or higher, the surface of the ink film is well cut off, and the winding blocking property is good when printing such as gravure printing or flexographic printing. When the softening point is 130 ° C. or lower, the printed film is flexible, and the adhesiveness and resistance to fringing are good. Furthermore, as the polyamide resin, a resin that is soluble to some extent in an alcohol-only solvent is more preferable. In particular, when a solvent having a solubility in isopropanol of 30% by mass or more is used, a printing ink composition excellent in pigment dispersibility, gloss, color developability, and low-temperature stability can be obtained.

Examples of the polybasic acid used as a raw material for the polyamide resin include adipic acid, sebacic acid, isophthalic acid, terephthalic acid, trimellitic acid, cyclohexanedicarboxylic acid, and polymerized fatty acid. Among them, polymerized fatty acids are preferable, and typical examples of the polymerized fatty acids include dimer acids having the following composition mainly composed of dimers obtained by polymerizing unsaturated fatty acids having 18 carbon atoms.

Monomer having 18 carbon atoms: usually 0 to 15% by mass (preferably 0 to 7% by mass)
Dimer having 36 carbon atoms: Usually 60 to 100% by mass (preferably 75 to 100% by mass)
Trimmer having 54 carbon atoms: Usually 0 to 25% by mass (preferably 0 to 20% by mass)
A monocarboxylic acid can be used in combination with the polybasic acid. Examples of the monocarboxylic acid used in combination include acetic acid, propionic acid, lauric acid, palmitic acid, benzoic acid, and cyclohexanecarboxylic acid. Examples of the polyvalent amine include ethylenediamine, diethylenetriamine, triethylenetetramine, 1,2-diaminopropane, 1,3-diaminopropane, hexamethylenediamine, xylylenediamine, and isophoronediamine.

The solvent used for the printing ink composition for dissolving the polyamide resin and used in the present invention is a non-aromatic hydrocarbon compound containing 20 to 100% by mass of a cyclic hydrocarbon compound (C) having 6 to 12 carbon atoms ( D), a mixed solvent comprising an alcohol (E) having 1 to 10 carbon atoms and, if necessary, another non-aromatic organic solvent (F). When the ratio of the cyclic hydrocarbon compound (C) in the non-aromatic hydrocarbon compound (D) is 20% by mass or more, the pigment dispersibility and low-temperature stability of the printing ink composition are improved.

Examples of the cyclic hydrocarbon compound (C) having 6 to 12 carbon atoms include cyclic saturated hydrocarbons such as cyclohexane, cycloheptane, cyclooctane, cyclodecane, and decalin, cyclohexene, cycloheptene, cyclooctene, 1,3,5,7 -Cyclic unsaturated hydrocarbons such as cyclooctatetraene, cyclododecene, dicyclopentadiene, methylcyclohexane, ethylcyclohexane, isopropylcyclohexane, n-butylcyclohexane, tert-butylcyclohexane, dimethylcyclohexane, trimethylcyclohexane, p-menthane, m- And cyclic hydrocarbons having an alkyl substituent such as menthane. Of these, methylcyclohexane and ethylcyclohexane are preferably used in terms of drying properties.

Other non-aromatic hydrocarbon compounds (D) to be mixed with the cyclic hydrocarbon compound (C) include n-hexane, isohexane, n-heptane, isoheptane, n-octane, isooctane, n-nonane, isononane and dodecane. And saturated hydrocarbon compounds such as isododecane, and unsaturated hydrocarbon compounds such as 1-hexene, 1-heptene and 1-octene. These may be used alone or in admixture of two or more.

The boiling point of each compound constituting the non-aromatic hydrocarbon compound (D) is preferably in the range of 65 to 250 ° C., more preferably in the range of 100 to 150 ° C. When the boiling point is higher than 65 ° C., when performing gravure printing or the like, the drying property of the printing ink is good, and the dried ink is not easily clogged in the plate cell. Moreover, when the boiling point is lower than 250 ° C., the drying property is good, and it is possible to prevent blocking during winding and the ink from adhering to the roll of the printing press and soiling the printed matter.

In the case of flexographic printing, since a solvent having a higher boiling point than gravure printing can be used, the boiling point of each compound is preferably 100 to 250 ° C.

The cyclic hydrocarbon compound (C) preferably has an aniline point or mixed aniline point specified by JIS K 2256 of −30 to 75 ° C. and a Kauributanol number calculated by the following method of 30 to 150. Further, the aniline point or mixed aniline point is preferably -30 to 50 ° C., and the Kauributanol value is preferably 50 to 150. The lower the aniline point of the cyclic hydrocarbon compound (C) and the higher the Kauri-butanol value, the better the solubility of the polyamide resin.

(Calculation method of Kauri-butanol value)
Take 20 ± 0.10 g of standard Kauributanol solution in a 250 ml flask, and drop the sample from the burette while shaking the flask. A newspaper is placed under the flask, and the end point is when the type stroke is unclear. The Kauri-butanol value is calculated by the following formula. The test is performed at 25 ± 1 ° C. The standard Kauributanol solution has a Kauributanol value of 100 to 110 when titrated with toluene, and a Kauributanol value of 40 when titrated with a mixed solution of toluene 25 ± 0.1: heptane 75 ± 0.1 by volume ratio. Adjust in advance.

Kauributanol value = 65 (ZY) / (XY) +40
X: Kauri-butanol number of toluene Y: Kauri-butanol number of toluene-heptane mixed solution Z: Sample dropping amount (ml)
The alcohol (E) having 1 to 10 carbon atoms is a primary to tertiary monoalcohol having 1 to 10 carbon atoms, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol. Tert-butanol, n-pentanol, isopentanol, neopentanol, n-hexanol, n-heptanol, n-octanol and the like.

The mass ratio of the non-aromatic hydrocarbon compound (D) component to the alcohol (E) component in the solvent is in the range of 20/80 to 80/20, and preferably in the range of 30/70 to 50/50. When the mass ratio of the component (D) and the component (E) is outside the above range, the solubility of the polyamide resin is insufficient, and the pigment dispersibility and the low-temperature stability of the printing ink composition are lowered.

The solvent of the printing ink composition of the present invention includes a non-aromatic hydrocarbon compound (D) and an alcohol (E) as a drying ink adjusting agent for gravure printing, flexographic printing, etc. The non-aromatic organic solvent (F) other than ()) can be used in the range of 70/30 to 99/1 in mass ratio of the sum of the (D) component and the (E) component and the (F) component. When the ratio of the component (F) is larger than the above range, the component (D) and the component (E) are decreased, so that the solubility of the polyamide resin is decreased and the stability of the printing ink tends to be decreased. Examples of other non-aromatic organic solvents (F) include ketones such as acetone, methyl ethyl ketone, methyl isopropyl ketone, and methyl isobutyl ketone, and esters such as methyl acetate, ethyl acetate, propyl acetate, butyl acetate, and isobutyl acetate. And glycols such as ethylene glycol, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and alkyl ethers thereof.

In the printing ink containing the polyamide resin B and the organic pigment of the present invention, a fiber-based resin such as nitrocellulose and cellulose acetate can be added as a heat resistance improver, if necessary.

In the printing ink composition used in the present invention, inorganic, organic or extender pigments that can generally be used in printing ink can be used as a colorant. Examples of inorganic pigments include colored pigments such as titanium oxide, bengara, ultramarine blue, carbon black, and graphite, and extender pigments such as calcium carbonate, kaolin, clay, barium sulfate, aluminum hydroxide, and talc. In particular, examples of organic pigments include soluble azo pigments, insoluble azo pigments, azo lake pigments, condensed azo pigments, copper phthalocyanine pigments, and condensed polycyclic pigments. An appropriate content of these pigments is 0.5 to 15% by mass in the ink composition.

In the printing ink composition used in the present invention, rosin-modified maleic acid and rosin ester can be used as additives.

The acid value of the rosin ester and rosin-modified maleic acid is preferably 10 to 40 mg KOH / g. When it is less than 10 mgKOH, the vinyl chloride blocking resistance is deteriorated, and when it is greater than 40 mgKOH / g, the compatibility with the binder resin is deteriorated, which is not preferable. The amount added is preferably 0.5 to 5.0% in terms of solid content in the ink composition. If it is 0.5% or less, the effect on the vinyl chloride blocking resistance is lowered, and if it is 5.0% or more, the ink becomes incompatible and is separated.

In the printing ink composition used in the present invention, a titanium chelate can be used as a cohesion improver.

The titanium chelate has a Ti—O—C type bond in one molecule, and specific examples thereof include titanium chelates such as titanium alkoxide and titanium acylate.

Representative examples of titanium chelates include titanium alkoxides such as tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, tetramethyl titanate, tetrastearyl titanate, triethanolamine titanate, titanium acetyl acetate, Mention may be made of titanium chelates such as titanium ethyl acetoacetate, titanium lactate, octylene glycol titanate, titanium tetraacetylacetonate. Among these, chelate-type titanium organic compounds generally require heating to complete the crosslinking reaction, but are hardly hydrolyzed at room temperature and have excellent stability and are suitable for use in inks. In particular, those having an amine in the molecule can be preferably used.

Titanium chelate contributes to the intermolecular or intramolecular crosslinking of the resin by having an alkoxy group in one molecule.

Furthermore, in the present invention, various hard resins and waxes can be added to the printing ink for the purpose of improving adhesiveness and various resistances.

Here, examples of the hard resin include dimer acid resin, maleic acid resin, petroleum resin, terpene resin, ketone resin, dammar resin, copal resin, and chlorinated polypropylene. When these hard resins are used, an effect of improving adhesiveness can be expected particularly for a plastic film that has not been surface-treated.

Also, the gravure printing ink for surface printing can contain a crosslinking agent or a wax component for the purpose of improving heat resistance, oil resistance and friction resistance. Various known waxes such as polyolefin wax and paraffin wax can be used as the wax.

Furthermore, the addition of various ink additives such as pigment dispersants, leveling agents, surfactants and plasticizers is optional.

As a method for producing printing ink using these materials, first, after stirring and mixing a pigment, a binder resin, an organic solvent, and, if necessary, a pigment dispersant, a surfactant, and the like, There is a method of kneading using a bead mill, a ball mill, a sand mill, an attritor, a roll mill, a pearl mill or the like, and further adding and mixing the remaining materials.

The ink composition for surface printing obtained from the above materials and production methods can be printed on an adherend such as various plastic films by a gravure printing method or a flexographic printing method.

The color ink film layer (3) is applied in a gravure printing method or flexographic printing method with a coating amount of 0 to 2.0 g / m ² on the previously coated white ink film layer (2). Do the work. Immediately after coating, dry with a dryer. Insufficient drying may increase the amount of residual solvent and cause poor adhesion due to whitening.

The printing ink laminate obtained by sequentially laminating the white ink film layer (2) and the color ink film layer (3) obtained as described above is made into a bag and used for packaging containers such as food. Is done.

In general, an ink film layer formed from a printing ink using a polyamide resin as a binder for a printing ink for surface printing has high gloss due to high pigment dispersibility, but tends to increase the residual solvent, resulting in high speed. There was a problem of lack of suitability for printing. Furthermore, since the surface tension of the ink coating film is relatively high, there is a problem that printing on the surface of the ink coating film cannot be performed by an inkjet method or the like.

On the other hand, ink film layers formed from printing inks that use urethane resin as a binder for printing inks for surface printing tend to have less residual solvent and are suitable for high-speed printing, but have pigment dispersibility compared to polyamide resins. , The glossiness of the ink coating surface tends to be low, and there is a problem that the design and cosmetic properties are insufficient.

In general gravure printing and flexographic printing, white ink has a large printing area, so it has a large effect on the amount of residual solvent and printing speed. In addition, ink coating by ink jet method in the filling process of date, lot, etc. Printing on the surface is important because it is almost always carried out on the white ink film. On the other hand, the color ink has a small printing area and thus has less influence on the residual solvent amount and the printing speed than the white ink, but it is desirable that the color ink has high gloss because design and cosmetic properties are required.

In the overprinting of inks, the difference in polarity occurs due to the difference in the resin system of the base ink that is applied first and the base ink that is applied later. Trapping is better than that. Incidentally, the trapping represents a state in which the upper ink is wet and spread when the ink is printed on the base ink.

That is, a white ink film layer (2) formed from a printing ink containing polyurethane resin A and a white inorganic pigment, and a color ink film layer (3) formed from a printing ink containing polyamide resin B and an organic pigment By forming a printing ink laminate that is laminated in order, a printing ink layer that has a low residual solvent amount, high glossy design properties, cosmetics, and printability on the ink coating surface by an ink jet method, etc. The body can be efficiently produced by high-speed printing.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. Moreover, although evaluation by the gravure printing method is performed in the embodiment of the present application, there is no intention to limit the printing method because a similar printed matter can be created by flexographic printing. In the present invention, parts and% represent parts by mass and mass% unless otherwise specified.

<Synthesis of polyurethane resin A>
(Synthesis Example 1)
A four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube has a number average molecular weight (hereinafter referred to as Mn) of 1000 polypropylene glycol (PPG1000, manufactured by NOF Corporation), isophorone diisocyanate 778. .5 parts, 0.30 part of stannous 2-ethylhexylate and 900 parts of ethyl acetate, reacted at 85 ° C. for 3 hours under a nitrogen stream, cooled by adding 1000 parts of ethyl acetate, and solvent for terminal isocyanate prepolymer 4624.5 parts of solution were obtained. Next, 4624.5 parts of the resulting terminal isocyanate prepolymer was gradually added to a mixture of 275.4 parts of isophoronediamine, 0.42 parts of di-n-butylamine, 3000 parts of ethyl acetate and 2100 parts of isopropyl alcohol at room temperature. Then, reaction was carried out at 50 ° C. for 1 hour to obtain a polyurethane varnish 1 having a solid content of 30% and a weight average molecular weight of 35,000.

(Synthesis Example 2)
A polyester diol of Mn1000 obtained from adipic acid and 3-methyl-1,5-pentanediol (PMPA1000, manufactured by Kuraray Co., Ltd.) 972 in a four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas introduction tube .9 parts, Mn1000 polypropylene glycol (PPG1000, manufactured by NOF Corporation) 972.9 parts, isophorone diisocyanate 778.5 parts, stannous 2-ethylhexylate 0.30 parts and ethyl acetate 900 parts, under nitrogen flow The mixture was allowed to react at 85 ° C. for 3 hours, and 1000 parts of ethyl acetate was added and cooled to obtain 4624.5 parts of a solvent solution of a terminal isocyanate prepolymer. Next, 4624.5 parts of the obtained terminal isocyanate prepolymer was gradually added at room temperature to a mixture of 275.4 parts of isophoronediamine, 0.42 parts of di-n-butylamine, 3000 parts of ethyl acetate and 2100 parts of isopropyl alcohol. Next, the reaction was carried out at 50 ° C. for 1 hour to obtain a polyurethane varnish 2 having a solid content of 30% and a weight average molecular weight of 35,000.

Polyurethane varnishes 3 to 4 were synthesized in the same manner as in Synthesis Example 1 with the formulation shown in Table 1.

<Preparation of vinyl chloride / vinyl acetate copolymer varnish>
25 parts of vinyl chloride / vinyl acetate copolymer (Solvain TA5R manufactured by Nissin Chemical Co., Ltd.) is mixed and dissolved in 75 parts of ethyl acetate to form a vinyl chloride / vinyl acetate copolymer varnish (bivinyl chloride (G)). Got. The hydroxyl value was 166.3 mgKOH / g.

<Preparation of titanium chelate additive>
41 parts of tetraisopropyl titanate (TPT, manufactured by Mitsubishi Gas Chemical Co., Inc.) was mixed with 59 parts of acetylacetone to obtain titanium acetylacetonate to obtain titanium chelate (H).

<Preparation of rosin-modified maleic resin varnish>
50 parts of rosin-modified maleic acid (Marquide 5 manufactured by Arakawa Chemical Co., Ltd., acid value: 25 mg KOH / g) is mixed and dissolved in 50 parts of ethyl acetate to obtain a rosin-modified maleic resin varnish (rosin resin varnish (I)). It was. The solid content was 50%.

<Urethane ink 1 (white ink)>
Titanium oxide (Titanics JR-808, manufactured by Teika Co., Ltd.) 22 parts, polyurethane resin (polyurethane varnish 1) 20 parts, vinyl chloride / vinyl acetate copolymer (salt vinegar bivarnish (G)) 17 parts, rosin-modified malein Acid resin (rosin resin (I)) 5 parts, tetraisopropyl titanate (titanium chelate (H)) 1 part, and methyl ethyl ketone: n-propyl acetate: ethyl acetate: isopropyl alcohol = 40: 25: 45: 5 (mass ratio) 35 parts of a mixed solvent consisting of the above was stirred and mixed, and pigment dispersion was performed according to a conventional method using a sand mill to obtain urethane ink 1.

<Urethane ink 2-4>
Urethane inks 2 to 4 were obtained by the same composition and method as urethane ink 1 except that polyurethane varnishes 2 to 4 were used in place of polyurethane varnish 1.

<Polyamide ink 1>
10 parts of phthalocyanine blue (“Rionol Blue FG-7400” manufactured by Toyo Ink Manufacturing Co., Ltd.), 50 parts of polyamide resin varnish (softening point 95 ° C., dimer acid polyamide VERSAMID950, manufactured by BASF) are methylcyclohexane: isopropanol = 50: 50 (Mass ratio) Preliminarily adjusted to a varnish with a solid content of 35% in a mixed solvent), 20 parts of methylcyclohexane and 20 parts of isopropanol (mass ratio) were stirred and mixed, and the pigment dispersion was dispersed in a conventional manner using a sand mill. And polyamide ink 1 was obtained.

<Polyamide ink 2-5>
Dimer acid polyamide is dimer acid polyamide (VERSAMID728, manufactured by BASF) with a softening point of 110 ° C, dimer acid polyamide (VERSAMID744, manufactured by BASF) with a softening point of 125 ° C, and dimer acid polyamide (VERSAMID725, BASF) with a softening point of 130 ° C. Polyamide inks 2 to 5 were obtained in the same manner as for polyamide ink 1 except that the dimer acid polyamide having a softening point of 141 ° C. (VERSAMID971, manufactured by BASF) was used.

<Urethane ink 5>
10 parts of phthalocyanine blue (Lionol Blue FG-7400), 50 parts of polyurethane resin (polyurethane varnish 2), 20 parts of vinyl chloride / vinyl acetate copolymer (bivarnish of salt vinegar (G)), and methyl ethyl ketone: n-propyl acetate: 20 parts of a mixed solvent composed of ethyl acetate: isopropyl alcohol = 40: 25: 45: 5 (mass ratio) was stirred and mixed, and pigment dispersion was performed according to a conventional method using a sand mill to obtain urethane ink 5.

<Polyamide ink 6>
Titanium oxide (Titanics JR-808, manufactured by Teika Co., Ltd.) 22 parts, polyamide resin varnish 37 parts (softening point 125 ° C.), rosin modified maleic resin (rosin resin (I)) 5 parts, tetraisopropyl titanate (titanium) 1 part of chelate (H)), 17.5 parts of methylcyclohexane and 17.5 parts (mass ratio) of isopropanol were stirred and mixed, and pigment dispersion was performed using a sand mill according to a conventional method to obtain polyamide ink 6.

<Adjustment of diluted ink>
In printing, urethane ink and polyamide ink were previously diluted with a diluent solvent (methyl ethyl ketone: n-propyl acetate: ethyl acetate: isopropyl alcohol = 40: 25: 45: 5 (mass ratio)) to prepare a diluted ink. All dilution inks were adjusted to 15 seconds with a Zahn cup N0.3.

<Description of transparent plastic film (1)>
The following five types of transparent plastic films were used as printing substrates.

Treatment OPP: Corona discharge treated biaxially stretched polypropylene film (FOH, manufactured by Nimura Chemical Co., Ltd.)
Processed CPP: Unstretched polypropylene film treated with corona discharge (CP-SC, manufactured by Mitsui Chemicals Tosero Co., Ltd.)
Treated PE: Corona discharge treated polyethylene film (Hybron, manufactured by Mitsui Toatsu Chemicals)
Untreated OPP; untreated biaxially stretched polypropylene film (P2001, manufactured by Toyobo Co., Ltd.)
Untreated CPP; Corona discharge untreated unstretched polypropylene film (CP-S, manufactured by Mitsui Chemicals, Inc.)
<Example 1>
On the treated OPP, using a gravure proofing machine, printing is performed in the order of white ink (urethane ink 2) and color ink (polyamide ink 3) with a corrosive plate having a plate depth of 30 microns, and a printed matter for evaluation (Example 1). Got. At that time, a printed matter with a single white ink was also prepared for evaluation of printability by an ink jet printer.

<Examples 2 to 12><Comparative Examples 1 to 3>
As shown in Table 2, white ink and color ink were printed on various transparent plastic films (1), and printed materials for evaluation of Examples 2 to 12 and Comparative Examples 1 to 3 were obtained. Table 2 shows the results of various evaluations.

<White / color trapping evaluation test>
About the obtained printed matter for evaluation, the color ink coating state was visually confirmed and evaluated visually.

In addition, it is desirable that the evaluation is a level B or higher.

AA: The color ink conceals the white ink, and the color ink is smoothed without unevenness. A: The color ink conceals the white ink, and the color ink is unevenly imprinted. B: Color Ink conceals white ink and partially shows unevenness in color ink inset C: State in which part of white ink is seen on the surface and unevenness in color ink inset in the overlapping portion <residue Measurement of solvent amount>
About the obtained printed matter for evaluation immediately after printing, the printed matter for evaluation sample was put in a 500 cc flask and heated (80 ° C., 30 minutes), and then the gas in the flask was measured by gas chromatography. Evaluation was made in terms of residual solvent per 1 m ^{2 of} printed matter.

The evaluation is desirably B or higher (residual solvent 0.3 mg / m ² or less).

AA: 0.02mg / ^{m 2} or less A: 0.02 more 0.1 mg / ^{m 2} or less A-: more than 0.1 0.2 mg / ^{m 2} or less B: more than 0.2 0.3 mg / m ² or less B-: More than 0.3 and 0.5 mg / m ² or less C: More than 0.5 mg / m ² <Gloss value measurement of white / color overlap portion>
The obtained printed matter for evaluation was measured with a gloss meter (60 ° -60 °). Although a gloss value of about 40 is practically used, it is desirable that the gloss value is 50 or more from the viewpoint of aesthetics.

<Applicability for printing with inkjet printers>
About the obtained white monochromatic evaluation printed matter, printing was performed with an industrial inkjet printer for date recording, and the printed state was visually determined. Note that the white printed product for evaluation was prepared in such a way that when the white / color overlap printed product was prepared, the uncoated portion of the color ink was left.

It should be noted that the evaluation is preferably at a level of A- or higher.

A: The characters are printed without being missing, and the ink-jet ink is in close contact.

A-: Defects are found near some corners of the characters, and the ink-jet ink is in close contact.

B: The character is defective regardless of the location, but the inkjet ink is in close contact.

C: There are characters that are not printed, and inkjet ink is not in close contact.

<Blocking resistance>
About the obtained printed matter for evaluation immediately after printing, the non-printed surface of the transparent plastic film (1) cut into the same size as the printed matter and the ink-coated surface of the printed matter are overlapped, and a load of 1.0 kg / cm ² is applied. Then, after leaving for 24 hours in an atmosphere of 50 ° C. and 80% RH, the printed surface and the transparent plastic film were peeled off, and blocking resistance was evaluated from the degree of ink peeling.

In addition, it is desirable that the evaluation is a level B or higher.

A: The ink was not peeled off at all A-: The area where the ink was peeled from the film was greater than 0 and 20% or less B: The area where the ink was peeled from the film was greater than 20 but less than 50% C: Ink In which the area peeled from the film is greater than 50 and less than 100% <Adhesiveness>
About the obtained printed material for single color evaluation immediately after printing, a cellophane tape was affixed to the printed surface and then peeled off strongly to visually determine the degree of ink peeling. In addition, the printed matter for evaluation of a single color was prepared by coating the transparent plastic film (1) directly with the color ink alone when creating the white / color overlap printed matter.

In addition, it is desirable that the evaluation is a level B or higher.

A: The ink was not peeled off at all A-: The area where the ink was peeled from the film was greater than 0 and 20% or less B: The area where the ink was peeled from the film was greater than 20 but less than 50% C: Ink With an area peeled from the film greater than 50 and less than 100%

Claims

To transparent plastic film (1),
A white ink film layer (2) formed from a printing ink containing polyurethane resin A and a white inorganic pigment;
A printing ink laminate in which a color ink film layer (3) formed from a printing ink containing a polyamide resin B and an organic pigment is sequentially laminated,
A printing ink laminate, wherein the polyurethane resin A is a polyurethane resin obtained by reacting a urethane prepolymer having an isocyanate group at a terminal obtained by reacting a polyisocyanate and a polymer polyol with an organic diamine.
The polymer polyol consists of polyester diol and polyether diol,
2. The printing ink laminate according to claim 1, wherein the polyester diol is 0 to 50% by mass and the polyether diol is 50 to 100% by mass in the polymer polyol.
The printing ink laminate according to claim 1 or 2, wherein the polyamide resin B has a softening point of 100 to 130 ° C.