JP7423392B2 - Liquid printing inks, printed materials, and laminates - Google Patents

Description

The present invention relates to a liquid printing ink that can be used as a gravure ink or a flexographic ink.

Liquid printing inks such as gravure inks and flexographic inks are widely used for the purpose of imparting cosmetic properties, functionality, and surface protection properties to printed materials. When this printing material is used as a packaging material, particularly as a food packaging material, it is generally laminated. In this case, various printing materials and lamination processes are used depending on the type of content and purpose of use.
Conventionally, printing inks using polyurethane urea resin as a binder have been widely used for such laminated products because of their excellent adhesion to various printing materials, lamination strength of various laminated products, and suitability for boiling retorts. Ta.

When the printing medium is made of a plastic material such as polyolefin or polyethylene terephthalate, printing with only process color ink may result in an image with poor color development and visibility due to the influence of the color of the base material. A method using white ink is known to solve this problem. In other words, before printing with color ink, we print white ink to prepare the base material, and then form an image with color ink on top of that, creating an image with excellent color development and visibility. It becomes possible to obtain. Similarly, before printing white ink, color ink is printed to prepare the base of the substrate, and then an image is formed on top of that with white ink, resulting in an image with excellent color development and visibility of white ink. obtain.

The white ink used for these uses mainly white inorganic pigments such as titanium oxide, and is blended into the ink at as high a concentration as possible in order to obtain higher whiteness and hiding properties. For example, in paragraph 0026 of Patent Document 1, it is stated that the content is preferably 10 to 60% by weight, more preferably 10 to 45% by weight based on 100% by weight of the ink, but The content remains at 30% by mass. Also in Patent Document 2, the content disclosed in the examples remains at 35% by mass. In addition, the content of titanium oxide is 30% by mass in Patent Document 3 and 40% by mass in Patent Document 4, which is essentially 40% by mass in the conventionally known methods. That is, the current situation is that it has not yet been possible to achieve the desired hiding performance while maintaining the lamination strength with respect to the plastic film.

Japanese Patent Application Publication No. 2018-127545 Japanese Patent Application Publication No. 2011-122064 Japanese Patent Application Publication No. 2018-044047 Japanese Patent Application Publication No. 2016-104842

An object of the present invention is to provide a liquid printing ink that has high hiding properties while maintaining lamination strength against plastic films.

In order to improve the hiding power, it is essential to increase the pigment concentration in the ink, but the amount of binder resin in the ink is relatively reduced. That is, when attempting to achieve the desired hiding property, various physical properties that depend on the binder resin, particularly adhesiveness and lamination strength, deteriorate.
The present inventors have discovered that, as an ink that satisfies these contradictory problems, a liquid printing ink that contains a binder resin, an organic solvent, and a white pigment and satisfies the following can solve the problems.
(1) The white pigment concentration in the ink is 40% by mass or more.
(2) The ratio of binder resin to white pigment (R/P) is in the range of 0.18-0.24.

That is, the present invention provides a liquid printing ink containing a binder resin, an organic solvent, and a white pigment, which satisfies the following.
(1) The white pigment concentration in the ink is 40% by mass or more.
(2) The ratio of binder resin to white pigment (R/P) is in the range of 0.18 to 0.24.

The present invention also provides the liquid printing ink described above, wherein the white pigment contains titanium oxide and contains 80% by mass or more of titanium oxide based on the total white pigment.

The present invention also provides the liquid printing ink described above, wherein the white pigment contains titanium oxide having a treatment layer of at least alumina and/or silica on the surface.

Further, the present invention provides the liquid as described above, wherein the binder resin contains a polyurethaneurea resin having a weight average molecular weight of 10,000 to 80,000 and a urethane bond concentration of 0.8 mmol/g to 2.5 mmol/g. Provide printing ink.

The present invention also provides the liquid printing ink described above, in which the polyurethane urea resin uses polyester polyol (a) and polyether polyol (b) as reaction raw materials, and satisfies (3) and (4).
(3) The polyester polyol (a) uses a branched diol having 3 to 6 carbon atoms as a reaction raw material, and the total weight of the branched diol having 3 to 6 carbon atoms is 30% of the total weight of the polyester polyol. ~50%.
(4) The polyether polyol (b) is polyoxyethylene with a number average molecular weight of 100 to 1,000.

The present invention also provides a printed matter having a printed layer formed by printing the liquid printing ink described above on a base material.

The present invention also provides a laminate in which an adhesive layer and a film layer are laminated in this order to the printed layer of the printed matter described above.

ADVANTAGE OF THE INVENTION According to the present invention, a liquid printing ink can be obtained that has high hiding properties while maintaining lamination strength against plastic films.

(definition of word)
In the present invention, the liquid printing ink refers to a liquid ink such as gravure ink or flexo ink that is applied to a printing method using a printing plate, and preferably gravure ink or flexo ink. Further, the liquid printing ink of the present invention does not contain active energy curable components, that is, it is a liquid ink that is non-reactive with active energy rays.
Note that all "ink" used in the following description refers to "printing ink." In addition, all "parts" refer to "parts by mass."

The liquid printing ink of the present invention is a liquid printing ink containing a binder resin, an organic solvent, and a white pigment, and is characterized by satisfying the following.
(1) The white pigment concentration in the ink is 40% by mass or more.
(2) The ratio of binder resin to white pigment (R/P) is in the range of 0.18-0.24.

(white pigment)
In the present invention, the white pigment may be any white pigment commonly used in liquid printing inks, such as titanium oxide, barium sulfate, calcium carbonate, silica, zinc oxide, zinc sulfide, mica, talc, pearl, etc. It will be done. Among them, titanium oxide is preferable, and it is preferable that titanium oxide is contained in an amount of 80% by mass or more based on the total white pigment.

(Titanium oxide)
The titanium oxide used in the present invention is not particularly limited in its manufacturing method, shape, crystal form, and particle size, and any known titanium oxide can be used. For example, the titanium oxide particles may be produced by a chlorine method or by a sulfuric acid method. It is preferable to use a sulfuric acid method to suppress wear of the doctor blade.

A specific example of the process for producing titanium oxide using the sulfuric acid method is as follows.
(1) Dissolution step: Dried and crushed ilmenite ore is dissolved in sulfuric acid to form a solution mainly of titanium sulfate (TiOSO ₄ ) and ferrous sulfate (FeSO ₄ ).
(2) Cooling and separation step: The dissolved stock solution is cooled and the crystallized ferrous sulfate (FeSO ₄ .7H ₂ O) is separated using a centrifuge to obtain a stock solution.
(3) Hydrolysis step: The stock solution from which ferrous sulfate has been separated is heated to separate titanium hydroxide (TiO(OH) ₂ ) and sulfuric acid.
(4) Firing step: The white precipitate of titanium hydroxide obtained by the hydrolysis reaction is thoroughly washed with water, filtered, and then calcined at 900°C or higher to produce rutile-type titanium oxide (TiO ₂ ) with a predetermined particle size. shall be.

The crystal form of the titanium oxide particles may be rutile type, anatase type, or brookite type. The rutile type is preferable in that it can obtain a higher hiding rate. The average particle diameter of the titanium oxide particles is preferably 0.1 to 1.0 μm, more preferably 0.1 to 0.5 μm, and even more preferably 0.2 to 0.0 μm, from the viewpoint of achieving high gloss and hiding rate. .3 μm. If the average particle diameter of the titanium oxide particles is less than 0.1 μm, the hiding rate will be lowered, and in addition to being more likely to be left unscraped by a doctor blade, this will likely cause plate fogging. Furthermore, when the average particle diameter of the titanium oxide particles exceeds 1.0 μm, the hiding rate and gloss may decrease.

It is preferable that the titanium oxide has a treated layer made of at least alumina and/or silica on its surface.
In titanium oxide surface-treated with alumina and/or silica, silica is generally used to adjust the acid/base state on the titanium oxide surface and to impart durability to the resulting ink/paint film. , alumina is used to improve the wetting of titanium oxide during dispersion. Furthermore, examples of surface treatment methods for titanium oxide include water-based treatment and gas-phase treatment. From the viewpoint of dispersion stability, the ratio of the amount of silica to alumina treated is preferably 35% by mass or more and 80% by mass or less. Further, the amount of the inorganic substance relative to titanium oxide is not necessarily limited, but is generally 30 parts or less relative to 100 parts of titanium oxide.

Commercially available titanium oxide surface-treated with silica and alumina may be used, for example, from titanium oxide manufacturers such as Ishihara Sangyo Co., Ltd. and Teika Co., Ltd. For example, there are products on the market that have a higher amount of silica treated than the amount of alumina treated, and types that have a higher amount of alumina treated than the amount of silica treated, and titanium oxide whose amount of alumina treated falls within the above ratio range is also available. Can be done.

The respective mass ratios of alumina and silica can be estimated from the amounts of alumina and silica present together with titanium oxide on the surface of titanium oxide. The abundance ratio of alumina and silica can be confirmed by analyzing and comparing the amounts of alumina or silica adsorbed on the titanium oxide surface using fluorescent X-rays, ESCA, or the like. In particular, measurement using fluorescent X-rays is simple and highly accurate. In addition to being present on the surface of titanium oxide, silica and alumina may also exist partly as free particles, and the total amount can be determined by measuring with fluorescent X-rays. Regarding the quantitative method using fluorescent X-rays, an analytical method using a calibration curve using standard materials has been established.
Therefore, titanium oxide with various mass ratios can be used by confirming the mass ratio of alumina and silica present on the surface of commercially available titanium oxide by measuring with fluorescent X-rays.

In this application,
(1) The concentration of the white pigment in the ink is 40% by mass or more.
(2) The ratio of binder resin to white pigment (R/P) is in the range of 0.18 to 0.24.
It is necessary to satisfy both of the following.

(1) The white pigment concentration of the white pigment in the ink is 40% by mass or more, specifically, it means that the white pigment concentration in the ink including the organic solvent is 40% by mass or more. The white pigment concentration is preferably 42% by mass or more, preferably 44% by mass or more, and most preferably 45% by mass or more. On the other hand, if the upper limit is approximately 60% by mass or less, suitability for lamination, etc. can be maintained.

(2) The ratio of the binder resin to the white pigment (R/P) is in the range of 0.18 to 0.24, specifically, the ratio R/P of the weight of the white pigment to the weight of the binder resin described below. is in the range of 0.18 to 0.24. The range is more preferably 0.185 to 0.225, most preferably 0.19 to 0.22.

A coloring agent can be added to the liquid printing ink of the present invention. As the colorant, organic or inorganic pigments or dyes used in general inks, paints, recording materials, etc. can be used. Examples of organic pigments include azo, phthalocyanine, anthraquinone, perylene, perinone, quinacridone, thioindigo, dioxazine, isoindolinone, quinophthalone, azomethine azo, dictopyrrolopyrrole, and isoindoline. Examples include pigments.

Examples of the inorganic pigments include carbon black, red iron, aluminum, mica, and the like. Furthermore, a glittering pigment (Metashine; manufactured by Nippon Sheet Glass Co., Ltd.), which is made of glass flakes or lumpy flakes as a base material and coated with a metal or a metal oxide, can also be used. From the viewpoint of cost and coloring power, it is preferable to use carbon black for black ink, aluminum for gold and silver inks, and mica for pearl ink. Aluminum is in the form of powder or paste, but from the viewpoint of ease of handling and safety, it is preferable to use it in paste form, and whether to use leafing or non-leafing is selected as appropriate from the viewpoint of brightness and density.

(binder resin)
The binder resin used in the present invention is not particularly limited as long as it is a binder resin used in a liquid ink that is normally applied to a printing method using a printing plate, such as gravure ink or flexo ink. It is preferable to use a polyurethane urea resin as the main binder resin because it has excellent lamination strength against the resin, and has a weight average molecular weight of 10,000 to 80,000 and a urethane bond concentration of 0.8 mmol/g or more and 2.5 mmol/g. It is preferable that the polyurethane urea resin is less than or equal to g.
Since such a polyurethaneurea resin has a low viscosity, the ratio (R/P) of the binder resin to the white pigment (2) can be set in the range of 0.18 to 0.24.

The polyurethaneurea resin used in the present invention is not particularly limited as long as it is a polyurethaneurea resin used in ordinary laminating gravure inks or flexographic inks, but it is a polyurethaneurea resin that achieves both high hiding properties, adhesion to films, and lamination strength. From this point of view, the solution viscosity of the resin is preferably 1500 mPa·s or less in an ethyl acetate/IPA=65/35 solution with a solid content of 30%. Among these, it is preferably 1000 mPa·s or less, and preferably 500 mPa·s or less. Note that the above viscosity is a viscosity measured at 25° C. using a B-type viscometer manufactured by Tokimec.

The polyurethaneurea resin preferably has a weight average molecular weight in the range of 10,000 to 80,000 from the viewpoint of achieving both high hiding power, adhesion to the film, and lamination strength. Among them, those in the range of 10,000 to 50,000 are more preferable.

The polyurethaneurea resin preferably contains 1 to 50% by mass of structural units derived from polyether polyol based on 100% by mass of the polyurethaneurea resin from the viewpoint of achieving both high hiding properties, adhesion to the film, and lamination strength. , more preferably in the range of 1 to 30% by mass.

Examples of the polyether polyol include polyether polyols of polymers or copolymers such as ethylene oxide, propylene oxide, and tetrahydrofuran. Specifically, known and commonly used ones such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol may be used. By using the polyether polyol in the above range, printed matter with excellent adhesion to the film, excellent lamination strength, and high opacity can be obtained. The number average molecular weight of the polyether polyol is preferably 100 to 3,500, more preferably 100 to 1,000. Among polyether polyols, polyoxyethylene is particularly preferred.

If the number average molecular weight of the polyether polyol, which is a component of the polyurethaneurea resin, is 100 or more, the polyurethaneurea resin film will not become hard and its adhesion to film substrates such as polyester films will tend to be maintained. . When the number average molecular weight is 3,500 or less, the blocking resistance of the ink film tends to be maintained without the polyurethaneurea resin film becoming brittle.

The number average molecular weights of polyether polyols and polyester polyols described below were measured by gel permeation chromatography (GPC) under the conditions described below.

The weight average molecular weight of the polyurethaneurea resin is a value measured by gel permeation chromatography (GPC) under the following conditions.
Measuring device: High-speed GPC device (“HLC-8220GPC” manufactured by Tosoh Corporation)
Column: The following columns manufactured by Tosoh Corporation were used by connecting them in series.
"TSKgel G5000" (7.8mm I.D. x 30cm) x 1 "TSKgel G4000" (7.8mm I.D. x 30cm) x 1 "TSKgel G3000" (7.8mm I.D. x 30cm) x 1 Book "TSKgel G2000" (7.8mm I.D. x 30cm) x 1 Detector: RI (differential refractometer)
Column temperature: 40℃
Eluent: Tetrahydrofuran (THF)
Flow rate: 1.0 mL/min Injection volume: 100 μL (Tetrahydrofuran solution with sample concentration 0.4% by mass)
Standard sample: A calibration curve was created using the following standard polystyrene.
(Standard polystyrene)
"TSKgel standard polystyrene A-500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-1000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-2500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-5000" manufactured by Tosoh Corporation
“TSKgel Standard Polystyrene F-1” manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-2" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-4" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-10" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-20" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-40" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-80" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-128" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-288" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-550" manufactured by Tosoh Corporation

The polyurethane urea resin used in the liquid printing ink of the present invention uses polyester polyol (a) and polyether polyol (b) as reaction raw materials from the viewpoint of achieving both high hiding properties, adhesion to films, and lamination strength. , (3), and (4) are preferably satisfied.
(3) The polyester polyol (a) uses a branched diol having 3 to 6 carbon atoms as a reaction raw material, and the total weight of the branched diol having 3 to 6 carbon atoms is 30% of the total weight of the polyester polyol. ~50%.
(4) The polyether polyol (b) is polyoxyethylene with a number average molecular weight of 100 to 1,000.

In the polyester polyol (a), the branched diol having 3 to 6 carbon atoms specifically includes 1,2-propylene diol, 1,3-butylene glycol, neopentyl glycol, 2-methyl-1, Examples include 3-propanediol and 3-methyl-1,5-pentanediol. Among them, neopentyl glycol and 2-methyl-1,3-propanediol are preferred.
The polycarboxylic acids to be reacted with these branched diols are not particularly limited, but include, for example, adipic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, Examples include polycarboxylic acids such as glutaric acid, pimelic acid, speric acid, azelaic acid, sebacic acid, trimellitic acid, and pyromellitic acid, or anhydrides thereof.

The urethane bond concentration of the polyurethane urea resin used in the liquid printing ink of the present invention is preferably 1.2 mmol/g or more and 2.5 mmol/g or less, and more preferably 1.3 mmol/g or more. If the urethane bond concentration of the liquid printing ink of the present invention is 1.2 mmol/g or more and 2.5 mmol/g or less, the adhesion with the film base material and lamination strength are good; is more preferable.

Urethane bond concentration = {(W1×OH1+W2×OH2+...+Wi×OHi)×1000}/(56100×S) Formula (1)

In formula (1), each is as follows.
When multiple types of polyols are used, they are calculated as polyol 1, polyol 2 to polyol i, respectively.
W1: mass of polyol 1 OH1: hydroxyl value of polyol 1 W2: mass of polyol 2 OH2: hydroxyl value of polyol 2 Wi: mass of polyol i OHi: hydroxyl value of polyol i S: mass of urethane resin solid content

The polyester polyol (a) and the polyether polyol (b) are used as reaction raw materials as the polyols used as necessary in the polyurethaneurea resin used in the liquid printing ink of the present invention, but they do not fall outside of this definition. Known polyols may be used in combination as appropriate within the ranges satisfying the above (3) and (4).
These known polyols can be used alone or in combination of two or more. For example, polyether polyols of polymers or copolymers such as methylene oxide, ethylene oxide, and tetrahydrofuran other than polyoxyethylene; ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1 , 3-propanediol, 2-ethyl-2butyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1,5pentanediol , hexanediol, octanediol, 1,4-butynediol, 1,4-butylenediol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, Saturated or unsaturated low-molecular polyols such as 1,2,4-butanetriol, sorbitol, and pentaesthritol; These low-molecular polyols and adipic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, Dehydration condensation or dehydration of polycarboxylic acids such as fumaric acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, superric acid, azelaic acid, sebacic acid, trimellitic acid, and pyromellitic acid, or their anhydrides. Polyester polyols obtained by polymerization (other than those defined in polyester polyol (a) above); cyclic ester compounds, such as lactones such as polycaprolactone, polyvalerolactone, and poly(β-methyl-γ-valerolactone) polyester polyols obtained by ring-opening polymerization; polycarbonate polyols obtained by reacting the above-mentioned low-molecular-weight polyols with, for example, dimethyl carbonate, diphenyl carbonate, ethylene carbonate, phosgene, etc.; polybutadiene glycols; bisphenol A Glycols obtained by adding ethylene oxide or propylene oxide to Examples include acrylic polyols obtained by copolymerizing acids, methacrylic acid, or esters thereof.

In addition, among the polyester polyols, polymer diols obtained from diols (glycols) and dibasic acids contain up to 5 mol% of the diols in the low-molecular polyols having three or more hydroxyl groups. Can be replaced.

Examples of the diisocyanate compound used in the polyurethaneurea resin in the liquid printing ink of the present invention include various known aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, etc. that are commonly used in the production of polyurethaneurea resins. For example, 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzylisocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3- Phenyl diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, cyclohexane-1 , 4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dimeryl diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, methylcyclohexane diisocyanate, norbornane diisocyanate, m-tetramethylxylylene diisocyanate Examples include isocyanate, 4,4-diphenylmethane diisocyanate, tolylene diisocyanate, bis-chloromethyl-diphenylmethane-diisocyanate, 2,6-diisocyanate-benzyl chloride, and dimer diisocyanate obtained by converting the carboxyl group of dimer acid into an isocyanate group. These diisocyanate compounds can be used alone or in combination of two or more.

Chain extenders used in the polyurethane urea resin in the liquid printing ink of the present invention include ethylenediamine, propylene diamine, hexamethylene diamine, diethylene triamine, triethylene tetramine, isophorone diamine, dicyclohexylmethane-4,4'-diamine, and others. , 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypyropyl Amines having a hydroxyl group in the molecule such as ethylenediamine, di-2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine can also be used. These chain extenders can be used alone or in combination of two or more.
Moreover, a monovalent active hydrogen compound can also be used as a terminal capping agent for the purpose of stopping the reaction. Examples of such compounds include alkylamines such as di-n-butylamine, and alcohols such as ethanol and isopropyl alcohol. Furthermore, especially when it is desired to introduce a carboxyl group into the polyurethane resin, amino acids such as glycine and L-alanine can be used as a reaction terminator. These terminal capping agents can be used alone or in combination of two or more.

The polyurethane urea resin used in the liquid printing ink of the present invention can be prepared, for example, by reacting the polyol and the diisocyanate compound in a proportion in which isocyanate groups are in excess to obtain a prepolymer with terminal isocyanate groups, and the resulting prepolymer is In a suitable solvent, i.e. ester organic solvents such as ethyl acetate, propyl acetate, butyl acetate, etc., commonly used as solvents for non-toluene gravure inks or flexo inks; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone. Solvents: Alcohol-based organic solvents such as methanol, ethanol, isopropyl alcohol, and n-butanol; Hydrocarbon-based solvents such as methylcyclohexane and ethylcyclohexane; or chain extenders and/or terminal blockers in these mixed solvents. It is produced by a two-step method in which the polyol, the diisocyanate compound, the chain extender, and/or the end-capping agent are reacted at once in a suitable solvent among the above. Among these methods, the two-stage method is preferred in order to obtain a uniform polyurethaneurea resin. In addition, when producing polyurethaneurea resin by a two-step method, the reaction is performed so that the total (equivalent ratio) of the amino groups of the chain extender and/or end-blocking agent is 1/0.9 to 1.3. It is preferable to let When the equivalent ratio of isocyanate groups to amino groups is less than 1/1.3, the chain extender and/or end-blocking agent remain unreacted, causing yellowing of the polyurethane urea resin and odor after printing. may occur.

The content of the polyurethane urea resin used in the liquid printing ink of the present invention is 15% by mass or more in the ink as a resin solution, from the viewpoint of ensuring sufficient adhesion of the ink to the printing substrate and lamination strength. From the viewpoints of concealment and workability, the amount is preferably 40% by mass or less, and more preferably 20 to 30% by mass.

(vinyl chloride vinyl acetate copolymer resin)
Furthermore, in the liquid printing ink of the present invention, in addition to the polyurethaneurea resin, a vinyl chloride vinyl acetate copolymer resin may be used in combination, which is preferred.

The vinyl chloride-vinyl acetate copolymer resin may be any known one without particular limitation, but among them, a vinyl chloride-vinyl acetate copolymer resin having a hydroxyl group is preferable, and the hydroxyl value is 50 to 200 mgKOH/g, and the above-mentioned More preferred is a vinyl chloride/vinyl acetate copolymer resin having a hydroxyl group in which the content ratio of the vinyl chloride component in the copolymer resin is 80 to 95% by weight.

The vinyl chloride vinyl acetate copolymer resin having a hydroxyl group used in the present invention can be obtained by two methods. One type is obtained by copolymerizing vinyl chloride monomer, vinyl acetate monomer, and vinyl alcohol in appropriate proportions. The other type is obtained by copolymerizing vinyl chloride and vinyl acetate and then partially saponifying the vinyl acetate. In a vinyl chloride-vinyl acetate copolymer resin having a hydroxyl group, the properties of the resin coating and the resin dissolution behavior are determined by the monomer ratio of vinyl chloride, vinyl acetate, and vinyl alcohol. That is, vinyl chloride provides toughness and hardness to the resin coating, vinyl acetate provides adhesiveness and flexibility, and vinyl alcohol provides good solubility in polar solvents.

In addition, the monomer ratio of the vinyl chloride-vinyl acetate copolymer resin having a hydroxyl group is, for example, 80 to 95 parts by mass of vinyl chloride to 100 parts by mass of the vinyl chloride-vinyl acetate copolymer resin having a hydroxyl group. It is more preferable because it has a well-balanced adhesive property. If the amount is 80 parts by mass or more, the toughness of the resin coating can be maintained and blocking resistance can be ensured. If it is 95 parts by mass or less, the resin coating will not become too hard and the adhesiveness will not easily deteriorate. Further, the hydroxyl value obtained from vinyl alcohol is preferably 50 to 200 mgKOH/g. If it is 50 mgKOH/g or more, the solubility in polar solvents is good, and the printability is easily stable. If it is 200 mgKOH/g or less, lamination suitability can also be maintained well.

When the above vinyl chloride vinyl acetate copolymer resin having a hydroxyl group is used in combination, it is preferably in the range of 1 to 30% based on the total resin solid content of the liquid printing ink.

(chlorinated polypropylene resin)
Furthermore, in the liquid printing ink of the present invention, in addition to the polyurethaneurea resin, a chlorinated polypropylene resin may be used in combination. As the chlorinated polypropylene resin, known ones can be used without particular limitation, but among them, when the degree of chlorination is 30 to 45% and the weight average molecular weight is 5,000 to 50,000, the solubility in organic solvents and the adhesion to the base film are improved. It is preferable that the gender is balanced. Here, the degree of chlorination in the present invention is the weight percent of chlorine atoms in the chlorinated polypropylene resin.

When the chlorinated polypropylene resin is used in combination, it is preferably 0.1 to 3.0% by mass based on the total solid content of the liquid printing ink. Within this range, it is possible to obtain an ink with a better balance of solubility in organic solvents and adhesion to the base film. The chlorinated polypropylene resin may be used in combination with the polyurethaneurea resin, or the polyurethaneurea resin and a vinyl chloride-vinyl acetate copolymer resin having a hydroxyl group.

(Other resins)
Further, examples of resins used in combination as necessary in the liquid printing ink of the present invention include ethylene-vinyl acetate copolymer resin, vinyl acetate resin, polyamide resin, acrylic resin, polyester resin, alkyd resin, and polyvinyl chloride. Examples include resins, rosin-based resins, rosin-modified maleic acid resins, ketone resins, cyclized rubbers, chlorinated rubbers, butyral, petroleum resins, and the like. The resins used in combination can be used alone or in combination of two or more. The content of the resin used in combination is preferably 1 to 25% by weight, more preferably 2 to 15% by weight based on the total weight of the ink.

(solvent)
The liquid printing ink of the present invention includes, for example, aromatic organic solvents, ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, ester solvents such as ethyl acetate, n-propyl acetate, butyl acetate, and propylene glycol monomethyl ether acetate; Examples include alcohol solvents such as n-propanol, inopropanol, n-butanol, and propylene glycol monomethyl ether, and these can be used alone or in a mixture of two or more. In recent years, from the viewpoint of the working environment, it is desirable not to use aromatic solvents such as toluene and xylene, and ketone solvents.

(water)
Water may be added to the liquid printing ink of the present invention together with the organic solvent as a volatile component. By adding water, the drying properties of the ink can be controlled, and especially in gravure printing, the gradation area with a small amount of ink transfer, which is a characteristic of gravure printing, can be clearly reproduced. The amount of water added is preferably in the range of 0.3 to 10% by mass based on the total amount of the ink composition in order to improve printability. When the amount of water added is 0.3% by mass or more, the reproducibility of the gradation part tends to be good without reducing the drying suppressing effect of the ink, and when the amount of water added is 10% by mass of the total amount of ink. If it is below, it is possible to suppress a decrease in ink stability.
Further, by adding water in this manner, it is also possible to reduce the amount of organic solvent used, leading to environmental friendliness. Water may be added to the organic solvent in advance to form a water-containing organic solvent, or a specific amount may be added separately.

(Other additives)
The present invention may further contain concomitant resins, extender pigments, pigment dispersants, leveling agents, antifoaming agents, waxes, plasticizers, infrared absorbers, ultraviolet absorbers, fragrances, flame retardants, etc., as necessary. .

(dispersant)
To stably disperse the white pigment in an organic solvent, the resin alone can be used, but a dispersant can also be used in combination to further stably disperse the pigment. As the dispersant, anionic, nonionic, cationic, amphoteric, and other surfactants can be used. Examples include a comb-shaped structured polymer compound obtained by adding polyester to polyethyleneimine, or an alkylamine derivative of α-olefin maleic acid polymer. Specific examples include the Solspers series (ZENECA), the Ajispers series (Ajinomoto), and the Homogenol series (Kao). Furthermore, BYK series (BYK Chemie), EFKA series (EFKA), etc. can also be used as appropriate. The dispersant is preferably contained in the ink in an amount of 0.05% by mass or more based on the total mass of the ink from the viewpoint of storage stability, and 5% by mass or less from the viewpoint of lamination suitability, more preferably 0.05% by mass or more based on the total mass of the ink. It is in the range of .1 to 2% by mass.

The liquid printing ink of the present invention can be produced by dissolving and/or dispersing the white pigment, binder resin, etc. in an organic solvent.

The particle size distribution of the pigment in the pigment dispersion is adjusted by appropriately adjusting the size of the crushing media of the dispersion machine, the filling rate of the crushing media, the dispersion processing time, the discharge speed of the pigment dispersion, the viscosity of the pigment dispersion, etc. be able to. As the dispersing machine, commonly used ones such as a roller mill, ball mill, pebble mill, attritor, and sand mill can be used.
If air bubbles or unexpected coarse particles are contained in the ink, it is preferable to remove them by filtration or the like, since this will reduce the quality of printed matter. A conventionally known filter can be used.

The viscosity of the ink produced by the above method is preferably in the range of 10 mPa s or more from the viewpoint of preventing sedimentation of the pigment and dispersing it appropriately, and 1000 mPa s or less from the viewpoint of workability efficiency during ink production and printing. preferable. Note that the above viscosity is a viscosity measured at 25° C. using a B-type viscometer manufactured by Tokimec.
The viscosity of the ink can be adjusted by appropriately selecting the types and amounts of raw materials used, such as polyurethaneurea resins, colorants, organic solvents, etc. The viscosity of the ink can also be adjusted by adjusting the particle size and particle size distribution of the pigment in the ink.

(Printed material)
The printed matter of the present invention is a printed matter having a printed layer formed by printing the liquid printing ink of the present invention on a base material. The liquid printing ink of the present invention has excellent adhesion to various base materials and can be used for printing on paper, synthetic paper, thermoplastic resin film, plastic products, steel plates, etc., and can be used for printing on electronic engraving intaglio etc. While it is useful as an ink for gravure printing using a gravure printing plate made by a company, or for flexo printing using a flexo printing plate made of a resin plate, etc., it is also useful as an ink for an inkjet method in which ink is ejected from an inkjet nozzle without using a plate. This excludes ink.
That is, in the case of inkjet ink, ink droplets ejected from a nozzle directly adhere to the substrate and form printed matter, whereas with the liquid printing ink of the present invention, the printing ink is once adhered to and transferred to the printing plate or printing pattern. After that, only the ink is brought into close contact with the base material again, and if necessary, it is dried to form a printed matter.
The film thickness of the printing ink formed by the gravure printing method or the flexographic printing method using the liquid printing ink of the present invention is, for example, 10 μm or less, preferably 5 μm or less.

The base material includes polyamide resins such as nylon 6, nylon 66, and nylon 46, polyethylene terephthalate (hereinafter sometimes referred to as PET), polyethylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polybutylene terephthalate, Biodegradable resins such as polyester resins such as polybutylene naphthalate, polyhydroxycarboxylic acids such as polylactic acid, aliphatic polyester resins such as poly(ethylene succinate) and poly(butylene succinate), polypropylene, polyethylene, etc. Examples include films made of thermoplastic resins such as polyolefin resins, polyimide resins, polyarylate resins, or mixtures thereof, and laminates thereof, among which films made of polyester, polyamide, polyethylene, and polypropylene are preferably used. These base films may be unstretched films or stretched films, and the manufacturing method thereof is not limited. Further, the thickness of the base film is not particularly limited, but it is usually in the range of 1 to 500 μm.
The printed surface of the base film is preferably subjected to corona discharge treatment, and silica, alumina, etc. may be deposited thereon.

(laminate)
Furthermore, the liquid printing ink of the present invention can be used to create not only a single printed layer but also a laminate having at least a first printed layer and a second printed layer on a plastic film in this order.
The first printing layer and the second printing layer are formed from the liquid printing ink of the present invention containing a binder resin, an organic solvent, a colorant, titanium oxide obtained by a sulfuric acid method, and an inorganic filler. It is characterized by
Further, when the second printing layer is an overprint varnish, it may not contain a colorant, or various pigments may be used for coloring purposes, and white pigments are preferred among them.

By using a polyurethane urea resin as the binder resin in the first printing layer, the coating film has flexibility, has high adhesion to the plastic film, and has high followability as the film base material deforms. In addition, polyurethane urea resins are excellent in terms of pigment dispersibility, resolubility during printing, and color development when pigments are dispersed, and are also compatible with pigments.

Furthermore, the liquid printing ink of the present invention is capable of forming a laminate having a third printing layer adjacent to the first printing layer and the second printing layer in this order, for example, a polyurethane urea resin. A first printing layer formed from a printing ink containing a colorant, a second white printing layer formed from a liquid printing ink containing a white pigment as a coloring agent, and a third white printing layer. A laminate having this order can also be produced.
A first printing layer formed on a plastic film using a printing ink containing a polyurethaneurea resin and a coloring agent can form a pattern using the coloring agent, and a second printing layer formed using a liquid printing ink containing a white pigment. The white printed layer and the third printed layer can be used as the background of the picture.
When the third printing layer is an overprint varnish, it may not contain a colorant, or various colored pigments may be used for coloring purposes, with white pigments being preferred.

The present invention will be explained in more detail with reference to Examples. Hereinafter, both "parts" and "%" are based on mass. A blank column in the table indicates that it is not blended.

In the present invention, the weight average molecular weight (in terms of polystyrene) was measured by GPC (gel permeation chromatography) using an HLC8220 system manufactured by Tosoh Corporation under the following conditions.
Separation columns: Four TSKgelGMHHR-N manufactured by Tosoh Corporation were used. Column temperature: 40°C. Mobile layer: Tetrahydrofuran manufactured by Wako Pure Chemical Industries, Ltd. Flow rate: 1.0ml/min. Sample concentration: 0.4% by mass. Sample injection volume: 100 microliters. Detector: Differential refractometer.
The viscosity was measured at 25° C. using a B-type viscometer manufactured by Tokimec.
The hydroxyl value is the amount of hydroxyl groups in 1 g of resin calculated by back titrating the remaining acid with an alkali when the hydroxyl groups in the polyurethane resin are acetylated with an excess of acetyl reagent, and the amount of hydroxyl groups in 1 g of the resin is calculated using potassium hydroxide (KOH). It is shown in mg number, and is based on JISK0070.

Urethane bond concentration = {(W1×OH1+W2×OH2+...+Wi×OHi)×1000}/(56100×S) Formula (1)
In formula (1), each is as follows.
When multiple types of polyols are used, they are calculated as polyol 1, polyol 2 to polyol i, respectively.
W1: mass of polyol 1 OH1: hydroxyl value of polyol 1 W2: mass of polyol 2 OH2: hydroxyl value of polyol 2 Wi: mass of polyol i OHi: hydroxyl value of polyol i S: mass of urethane resin solid content

(Synthesis Example 1) Polyurethaneurea resin solution P-1
In a four-necked flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, 60.0 parts of polyester polyol (hydroxyl value: 112.0 mgKOH/g) consisting of neopentyl glycol and adipic acid and polyethylene were placed. 40.0 parts of glycol (hydroxyl value: 280 mgKOH/g) and 45.72 parts of isophorone diisocyanate were charged and reacted at 90°C for 16 hours under a nitrogen stream to produce a urethane prepolymer with an isocyanate group content of 2.67% by weight. After that, 97.0 parts of ethyl acetate was added to this to obtain a homogeneous solution of urethane prepolymer. Next, the urethane prepolymer solution was added to a mixture consisting of 7.95 parts of isophoronediamine, 0.62 parts of di-n-butylamine, 119.0 parts of ethyl acetate, and 144.0 parts of isopropyl alcohol, and the mixture was heated at 45°C for 5 minutes. The reaction was carried out with stirring for a period of time to obtain a polyurethaneurea resin solution P-1.
The obtained polyurethane urea resin solution P-1 has a resin solid content concentration of 30.1% by weight, a resin solid content Mw of 52,000, and a urethane bond concentration of 2.07 mmol/ It was g.
The polyester polyol contains 46.9% branched diol, and the polyurethaneurea resin (154.3 parts in total) contains 25.9% by mass of polyethylene glycol (40.0 parts) as a polyether polyol.

(Synthesis Example 2) Polyurethaneurea resin solution P-1-2
40.0 parts of a polyester polyol consisting of neopentyl glycol, propylene glycol, and adipic acid (neopentyl glycol/propylene glycol = 1 /2 mol, hydroxyl value: 56.0 mgKOH/g), 2-methyl-1,3-propanediol, and adipic acid, 50.0 parts of polyethylene glycol (hydroxyl value: 34.5 mgKOH/g), 10. 0 parts (hydroxyl value: 280 mgKOH/g) and 22.00 parts of isophorone diisocyanate were charged and reacted at 90°C for 16 hours under a nitrogen stream to produce a urethane prepolymer with an isocyanate group content of 2.67% by weight. 81.3 parts of ethyl acetate was added to make a homogeneous solution of urethane prepolymer. Next, the urethane prepolymer solution was added to a mixture consisting of 6.65 parts of isophoronediamine, 0.52 parts of di-n-butylamine, 99.5 parts of ethyl acetate, and 120.6 parts of isopropyl alcohol, and the mixture was heated at 45°C for 5 minutes. The reaction was carried out with stirring for a period of time to obtain a polyurethaneurea resin solution P-1-2.
The obtained polyurethane urea resin solution P-1-2 had a resin solid content concentration of 30.0% by weight, a resin solid content Mw of 54,000, and a urethane bond concentration of 0.0% by the calculation method according to formula (1). It was 93 mmol/g.
The polyester polyol contained 39.3% branched diol, and the polyurethaneurea resin (129.2 parts in total) contained 7.7% by mass of polyethylene glycol (10.0 parts) as a polyether polyol.

(Synthesis Example 3) Polyurethaneurea resin solution P-2
100.0 parts of a polyester polyol (neopentyl glycol/ 1,6-hexanediol = 1/1 mol, hydroxyl value: 22.0 mgKOH/g) and 12.27 parts of isophorone diisocyanate were charged and reacted at 90°C for 16 hours under a nitrogen stream to obtain an isocyanate group content of 2.67 weight. % of urethane prepolymer was produced, 74.8 parts of ethyl acetate was added thereto to obtain a homogeneous solution of urethane prepolymer. Next, the urethane prepolymer solution was added to a mixture consisting of 6.12 parts of isophoronediamine, 0.47 parts of di-n-butylamine, 91.6 parts of ethyl acetate, and 110.9 parts of isopropyl alcohol, and the mixture was heated at 45°C for 5 minutes. The reaction was carried out with stirring for a period of time to obtain a polyurethaneurea resin solution P-2.
The obtained polyurethaneurea resin solution P-2 has a resin solid content concentration of 30.3% by weight, a resin solid content Mw of 56,000, and a urethane bond concentration of 0.33 mmol/ It was g.
The polyester polyol contains 20.7% branched diol.

(Synthesis Example 4) Polyurethaneurea resin solution P-3
In a four-neck flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, 100.0 parts of polyester polyol (hydroxyl value: 112.0 mgKOH/g) consisting of diethylene glycol and adipic acid and 31 parts of isophorone diisocyanate were placed. .48 parts of ethyl acetate was added and reacted for 16 hours at 90°C under a nitrogen stream to produce a urethane prepolymer with an isocyanate group content of 2.68% by weight, and then 87.7 parts of ethyl acetate was added to produce a urethane prepolymer. A homogeneous solution was obtained. Next, the urethane prepolymer solution was added to a mixture consisting of 7.21 parts of isophoronediamine, 0.56 parts of di-n-butylamine, 107.2 parts of ethyl acetate, and 130.0 parts of isopropyl alcohol, and the mixture was heated at 45°C for 5 minutes. The reaction was stirred for a period of time to obtain a polyurethaneurea resin solution P-3.
The obtained polyurethaneurea resin solution P-3 has a resin solid content concentration of 30.3% by weight, a resin solid content Mw of 57,000, and a urethane bond concentration of 1.43 mmol/ It was g.

(Preparation of vinyl chloride vinyl acetate copolymer resin solution)
Vinyl chloride vinyl acetate copolymer resin having hydroxyl groups used in combination with polyurethane urea resin (resin monomer composition in weight% vinyl chloride/vinyl acetate/vinyl alcohol = 92/3/5, hydroxyl value (mgKOH) = 64) A 15% solution was prepared with ethyl acetate, and this was used as a vinyl chloride vinyl acetate copolymer resin solution (B-1).

(chlorinated polypropylene resin)
As the chlorinated polypropylene, "Super Chron 390S chlorine content 36%" manufactured by Nippon Paper Chemicals was used.

(Example, Comparative Example Method for manufacturing liquid printing ink)
Using a synthesized polyurethane urea resin solution, a mixture prepared at the blending ratio shown in Table 1 was kneaded using a Mighty Mill (manufactured by Inoue Seisakusho Co., Ltd.), and the mixture was mixed in Examples 1 to 18 and Comparative Examples 1 to 9. The white inks described above were prepared, and the following evaluations were carried out for each.

[Manufacturing method for printed matter]
The viscosity of the obtained liquid printing ink was adjusted to 15 seconds (25°C) using a mixed organic solvent of ethyl acetate/isopropyl alcohol = 80/20 using Zahn Cup #3 (manufactured by Rigosha). The adjusted ink was applied to a biaxially oriented polyester film (hereinafter referred to as PET film, E-5100 manufactured by Toyobo Co., Ltd., thickness 12 μm), which had undergone corona treatment on one side, using a gravure proofing machine equipped with a gravure plate with a plate depth of 30 μm. It was printed on and dried to obtain a PET film print.

[Concealment]
The transmission density of the PET film printed matter obtained by the above-mentioned "method for producing printed matter" was measured using a transmission densitometer X-Rite 361T (V). Concealability is evaluated on a scale of 10, with 10 being the highest and 1 being the lowest, with a pass of 6 or higher.

[Adhesiveness]
After leaving the PET film printed matter obtained by the above "method for producing printed matter" for one day, cellophane tape (12 mm width, manufactured by Nichiban) was attached to the printed surface, and when this was rapidly peeled off, the appearance of the printed film was observed. evaluated. Note that if the adhesiveness is 6 or more, it is considered to be passed.
(Evaluation criteria)
10: The printed film did not peel off at all.
9: More than 90% of the printed film remained on the film 8: More than 80% to less than 90% of the printed film remained on the film 7: More than 70% to less than 80% of the printed film remained on the film 6: Printing 60% to less than 70% of the printed film remained on the film 5: 50% to less than 60% of the printed film remained on the film 4: 40% or more to less than 50% of the printed film remained on the film 3: 30% or more and less than 40% of the printed film remained on the film 2: 20% or more and less than 30% of the printed film remained on the film 1: 10% or more and less than 20% of the printed film remained on the film 0 :Less than 10% of the printed film remained on the film.

[Suitability for lamination]
A urethane-based dry laminating adhesive Dick Dry LX-703VL/KR-90 (manufactured by DIC) was applied to the printed surface of the PET film printed matter obtained by the above-mentioned "method for manufacturing printed matter" using a dry laminating machine (manufactured by DIC Engineering). A non-stretched polypropylene film (hereinafter referred to as R-CPP: ZK-75, manufactured by Toray Synthetic Film Co., Ltd., 50 μm) was laminated on the adhesive-coated surface. Thereafter, aging was performed at 40° C. for 5 days to obtain a laminate.
The obtained laminate was cut into a 15 mm width, and a 90 degree peel test was conducted at a pulling speed of 300 mm/min. In addition, if the lamination strength is 3 or more, it is considered as a pass.
(Evaluation criteria)
5: Lamination strength is 4N/15mm or more.
4: Lamination strength is 3N/15mm or more and less than 4N/15mm.
3: Lamination strength is 2N/15mm or more and less than 3N/15mm.
2: Lamination strength is 1N/15mm or more and less than 2N/15mm.
1: Lamination strength is less than 1N/15mm.

[Retort resistance]
A urethane-based dry laminating adhesive Dick Dry LX-500/KW-75 (manufactured by DIC) was applied to the printed surface of the PET film printed matter obtained by the above-mentioned "method for producing printed matter" in a coating amount of 3.5 g/m2. After coating and drying, aluminum foil (hereinafter referred to as AL: Aluminum foil C manufactured by Toyo Aluminum Industry Co., Ltd., 15 μm) was laminated using a dry laminating machine (Musashino Kikai Design Office Co., Ltd.) to form a two-layer laminate. I got item 1. Next, an adhesive was similarly applied on the AL of laminate 1, and an unstretched polypropylene film (hereinafter referred to as R-CPP: ZK-93KM 50 μm manufactured by Toray Synthetic Film Co., Ltd.) was laminated and aged at 40 ° C. for 5 days. A three-layer composite laminate 2 was obtained. Thereafter, the obtained laminate 2 was made into a pouch with a size of 120 mm x 120 mm, and the pouch was filled with 70 g of a simulated food containing water/salad oil at a ratio of 1:1 (weight ratio) and sealed. After the prepared pouches were subjected to steam retort sterilization treatment at 135° C. for 30 minutes, changes in appearance were visually evaluated using the following criteria. In addition, if the retort suitability is 4 or higher, you will pass (evaluation criteria)
5: No change was observed in appearance.
4: Intermediate between 3 and 5 3: Slight blister marks or laminate lifting were observed in the appearance.
2: Intermediate between 1 and 3 1: Significant blister marks or laminate lifting were observed in the appearance.

The results are shown below.

In the table, the abbreviations are as follows.
Titanium oxide (A): Alumina-silica-treated titanium oxide obtained by the sulfuric acid method and having a mass ratio of titanium oxide/alumina/silica (Ti/Al/Si) of 92/4/4 Titanium oxide (B): Sulfuric acid method Alumina-silica-treated titanium oxide with a titanium oxide/alumina/silica (Ti/Al/Si) mass ratio of 96/4/0 obtained by

As a result, the liquid printing inks of Examples were excellent in hiding properties, adhesive properties, lamination suitability, and retort suitability. It can be seen that inks that do not contain a white pigment concentration of 40% by mass or more have poor hiding properties. In addition, even if the white pigment concentration in the ink is 40% by mass or more, if the R/P is not within the range of 0.18 to 0.24, the adhesion to the film, lamination strength, and retort suitability may be affected. I know it's inferior. On the other hand, inks containing a white pigment concentration of 40% by mass or more and an R/P in the range of 0.18 to 0.24 have excellent hiding properties and film It can be seen that it has excellent adhesion, lamination strength, and retort suitability.

Claims (5)

A liquid printing ink containing a binder resin, an organic solvent, and a white pigment, which satisfies the following.
(1) The white pigment concentration in the ink is 40% by mass or more.
(2) The ratio of binder resin to white pigment (R/P) is in the range of 0.18 to 0.24.
The binder resin has a weight average molecular weight of 10,000 to 80,000 and a urethane bond concentration of 0.8 mmol/g to 2.5 mmol/g, and the polyester polyol (a) and polyether polyol (b) are used as reaction raw materials. Contains a polyurethaneurea resin that satisfies (3) and (4).
(3) The polyester polyol (a) uses a branched diol having 3 to 6 carbon atoms as a reaction raw material, and the total weight of the branched diol having 3 to 6 carbon atoms is 30% of the total weight of the polyester polyol. ~50%.
(4) The polyether polyol (b) is polyoxyethylene with a number average molecular weight of 100 to 1,000. The liquid printing ink according to claim 1, wherein the white pigment contains titanium oxide and contains titanium oxide in an amount of 80% by mass or more based on the total white pigment. The liquid printing ink according to claim 1 or 2, wherein the white pigment contains titanium oxide having a treatment layer of at least alumina and/or silica on the surface. A printed material having a printed layer formed by printing the liquid printing ink according to any one of claims 1 to 3 on a substrate. A laminate in which an adhesive layer and a film layer are laminated in this order to the printing layer of the printed matter according to claim 4 .