JP7156796B2 - Liquid printing ink composition for surface printing and printed matter - Google Patents

Description

The present invention relates to a liquid printing ink composition for surface printing, which can be used as a liquid ink for flexible packaging.

Liquid inks such as liquid inks and flexographic inks are widely used for the purpose of imparting cosmetic properties and functionality to printed materials of flexible packaging films. When gravure-printed or flexo-printed substrates are used as packaging materials, especially as flexible packaging materials for food or sanitary goods, packaging for products should include packaging that touches the contents to prevent contact with the contents. Surface printing is performed in which the design is printed only on the outside of the packaging material without printing on the back side, which is the side of the packaging material.
Liquid printing ink compositions for surface printing are required to have film strength and various resistances because the ink film printed on the front side of the film substrate rubs against direct external forces and comes into contact with other substances. be.

That is, adhesion to various film substrates, blocking resistance that does not adhere to each other when the front printed surface and the printed surface, or the front printed surface and the back surface of the film are in close contact, and on a vinyl chloride table cloth When the product is placed, it will not stick to the PVC blocking resistance, and when alcohol adheres to the printed surface, the pattern will not come off. It is desirable to have oil resistance, etc., so that the pattern will not melt or peel off when oil is adhered.
In addition, while maintaining the above performance, even in high-speed printing, the highlight points corresponding to the small halftone dots are not blurred, and the halftone dot reproducibility is excellent. It is desirable to have printability as well.
For example, the invention of a gravure ink composition using a urethane resin and a cellulose derivative (e.g., Patent Documents 1 and 2), surface printing gravure ink composition containing a polyurethane resin, a vinyl chloride vinyl acetate copolymer, a rosin, and a chelate (for example, Patent Documents 3 and 4), and an invention of a surface printing gravure ink composition using an ester resin and an ester dispersant (for example, Patent Document 5). It cannot be said that both the above-mentioned printability and the above-mentioned printability can be achieved at the same time, and above all, it is by no means easy to achieve both oil resistance, blocking resistance to vinyl chloride, and printability.

JP 2007-246822 A Japanese Patent Application Laid-Open No. 2002-294128 JP 2012-012597 A JP 2013-256551 A JP 2017-039896 A

The subject of the present invention is to achieve not only excellent various ink film properties such as substrate adhesion to the substrate film, but also oil resistance, blocking resistance to vinyl chloride, and high-speed printing, which corresponds to small halftone dots even in high-speed printing. A liquid printing ink composition for surface printing, which has excellent halftone dot reproducibility without blurring of light spots and has printability in which printing stains are hardly generated in non-printing areas having no pattern, and a liquid printing ink composition for surface printing. related to printed matter.

It has been found that the liquid printing ink composition for surface printing of the present invention is effective in solving the problems by containing a polyurethane resin using polycaprolactone polyol as a reaction raw material, a chelate cross-linking agent, a pigment, and an organic solvent.

That is, the present invention provides a liquid printing ink composition for surface printing containing a polyurethane resin (P1) using a polyol and a polyisocyanate as reaction raw materials, a chelate cross-linking agent (A), a pigment (B), and an organic solvent (C). , wherein said polyol comprises a polycaprolactone polyol (pp1).

Furthermore, the present invention relates to a liquid printing ink composition for surface printing comprising a cellulose resin (D) and/or a vinyl chloride vinyl acetate copolymer resin (E).

Further, the present invention relates to a liquid printing ink composition for surface printing, wherein the polycaprolactone polyol (pp1) has a number average molecular weight of 300-5000.

Furthermore, the present invention relates to a liquid printing ink composition for surface printing, wherein the polyol contains a polyester polyol (pp2) or a polyether polyol (pe1) having a number average molecular weight of 400-6000.

Furthermore, the present invention provides a liquid printing ink composition for surface printing, wherein the mass % of the polyester polyol (pp2) or the polyether polyol (pe1) to the polycaprolactone polyol (pp1) is in the range of 100:0 to 5:95. Regarding.

Furthermore, the present invention relates to a liquid printing ink composition for surface printing containing 0.1 to 3.0% by mass of the fatty acid amide (F) relative to the total amount of the liquid printing ink composition for surface printing.

Further, in the present invention, the organic solvent (C) does not contain an aromatic hydrocarbon-based organic solvent and contains an alcohol having a specific evaporation rate of 100 or less when the evaporation rate of butyl acetate is 100. It relates to a liquid printing ink composition for printing.

Furthermore, the present invention relates to a printed matter obtained by printing the liquid printing ink composition for surface printing.

According to the present invention, in addition to excellent various ink film properties such as substrate adhesion to substrate films, especially oil resistance, blocking resistance to vinyl chloride, and highlight points corresponding to small halftone dots even in high-speed printing A liquid printing ink composition for surface printing that has excellent halftone dot reproducibility without blurring and printability that makes it difficult for printing stains to occur in non-printing areas without patterns, and a liquid printing ink composition for surface printing. It is possible to provide printed matter that will be done.

The present invention will be described in detail. Note that "ink" used in the following description all means "liquid printing ink". All "parts" indicate "parts by mass", and all "%" indicate "% by mass".

The liquid ink composition for surface printing of the present invention contains a polyurethane resin (P1) in which a polyol and a polyisocyanate are used as reaction raw materials, a chelate cross-linking agent (A), a pigment (B), and an organic solvent (C). A liquid printing ink composition for surface printing, characterized in that the polyol contains a polycaprolactone polyol (pp1).

(Polyurethane resin (P1))
The polycaprolactone polyol (pp1), which is the raw material of the polyurethane resin (P1) used in the present invention, is not particularly limited. Polycaprolactone diol obtained by reacting with diol such as tetramethylene glycol, 1,2-polybutylene glycol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 1,4-butanediol etc. can be used.

The number average molecular weight (hereinafter sometimes referred to as Mn) of the polycaprolactone polyol (pp1) is preferably from 300 to 5,000, more preferably from 400 to 4,000. If the polycaprolactone polyol (pp1) has a number average molecular weight of 300 or more and 5000 or less, it tends to be particularly excellent in oil resistance.

In the present invention, there is no particular limitation except that polycaprolactone polyol (pp1) is used as a raw material for the polyurethane resin, and the polyurethane resin can be produced using known raw materials.
Generally, to obtain a polyurethane resin, a polyol, a polyisocyanate, and, if necessary, a chain extender, a reaction terminator, etc., are prepared by a conventionally known method.

As the polyol, various known polyols generally used for producing polyurethane resins can be used, and one or more of them may be used in combination.
For example, polyether polyols (1) such as polyethylene glycol, polypropylene glycol, and polyoxytetramethylene glycol, which are polymers or copolymers of methylene oxide, ethylene oxide, tetrahydrofuran, and the like;
Ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 1,3-butanediol, 1,4-butane Diol, neopentyl glycol, pentanediol, 3-methyl-1,5 pentanediol, hexanediol, octanediol, 1,4-butynediol, 1,4-butylenediol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerin , trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, 1,2,4-butanetriol, sorbitol, pentaerythritol, and other saturated or unsaturated low-molecular-weight polyols (2);
These low-molecular-weight polyols (2), adipic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, spelic acid, azelaic acid, Polyester polyols (3) obtained by dehydration condensation or polymerization of polyvalent carboxylic acids such as sebacic acid, trimellitic acid and pyromellitic acid, or anhydrides thereof;
Polyester polyols (4) obtained by ring-opening polymerization of lactones such as cyclic ester compounds such as polyvalerolactone and poly(β-methyl-γ-valerolactone);
Polycarbonate polyols (5) obtained by reacting the low-molecular-weight polyols (2) or the like with, for example, dimethyl carbonate, diphenyl carbonate, ethylene carbonate, phosgene, or the like;
polybutadiene glycols (6);
Glycols obtained by adding ethylene oxide or propylene oxide to bisphenol A (7);
Obtained by copolymerizing one or more hydroxyethyl, hydroxypropyl acrylate, acrylic hydroxybutyl, etc. in one molecule, or their corresponding methacrylic acid derivatives, etc. with, for example, acrylic acid, methacrylic acid, or an ester thereof. acrylic polyol (8) and the like.

Among the polyester polyols (3), the polymer diols obtained from diols (glycols) and dibasic acids account for up to 5 mol% of the diols as low molecular weight diols having three or more hydroxyl groups. Polyols (2) can be substituted.

Among the above polyols, polyether polyols (1) or polyester polyols (3) are preferable, and among them, polyether polyols (1) having a number average molecular weight of 400 to 6000 (hereinafter referred to as polyether polyol (pe1)) , or polyester polyol (1) having a number average molecular weight of 400 to 6000 (hereinafter referred to as polyester polyol (pp2)).

The content ratio of the polycaprolactone polyol (pp1) is preferably 10 to 95 parts by mass with respect to 100 parts by mass of the polyol which is the reaction raw material of the polyurethane resin (A). Further, the mass % of polyester polyol (pp2) or polyether polyol (pe1) to polycaprolactone polyol (pp1) is preferably in the range of 100:0 to 5:95 from the viewpoint of oil resistance.

As the diisocyanate compound used in the polyurethane resin (P1) in the liquid printing ink composition for surface printing of the present invention, various known aromatic diisocyanates, aliphatic diisocyanates, alicyclic and diisocyanate. For example, 1,5-naphthylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyldimethylmethane diisocyanate, 4,4′-dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3- Phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, cyclohexane-1 ,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dimeryl diisocyanate, 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 resin (P1) in the liquid printing ink composition for surface printing of the present invention include ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, dicyclohexylmethane-4, In addition to 4'-diamine, etc., 2-hydroxyethylethylenediamine, 2-hydroxyethylpropyldiamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylenediamine, di-2-hydroxyethylpropylene Amines having a hydroxyl group in the molecule, such as diamine, 2-hydroxypyropyrethylenediamine, di-2-hydroxypyropyrethylenediamine, and di-2-hydroxypropylethylenediamine, can also be used. These chain extenders can be used alone or in combination of two or more.
A monovalent active hydrogen compound can also be used as a terminal blocker for the purpose of terminating the reaction. Examples of such compounds include dialkylamines such as di-n-butylamine and alcohols such as ethanol and isopropyl alcohol. Furthermore, amino acids such as glycine and L-alanine can be used as a reaction terminator, especially when it is desired to introduce a carboxyl group into the polyurethane resin. These terminal blocking agents can be used alone or in combination of two or more.

The polyurethane resin (P1) in the liquid printing ink composition for surface printing of the present invention is obtained, for example, by reacting a polycaprolactone polyol (pp1) and a polyol used in combination with a diisocyanate compound at a ratio in which the isocyanate group is excessive, and obtaining a terminal isocyanate. A prepolymer of the group is obtained, and the resulting prepolymer is treated with a suitable solvent, namely an ester solvent such as ethyl acetate, propyl acetate, butyl acetate, etc., which are commonly used as solvents for liquid inks; acetone, methyl ethyl ketone, methyl isobutyl ketone. ketone solvents such as; alcohol solvents such as methanol, ethanol, isopropyl alcohol, n-butanol; hydrocarbon solvents such as toluene, xylene, methylcyclohexane, ethylcyclohexane; agent, or a one-step method in which polypropylene glycol and combined polyol, diisocyanate compound, chain extender and (or) terminal blocking agent are reacted together in a suitable solvent among those mentioned above. Among these methods, the two-step method is preferable for obtaining a uniform polyurethane resin. Furthermore, in recent years, from the viewpoint of work environment, it is more preferable not to use aromatic hydrocarbon organic solvents such as toluene and xylene, and ketone solvents.

The weight average molecular weight of the polyurethane resin (P1) thus obtained is preferably in the range of 15,000 to 100,000, more preferably in the range of 15,000 to 80,000. When the weight-average molecular weight of the polyurethane resin is less than 15,000, the blocking resistance of the resulting ink composition, the strength of the printed film, the oil resistance, etc. tend to be low. , the viscosity of the resulting ink composition tends to be high and the glossiness of the printed film tends to be low.
The content of the polyurethane resin (P1) used in the liquid printing ink composition for surface printing of the present invention in the ink is 4 mass with respect to the total mass of the ink from the viewpoint of sufficient adhesion of the ink to the substrate to be printed. % or more, preferably 25% by mass or less, more preferably 6 to 15% by mass, from the viewpoint of appropriate ink viscosity and work efficiency during ink production and printing.

(Chelate cross-linking agent)
The liquid printing ink composition for surface printing of the present invention must contain a chelate cross-linking agent (A). Among them, a chelate-type metal organic compound for improving the cohesion is preferable. Organic titanium, organic zirconium, and organic aluminum compounds can be used as metal chelate compounds. If a chelate-type metal organic compound is used, the cross-linking reaction can be completed without heating, and hydrolysis at room temperature is unlikely to occur, resulting in a stable cross-linking reaction. The effect is large.

As described above, since the liquid printing ink composition for surface printing is printed on the front side of the packaging material, the ink film is exposed to the outside and comes into direct contact with various substances. Therefore, tough physical properties such as heat resistance and oil resistance are required in addition to adhesion to the film substrate. Especially in recent years, there is a demand for a surface printing ink that has high heat resistance to heat sealing during film bag making and oil resistance to oil contained in food. excellent film physical properties can be obtained.

The titanium chelate has a Ti--O--C bond in one molecule, and having this alkoxy group serves to strengthen the inter- or intra-molecular cross-linking of the resin. Examples of titanium chelate include titanium alkoxide and titanium acylate. Examples of the titanium alkoxide include tetraisopropyl titanate, tetra-normal butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, tetramethyl titanate, tetrastearyl titanate, triethanolamine titanate, titanium acetylacetate, and titanium ethylacetoacetate. , titanium lactate, octylene glycol titanate, titanium tetraacetyl acetate, titanium phosphate compounds, and the like. Among organic titanium compounds, titanium phosphate compounds and titanium acetylacetate are preferred. Commercially available products include titanium TAA chelating agent (manufactured by BORICA): titanium acetylacetonate CAS: 17927-27-9.
The amount of the chelate cross-linking agent to be blended is preferably 0.1 to 5.0% by mass, more preferably 0.5 to 3.0% by mass, based on the total amount of the liquid printing ink composition for surface printing.

(Pigment (B))
The pigment (B) used in the liquid printing ink composition for surface printing of the present invention may be either a color pigment or a white pigment. If a white pigment is added, it can be used as a white ink corresponding to the background of a pattern, for example, in surface liquid printing. If these pigments are not added, it can also be used as an overcoat varnish.

Examples of the coloring pigment used in the liquid printing ink composition for surface printing of the present invention include organic pigments and dyes used in general inks, paints, recording agents, and the like. Organic pigments include azo, phthalocyanine, anthraquinone, perylene, perinone, quinacridone, thioindigo, dioxazine, isoindolinone, quinophthalone, azomethineazo, diketopyrrolopyrrole, and isoindoline pigments. pigments.

As a color index name,
C. I. Pigment Yellow 1, 3, 12, 13, 14, 17, 42, 74, 83;
C. I. Pigment Orange 16;
C. I. Pigment Red 5, 22, 38, 48:1, 48:2, 48:4, 49:1, 53:1, 57:1, 63:1, 81, 101;
C. I. Pigment Violet 19, 23;
C. I. Pigment Blue 23, 15:1, 15:3, 15:4, 17:1, 18, 27, 29
C. I. Pigment Green 7, 36, 58, 59;
C. I. Pigment Black 7;
C. I. Pigment White 4, 6, 18 and the like.

C.I. I. Pigment Blue 15:3 (copper phthalocyanine), yellow ink is C.I. I. Pigment Yellow 83, C.I. I. Pigment Red 57:1 is preferably used. It is preferable to use carbon black for black ink, aluminum for gold and silver inks, and mica for pearl ink from the viewpoint of cost and coloring power. Aluminum is in the form of powder or paste, but it is preferable to use it in the form of paste from the standpoint of ease of handling and safety, and whether to use leafing or non-leafing is selected as appropriate in terms of brightness and density.

Examples of white pigments used in the liquid printing ink composition for surface printing of the present invention include titanium oxide, zinc sulfide, lead white, zinc white, litbon, antimony white, basic lead sulfate, and basic silicic acid. Examples include lead, barium sulfate, calcium carbonate, gypsum, silica, and the like.
The average particle size of the pigment is preferably in the range of 10-200 nm, more preferably about 50-150 nm.
The amount of the pigment to be added is preferably in the range of 1 to 20% by mass based on the total amount of the ink in order to obtain sufficient image density and lightfastness of the printed image.

(Organic solvent (C))
The organic solvent (C) used in the liquid printing ink composition for surface printing of the present invention is not particularly limited. Aliphatic hydrocarbon organic solvents such as hexane, methylcyclohexane, heptane, octane, and decane; Various organic solvents are mentioned. Water-miscible organic solvents include alcohols such as methanol, ethanol, propanol, butanol and isopropyl alcohol, ketones such as acetone, methyl ethyl ketone and cyclohaxanone, ethylene glycol (mono, di) methyl ether, and ethylene glycol (mono, di) ethyl. Ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, monobutyl ether, diethylene glycol (mono, di) methyl ether, diethylene glycol (mono, di) ethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, triethylene glycol (mono, Di)methyl ether, propylene glycol (mono, di)methyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol (mono, di)methyl ether, and other glycol ether organic solvents can be used. These may be used alone or in combination of two or more.

Among them, it is preferable to contain an alcohol that does not contain an aromatic hydrocarbon-based organic solvent and has a specific evaporation rate of 100 or less when the evaporation rate of butyl acetate is taken as 100.
Such alcohols include, for example, 1-propyl alcohol (CAS number 71-23-8, evaporation rate 94), isobutyl alcohol (CAS number 78-83-1, evaporation rate 64), 1-butanol (CAS number 71- 36-3, evaporation rate 47), 2-butanol (CAS number 78-92-2, evaporation rate 89), 4-hydroxy-4-methyl-2-pentanone (CAS number 123-42-2, evaporation rate 15) , ethylene glycol monomethyl ether (CAS number 109-86-4, evaporation rate 53), ethylene glycol monoethyl ether (CAS number 110-80-5, evaporation rate 38), ethylene glycol mono-normal butyl ether (CAS number 111-76 -2, evaporation rate 8), ethylene glycol monotertiary butyl ether (CAS number 7580-85-0, evaporation rate 19), 3-methoxy-3-methylbutanol (CAS number 56539-66-3, evaporation rate 7), 1-methoxy-2-propanol (CAS number 107-98-2, evaporation rate 71), 1-ethoxy-2-propanol (CAS number 1569-02-4, evaporation rate 34), propylene glycol monopropyl ether (CAS number 1569-01-3, evaporation rate 22).

By containing an alcohol having a specific evaporation rate of 100 or less, it is possible to maintain the highlight transfer property with a halftone dot area of 10% or less and improve the highlight.
The mechanism has the following two points. First of all,
1) About half of the ink remains in the cells of the gravure plate after the ink is transferred to the film.
2) The remaining ink evaporates from the solvent until it comes into contact with the ink in the ink pan again, and becomes semi-dry. Furthermore, since the solvent evaporates faster, it evaporates first, so the solvent with the slower evaporates remains in the ink pan.
3) At this time, if a solvent with a high resin solubility remains, the semi-dried ink will re-dissolve when it comes into contact with the ink again, preventing the ink from solidifying in the cell.
General-purpose alcohols having a specific evaporation rate exceeding 100 when the evaporation rate of butyl acetate is taken as 100 have a high volatilization rate, so the above mechanism tends to be difficult to function.
Secondly, alcohols with a specific evaporation rate of 100 or less when the evaporation rate of butyl acetate is 100 have a low ratio of hydroxyl groups (alcohol groups) in one molecule of alcohol, which reduces the solubility of the polyurethane resin. tend to increase.

In terms of work hygiene during printing and the toxicity of packaging materials, use ethyl acetate, propyl acetate, isopropanol, normal propanol, etc., and do not use aromatic solvents such as toluene or ketone solvents such as methyl ethyl ketone. is more preferred.
Among them, a mixture of isopropyl alcohol/ethyl acetate/n-propyl acetate/methylcyclohexane is more preferable from the viewpoint of solubility in polyurethane resin and nitrocellulose. For drying adjustment, glycol ethers can be added as long as they are less than 10% by mass of the total amount of the composition.

(Cellulose resin (D) and vinyl chloride vinyl acetate copolymer resin (E))
Furthermore, the liquid ink composition for surface printing of the present invention may further contain a cellulose resin (D) and/or a vinyl chloride vinyl acetate copolymer resin (E).

As the cellulose-based resin (D) used in the liquid printing ink composition for surface printing of the present invention, high dispersibility of the pigment can be obtained, and the heat resistance and oil resistance of the printing ink coating film can be improved. .
The cellulose resin (D) preferably has a nitrogen content of 10 to 13% by mass and an average polymerization degree of 30 to 500, more preferably a nitrogen content of 10 to 13% by mass and an average polymerization degree of 45 to 290. . The amount of the cellulose resin (D) added is preferably 0.05 to 10% by mass based on the solid content of the ink. More preferably, it is 0.1 to 3% by mass.

The vinyl chloride-vinyl acetate copolymer resin (E) having a hydroxyl group has a hydroxyl value of 50 to 200 mgKOH/g and a content ratio of the vinyl chloride component in the copolymer resin of 80 to 95% by mass. things are preferable.

The hydroxyl-containing vinyl chloride-vinyl acetate copolymer resin (E) used in the liquid printing ink composition for surface printing of the present invention can be obtained by two methods. One is obtained by copolymerizing vinyl chloride monomer, vinyl acetate monomer and vinyl alcohol in appropriate proportions. The other is obtained by copolymerizing vinyl chloride and vinyl acetate and then partially saponifying vinyl acetate. The vinyl chloride-vinyl acetate copolymer resin having a hydroxyl group determines the properties of the resin film and the dissolution behavior of the resin depending on the monomer ratio of vinyl chloride, vinyl acetate and vinyl alcohol. That is, vinyl chloride imparts toughness and hardness to the resin coating, vinyl acetate imparts adhesiveness and flexibility, and vinyl alcohol imparts good solubility in polar solvents.

(Fatty acid amide (F))
The liquid printing ink composition for surface printing of the present invention can preferably be improved in heat resistance, oil resistance and anti-blocking resistance against polyvinyl chloride by further adding a fatty acid amide (F) and using it in combination with a polyurethane resin.
The fatty acid amide (F) is preferably added in an amount of 0.1 to 3.0% by mass, more preferably 0.5 to 2.0% by mass, based on the total amount of the liquid printing ink composition for surface printing. If the content is less than 0.1% by mass, the anti-blocking property against PVC may deteriorate, and if it is 3.0% by mass or more, the oil resistance tends to decrease.

The fatty acid amide (F) used in the liquid ink composition of the present invention may be a very common polycondensate of polycarboxylic acid and polyamine such as polymerized fatty acid and various vegetable fatty acids.

The polymerized fatty acid is obtained by polymerization of an unsaturated fatty acid having 16 to 22 carbon atoms or an ester thereof, and includes monobasic fatty acid, dimerized polymerized fatty acid, trimerized polymerized fatty acid, and the like. Specific examples include dimer acid and hydrogenated dimer acid.
As various vegetable fatty acids, the polymerized fatty acids are those obtained by polymerization of unsaturated fatty acids having 16 to 22 carbon atoms or esters thereof, such as monobasic fatty acids, dimerized polymerized fatty acids, and trimerized fatty acids. It contains fatty acids and the like. Specifically, tall oil fatty acid, palm oil fatty acid, coconut oil fatty acid, soybean oil fatty acid, cocoa fatty acid, rice bran fatty acid, and mixed fatty acids of these natural oils and fats may be used as reaction raw materials.

Examples of polyamines include aliphatic diamines such as ethylenediamine, propylenediamine, and hexamethylenediamine; aliphatic polyamines such as diethylenetriamine and triethylenetetramine; and alicyclic diamines such as cyclohexylenediamine and isophoronediamine. Examples include xylylenediamine, etc., which are group diamines, and phenylenediamine, diaminodiphenylmethane, etc., which are aromatic diamines.
Primary and secondary monoamines also include mono- and di-alkylamines such as butylamine, octylamine and diethylamine, mono- and di-alkanolamines such as monoethanolamine, monopropanolamine, diethanolamine and dipropanolamine. be able to.
Further, if a polyamide resin having a hydroxyl group in the molecule obtained by using an alkanolamine as a primary or secondary monoamine component is used, the reactivity with the chelating agent tends to increase, and the hydroxyl value in that case is 0.5 to 0.5. A range of 10 is preferred.

Specifically, lauric acid amide (weight average molecular weight: 199.3, CAS number: 1120-16-7) and the like are particularly preferred for improving the anti-blocking property of soft vinyl chloride sheets used for tablecloths.

Polyamide resins having a number average molecular weight of 500 to 10,000 are also preferably used. More preferably, the number average molecular weight is from 1,000 to 10,000.
If the number average molecular weight of the polyamide resin is less than 500, the resistance to blocking with vinyl chloride tends to be lowered.
From the viewpoint of high-speed printing suitability, it is preferably 20% by mass or less based on the total amount of the polyurethane resin and the cellulose resin, and more preferably 10% by mass or less if the anti-blocking property against PVC can be maintained.

For the liquid printing ink composition for surface printing of the present invention, if necessary, a combination resin, an extender pigment, a pigment dispersant, a leveling agent, an antifoaming agent, waxes, a plasticizer, an infrared absorbent, an ultraviolet absorbent, and a fragrance It may also contain additives, flame retardants, and the like. Among them, fatty acid amides such as paraffin wax, polyethylene wax, carnauba wax, oleic acid amide, stearic acid amide, and erucic acid amide for imparting friction resistance and slipperiness, and for suppressing foaming during printing Silicon-based and non-silicon-based antifoaming agents and various dispersants that improve pigment wetting are useful.

(Method for producing ink composition)
The liquid ink composition for surface printing of the present invention is produced by, for example, polyurethane resins, chelate cross-linking agents, pigments, fatty acid amides, organic solvents, and, if necessary, antistatic agents, antiblocking agents, plasticizers, and the like. Additives, dispersants for improving ink fluidity and dispersibility, surfactants, or resins compatible with polyurethane resins are used in combination to the extent that thickening and gelling do not occur over time. This is done by kneading using a normal printing ink manufacturing apparatus such as an attritor or a sand mill. In particular, the addition of an antistatic agent is effective in suppressing electrostatic troubles during printing, such as whiskers and thunder streaks, which are likely to occur when using an ester solvent or a ketone solvent.

(printed matter)
The printed matter of the present invention is obtained by printing a liquid printing ink composition for surface printing onto a plastic film or the like by a known printing method such as gravure printing or flexographic printing. The ink composition of the present invention is preferably used for surface printing.

The plastic film that can be used for the liquid printing ink composition for surface printing of the present invention is not particularly limited. Polyester resins such as phthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate, polyhydroxycarboxylic acids such as polylactic acid, poly(ethylene succinate), poly(butylene succinate), etc. Biodegradable resins typified by aliphatic polyester resins, polypropylene (PP), polyolefin resins such as polyethylene, polyimide resins, polyarylate resins, or thermoplastic resins such as mixtures thereof. Among them, films made of polyester, polyamide, polyethylene, and polypropylene can be preferably used. These base films may be either unstretched films or stretched films, and the manufacturing method thereof is not limited. Also, the thickness of the base film is not particularly limited, but it is usually in the range of 1 to 500 μm.
Further, if the printing surface of the substrate film is subjected to a corona discharge treatment, the adhesiveness to the substrate can be further improved, which is preferable. Also, silica, alumina, or the like may be vapor-deposited.

EXAMPLES The present invention will be specifically described below using examples. In the examples, "parts" means parts by mass, and "%" means % by mass.
The number-average molecular weight and weight-average molecular weight (in terms of polystyrene) of the polyurethane resin were measured by GPC (gel permeation chromatography) in the present invention using an HLC8220 system manufactured by Tosoh Corporation under the following conditions.
Separation column: Four TSKgelGMH _HR -N manufactured by Tosoh Corporation are used. Column temperature: 40°C. Moving bed: Tetrahydrofuran manufactured by Wako Pure Chemical Industries, Ltd. Flow rate: 1.0 ml/min. Sample concentration: 0.4% by mass. Sample injection volume: 100 microliters. Detector: differential refractometer.
Moreover, the Gardner viscosity at 25° C. was confirmed with a Gardner viscometer.

(Synthesis Example 1: Synthesis of polyurethane resin solution (Pu1))
229.37 parts of polycaprolactone polyol (number average molecular weight: 2,000) and 50.97 parts of isophorone diisocyanate were charged into a four-neck flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas inlet tube, and the mixture was stirred for 90 minutes under a stream of nitrogen. °C for 5 hours. After completion of the reaction, 200 parts of normal propyl acetate was added to dilute the reaction solution. After cooling the reaction solution to 45° C. or lower, 200 parts of isopropyl alcohol was added. The reaction solution was maintained at about 35 to 40°C, 17.19 parts of isophoronediamine dissolved in 150 parts of ethyl acetate was added dropwise, and the mixture was allowed to react at 50°C for 3 hours while stirring. Then, 2.48 parts of cyclohexylamine was added and reacted at 50° C. for 30 minutes while stirring. Finally, 150 parts of ethyl acetate was added to obtain a polyurethane resin solution (Pu1) having a nonvolatile content of 30.0%, a Gardner viscosity of VW (25° C.) and a weight average molecular weight (hereinafter referred to as Mw) of 58,000.

(Synthesis Example 2: Synthesis of polyurethane resin solution (Pu2))
67.62 parts of polycaprolactone polyol (number average molecular weight: 1,000), adipic acid and 3-methyl-1,5-pentanediol were added to a four-neck flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas inlet tube. 135.24 parts of the obtained polyester polyol having a number average molecular weight (Mn) of 2,000 and 69.12 parts of isophorone diisocyanate were charged and reacted at 90° C. for 5 hours under a nitrogen stream. After completion of the reaction, 200 parts of normal propyl acetate was added to dilute the reaction solution. After cooling the reaction solution to 45° C. or lower, 200 parts of isopropyl alcohol was added. The reaction solution was maintained at about 35 to 40°C, 25.34 parts of isophoronediamine dissolved in 150 parts of ethyl acetate was added dropwise, and the reaction was allowed to proceed at 50°C for 3 hours while stirring. Then, 2.68 parts of cyclohexylamine was added and reacted at 50° C. for 30 minutes while stirring. Finally, 150 parts of ethyl acetate was added to obtain a polyurethane resin solution (Pu2) having a non-volatile content of 30.0%, a Gardner viscosity of U (25° C.) and an Mw of 40,000.

(Synthesis Example 3: Synthesis of polyurethane resin solution (Pu3))
175.37 parts of polycaprolactone polyol (number average molecular weight 1,000) and 37 parts of polypropylene glycol having a number average molecular weight (Mn) of 1,000 were placed in a four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas inlet tube. 58 parts of isophorone diisocyanate and 61.23 parts of isophorone diisocyanate were charged and reacted at 90° C. for 5 hours under a nitrogen stream. After completion of the reaction, 200 parts of normal propyl acetate was added to dilute the reaction solution. After cooling the reaction solution to 45° C. or lower, 200 parts of isopropyl alcohol was added. The reaction solution was maintained at about 35 to 40°C, 21.76 parts of isophoronediamine dissolved in 150 parts of ethyl acetate was added dropwise, and the mixture was allowed to react at 50°C for 3 hours while stirring. Then, 4.06 parts of di-n-butylamine was added and reacted at 50° C. for 30 minutes while stirring. Finally, 150 parts of ethyl acetate was added to obtain a polyurethane resin solution (Pu3) having a nonvolatile content of 30.0%, a Gardner viscosity of V (25° C.) and an Mw of 45,000.

(Synthesis Example 4: Synthesis of polyurethane resin solution (Pu4))
A polyester polyol having a number average molecular weight (Mn) of 2,000 (number average molecular weight of 2,000) obtained from adipic acid and neopentyl glycol was added to a four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas inlet tube. 0.69 parts of isophorone diisocyanate and 52.65 parts of isophorone diisocyanate were charged and reacted at 90° C. for 5 hours under a nitrogen stream. After completion of the reaction, 200 parts of normal propyl acetate was added to dilute the reaction solution. After cooling the reaction solution to 45° C. or lower, 200 parts of isopropyl alcohol was added. The reaction solution was maintained at about 35 to 40°C, 17.97 parts of isophoronediamine dissolved in 150 parts of ethyl acetate was added dropwise, and the mixture was allowed to react at 50°C for 3 hours while stirring. Then, 3.69 parts of cyclohexylamine was added and reacted at 50° C. for 30 minutes while stirring. Finally, 150 parts of ethyl acetate was added to obtain a polyurethane resin solution (Pu4) having a non-volatile content of 30.0%, a Gardner viscosity of U (25° C.) and an Mw of 46,000.

(Synthesis Example 5: Synthesis of polyurethane resin solution (Pu5))
Polyester polyol of Mn 2,000 (number average molecular weight 2,000) obtained from adipic acid and 3-methyl-1,5-pentanediol was placed in a four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas inlet tube. 187.23 parts, 40.12 parts of polyethylene glycol having a number average molecular weight (Mn) of 1,000, and 53.49 parts of isophorone diisocyanate were charged and reacted at 90° C. for 5 hours under a nitrogen stream. After completion of the reaction, 200 parts of normal propyl acetate was added to dilute the reaction solution. After cooling the reaction solution to 45° C. or lower, 200 parts of isopropyl alcohol was added. The reaction solution was maintained at about 35 to 40°C, 16.40 parts of isophoronediamine dissolved in 150 parts of ethyl acetate was added dropwise, and the mixture was allowed to react at 50°C for 3 hours while stirring. Then, 2.77 parts of di-n-butylamine was added and reacted at 50° C. for 30 minutes while stirring. Finally, 150 parts of ethyl acetate was added to obtain a polyurethane resin solution (Pu5) having a non-volatile content of 30.0%, a Gardner viscosity of V (25° C.) and an Mw of 42,000.

Table 1 shows the materials used in synthesizing the polyurethane resin solutions (Pu1) to (Pu5) in terms of parts by mass. The numbers in Table 1 are parts by mass.

In the table, abbreviations have the following meanings.
Polyol A: modified polycaprolactone polyol Number average molecular weight (Mn): 2000
Polyol B: polycaprolactone polyol Number average molecular weight (Mn): 1000
Polyol C: Polyester polyol consisting of adipic acid/3-methyl-1,5-pentanediol=1/1. Number average molecular weight (Mn): 2000
Polyol D: polycaprolactone polyol Number average molecular weight (Mn): 1000
Polyol E: Polypropylene glycol Number average molecular weight (Mn): 1000
Polyol F: Polyester polyol composed of adipic acid/neopentyl glycol=1/1. Number average molecular weight (Mn): 2000
Polyol G: Polyethylene glycol Number average molecular weight (Mn): 1,000

(Adjustment of nitrocellulose solution N)
Industrial nitrocellulose H1/2 (nitrocellulose, solid content 30%, viscosity 9.0 to 14.9% at a solution concentration of 25.0% according to JIS K-6703, manufactured by Taihei Chemicals Co., Ltd.) to 37.5 parts , and 62.5 parts of a mixture of isopropyl alcohol/ethyl acetate/n-propyl acetate/methylcyclohexane (ratio by mass: 25/25/13/10) were added and thoroughly mixed to prepare a nitrocellulose solution N.

(Adjustment of vinyl chloride vinyl acetate copolymer resin solution V)
A vinyl chloride vinyl acetate copolymer resin having a hydroxyl group used in combination with a polyurethane resin (vinyl chloride/vinyl acetate/vinyl alcohol = 92/3/5, hydroxyl value (mgKOH) = 64 in terms of mass% resin monomer composition) is mixed with acetic acid. A 15% solution was made with n-propyl, and this was used as a vinyl chloride resin solution (V).

(Preparation of rosin resin solution R)
50 parts of rosin resin (trade name: NEOCITE F-896, manufactured by Konan Kasei Co., Ltd.) was dissolved in 50 parts of isopropyl alcohol to obtain a rosin resin solution with a solid content of 50%.

[Examples 1 to 3, Comparative Examples 1 and 2: Ink preparation method]
Using the polyurethane resin solutions Pu1 to Pu5 shown in Table 1, a mixture obtained by mixing at the compounding ratio shown in Table 2 was kneaded using a Mighty Mill (manufactured by Inoue Seisakusho Co., Ltd.), Examples 1 to 3 and Comparative Example 1. , 2 were prepared and the following evaluations were carried out on each.
As the metal chelate crosslinking agent, a titanium TAA chelating agent (titanium acetylacetonate, CAS number 17927-27-9) manufactured by BORICA was used.

[Substrate Adhesion]
The indigo ink shown in Table 2 was applied to a biaxially stretched polypropylene film (Futamura Chemical Co., Ltd. FOR, thickness 20 μm) with one side subjected to corona discharge treatment, using a bar coater #10, and left for 24 hours to create a printed matter. did.
Next, after affixing a cellophane tape (manufactured by Nichiban Co., Ltd.) to the printed surface, the tape was quickly peeled off, and the state of the printed surface was visually evaluated. An evaluation of 4 or higher is within the practical range.
(Evaluation criteria)
5: The printed film does not peel off from the film at all.
4: Less than 20% of the area of the printed film is peeled off from the film.
3: The area ratio of the printed film is 20% or more and less than 50% is a film
peel from.
2: The area ratio of the printed film is 50% or more and less than 80% is a film
peel from.
1: 80% or more of the printed surface is peeled off from the film.

[Blocking resistance]
Dilute the indigo ink shown in Table 2 with a mixed organic solvent consisting of ethyl acetate/n-propyl acetate/cyclohexane in the same ratio as used in the preparation of the ink, and dilute to 16 seconds with Zahn Cup No. 3 manufactured by Rigosha. did. A biaxially oriented polypropylene film (Futamura Chemical Co., Ltd. FOR Printing was carried out on the treated surface with a thickness of 20 μm).
Next, the resulting printed material was cut into a size of 4 cm x 4 cm. After tightening with a load of ^c and left in an atmosphere of 40° C. and 80% humidity for 24 hours, the printed surface and the plastic film were separated by hand, and the blocking resistance was evaluated from the degree of ink peeling. An evaluation of 4 or higher is within the practical range.
(Evaluation criteria)
5: There is no peeling of the printed film, and no peeling resistance is felt at all.
4: There is no peeling of the printed film, but a slight peeling resistance is not felt.
3: The printed film was slightly peeled, and peeling resistance was felt.
2: The printed film was peeled off, and the peeling resistance was felt strongly.
1: Most of the printed film was peeled off, and peeling resistance was felt strongly.

[PVC blocking resistance]
A soft vinyl chloride sheet (manufactured by Doit Co., Ltd.) cut to the same size as the printed material used in the blocking resistance evaluation was superimposed on the printed surface, and a load of 0.5 kg/cm ² was applied. After being left in an atmosphere of 50° C. and 80% humidity for 24 hours, the printed surface was peeled off from the polyvinyl chloride sheet, and the anti-blocking property against polyvinyl chloride was evaluated from the degree of ink peeling.
An evaluation of 4 or higher is within the practical range.
(Evaluation criteria)
5: The printed film was not peeled off at all.
4: 20% or more and less than 50% of the printed film peeled off from the film.
3: 50% or more and less than 75% of the printed film peeled off from the film.
2: 75% or more and less than 90% of the area where the printed film was peeled off from the film.
1: 90% or more of the printed film peeled off from the film.

[Alcohol resistance suitability]
The printed surface of each printed matter was rubbed 100 times under a load of 200 g with a cloth impregnated with ethanol using a Gakushin rub resistance tester, and the alcohol suitability was evaluated from the change in the printed surface.
An evaluation of 4 or higher is within the practical range.
(Evaluation criteria)
5: No change in both the printed surface and the patch cloth.
4: There is no change in the printed surface, but the patch is colored.
3: A streak-like flaw is observed on the printed surface.
2: Thick streaky scratches are observed on the printed surface.
1: Planar scratches are observed on the printed surface.

〔Heat-resistant〕
The indigo ink shown in Table 2 was applied to a biaxially oriented polypropylene film (manufactured by Futamura Chemical Co., Ltd., FOR, thickness 20 μm) with corona discharge treatment on one side, using a bar coater #10, and left for 24 hours to prepare a printed matter. did.
Then, using a heat seal tester equipped with a hot plate having a thermal gradient of 80 to 200°C on each printed surface, the printed surface and aluminum foil, and the printed surface and the printed surface were subjected to 2.0 kg / cm. A pressure of ² was applied for 1 second. The heat resistance was evaluated from the lowest temperature at which the ink on the printed surface transferred to the aluminum foil.
An evaluation of 4 or higher is within the practical range.
(Evaluation criteria)
5: 180°C or higher.
4: 160°C or more and less than 180°C.
3: 140°C or more and less than 160°C.
2: 120°C or more and less than 140°C.
1: Lower than 120°C.

〔Oil resistance〕
The printed surface of each printed matter is rubbed 100 times under a load of 200 g with a cloth impregnated with edible salad oil and butter at a ratio of 1:1 using a Gakushin rub resistance tester, and the oil resistance is evaluated from the change in the printed surface. did. An evaluation of 4 or higher is within the practical range.
(Evaluation criteria)
5: No change in both the printed surface and the patch cloth.
4: There is no change in the printed surface, but the patch is colored.
3: A streak-like flaw is observed on the printed surface.
2: Thick streaky scratches are observed on the printed surface.
1: Planar scratches are observed on the printed surface.

[Printability test: blur test]
Isopropyl alcohol: normal propyl alcohol: ethyl acetate: normal propyl acetate: cyclohexane = (mass ratio 6 parts: 5 parts: 20 parts: 15 parts: 10 parts), and then diluted with Zahn Cup No. 3 manufactured by Rigo Co., Ltd. to 16 seconds. A biaxially oriented polypropylene film (Futamura Chemical Co., Ltd. FOR Printing was carried out on the treated surface with a thickness of 20 μm).
In the blurring test, the ratio of the blurring area in the highlight printed portion (less than 10% halftone dot area) when the circumference of the gravure plate is 600 mmφ and the printing speed is 200 m/min. . An evaluation of 4 or higher is within the practical range.
(Evaluation criteria)
5: There is no fading and no smearing in the non-printed area.
4: Slight blurring is observed, or stains are slightly observed in the non-printed area.
3: Slight blurring is observed, and stains are slightly observed in the non-printed area.
2: Blurs are observed, and stains are observed in the non-printed area.
1: A large amount of faintness is observed, and a large amount of stain is also observed in the non-printed area.

Table 2 shows the formulation of each indigo ink and the evaluation results.

In the table, abbreviations have the following meanings.
- Metal chelate cross-linking agent: BORICA titanium TAA chelating agent (titanium acetylacetonate, CAS number 17927-27-9)

From the above results, printed matter using the liquid printing ink composition for surface printing of the present invention, in addition to excellent various ink film properties, particularly oil resistance, blocking resistance to vinyl chloride, and small netting even in high-speed printing. The result is excellent halftone dot reproducibility without blurring of highlight points corresponding to dots, and printability with less occurrence of fading of pattern and printing stains in non-printing areas.

INDUSTRIAL APPLICABILITY The liquid printing ink composition for surface printing of the present invention can be widely used as various liquid surface printing materials for industrial products such as food packaging materials, sanitary products, cosmetics, and electronic parts.

Claims (6)

A liquid printing ink composition for surface printing containing a polyurethane resin (P1) having a polyol and a polyisocyanate as reaction raw materials, a chelate cross-linking agent (A), a pigment (B), and an organic solvent (C), A liquid printing ink composition for surface printing, wherein the polyol contains polycaprolactone polyol (pp1) and polyester polyol (pp2) or polyether polyol (pe1).
However, the mass % of the polyester polyol (pp2) or polyether polyol (pe1) to the polycaprolactone polyol (pp1) is in the range of 99:1 to 33:67.
The polyester polyol (pp2) excludes polycaprolactone polyol (pp1).
Further, the organic solvent (C) does not contain an aromatic hydrocarbon organic solvent and contains an alcohol having a specific evaporation rate of 100 or less when the evaporation rate of butyl acetate is taken as 100.
The liquid printing ink composition for surface printing according to claim 1, further comprising a cellulose resin (D) and/or a vinyl chloride vinyl acetate copolymer resin (E).
The liquid printing ink composition for surface printing according to claim 1 or 2, wherein the polycaprolactone polyol (pp1) has a number average molecular weight of 300 to 5,000.
Surface printing according to any one of claims 1 to 3, wherein the polyol contains a polyether polyol (pe1) having a number average molecular weight of 400 to 6000 or a polyester polyol (pp2) having a number average molecular weight of 400 to 6000. liquid printing ink composition for printing.
The liquid printing ink composition for surface printing according to any one of claims 1 to 4, further comprising 0.1 to 3.0% by mass of a fatty acid amide (F) relative to the total amount of the liquid printing ink composition for surface printing. thing.
A printed matter obtained by printing the liquid printing ink composition for surface printing according to any one of claims 1 to 5 .