JP2021119228A - Solution of binder for printing ink, and printing ink composition for packaging laminate - Google Patents

Abstract

To provide a binder for printing ink for obtaining ink which has excellent printability, laminate strength, boiling suitability and retort suitability without requiring a ketone-based organic solvent or an aromatic organic solvent.SOLUTION: A binder for printing ink contains a polyurethane resin. The polyurethane resin is a polymer containing (A) polyol, (B) a dimethylolpropionic acid, (C) a diisocyanate compound and (D) a chain extender. The (A) polyol contains polyester polyol having a number average molecular weight of 1,000 to 6,000. A content of the (B) dimethylolpropionic acid in the polyurethane resin is 0.01-5 mass% with respect to the mass of the polyurethane resin.SELECTED DRAWING: None

Description

The present invention relates to binders for printing inks, printing ink compositions for packaging laminates, and printed matter.

In recent years, plastic films have come to be used in various fields as packaging materials. Printing on such a plastic film is performed by gravure printing or flexographic printing. With the diversification of packaging base materials, the performance required for printing inks and coating agents used for decoration or surface protection is becoming more and more sophisticated.

For example, a printing ink for a plastic film needs to have excellent printability, adhesiveness, blocking resistance, gloss, and the like for a wide variety of films. Further, in the field of food packaging containers, packaging containers that are hygienically laminated so that the ink does not come into direct contact with the contents are used.

Generally, the laminating process includes the following two methods, that is, printing ink using various plastic films as a printing base material, and applying molten polyolefin or the like to the formed printing film surface (printing surface) via an anchor coating agent. There are an extrusion laminating method for laminating and a dry laminating method for laminating a plastic film on the printed surface via an adhesive.

The laminating ink used in the laminating method must adhere well to a printing substrate such as various plastic films, and must be excellent in adhesiveness to the laminated plastic film, printability, and laminating strength. Further, for the purpose of sterilizing the contents, when the boil treatment or the retort treatment of immersing the laminated packaging container in hot water is performed, the boil does not cause the laminate to float or wrinkle during the treatment. Aptitude and retort aptitude are required.

Most of the above ink performances often depend mainly on the performance of the binder resin. Therefore, various binder resins are used according to the performance required for each. Generally, a polyurethane resin is used as a binder resin for laminating ink (see Patent Documents 1 to 3).

Japanese Unexamined Patent Publication No. 2010-270215 Japanese Unexamined Patent Publication No. 2010-270216 Japanese Patent No. 4882206

Generally, as the binder resin for laminating ink, a polyurethane resin having an intramolecular urethane bond concentration as high as possible is used. However, when the urethane bond concentration is high, the boil suitability and retort suitability of the ink tend to be poor. In addition, the solubility in solvents such as methyl ethyl ketone, ethyl acetate, and isopropyl alcohol is reduced, and when these solvents are used, the solid content of the ink is deposited in the plate, which is called plate clogging. There is a problem that printing defects occur in the part (decrease in printability).

When an aromatic organic solvent such as toluene is used, the polyurethane resin skeleton is hardened to improve blocking resistance, and by adding chlorinated polypropylene (PP), boil suitability, retort suitability, laminate strength, print suitability, An ink with good adhesiveness and blocking resistance can be obtained. However, from the viewpoint of working environment and the like, the use of aromatic organic solvents or organic solvents that do not contain ketone organic solvents such as methyl ethyl ketone are being promoted (non-toluene, etc.). In addition, it has been difficult for conventional inks containing an organic solvent containing no aromatic organic solvent and a polyurethane resin to meet the demand for a wide variety of films.

In one aspect, an object of the present invention is for a printing ink for obtaining an ink having excellent printability, laminate strength, boil suitability, and retort suitability without the need for a ketone organic solvent or an aromatic organic solvent. To provide a binder. Another object of the present invention is also to provide a printing ink composition for packaging lamination using the binder for printing ink and a printed matter obtained from the composition.

As a result of diligent research, the present inventors have found that polyurethane resins containing dimethylol propionic acid have excellent printability even when an organic solvent containing no ketone-based organic solvent or aromatic-based organic solvent is used. It has been found to be effective for obtaining a printing ink having laminate strength, boil suitability and retort suitability. The present invention has been completed based on such findings.

One aspect of the present invention relates to a binder for printing ink containing a polyurethane resin as a main component. The polyurethane resin is a polymer containing (A) polyol, (B) dimethylolpropionic acid, (C) diisocyanate compound, and (D) chain extender. This polyurethane resin is obtained by reacting at least (A) polyol, (B) dimethylolpropionic acid, (C) diisocyanate compound, and (D) chain extender. (A) The polyol contains a polyester polyol having a number average molecular weight of 1000 to 6000. The content of (B) dimethylolpropionic acid in the polyurethane resin is 0.01 to 5% by mass with respect to the mass of the polyurethane resin.

When the binder contains a polyurethane resin containing dimethylolpropionic acid, the printability of the printing ink is improved. Further, when the content of dimethylolpropionic acid is within the above range, the laminate strength, boil suitability, retort suitability, print suitability and the like are improved.

The polyol (A) may contain a polyether polyol (polyesters) having a number average molecular weight of 200 to 4000. The polyether polyol contained in the polyol (A) may be one or more kinds of polyether polyols selected from the group consisting of polyethylene glycol, polypropylene glycol and polytetramethylene ether glycol. These particular polyether polyols can contribute to further improvements in printability.

If necessary, in addition to the polyurethane resin, the following resins can be used in combination as sub-ingredients. Examples thereof include polyurethane resins, polyamides, nitrocelluloses, poly (meth) acrylic acid esters, polyvinyl chlorides, vinyl chloride vinyl acetate copolymers, rosin-based resins, and ketone resins other than the above.

In another aspect, the present invention relates to a printing ink composition for packaging lamination containing the above-mentioned binder for printing ink, colorant and organic solvent as components.

The organic solvent in the printing ink composition for packaging lamination may be substantially free of either an aromatic organic solvent or a ketone organic solvent. The above binder for printing ink is particularly suitable for an ink composition for packaging lamination that does not contain an aromatic organic solvent or a ketone organic solvent. However, it is also possible to use the binder in an ink composition containing an aromatic organic solvent or a ketone organic solvent, and even in that case, excellent properties can be exhibited.

Yet another aspect of the present invention relates to a printed matter formed by printing the above ink composition for packaging lamination. This printed matter has a printing film containing a binder for printing ink and a colorant.

The present invention can provide a binder for a printing ink for obtaining an ink having excellent printability, laminate strength, boil suitability and retort suitability. Since this binder has excellent solubility in a solvent, it suppresses plate clogging and is less likely to cause printing defects in the image area.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

The binder for printing ink according to one embodiment is a binder (binder resin) containing a polyurethane resin as a main component. Usually, 50 to 100% by mass of the entire binder is composed of polyurethane resin.

The polyurethane resin in the binder may be a polymer obtained by reacting at least (A) polyol, (B) dimethylolpropionic acid, (C) diisocyanate compound, and (D) chain extender. .. This polyurethane resin is derived from each of a polyol, dimethylolpropionic acid, a diisocyanate compound, and a chain extender. The content of (B) dimethylolpropionic acid in the polyurethane resin (content of the structural unit derived from dimethylolpropionic acid) may be 0.01 to 5% by mass with respect to the mass of the polyurethane resin.

The polyol (A) includes a polyester polyol. The polyester polyol is a polyester containing a diol, a dicarboxylic acid, and the like, and has a hydroxyl group at the terminal.

The number average molecular weight of the polyester polyol may be 1000 to 6000. As used herein, the number average molecular weight of each material may be converted to standard polystyrene as measured by gel permeation chromatography (GPC).

Examples of the diol constituting the polyester polyol include ethylene glycol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, triethylene glycol, 1- or 2-methyl-1,3-butylene glycol, and the like. 1-or 2-methyl-1,3-butylene glycol, 1-or 2-methyl-1,4-pentylene glycol, 2,4-diethyl-1,5-pentanediol, tripropylene glycol, 1,2- Propylene glycol, 1,3-butanjiol, 1-, 2- or 3-methyl-1,5-pentandiol, 2-methyl-1,3-propanediol, ethylene oxide of bisphenol A, propylene oxide, ethylene Examples thereof include alkylene oxide adducts such as propylene oxide, neopentyl glycol, butyl ethyl propanediol and the like. Of these, 3-methyl-1,5-pentanediol and / or neopentyl glycol may be particularly selected. By selecting 3-methyl-1,5-pentanediol and / or neopentyl glycol, the effects of the present invention can be more pronounced.

The polyester polyol may further contain polyfunctional polio. Examples of polyfunctional polyols include glycerin, trimetyl propane, trimetyl ethane, 1,2,6-hexanetriol, 1,2,4-butantriol, sorbitol, and pentaerythritol. Be done.

Examples of the dicarboxylic acid constituting the polyester polyol include adipic acid, succinic acid, sebacic acid, azelaic acid, fumaric acid, maleic acid, terephthalic acid, isophthalic acid, and a combination of two or more thereof. Of these, adipic acid and / or sebacic acid may be particularly selected. By particularly selecting adipic acid and / or sebacic acid, the effects of the present invention can be more pronounced.

The polyester polyol may contain an anhydride of the dicarboxylic acid and / or an esterified product of a lower alcohol having 1 to 5 carbon atoms of the dicarboxylic acid together with or instead of the dicarboxylic acid.

The polyester polyol in the present embodiment can be obtained by the same method as the usual polyester production method. For example, a polyester polyol can be obtained by dehydrating and condensing a diol with a dicarboxylic acid or an acid anhydride.

The polyol (A) may contain a polyether polyol (polyesters) having a number average molecular weight of 200 to 4000. Examples of the polyether polyol include polyoxyalkylene glycols such as polyethylene glycol (PEG), polypropylene glycol (PPG), and polytetramethylene ether glycol (PTMG), and alkylene oxide adducts of bisphenol A. The alkylene oxide added to the bisphenol A may be, for example, ethylene oxide, propylene oxide, or a combination thereof.

When the polyether polyol contained in the polyol (A) is at least one selected from the group consisting of polyethylene glycol, polypropylene glycol and polytetramethylene ether glycol, printability can be further improved. From the same viewpoint, the number average molecular weight of these glycols may be 600 to 3000.

The polyurethane resin is obtained by reacting (B) dimethylolpropionic acid (DMPA) with another monomer. This polyurethane resin may be referred to as "DMPA-modified polyurethane resin" in the present specification.

The content of (B) dimethylolpropionic acid may be 0.01 to 5% by mass with respect to the mass of the polyurethane resin. (B) When the content of DMPA is 0.01% by mass or more, the pigment dispersibility of the printing ink is good. When this content is 5% by mass or less, the film (printing film) does not become excessively hard, and good lamination strength, boil suitability, and retort suitability can be easily obtained. That is, when the content of DMPA is in the range of 0.01 to 5% by mass, effects such as improvement of laminate strength, boil suitability, retort suitability, and print suitability can be obtained. From the same viewpoint, the content of DMPA may be 0.05 to 4% by mass, or 0.1 to 3% by mass.

The (C) diisocyanate compound constituting the polyurethane resin is a compound having two isocyanate groups, and can be various diisocyanates of aromatic, aliphatic or alicyclic group.

Typical examples of isocyanate compounds are 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyldiisocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane. Diisocyanate, 1,3-phenylenediocyanate, 1,4-phenylenediocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, lysine diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis (isocyanatemethyl) cyclohexane, Examples thereof include methylcyclohexane diisocyanate, m-tetramethylxylylene diisocyanate, and dimerized isocyanate obtained by converting the carboxyl group of dimer acid into an isocyanate group. These diisocyanate compounds may be used alone or in combination of two or more. Of these, alicyclic diisocyanates, especially isophorone diisocyanate (IPDI), may be selected. By using the alicyclic diisocyanate, the effect according to the present invention can be exerted even more remarkably.

The chain extender (D) constituting the polyurethane resin can be arbitrarily selected from those usually used as the chain extender for the polyurethane resin, and may be, for example, polyamine or glycol. Examples of the chain extender include ethylenediamine, propylenediamine, hexamethylenediamine, triethylenetetramine, diethylenetriamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, and dimerdiamine. Examples of other chain extenders are 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, and di-2-. Examples thereof include diamines having a hydroxyl group in the molecule such as hydroxypropylethylenediamine, glycols already exemplified as polyols constituting polyester polyols, and other glycols. One of these chain extenders may be used alone, or two or more thereof may be used in combination. Of these, isophorone diamine may be selected. By selecting the isophorone diamine, the effect according to the present invention can be exerted even more remarkably.

The chain extender is a diol having a tertiary amine structure such as methyldiethanolamine, methyldiisopropanolamine, phenyldiisopropanolamine, 4-methylphenyldiisopropanolamine, 4-methylphenyldiethanolamine, or a combination of two or more thereof. There may be.

When synthesizing the polyurethane resin, a chain length terminator can also be used if necessary. Examples of such a chain length terminator include monoalcohols and monoamines. Examples of monoalcohols include methanol, propanol, butanol, and 2-ethylhexanol. Examples of monoamines include mono or dialkylamines having 2 to 8 carbon atoms (butylamine, dibutylamine, etc.) and mono or dialkanolamines having 2 to 6 carbon atoms (monoethanolamine, diethanolamine, propanolamine, etc.).

The contents of each of the (A) polyol, (C) diisocyanate compound, and (D) chain extender in the polyurethane resin can be arbitrarily adjusted.

The polyurethane resin is, for example, produced a urethane prepolymer having a urethane bond and an isocyanate group by a reaction of a raw material mixture containing (A) polyol, (B) dimethylol propionic acid and (C) diisocyanate compound, and urethane pre. It can be synthesized by a method including producing a polyurethane resin by reacting a polymer with a (D) chain extender. The synthesis conditions and the like can be appropriately set according to a conventional method for synthesizing a polyurethane resin.

The ink composition according to one embodiment contains the binder for printing ink, a colorant, and an organic solvent. This ink composition can be a packaging laminating ink composition used for forming a printing film of a packaging container produced by a laminating method. The content of the binder (concentration of resin solid content) in the ink composition is usually about 3 to 50% by mass with respect to the mass of the ink composition.

The colorant in the ink composition can be appropriately selected from those usually used as a colorant for printing ink. Examples of colorants include pigments such as cyanine blue. The content of the colorant in the ink composition is usually about 1 to 60% by mass with respect to the mass of the ink composition.

The organic solvent constituting the ink composition may be, for example, ethyl acetate, isopropyl alcohol, or a combination thereof. The organic solvent may be substantially free of either an aromatic organic solvent or a ketone organic solvent. More specifically, the total content of the aromatic organic solvent and the ketone organic solvent in the organic solvent may be 0 to 1% by mass with respect to the mass of the organic solvent.

The printed matter according to one embodiment has a base material and a printed film formed on the base material. The printing film contains the binder for printing ink and a colorant. This printed matter may be a packaging container (particularly, a food packaging container) having a plastic film laminated on a base material while covering the printed film. The printing film can be formed by a method including printing the ink composition on a substrate and removing an organic solvent from the printed ink composition. The printing method is not particularly limited, and may be, for example, gravure printing or flexographic printing. The thickness of the printing film is usually about 0.1 to 30 μm. The base material constituting the printed matter, the plastic film to be laminated, the adhesive used for laminating, and the like are not particularly limited and can be appropriately selected from commonly used materials.

Hereinafter, preferred examples of the present invention will be described, but the present invention is not limited to these examples. Hereinafter, "part" represents "parts by mass" and "%" represents "% by mass".

Synthesis Example 1 (Synthesis of Polyurethane Resin A)
A polyester polyol (manufactured by Hitachi Chemical Industries, Ltd., 3-methyl-1,5-pentanediol) having a number average molecular weight of 3000 as a component (A) in a round bottom flask equipped with a stirrer, a thermometer and a nitrogen gas introduction tube. Adipate) 300 parts, (B) component dimethylolpropionic acid (DMPA, Wako Pure Chemical Industries, Ltd.) 1.5 parts, and (C) component isophorone diisocyanate (IPDI, Wako Pure Chemical Industries, Ltd.) Company) 49.4 copies were prepared. These were reacted at 105 ° C. for 6 hours under a nitrogen stream to produce a prepolymer having an isocyanate group content of 2.66%. 234 parts of ethyl acetate (Wako Pure Chemical Industries, Ltd.) was added thereto to obtain a uniform urethane prepolymer solution. Subsequently, as component (D), isophorone diamine (IPDA, Wako Pure Chemical Industries, Ltd.) 20.1 parts, and di-n-butylamine (DBA, Wako Pure Chemical Industries, Ltd.) 1.7 parts. , 585 parts of the urethane prepolymer solution was added to a mixture of 375 parts of ethyl acetate (Wako Pure Chemical Industries, Ltd.) and 261 parts of isopropyl alcohol (Wako Pure Chemical Industries, Ltd.) as an organic solvent. The obtained solution was heated to 60 ° C. and reacted for 3 hours to obtain a solution of a polyurethane resin (DMPA-modified polyurethane resin) containing dimethylolpropionic acid. Regarding this solution of DMPA-modified polyurethane resin (hereinafter referred to as "polyurethane resin solution A"), the concentration (NV) of the resin solid content (polyurethane resin) is 30%, the viscosity is 500 mPa · s (25 ° C.), and the amine value is 0. It was .5 mgKOH / g. The content of DMPA in the DMPA-modified polyurethane resin was 0.4% when calculated from the amount of raw materials charged.

(Synthesis Examples 2-12)
Using the raw materials shown in Tables 1 and 2, polyurethane resin solutions B to L were obtained in the same manner as in Synthesis Example 1.

1. 1. Preparation of ink composition (Examples 1 to 10 and Comparative Examples 1 to 3)
Ink composition for evaluating color pigment dispersibility In Example 1, 28 parts of the polyurethane resin solution, 10 parts of cyanine blue, and 52 parts of the mixed solvent (ethyl acetate / isopropyl alcohol) of Synthesis Examples 1 to 12 were compared with the nitrocellulose solution (solvent) in Example 1. : Mixed solvent, concentration: 30%) 3.5 parts, and in Examples 2 to 10 and Comparative Examples 1 to 3, 10 parts of a solution of vinyl chloride vinyl acetate copolymer resin (solvent: ethyl acetate, concentration: 15%). Mixed.
Each of the obtained mixtures was dispersed for 3 hours using a pigment disperser (paint shaker). Then, the viscosity of the obtained dispersion was adjusted to the Zahn Cup No. 1 using a mixed solvent. The number of seconds measured in 3 was adjusted to 15 seconds to obtain an ink composition for evaluating color pigment dispersibility.
The mixing ratio of the mixed solvent used for preparing the ink composition was ethyl acetate / isopropyl alcohol = 7/3 (mass ratio).

Other Ink Compositions for Evaluation 35 parts of the polyurethane resin solution, 35 parts of titanium white, and 20 parts of the mixed solvent (ethyl acetate / isopropyl alcohol) of Synthesis Examples 1 to 12 are compared with the solution of nitrocellulose in Example 1. 3.5 parts (solvent: mixed solvent, concentration: 30%), and in Examples 2 to 10 and Comparative Examples 1 to 3, a solution of vinyl chloride vinyl acetate copolymer resin (solvent: ethyl acetate, concentration: 15%) 10 The parts were mixed.
Each of the obtained mixtures was dispersed for 1 hour using a pigment disperser (paint shaker). The viscosity of the obtained dispersion was adjusted to Zahn Cup No. 1 using a mixed solvent. The number of seconds measured in 3 was adjusted to 15 seconds to obtain the ink compositions for evaluation (2) to (6) below.
The mixing ratio of the mixed solvent used for preparing the ink composition was ethyl acetate / isopropyl alcohol = 7/3 (mass ratio).

2. Evaluation (1) Color Pigment Dispersibility The above ink composition was printed on a polyethylene terephthalate film (hereinafter abbreviated as "PET film") to prepare a printing film having a coating film as a printing film. The state of the coating film (printing film) of the obtained printing film was visually observed, and the color pigment dispersibility was determined according to the following criteria. The uneven color of the coating film means that the dispersibility of the pigment is poor.
"A" ... There is no color unevenness in the coating film.
"B" ... There is uneven color in a part of the coating film.
"C" ... The coating film has uneven color.

(2) The above ink composition containing titanium white was printed on an adhesive PET film or nylon film (hereinafter abbreviated as "NY film") to prepare a printing film having a coating film as a printing film. .. After leaving this printing film for 24 hours, a cellophane tape was attached to the coating film, and the cellophane tape was rapidly peeled off. The state of the coating film at this time was observed, and the adhesiveness of the coating film was evaluated according to the following criteria.
"A" ... 80% or more of the coating film remains on the film.
"B" ... 50 to 80% of the coating film remains on the film.
"C" ... 50% or less of the coating film remains on the film.

(3) Printability The above ink composition containing titanium white was printed on a PET film using a small gravure printing tester to form a printing pattern (printing film). After that, the state of the print pattern, that is, the state of the plate running out of the doctor and the lack of the print pattern related to the cell clogging were visually observed, and the printability was judged according to the following criteria.
"A" ... Good printability.
"B" ... The printability is insufficient.
"C" ... The printability is extremely poor.

(4) Dry (DL) Laminate Strength The above ink composition containing titanium white was printed on a PET film or NY film to obtain a printed matter having a coating film as a printing film. A non-stretched polypropylene film (CPP film) was laminated on the coating film by a dry laminating machine with a urethane adhesive sandwiched between them. The obtained laminate was aged at 40 ° C. for 2 days (3 days after lamination), cut into 15 mm widths, and 180 ° peel strength was measured.

(5) Boil Suitability Test The above ink composition containing titanium white was printed on a PET film or NY film to obtain a printed matter having a coating film as a printing film. After applying an isocyanate-based adhesive to the coating film, a 60 μm polyethylene film was laminated by a dry laminating machine to obtain a laminated product. A bag was prepared using this laminated product, a water / oil mixture was placed therein, and the bag was sealed. Next, the bag was heated in hot water at 95 ° C. for 30 minutes, the floating state of the laminated product was observed, and the boil suitability was evaluated based on the following criteria.
"A": There was no floating in the laminated product.
"B": The laminated product was partially lifted.
"C": Floating occurred on the entire surface of the laminated product.

(6) Retort Suitability Test A coating film of the above ink composition containing titanium white was printed on a PET film or a NY film to obtain a printed matter. After applying an isocyanate-based adhesive to the coating film, a 60 μm unstretched polypropylene (CPP) film was laminated by a dry laminating machine to obtain a laminated product. A bag was prepared using this laminated product, a water / oil mixture was placed therein, and the bag was sealed. Next, the bag was heated in pressurized hot water at 120 ° C. for 30 minutes, the floating state of the laminated product was observed, and the retort suitability was evaluated based on the following criteria.
"A": There was no floating on the laminated product.
"B": The laminated product was partially lifted.
"C": Floating occurred on the entire surface of the laminated product.

The evaluation result "AB" in the table means that the evaluation was intermediate between A and B. As shown in Tables 3 and 4, the ink compositions of Comparative Examples 1 to 3 containing a polyurethane resin in which the content of dimethylolpropionic acid is not in the range of 0.01 to 5% by mass as a binder have color pigment dispersibility. , Adhesiveness, printability, boilability, and retort suitability did not show sufficient properties.

On the other hand, the ink compositions of Examples 1 to 10 containing a polyurethane resin having a dimethylolpropionic acid content in the range of 0.01 to 5% by mass as a binder have color pigment dispersibility, adhesiveness, and printability. , Laminate strength, boil suitability, and retort suitability are all excellent.

Therefore, the ink composition containing the binder for printing ink of the present invention can have good color pigment dispersibility without using an aromatic organic solvent or a ketone organic solvent. In addition, the ink composition containing the printing ink binder of the present invention is excellent in adhesiveness (lamination strength) and printing suitability, and is also excellent in boiling suitability and retort suitability. Therefore, the printing ink binder used for food packaging containers and the like. It is extremely useful as.

Claims (6)

A binder for printing inks containing polyurethane resin.
The polyurethane resin is a polymer containing (A) polyol, (B) dimethylolpropionic acid, (C) diisocyanate compound, and (D) chain extender.
The polyol (A) contains a polyester polyol having a number average molecular weight of 1000 to 6000.
The content of (B) dimethylolpropionic acid in the polyurethane resin is 0.01 to 5% by mass with respect to the mass of the polyurethane resin.
Binder for printing ink. The binder for printing ink according to claim 1, wherein the polyol (A) further contains a polyether polyol having a number average molecular weight of 200 to 4000. The binder for printing ink according to claim 2, wherein the polyether polyol is at least one selected from the group consisting of polyethylene glycol, polypropylene glycol and polytetramethylene ether glycol. A printing ink composition for packaging laminating, which comprises the binder for printing ink, a colorant, and an organic solvent according to any one of claims 1 to 3. The printing ink composition for packaging lamination according to claim 4, wherein the organic solvent does not substantially contain either an aromatic organic solvent or a ketone organic solvent. A printed matter having a printing film containing the binder for printing ink and the colorant according to any one of claims 1 to 3.