JPH05132537A - Anionic polyurethane for water-base printing ink - Google Patents

Abstract

PURPOSE:To provide the subject polyurethane having good adhesion to a plastic such as polypropylene or polyester and excellent storage stability and long-term viscosity stability. CONSTITUTION:The objective anionic polyurethane for a water-base printing ink substantially consists of a polymeric polyol, a diisocyanate and a chain extender, wherein the polyol contains at least 30wt.% ring-opening polymer of a lactone prepared in the presence of an initiator comprising a dihydroxy compound containing a benzene ring as a skeleton and containing one or two metal sulfonate groups. This polyurethane can give a water-base printing ink having excellent adhesion to a substrate of a plastic such as polypropylene or polyester, good hydrolysis stability, and excellent storage stability and long- term viscosity stability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to anionic polyurethane for water-based printing inks, and more specifically, it has good adhesion to plastics such as polypropylene and polyester, and also has excellent storage stability and viscosity stability over time. The present invention relates to anionic polyurethane for use.

[0002]

2. Description of the Related Art Conventionally, many organic solvent-based printing inks have been used, but in recent years, from the viewpoints of preventing air pollution, regulations under the Fire Service Act, occupational safety and health, etc., water-based printing inks that do not use the organic solvent. However, the performance of the water-based ink largely depends on the characteristics of the binder which is the main component thereof.

As the binder, various resins having a carboxyl group, mainly acrylic resin, polyester resin and polyurethane resin have been proposed. Of these, acrylic resins generally have good adhesion to polypropylene films, but poor adhesion to polyester films. On the other hand, the polyester resin adheres well to the polyester film, but has poor adhesion to the polypropylene film. Since a polyurethane resin is a general-purpose binder for organic solvent-based printing inks for plastic films, various attempts have been made to make it water-soluble or water-dispersed. It is still unsatisfactory in terms of adhesion to, storage stability, etc.

[0004]

SUMMARY OF THE INVENTION In view of the present state of the binder for water-based printing inks, the present invention is excellent not only in adhesion to various plastic films such as polyester, polyethylene and polypropylene as a material to be printed but also in various stability. The object is to provide a polyurethane for water-based printing inks.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventor contains a certain amount or more of a lactone polymer obtained by ring-opening polymerization of a lactone with a specific initiator. When using a specific anionic polyurethane constituted by using a high molecular weight polyol, surprisingly found that it is possible to solve the above problems,
The present invention has been completed.

That is, according to the present invention, in an anionic polyurethane for an aqueous printing ink, which is substantially composed of a polymer polyol, a diisocyanate and a chain extender, the polymer polyol has a benzene ring as a skeleton and two hydroxyl groups. The present invention relates to an anionic polyurethane for a water-based printing ink, which contains at least 30% by weight of a ring-opening polymer of a lactone that uses a dihydroxy compound having one or two metal sulfonate groups as an initiator.

The lactone polymer, which is known as a high molecular weight diol which is a constituent raw material of a polyurethane resin, is generally obtained by ring-opening polymerization of lactones using a diol such as ethylene glycol, diethylene glycol or neopentyl glycol as an initiator. It has been done. On the other hand, the lactone polymer that characterizes the present invention uses a specific dihydroxy compound having a benzene ring as a skeleton and having two hydroxyl groups and one or two metal sulfonate metal bases as an initiator to produce lactones. It is obtained by ring-opening polymerization.

In the present invention, examples of the compound used as an initiator include dihydroxy compounds represented by the following general formula.

[0009]

[Chemical 1]

[0010]

[Chemical 2]

[0011]

[Chemical 3]

(In the above Chemical formula 1, Chemical formula 2 and Chemical formula 3,
= 1 or 2, an integer of b = 1-5, an integer of m and n = 1-3 are shown, and R is

[0013]

[Chemical 4]

X is --O-- or --COO--, M
Represents Li, Na or K. )

Preferably, a dihydroxy compound represented by the following chemical formula can be mentioned.

[0016]

[Chemical 5]

[0017]

[Chemical 6]

[0018]

[Chemical 7]

[0019]

[Chemical 8]

[0020]

[Chemical 9]

(In the above Chemical Formulas 5 to 9, M represents Na or K.)

Among the compounds represented by Chemical Formulas 5 to 9 above, the compounds represented by Chemical Formulas 5 and 6 are more preferable. Further, ethylene glycol solutions of these compounds can also be used.

The lactone which is a constituent component of the polymer polyol is not particularly limited, and examples thereof include various known ones such as ε-caprolactone, γ-butyrolactone and γ-valerolactone, which may be used alone or in combination. Can be used.

The lactone polymer according to the present invention can be obtained by heating these lactones at 130 to 240 ° C. for several hours in the presence of the above-mentioned initiator to cause ring-opening polymerization. From the viewpoint of the color tone of the resulting lactone polymer, it is preferable to carry out the reaction under a stream of an inert gas such as nitrogen gas. Further, the ring-opening polymerization is preferably carried out in the presence of a catalyst in order to accelerate the reaction. Such catalysts include tetrabutyl titanate, organotitanium compounds such as tetrapropyl titanate, organotin compounds such as dibutyltin laurate, tin octylate, dibutyltin oxide,
Examples thereof include stannous halides such as stannous chloride, stannous bromide and stannous iodide. The amount used is 0.01 to 1000 pp with respect to the total amount of the initiator and lactone used.
About m is preferable.

That is, the lactone polymer has at least two lactone chains grown from hydroxyl groups derived from the initiator as soft segments, and one or two pendant sulfone groups derived from the initiator. It is a specific compound having an acid metal base.

In the polyurethane of the present invention, it is essential that the specific lactone polymer is contained in the high molecular weight polyol in an amount of 30% by weight or more, preferably 40% by weight or more. Various well-known polymer polyols used in the polyurethane resin can be used as they are. For example, polyether polyols such as polymers or copolymers of ethylene oxide, propylene oxide, tetrahydrofuran, etc .; ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1 , 3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3-
Various known saturated or unsaturated low-molecular-weight glycols such as methyl-1,5-pentanediol, 1,6-hexanediol, octanediol, 1,4-butynediol, dipropylene glycol or n-butylglycidyl ether, Alkyl glycidyl ethers such as 2-ethylhexyl glycidyl ether, monocarboxylic acid glycidyl esters such as versatic acid glycidyl ester, dimer diol obtained by reducing dimer acid, and adipic acid, maleic acid, fumaric acid, phthalic anhydride , Diphthalic acid such as isophthalic acid, terephthalic acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, azelaic acid, sebacic acid and suberic acid, or their corresponding acid anhydrides and dimer acids Polyester that can be condensed Liols; polyester polyols obtained by ring-opening polymerization of cyclic ester compounds; other polycarbonate polyols, polybutadiene glycols, generally polyurethanes such as glycols obtained by adding ethylene oxide or propylene oxide to bisphenol A, etc. Various well-known polymer polyols used for the above can be mentioned.

The number average molecular weight of the polymer polyol as a whole including the lactone polymer is usually 600 to 10
000, preferably in the range of 1000 to 6000. If the number average molecular weight is less than 600, the resulting aqueous polyurethane film tends to be too hard, and
This is because if it exceeds 000, the drying property and blocking resistance tend to decrease.

As the diisocyanate compound used in the production of the polyurethane, various known aromatic, aliphatic or alicyclic diisocyanates can be used. 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, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate,
Xylylene diisocyanate, isophorone diisocyanate, lysine diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, methylcyclohexane diisocyanate, m-tetramethylxylylene diisocyanate and dimer acid carboxyl groups are isocyanates. A typical example thereof is dimerisocyanate converted into a group.

In the present invention, various known chain extender components can be used. For example, ethylenediamine, propylenediamine, hexamethylenediamine,
Triethylenetetramine, diethylenetriamine, isophoronediamine, dicyclohexylmethane-4,4'-
Examples include amines such as diamines and water. Other,
2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine and the like have a hydroxyl group in the molecule. Representative examples thereof include the diamines possessed, various well-known low-molecular glycols listed in the section of the description of the polyester diol, and dimer-diamine in which the carboxyl group of dimer is converted into an amino group.

The polyurethane of the present invention is a water-based anionic resin as described above, and an anionic property is imparted by introducing a metal sulfonate group-containing compound into the polyurethane resin. The introduction of such a metal sulfonate group is
This is achieved in the production stage of the lactone polymer. Further, if necessary, by using a compound having a free carboxyl group and at least one active hydrogen capable of reacting with an isocyanate group as a chain extender and / or a chain length terminator, a carboxyl group can be added to the polyurethane resin. It is also possible to add. However, the anionic property is mainly based on the metal sulfonate base.

Examples of the compound having a free carboxyl group and at least one active hydrogen capable of reacting with an isocyanate group include glyceric acid, dioxymaleic acid, dioxyfumaric acid, tartaric acid, 2,6-dioxybenzoic acid and dimethylol. Propionic acid, 2,2-dimethylolvaleric acid,
2,2-dimethylolpentanoic acid, 4-hydroxyisophthalic acid, salicylic acid, malic acid, lanolin fatty acid, glycolic acid, hydroxypivalic acid, 11-oxyhexadecanoic acid, ricinoleic acid, 2-oxidedecanoic acid, p
-Hydroxycarboxylic acids such as oxynaphthoic acid, castor oil fatty acid, gluconic acid, sugar acid, mucus acid, 4,4-bis (hydroxyphenyl) butyric acid, 4,4-bis (hydroxyphenyl) valeric acid and glucuronic acid; glutamic acid ,
Alanine, tyrosine, serine, cysteine, glycine,
6-aminocaproic acid, 4-aminobutyric acid, monoaminobenzoic acid, diaminobenzoic acid, lysine, arginine, α,
δ-diaminovaleric acid, 4,4-bis (aminophenyl) butyric acid, 3,3′-dicarboxybenzidine, 3,
Aminocarboxylic acids such as 3'-dicarboxy-4,4'-diaminodiphenylmethane; tris (hydroxymethyl) amine, 2-amino-2-ethyl-1,3-propanediol, diethanolamine, diisopropanolamine, monoethanolamine , 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine,
Amine having a hydroxyl group in the molecule such as di-2-hydroxyethyl propylene diamine, maleic anhydride, phthalic anhydride, trimellitic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrabromophthalic anhydride, glutaric anhydride Rings such as acids, succinic anhydride, citraconic anhydride, camphor anhydride, 2,3-dimethylmaleic anhydride, cis-1,2-cyclohexanedicarboxylic anhydride, endomethylenetetrahydrophthalic anhydride, hexahydropyromellitic anhydride Various publicly known compounds such as a condensate with the formula dicarboxylic acid anhydride can be exemplified.

The content of the metal sulfonate group in the solid content of the polyurethane resin in the present invention is not particularly limited as long as it can be water-solubilized by the operation described later, but is usually 0.1 to 2.0 meq / polyurethane solid content. It is in the range of g, preferably in the range of 0.2 to 1.5 meq / g.

In the present invention, in order to control the molecular weight of polyurethane, a chain length terminating agent can be used if necessary. Examples of such chain length terminators include di-
Examples include dialkylamines such as n-butylamine and alcohols such as ethanol and isopropyl alcohol.

Examples of the method for producing the polyurethane of the present invention include the following methods. (1) The polymer polyol and the diisocyanate compound are reacted under conditions of excess isocyanate groups to prepare a prepolymer having an isocyanate group at the terminal of the polymer polyol, and the prepolymer is then used as an aromatic solvent or ketone system. It is reacted with a chain extender and optionally a chain length terminating agent in a suitable organic solvent selected from a solvent, an ester solvent and the like. Then, after adding water, the organic solvent remaining in the system is distilled off under reduced pressure to carry out phase conversion into an aqueous solution. In addition,
At this time, if necessary, various known surfactants may be used in small amounts. (2) A method in which a polymer polyol component, a diisocyanate compound, a chain extender and, if necessary, a chain length terminating agent are reacted at once in the same organic solvent as described above, and then similarly phase-converted into an aqueous solution. 3. Polymer polyol and diisocyanate are reacted in an appropriate organic solvent under conditions of excess isocyanate groups to prepare a prepolymer having isocyanate groups at the molecular ends, and then phase conversion to an aqueous solution by adding water After that, a chain extender and, if necessary, a chain length terminating agent are reacted, and then the organic solvent present in the system is distilled off under reduced pressure. Whichever method is adopted, it is preferable to react so that the metal sulfonate group contained in the finally obtained polyurethane resin is within the above range.

The end point of the reaction in the above reaction may be appropriately determined by paying attention to the solid content of the obtained polyurethane resin. Usually, the weight average molecular weight of the solid content is 5,000 to 30.
It is preferable that the range is about 0000. If the weight average molecular weight is less than 5,000, the drying properties, blocking resistance, film strength, etc. of the printing ink using this as a vehicle are likely to decrease. On the other hand, when it exceeds 300,000, the gloss and printability of the obtained printing ink are likely to deteriorate. The weight average molecular weight referred to in the present specification is a polystyrene conversion value obtained by GPC measurement.

The solid content concentration and viscosity of the polyurethane resin of the present invention are not particularly limited, but may be appropriately determined in consideration of workability during printing. Normally, the solid content concentration is 15-
It is practically suitable to adjust the viscosity to 60% by weight and the viscosity to the range of 10 to 100,000 cP / 25 ° C. Further, in the present invention, a conventionally known water-based resin other than the water-based anionic polyurethane resin of the present invention may be used in combination, if necessary, without departing from the scope of the invention. For example, water-based polyurethane resin other than the present invention, water-based polyamide resin, water-based acrylic acid ester-based copolymer salt, water-based styrene-maleic acid-based copolymer salt and the like can be mentioned.

When an aqueous printing ink composition is prepared using the thus obtained aqueous polyurethane for a printing ink of the present invention, the preparation method is not particularly limited. Usually, various pigments are added to the aqueous polyurethane of the present invention,
A water-based printing ink composition can be easily obtained by dispersing and appropriately blending the above-mentioned combination resin and additives such as an anti-blocking agent and a plasticizer, if necessary.

[0038]

According to the present invention, for plastics such as polypropylene and polyester as a material to be printed,
It has a great effect that it is possible to provide an aqueous printing ink having excellent adhesion and excellent storage stability and viscosity stability over time because it has good hydrolysis stability.

Although the reason why the polyurethane of the present invention exhibits the above effect is not clear, the metal sulfonate group contained in the specific lactone polymer is relatively non-localized in view of the entire structure of the polyurethane. It is thought that this is because they are arranged evenly.

[0040]

EXAMPLES The present invention will be specifically described below with reference to production examples, examples and comparative examples, but the present invention is not limited to these examples. Parts and% are based on weight.

Production Example 1 Di-2-hydroxyethyl sodium salt of 5-sulfoisophthalic acid [in the compound of the above Chemical Formula 5, M
= Na] 276.8 parts, ε-caprolactone 500 parts and tetrabutyl titanate 0.16 parts were charged, and 190
The reaction was carried out at 0 ° C for 6 hours. The obtained lactone polymer A is
The hydroxyl value was 112.6, the number average molecular weight was 996, and the metal sulfonate content was 1 meq / solid content 1 g.

Production Example 2 108.4 parts of di-2-hydroxyethyl sodium salt of 5-sulfoisophthalic acid was placed in the same reactor as in Production Example 1.
500 parts of ε-caprolactone and 0.12 part of tetrabutyl titanate were charged and reacted in the same manner. A lactone having a hydroxyl value of 56.8, a number average molecular weight of 1975, and a metal sulfonate content of 0.5 meq / solid content of 1 g. Polymer B was obtained.

Production Example 3 A reaction apparatus similar to that of Production Example 1 was charged with sulfoterephthalic acid di-
2-Hydroxyethyl sodium salt [compound of the above chemical formula 6, M = Na] 108.4 parts, ε-caprolactone 50
Charge 0 parts and 0.12 parts of tetrabutyl titanate,
Similarly reacted, hydroxyl value is 56.6, number average molecular weight is 1982, metal sulfonate content is 0.5 meq.
/ Lactone polymer B having a solid content of 1 g was obtained.

Production Example 4 Ethylene glycol 1 was placed in the same reactor as in Production Example 1.
6.0 parts, ε-caprolactone 500 parts and tetrabutyl titanate 0.10 parts were charged and reacted in the same manner,
A lactone polymer D having a hydroxyl value of 56.1, a number average molecular weight of 2000 and an acid value of 0.3 was obtained.

Example 1 100 parts of the lactone polymer A obtained in Preparation Example 1 and 35 parts of isophorone diisocyanate were added to a reactor similar to that of Preparation Example 1.
7 parts and 58.1 parts of methyl ethyl ketone were charged and reacted at 80 ° C. for 6 hours under a nitrogen stream to obtain a prepolymer having an isocyanate terminal. After adding 425 parts of water to this prepolymer solution and emulsifying, 8.2 parts of isophoronediamine and 2.3 parts of di-n-butylamine were added and the mixture was mixed at 50 ° C. for 3
Reacted for hours. Then, methyl ethyl ketone was distilled off under heating and reduced pressure to obtain a transparent polyurethane resin aqueous solution A. Resin solid content concentration is 30%, viscosity is 300 cP / 25
℃, pH 8.4, weight average molecular weight 59000 (GP
C is HLC802A manufactured by Tosoh Corporation, and column is TSKg.
(using elG2000H and 4000H), the metal sulfonate content in the resin solid content was 0.68 meq / g. This polyurethane resin aqueous solution A was kept warm at 40 ° C. for 1 month, and the weight average molecular weight was measured again to be 55.
000 and the viscosity was 290 cP / 25 ° C.

Example 2 100 parts of the lactone polymer B obtained in Preparation Example 2 and isophorone diisocyanate 22. were added in the same reactor as in Preparation Example 1.
5 parts of methyl ethyl ketone and 52.4 parts of methyl ethyl ketone were charged and reacted at 80 ° C. for 6 hours under a nitrogen stream to obtain a prepolymer having an isocyanate terminal. 366 parts of water was added to this prepolymer solution for emulsification, and then di-n-butylamine 2.0 was added.
Parts were added and reacted at 50 ° C. for 3 hours. Then, methyl ethyl ketone was distilled off under reduced pressure with heating to obtain a semi-transparent polyurethane resin aqueous solution B. The resin solid content concentration was 30%, the viscosity was 250 cP / 25 ° C., the pH was 8.3, the weight average molecular weight was 84000, and the metal sulfonate metal base content in the resin solid content was 0.4 meq / g. After keeping this polyurethane resin aqueous solution B at 40 ° C. for 1 month, the weight average molecular weight was measured again to be 81,000 and the viscosity was 230.
It was cP / 25 ° C.

Example 3 80 parts of the lactone polymer C obtained in Preparation Example 3, 20 parts of polybutylene adipate diol having a molecular weight of 2000, and isophorone diisocyanate 1 were placed in the same reactor as in Preparation Example 1.
7.9 parts and 50.5 parts of methyl ethyl ketone were charged and reacted under a nitrogen stream at 80 ° C. for 6 hours to obtain a prepolymer having an isocyanate terminal. 358 parts of water was added to this prepolymer solution for emulsification, and then isophoronediamine 3.
5 parts and 1.9 parts of di-n-butylamine were added and reacted at 50 ° C. for 3 hours. Thereafter, methyl ethyl ketone was distilled off under heating and reduced pressure to obtain a translucent polyurethane resin aqueous solution C. Resin solid content concentration is 30%, viscosity is 600 cP / 2
5 ° C., pH 8.8, weight average molecular weight 45000, metal sulfonate content in resin solids is 0.32 me
It was q / g. 40% of this polyurethane resin aqueous solution C
After keeping the temperature at 0 ° C. for 1 month, the weight average molecular weight was measured again to be 42,000 and the viscosity was 550 cP / 25 ° C.

Example 4 60 parts of the lactone polymer B obtained in Production Example 2 and poly (3-methyl-) having a molecular weight of 2000 were placed in the same reactor as in Production Example 1.
40 parts of pentane adipate) diol, 2.1 parts of dimethylolpropionic acid, 2 parts of isophorone diisocyanate
3.3 parts and 53.7 parts of methyl ethyl ketone were charged and reacted at 80 ° C. for 6 hours under a nitrogen stream to obtain a prepolymer having an isocyanate terminal. To this prepolymer solution, 3.2 parts of triethylamine and 417 parts of water were added and emulsified, 2.1 parts of di-n-butylamine was added, and the mixture was reacted at 50 ° C. for 3 hours. Then, methyl ethyl ketone was distilled off under heating and reduced pressure to obtain a translucent polyurethane resin aqueous solution D. Resin solid content concentration is 30%, viscosity is 200 cP / 2
5 ° C., pH 8.5, weight average molecular weight 72000, metal sulfonate content in resin solids is 0.23 me
q / g, the carboxyl group content is 0.12 meq
/ G. This polyurethane resin aqueous solution D is 40 ° C
After keeping the temperature for 1 month, the weight average molecular weight was measured again and found to be 65,000 and the viscosity was 190 cP / 25 ° C.

Example 5 30 parts of the lactone polymer A obtained in Preparation Example 1, 70 parts of polyoxytetramethylene glycol having a molecular weight of 2000, 2.0 parts of dimethylolpropionic acid, and isophorone diisocyanate were placed in the same reactor as in Preparation Example 1. Charge 23.1 parts and 53.6 parts of methyl ethyl ketone, and add 8 under a nitrogen stream.
The reaction was carried out at 0 ° C. for 6 hours to obtain a prepolymer having an isocyanate terminal. To this prepolymer solution, 3.0 parts of triethylamine and 397 parts of water were added and emulsified.
-Butylamine (2.2 parts) was added, and the mixture was reacted at 50 ° C for 3 hours. Then, methyl ethyl ketone was distilled off under heating and reduced pressure to obtain a translucent polyurethane resin aqueous solution E. Resin solid content concentration is 30%, viscosity is 600 cP / 25 ° C., pH is 8.9, weight average molecular weight is 120,000, metal sulfonate content in resin solid is 0.24 meq / g, and carboxyl group is contained. The amount was 0.12 meq / g. This polyurethane resin aqueous solution E was kept at 40 ° C. for 1 month, and the weight average molecular weight was measured again to be 1180.
The viscosity was 570 cP / 25 ° C.

Comparative Example 1 100 parts of the lactone polymer D obtained in Production Example 4 and 11.4 of dimethylolpropionic acid were placed in the same reactor as in Production Example 1.
Parts, 48.1 parts of isophorone diisocyanate and 68.3 parts of methyl ethyl ketone were charged and reacted at 80 ° C. for 6 hours under a nitrogen stream to obtain a prepolymer having an isocyanate terminal. To this prepolymer solution, 17.2 parts of triethylamine and 473 parts of water were added and emulsified, and then 2.7 parts of di-n-butylamine was added and reacted at 50 ° C. for 3 hours. Thereafter, methyl ethyl ketone was distilled off under reduced pressure with heating to obtain a semitransparent polyurethane resin aqueous solution F. The resin solid content concentration was 30%, the viscosity was 200 cP / 25 ° C., the pH was 8.4, the weight average molecular weight was 48,000, and the carboxyl group content in the resin solid content was 0.52 meq / g.
After the temperature of this aqueous solution of polyurethane resin F was kept at 40 ° C. for 1 month, the weight average molecular weight was measured again and found to be 25,000, and the viscosity was also reduced to 90 cP / 25 ° C.

Ink test of Examples 1 to 5 and Comparative Example 1 Titanium white (rutile type) 30 parts Polyurethane resin aqueous solution A to F 50 parts Water 10 parts Isopropyl alcohol 10 parts Mixtures of the above composition were each kneaded with a paint shaker. Meat and white printing ink was prepared. This white printing ink was applied to a discharge proof surface of a corona discharge stretch treated polypropylene film (OPP) having a thickness of 20 μm and a polyethylene terephthalate thickness of 11 μm by a simple gravure printing machine equipped with a gravure plate having a plate depth of 30 μm. It printed on one side of (PET) and dried at 40-50 degreeC, and the printing film was obtained. After leaving the obtained printing film for 24 hours, a cellophane tape was attached to the printing surface, and the appearance of the printed film when peeled off rapidly at an angle of 60 ° was observed and evaluated according to the following criteria. The evaluation results are shown in Table 1. ○ -------- More than 80% of the printed film remained on the film side. △ -------- 50-80% of the printed film remained on the film side. × -------- Only 50% or less of the printed film remained on the film side.

[0052]

INDUSTRIAL APPLICABILITY According to the present invention, an anionic polyurethane for water-based printing ink having excellent adhesiveness to various plastic films such as polyester and polypropylene as an object to be printed and excellent in hydrolysis stability can be obtained. ..

[0053]

[Table 1]

Claims (4)

[Claims] 1. An anionic polyurethane for a water-based printing ink, which is substantially composed of a polymer polyol, a diisocyanate and a chain extender, wherein the polymer polyol has a benzene ring as a skeleton and two hydroxyl groups and one or An anionic polyurethane for a water-based printing ink, which contains at least 30% by weight of a ring-opening polymer of a lactone that uses a dihydroxy compound having two metal sulfonate groups as an initiator. 2. The polyurethane according to claim 1, wherein the polymer polyol has a number average molecular weight in the range of 600 to 10,000. 3. The polyurethane has a weight average molecular weight of 5
The polyurethane according to claim 1, which is in the range of 000 to 300,000. 4. The content of metal sulfonate group in the polyurethane is 0.1 to 2.0 m per polyurethane solid content.
The polyurethane according to claim 1, which is in the range of eq / g.