JP2012153883A - Binder for printing ink, and printing ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a binder for printing ink which uses neither aromatic solvents nor ketone solvents, is stable as a solution of an organic solvent comprising esters and alcohols, and ensures excellent adhesion of an ink film to various plastic films.SOLUTION: The binder for printing ink is obtained by dissolving, in an organic solvent (F) comprising esters and alcohols, a polyurethane resin prepared by reacting a hydroxyl group-containing chlorinated polypropylene (A), a polyester polyol (B) comprising dicarboxylic acids (b1) and branched glycols (b2), a diisocyanate compound (C), a chain extender (D), and a chain length terminating agent (E) containing a diketimine compound having one amino group within the molecule.

Description

  The present invention relates to a printing ink binder and a printing ink composition.

  Polyurethane resin is highly flexible and has excellent adhesion to various plastic films such as polyester film (PET) and nylon film (NY), so it is widely used as a binder for printing ink, especially special gravure printing ink for packaging. Yes. However, polyolefin films such as polypropylene (PP) generally do not exhibit sufficient adhesion. Thus, for example, a printing ink binder has been proposed that uses a mixture of urethane-modified chlorinated polypropylene and other polyurethane resins whose main raw materials are chlorinated polypropylene having a plurality of hydroxyl groups in the molecule (Patent Document 1). See). However, since two types of polyurethane resins are essential, there are difficulties in manufacturing and handling.

  In recent years, as organic solvents used in printing ink binders have increased in interest in the work environment and workers' health, conventionally used aromatic solvents (such as toluene) and ketone solvents (such as methyl ethyl ketone) have been used. Substitution with ester solvents (such as ethyl acetate) and alcohol solvents (such as isopropyl alcohol) is required. However, polyurethane resins mainly composed of hydroxyl group-containing chlorinated polypropylene are generally difficult to dissolve in esters and alcohols. For example, a stable solution is obtained when the urethane-modified chlorinated polypropylene of Patent Document 1 is produced in a solvent containing esters. There were problems such as being unable to obtain.

JP-A-6-41488

  The present invention provides a printing ink binder which is stable as an organic solvent solution composed of esters and alcohols (hereinafter referred to as solution stability) and has excellent adhesion of an ink film to various plastic films, particularly polyolefin films. The issue is to provide.

  As a result of intensive studies, the present inventor has used a hydroxyl group-containing chlorinated polypropylene and a polyester polyol as the polyol constituting the polyurethane resin, and a printing that can solve the above problems by using a specific ketimine compound as a chain length terminator. It has been found that an ink binder can be provided.

  That is, the present invention relates to a polyester polyol (B) comprising a hydroxyl group-containing chlorinated polypropylene (A), dicarboxylic acids (b1) and branched glycols (b2), a diisocyanate compound (C), a chain extender (D), and a molecule. A binder for printing ink obtained by dissolving a polyurethane resin obtained by reacting a chain length terminator (E) containing a diketimine compound having one amino group in an organic solvent (F) comprising esters and alcohols, In addition, the present invention relates to a printing ink composition containing the printing ink binder.

  The binder for printing ink of the present invention can be used as a stable solution (varnish) of a solvent composed of esters and alcohols, and meets the recent environmental awareness in the industry. The binder is stable not only at room temperature but also at a low temperature of 0 ° C. or less. Moreover, according to the said binder, the printing ink composition excellent in the adhesiveness with respect to the plastic film which consists of polyolefin resin and other synthetic resins (polyester, nylon, etc.) is obtained. The printing ink composition is suitable as a binder for intaglio inks such as gravure printing inks, especially for special gravure printing inks for packaging.

  The binder for printing ink of the present invention comprises a hydroxyl group-containing chlorinated polypropylene (A) (hereinafter referred to as component (A)), dicarboxylic acids (b1) (hereinafter referred to as component (b1)) and branched glycols (b2) ( Hereinafter, polyester polyol (B) (hereinafter referred to as component (B)) composed of (b2) component), diisocyanate compound (C) (hereinafter referred to as component (C)), chain extender (D) (hereinafter referred to as ( D) component), and a polyurethane resin obtained by reacting a chain length terminator (E) containing a diketimine compound having one amino group in the molecule (hereinafter referred to as component (E)) from esters and alcohols. And dissolved in an organic solvent (F) (hereinafter referred to as component (F)).

  As the component (A), various known materials can be used without particular limitation as long as they are chlorinated polypropylene having a hydroxyl group in the molecule. Although the physical properties of the component (A) are not particularly limited, the number average molecular weight is usually about 500 to 50000, preferably 700 to 30000, and the chlorine content is usually 20 to 60% from the viewpoint of solution stability and adhesion. Degree, preferably 25-45%. “%” Means% by weight (the same applies hereinafter).

  The component (A) can be produced by various known methods. Specifically, it can be obtained, for example, by reacting a commercially available chlorinated polypropylene with a compound having a hydroxyl group and a radical polymerizable double bond by a known method. Examples of the double bond compound include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, allyl alcohol, and 1,4-butenediol. The component (A) is preferably used as a solution (dispersion) of esters described later.

  The present invention is characterized in that the component (B) is used together with the component (A) as the soft segment component forming the polyurethane resin. By using together (B) component, the solubility to the (F) component of the polyurethane resin which concerns on this invention can be ensured now.

  Examples of the component (b1) constituting the component (B) include aromatic dicarboxylic acids such as phthalic anhydride, isophthalic acid, terephthalic acid, adipic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, And aliphatic dicarboxylic acids such as azelaic acid and sebacic acid. As the component (b2), 1,2-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2,2-diethyl-1, Examples thereof include branched aliphatic diols such as 3-propanediol and 2-ethyl-2-butyl-1,3-propanediol. A small amount of linear glycols such as ethylene glycol, 1,4-butanediol and 1,6-hexanediol may be used together with the component (b2). Usually, it is less than 10 mol%.

  The production method of the component (B) is not particularly limited. For example, the component (b1) and the component (b2) are used in an amount ratio in which the component (b2) is slightly excessive, specifically, the component (b1): ( The dehydration condensation reaction may be performed in the range where the molar ratio of the component b2) is about 1: 1.02 to 1: 1.15. The reaction temperature is usually about 150 to 250 ° C., the reaction time is usually about 5 to 10 hours, and the reaction can be performed under normal pressure or reduced pressure.

  The physical properties of the component (B) are not particularly limited, but from the viewpoints of solution stability and adhesion, the number average molecular weight is usually about 1000 to 10,000, preferably 2000 to 6000, and the hydroxyl value is usually 11 to 110 mgKOH / g. Degree, preferably 19-56 mg KOH / g.

  In addition to the component (B), other polyols such as polyether polyols, polyester polyols other than the component (B), and polycarbonate polyols can be used in combination, but the amount is usually (B) from the viewpoint of solution stability. Usually less than 10% by weight with respect to the components.

  Although the usage-amount of (A) component and (B) component is not specifically limited, from viewpoints of solution stability, adhesiveness, etc., it occupies for 100 weight% (non-volatile matter conversion) total of (A) component and (B) component. The ratio of the component (A) is usually in the range of about 1 to 10% by weight, preferably 2 to 5% by weight.

  As the component (C), various known diisocyanate compounds can be used. Specifically, for example, butane-1,4-diisocyanate, 1,6-hexamethylene diisocyanate, lysine diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, etc. Chain aliphatic diisocyanate; cycloaliphatic-1,4-diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, 1,3-bis (isocyanatemethyl) cyclohexane, and the like; 1,5-naphthylene diene Examples thereof include aromatic diisocyanates such as isocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyldimethylmethane diisocyanate, and tolylene diisocyanate. Among these, the linear aliphatic diisocyanate and / or alicyclic diisocyanate, particularly a linear aliphatic diisocyanate having 4 to 9 carbon atoms, is preferable from the viewpoint of solution stability and particularly adhesion.

  The use ratio of the components (A) and (B) and the component (C) is not particularly limited, but considering the solution stability, adhesion, etc., the total amount of hydroxyl groups of the components (A) and (B) is 1 mol. The isocyanate group contained in the component (C) is usually in the range of about 1.1 to 5 mol, preferably 1.3 to 4 mol.

  As the component (D), the above-described component (b2) and various known diamines can be used. Examples of diamines include ethylene diamine, propylene diamine, hexamethylene diamine, isophorone diamine, and dicyclohexylmethane-4,4'-diamine.

  The component (E) includes a diketimine compound having one amino group in the molecule. The amount is usually about 30 to 100 mol%, preferably about 30 to 60 mol% in the whole component (E). As the diketimine compound, various known compounds can be used without particular limitation, but those represented by the following general formula are preferable.

(In the formula, each R may be the same or different and each represents —CH ₃ , —CH ₂ CH ₃ , —CH ₂ —CH (CH ₃ ) ₂ , and n is an integer of 1 to 4 Represents.)

  The diketimine compound represented by the formula can be obtained from various known dialkylenetriamines and ketone compounds. Examples of the dialkylene triamines include diethylene triamine, dipropylene triamine, and dibutylene triamine. Examples of the ketone compound include acetone, methyl ethyl ketone, diethyl ketone, and methyl isobutyl ketone.

  In addition, examples of the remainder of the component (E) include monoamines such as di-n-butylamine, mono-n-butylamine, diethanolamine, and monoethanolamine.

  The binder for printing ink of the present invention is obtained by dissolving a polyurethane resin obtained by reacting the components (A) to (E) in (F). Examples of the method for producing the polyurethane resin include various known one-pot methods and prepolymer methods. In the prepolymer method, once the (A) component, (B) component, and (C) component are reacted usually at about 80 to 90 ° C. for about 3 to 4 hours, a urethane prepolymer having isocyanate groups at both ends is produced. To do. In the urethanization reaction, a catalyst such as tin octylate can be used. Next, the urethane prepolymer is reacted with the component (D) and the component (E).

  Although the usage-amount of (D) component and (E) component is not specifically limited, Usually, (D) component and (D) component with respect to 1 mol of isocyanate groups which the prepolymer obtained from (A) component-(C) component has. The amino group (total) of the component (E) is usually in the range of about 0.5 to 2 mol, preferably 0.5 to 1.4 mol. Further, the use ratio of the component (D) and the component (E) is not particularly limited, but the ratio of the component (D) in the total 100% by weight of the component (D) and the component (E) is usually 25 to 85% by weight. %, Preferably 40 to 70% by weight. The conditions for reacting the component (D) and the component (E) are usually about 40 to 50 ° C. and about 2 to 3 hours.

  Although the physical properties of the polyurethane resin thus obtained are not particularly limited, for example, the number average molecular weight is usually about 5,000 to 100,000 in consideration of solution stability, adhesion, printing ink viscosity, and the like.

  The component (F) is composed of esters and alcohols. Examples of the esters include ethyl acetate, n-propyl acetate, and butyl acetate. Examples of the alcohols include methanol, ethanol, isopropanol, and n-butanol. . The weight ratio of the two is usually about 2/1 to 6/1. Moreover, the usage-amount of (F) component in the binder of this invention is not restrict | limited in particular, Usually, it is the range from which the non volatile matter of the obtained polyurethane resin solution will be about 20 to 50 weight%. The component (F) can also be used as a reaction solvent in the above production method. In this case, the obtained polyurethane resin solution can be used as it is as a binder for printing ink.

  The printing ink composition of the present invention comprises the binder for printing ink of the present invention, and usually contains a colorant, a surfactant, a wax, and other additives, such as a ball mill, an attritor, and a sand mill. Manufacture using equipment. Further, as the ink solvent, in addition to the component (F), a ketone solvent such as methyl ethyl ketone may be used in combination. Further, the content of the polyurethane resin according to the present invention is about 3 to 20% by weight in terms of nonvolatile content. In addition, you may use together polyurethane resins other than the polyurethane resin based on this invention, resin, such as nitrified cotton and an ethylene / vinyl acetate copolymer.

  Examples of the substrate to which the printing ink composition is applied include polyolefin films such as a polyester film, a nylon film, and a polypropylene film. These may be subjected to various surface treatments (such as corona treatment).

  Hereinafter, the present invention will be described in detail through examples and comparative examples, but is not limited thereto. In each example, parts and% are based on weight unless otherwise specified.

Example 1
In a round bottom flask equipped with a stirrer, a thermometer and a nitrogen gas inlet tube, 16 parts of ethyl acetate dispersion (nonvolatile content 60%) of a hydroxyl group-containing chlorinated polypropylene having a chlorine content of 30%, adipic acid and 3 -500 parts of a polyester diol having a number average molecular weight of 5000 obtained from methyl-1,5-pentanediol, 56 parts of isophorone diisocyanate, and 30 parts of ethyl acetate, and subjected to urethanization reaction at 70 ° C for 2 hours under a nitrogen stream. Carried out. Next, 0.1 part of tin octylate was added for 2 hours, and then 0.1 part of tin octylate was added again and the mixture was kept warm for 2 hours. Then, 220 parts of ethyl acetate was added to obtain a uniform solution of urethane prepolymer. Next, 19 parts of isophoronediamine, 3 parts of di-n-butylamine, 1 part of diethanolamine, ketimine compound (1) obtained from diethylenetriamine and methylisobutylketone (1) (see formula below), 670 parts of ethyl acetate, and isopropyl While the solution consisting of 460 parts of alcohol was added dropwise, the reaction system was kept at 50 ° C. for 3 hours to obtain a polyurethane resin solution having a nonvolatile content of 30%. In addition, separation and gel-like substance were not recognized in the appearance. The polyurethane resin solution was directly used as a binder for printing ink.

  The hydroxyl group-containing chlorinated polypropylene (nonvolatile content 60%) was produced as follows. That is, 4 kg of isotactic polypropylene having a melt index of 14 g / 10 min was uniformly dissolved in 80 liters of carbon tetrachloride under pressure, and chlorination was performed by blowing chlorine gas while irradiating ultraviolet rays at 100 ° C. A sample having a chlorine content of 30% was extracted, and carbon tetrachloride was distilled off and replaced with ethyl acetate to obtain a chlorinated polypropylene dispersion having a nonvolatile content of 59%. 800 parts of the obtained chlorinated polypropylene solution, 19 parts of 2-hydroxyethyl acrylate, and 6 parts of t-butyl peroxybenzoate were charged into the same round bottom flask as in Example 1, and reacted at 100 ° C. for 4 hours. Further, 1 part of t-butyl peroxybenzoate was added every 2 hours and reacted for 4 hours to obtain an ethyl acetate dispersion of a hydroxyl group-containing chlorinated polypropylene having a nonvolatile content of 60%.

Example 2
In a round bottom flask similar to that in Example 1, 16 parts of the hydroxyl group-containing chlorinated polypropylene ethyl acetate dispersion (non-volatile content 60%) obtained by the above method was added from adipic acid and 3-methyl-1,5-pentanediol. 500 parts of the resulting polyester diol having a number average molecular weight of 5000, 43 parts of hexamethylene diisocyanate and 30 parts of ethyl acetate were charged, and urethanization reaction was carried out at 70 ° C. for 2 hours under a nitrogen stream. Next, 0.1 part of tin octylate was added for 2 hours, 0.1 part of tin octylate was added again and the mixture was kept warm for 2 hours, and then 210 parts of ethyl acetate was added to obtain a uniform solution of urethane prepolymer. Next, while dropping a solution comprising 18 parts of isophoronediamine, 4 parts of di-n-butylamine, 1 part of diethanolamine, 8 parts of the ketimine compound (1), 660 parts of ethyl acetate and 450 parts of isopropyl alcohol, the reaction system was dropped. Was kept at 50 ° C. for 3 hours to obtain a polyurethane resin solution having a nonvolatile content of 30%. Further, no separation or gel-like substance was observed in the appearance. The polyurethane resin solution was directly used as a binder for printing ink.

Example 3
In a round bottom flask equipped with a stirrer, a thermometer and a nitrogen gas introduction tube, 16 parts of the hydroxyl group-containing chlorinated polypropylene ethyl acetate dispersion (nonvolatile content 60%) obtained by the above method, adipic acid and 2-methyl- 500 parts of a polyester diol having a number average molecular weight of 4000 obtained from 1,3-propanediol, 78 parts of isophorone diisocyanate, and 30 parts of ethyl acetate were charged, and a urethanization reaction was carried out at 70 ° C. for 2 hours in a nitrogen stream. Next, 0.1 part of tin octylate was added for 2 hours, and again 0.1 part of tin octylate was added and the mixture was kept warm for 2 hours. Then, 215 parts of ethyl acetate was added to obtain a uniform solution of urethane prepolymer. Next, while adding dropwise a solution comprising 28 parts of isophoronediamine, 4 parts of di-n-butylamine, 1 part of diethanolamine, 9 parts of the ketimine compound (1), 720 parts of ethyl acetate, and 490 parts of isopropyl alcohol to the solution, the reaction was performed. The system was kept at 50 ° C. for 3 hours to obtain a polyurethane resin solution having a nonvolatile content of 30%. In addition, separation and gel-like substance were not recognized in the appearance. The polyurethane resin solution was directly used as a binder for printing ink.

Comparative Example 1
In a round bottom flask similar to that in Example 1, 16 parts of the hydroxyl group-containing chlorinated polypropylene ethyl acetate dispersion (non-volatile content 60%) obtained by the above method was added from adipic acid and 3-methyl-1,5-pentanediol. 500 parts of the resulting polyester diol having a number average molecular weight of 5000, 45 parts of isophorone diisocyanate, and 30 parts of ethyl acetate were charged, and urethanization reaction was carried out at 70 ° C. for 2 hours under a nitrogen stream. Next, 0.1 part of tin octylate was added for 2 hours, and again 0.1 part of tin octylate was added and the mixture was kept warm for 2 hours. Then, 210 parts of ethyl acetate was added to obtain a uniform solution of urethane prepolymer. Next, the reaction system is kept at 50 ° C. for 3 hours while dropwise adding a solution comprising 14 parts of isophoronediamine, 2 parts of di-n-butylamine, 1 part of diethanolamine, 640 parts of ethyl acetate and 440 parts of isopropyl alcohol to the solution. As a result, a polyurethane resin solution having a nonvolatile content of 30% was obtained. Further, no separation or gel-like substance was observed in the appearance. The polyurethane resin solution was directly used as a binder for printing ink.

Comparative Example 2
In a round bottom flask similar to that in Example 1, 500 parts of a polyester diol having a number average molecular weight of 5000 obtained from adipic acid and 3-methyl-1,5-pentanediol, 56 parts of isophorone diisocyanate, and 30 parts of ethyl acetate. After charging and reacting at 120 ° C. for 6 hours under a nitrogen stream, 200 parts of ethyl acetate was added to obtain a uniform solution of urethane prepolymer. The reaction system was then added dropwise to a solution comprising 18 parts isophoronediamine, 3 parts di-n-butylamine, 1 part diethanolamine, 8 parts ketimine compound (1), 670 parts ethyl acetate and 450 parts isopropyl alcohol. By maintaining the temperature at 50 ° C. for 3 hours, a polyurethane resin solution having a nonvolatile content of 30% was obtained. Further, no separation or gel-like substance was observed in the appearance. The polyurethane resin solution was directly used as a binder for printing ink.

Comparative Example 3
In a round bottom flask similar to Example 1, 16 parts of a hydroxyl group-containing chlorinated polypropylene ethyl acetate dispersion (non-volatile content 60%) obtained by the above method, a number average molecular weight consisting of 1,4-butanediol and adipic acid 500 parts of 2000 polyester diol, 112 parts of isophorone diisocyanate and 26 parts of ethyl acetate were charged, and urethanization reaction was carried out at 70 ° C. for 2 hours under a nitrogen stream. Next, 0.1 part of tin octylate was added for 2 hours, 0.1 part of tin octylate was added again for 2 hours, and the mixture was kept warm for 2 hours. The reaction system was then added dropwise to a solution comprising 24 parts isophoronediamine, 11 parts di-n-butylamine, 1 part diethanolamine, 9 parts ketimine compound (1), 610 parts ethyl acetate and 520 parts isopropyl alcohol. By maintaining the temperature at 50 ° C. for 3 hours, a polyurethane resin solution having a resin solid content concentration of 30% was obtained. Further, no separation or gel-like substance was observed in the appearance.

Comparative Example 4
In a round bottom flask similar to that in Example 1, 16 parts of the hydroxyl group-containing chlorinated polypropylene ethyl acetate dispersion (nonvolatile content 60%) obtained by the above method, 500 parts of polypropylene glycol having a number average molecular weight of 2000, and isophorone diisocyanate were added. 112 parts and 26 parts of ethyl acetate were charged. However, part of the chlorinated polypropylene precipitated immediately after mixing, and a uniform urethane prepolymer could not be obtained.

Comparative Example 5
In the same round-bottom flask as in Example 1, 16 parts of the hydroxyl group-containing chlorinated polypropylene ethyl acetate dispersion (non-volatile content 60%) obtained by the above method, number average molecular weight consisting of 1,6-hexanediol and dimethyl carbonate 500 parts of 2000 polycarbonate diol, 112 parts of isophorone diisocyanate and 26 parts of ethyl acetate were charged, and urethanization reaction was carried out at 70 ° C. for 2 hours under a nitrogen stream. Next, 0.1 part of tin octylate was added for 2 hours, and then 0.1 part of tin octylate was added again and the mixture was kept warm for 2 hours. Then, 370 parts of ethyl acetate was added to obtain a uniform solution of urethane prepolymer. The reaction system was then added dropwise to a solution comprising 24 parts isophoronediamine, 11 parts di-n-butylamine, 1 part diethanolamine, 9 parts ketimine compound (1), 610 parts ethyl acetate and 520 parts isopropyl alcohol. By maintaining the temperature at 50 ° C. for 3 hours, a polyurethane resin solution having a nonvolatile content of 30% was obtained. Further, no separation or gel-like substance was observed in the appearance.

Comparative Example 6
The same round bottom flask as in Example 1 was charged with 500 parts of a polyester diol having a number average molecular weight of 5000 obtained from adipic acid and 3-methyl-1,5-pentanediol, 56 parts of isophorone diisocyanate, and 30 parts of ethyl acetate. After reacting at 120 ° C. for 6 hours under a nitrogen stream, 200 parts of ethyl acetate was added to obtain a uniform solution of urethane prepolymer. Next, the reaction system is kept at 50 ° C. for 3 hours while dropwise adding a solution comprising 23 parts of isophoronediamine, 3 parts of di-n-butylamine, 1 part of diethanolamine, 670 parts of ethyl acetate and 450 parts of isopropyl alcohol to the solution. As a result, a polyurethane resin solution having a nonvolatile content of 30% was obtained. Further, no separation or gel-like substance was observed in the appearance. The polyurethane resin solution was directly used as a binder for printing ink.

Comparative Example 7
The same round bottom flask as in Example 1 was charged with 500 parts of an ethyl acetate dispersion (60% non-volatile content) of the hydroxyl group-containing chlorinated polypropylene obtained by the above method, 17 parts of isophorone diisocyanate, and 12 parts of ethyl acetate. The urethanization reaction was carried out at 70 ° C. for 2 hours under a nitrogen stream. Next, 0.1 part of tin octylate was added for 2 hours, and 0.1 part of tin octylate was added again for 2 hours, and then a uniform solution of urethane prepolymer was obtained. Next, while the solution consisting of 3 parts of isophoronediamine, 4 parts of di-n-butylamine, 98 parts of ethyl acetate, and 188 parts of isopropyl alcohol was added dropwise to the solution, the reaction system was kept at 50 ° C. for 3 hours to obtain a nonvolatile content. A polyurethane resin solution having a ratio of 40% was obtained. The polyurethane resin solution was not soluble and could not be used as an ink binder because a gel-like substance was deposited.

Reference example 1
4 kg of isotactic polypropylene having a melt index of 14 g / 10 min was uniformly dissolved in 80 liters of carbon tetrachloride under pressure, and chlorination was performed by blowing in chlorine gas while irradiating ultraviolet rays at 100 ° C. A sample having a chlorine content of 30% was extracted, and carbon tetrachloride was distilled off and replaced with toluene to obtain a chlorinated polypropylene solution having a nonvolatile content of 49%. 800 parts of the obtained chlorinated polypropylene solution, 16 parts of 2-hydroxyethyl acrylate, and 5 parts of t-butyl peroxybenzoate were charged and reacted at 100 ° C. for 4 hours. Further, 1 part of t-butyl peroxybenzoate was added every 2 hours and reacted for 4 hours to obtain a toluene solution of a hydroxyl group-containing chlorinated polypropylene having a nonvolatile content of 50%.

  Next, 500 parts of the toluene solution, 18 parts of isophorone diisocyanate, and 29 parts of toluene were charged into the same round bottom flask as in Example 1, and reacted at 70 ° C. for 2 hours in a nitrogen stream. Further, 0.2 part of tin octylate was added by 0.1 parts every 2 hours and reacted for 4 hours. Subsequently, the reaction system is kept at 50 ° C. for 3 hours while adding dropwise a solution comprising 4 parts of isophoronediamine, 2 parts of di-n-butylamine and 73 parts of isopropyl alcohol to the solution, whereby the nonvolatile content is 40%. A polyurethane resin solution was obtained. Further, no separation or gel-like substance was observed in the appearance. Further, a mixture of 12 parts of the polyurethane resin solution and 100 parts of the polyurethane resin solution of Comparative Example 3 (nonvolatile content: 31%) was used as a binder for printing ink.

  In addition, the toluene solution of the hydroxyl group-containing chlorinated polypropylene of Reference Example 1 was prepared as follows. That is, 4 kg of isotactic polypropylene having a melt index of 14 g / 10 min was uniformly dissolved in 80 liters of carbon tetrachloride under pressure, and chlorine gas was blown while irradiating ultraviolet rays at 100 ° C. to carry out a chlorination reaction. Next, a sample having a chlorine content of 30% was extracted, and carbon tetrachloride was distilled off and replaced with toluene to obtain a chlorinated polypropylene solution having a nonvolatile content of 49%. Next, 800 parts of the obtained chlorinated polypropylene solution, 16 parts of 2-hydroxyethyl acrylate, and 5 parts of t-butyl peroxybenzoate were charged into the same round bottom flask as in Example 1, and reacted at 100 ° C. for 4 hours. Furthermore, a toluene solution of a hydroxyl group-containing chlorinated polypropylene having a nonvolatile content of 50% was obtained by adding 1 part of t-butyl peroxybenzoate every 2 hours and reacting for 4 hours.

(Evaluation of low temperature stability)
5 parts of the binder of Example 1 was transferred to a test tube that could be sealed with a lid, and left in a constant temperature water bath at -10 ° C. for 1 week to evaluate the appearance.

(Preparation of printing ink)
30 parts of the binder of Example 1, 10 parts of phthalocyanine blue, 36 parts of ethyl acetate, 12 parts of isopropyl alcohol, and 12 parts of normal propyl acetate were kneaded with a pent shaker to prepare an indigo printing ink. Subsequently, the obtained indigo color printing ink was used as a bar coater No. 8 was applied to the discharge-treated surface of a corona discharge-treated polypropylene film (OPP) having a thickness of 15 μm and dried at 40 to 50 ° C. to obtain a printed film. For the binders of Examples 2 to 3 and Comparative Examples 1, 2, 5 and Reference Example 1, a deep blue printing ink was prepared in the same manner to obtain a printing film.

(Adhesive evaluation)
After producing the printing film which concerns on Example 1, after leaving still for 30 minutes, the adhesive tape was affixed on the printing surface, and the external appearance of the ink film when peeled was visually evaluated on the following references | standards. Printing films were obtained in the same manner for the indigo printing inks of Examples 2-3 and Comparative Examples 1, 2, 5 and Reference Example 1.

5 --- 100% of the ink film remained on the film.
4 --- Over 75% of the ink film and less than 100% remained in the film.
3 --- More than 50% and less than 75% of the ink film remained on the film.
2 --- More than 25% and less than 50% of the ink film remained on the film.
1 --- 25% or less of the ink film remained in the film.

Claims (5)

Hydroxyl group-containing chlorinated polypropylene (A), polyester polyol (B) composed of dicarboxylic acids (b1) and branched glycols (b2), diisocyanate compound (C), chain extender (D), and amino group in the molecule A binder for printing ink obtained by dissolving a polyurethane resin obtained by reacting a chain length terminator (E) containing one diketimine compound in an organic solvent (F) composed of esters and alcohols. The binder for printing inks of Claim 1 whose ratio of (A) component which occupies for 100 weight% (non-volatile matter conversion) total of (A) component and (B) component is 1 to 10 weight%. (C) The binder for printing inks of Claim 1 or 2 whose component is C4-C8 linear aliphatic diisocyanate. The binder for printing inks in any one of Claims 1-3 whose said diketimine compound is shown by the following general formula.
(In the formula, each R may be the same or different and each represents —CH ₃ , —CH ₂ CH ₃ , —CH ₂ —CH (CH ₃ ) ₂ , and n is an integer of 1 to 4 Represents.) A printing ink composition comprising the binder for printing ink according to claim 1.