JPH05331400A - Binder for printing ink - Google Patents

Abstract

PURPOSE:To improve adhesion to plastic films, boiling resistance and storage stability by incorporating a polyurethane resin having an oxazolinyl group (derivative) as a main component. CONSTITUTION:A high molecular weight polyol and a diisocyanate compound are reacted in a hydroxyl to isocyanate equivalent ratio of l/1.2 to l/3 in the presence of a chain extender and a chain terminator to obtain the title binder composed of a polyurethane resin containing an oxazolinyl group (derivative) the formula (wherein each of R<1> and R<2> is H, halogen, 1-20C alkyl, halogenated alkyl, hydroxyalkyl or phenyl provided that R<1> and R<2> may be combined to form 3-10C alkylene) in an amount of 1X10<-6> to 1X10<-3>g equivalent/g polyurethane resin solid content, the resin having a number-average molecular weight of 5000 to 100,000.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a binder for printing inks.

[0002]

2. Description of the Related Art In recent years, various plastic films have been developed as a packaging material in accordance with the complexity of packaging contents and the sophistication of packaging technology. As a result, a plastic film suitable for the contents can be appropriately selected. Came to be used. As a result, printing inks used for decoration of plastic films or for surface protection have also been required to have high performance.

Polyurethane resins have been widely used as binders for such printing inks. Generally, a printing ink having a polyurethane resin as a binder has excellent adhesive strength to polyester and nylon films alone, but does not have sufficient adhesive strength to polyethylene films and polypropylene films, which are general-purpose films.

In view of the above-mentioned drawbacks, the polyurethane resin has been used as a two-component reactive ink containing a polyisocyanate compound, not alone. However, the two-component reactive ink is inconvenient to handle because it needs to be mixed with a curing agent immediately before printing, and further has various disadvantages in terms of practical use in terms of pot life (pot life). ..

Therefore, in the art, it can be used as a one-component ink which does not need to contain a polyisocyanate compound,
Moreover, various polyurethane resins having excellent adhesiveness to various plastic films are being researched and developed.

As described above, various one-pack type inks having good adhesiveness have been developed, and the problem of adhesiveness has been solved to some extent. However, the one-pack type ink is sterilized by boil and retort after food packaging. When it is used for printing a plastic film used as a packaging base material through a sterilization process, there is a drawback that the boiling resistance and the retort resistance are still inferior. Therefore, in the field where boil resistance and retort resistance are required, it is difficult to use the one-pack type ink, and despite having the above-mentioned problems, the two-pack reactive ink containing a polyisocyanate compound still occupies the mainstream. It is the current situation.

[0007]

INDUSTRIAL APPLICABILITY The present invention can be used as a one-pack type printing ink having excellent adhesiveness and boil resistance to various plastic films such as polyester, nylon, polyethylene and polypropylene as an object to be printed. It is intended to provide a binder for printing ink.

[0008]

SUMMARY OF THE INVENTION In view of the above technical background, the present inventors have conducted extensive studies to solve the problems of the prior art, and as a result, printed a polyurethane resin having a specific functional group in the molecule. The inventors have found that the above problems can be solved by using it as a binder for ink, and have completed the present invention.

That is, the present invention relates to a polymer polyol,
In a binder for a printing ink containing a polyurethane resin as a main component, which is obtained by reacting a diisocyanate compound, a chain extender and optionally a chain length terminating agent, the polyurethane resin has an oxazolinyl group and / or a derivative of an oxazolinyl group. The present invention relates to a binder for printing ink.

The constituent components of the polyurethane resin which is the main binder of the present invention are as follows. First, as the polymer polyol component, polyether polyols such as polymers or copolymers of ethylene oxide, propylene oxide, tetrahydrofuran, etc .; ethylene glycol, 1,2-
Propanediol, 1,3-Propanediol, 1,3
-Butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1,
5-pentanediol, hexanediol, octanediol, 1,4-butynediol, diethylene glycol, triethylene glycol, dipropylene glycol, and various other saturated and unsaturated known low-molecular-weight glycols or n-butylglycidyl ether, 2- Alkyl glycidyl ethers such as ethylhexyl glycidyl ether, monocarboxylic acid glycidyl esters such as versatic acid glycidyl ester, dimer diol obtained by reducing dimer acid, and adipic acid, phthalic anhydride, isophthalic acid, terephthalic acid, maleic acid Acid, fumaric acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and other dibasic acids or their corresponding acid anhydrides and dimer acids are dehydrated and condensed. Polyester polyols obtained by ring-opening polymerization of cyclic ester compounds; other polycarbonate polyols, polybutadiene glycols, glycols obtained by adding ethylene oxide or propylene oxide to bisphenol A, etc. Examples include various known polymer polyols that are generally used for producing polyurethane.
In the case of a polymer polyol obtained from glycols and a dibasic acid among the above, up to 5 mol% of the glycol component can be substituted with the following various polyols. That is, for example, glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, 1,2,4-butanetriol, pentaerythritol, sorbitol and the like can be exemplified.

The molecular weights of the above various polymer polyols are
It is appropriately determined in consideration of the solubility, drying property, blocking resistance, etc. of the resulting polyurethane resin, and usually 500 to 6
It is preferable to set it within the range of 000. When the molecular weight is less than 500, the printability tends to be poor due to the decrease in solubility, while when it exceeds 6000, the drying property and blocking resistance tend to be reduced.

Examples of the diisocyanate compound which is another constituent of the polyurethane resin of the present invention include aromatic, aliphatic and alicyclic diisocyanates. 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, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, cyclohexane- Typical examples thereof include 1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, methylcyclohexane diisocyanate, and dimerisocyanate. .. These isocyanates may be used alone or in combination of two or more.

As the chain extender, polyamines such as ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, dicyclohexylmethane-4,4'-diamine and dimerdiamine can be used.
Further, in the molecule of 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, etc. Diamines having a hydroxyl group and the low molecular weight glycols can be similarly used as the chain extender.
Further, as the chain length terminator used if necessary, di-
Dialkylamines such as n-butylamine, dihydroxyalkylamines such as diethanolamine, and alcohols such as ethanol and isopropyl alcohol can be used.

The oxazolinyl group and / or the derivative of the oxazolinyl group introduced into the polyurethane are represented by the general formula (1):

[0015]

[Chemical 1]

(R ¹ and R ² are hydrogen atoms, halogen atoms,
An alkyl group having 1 to 20 carbon atoms, a halogenated alkyl group,
An oxyalkyl group, a phenyl group, or R ¹ and R ² are combined to form an alkylene group having 3 to 10 carbon atoms. The functional group represented by) can be illustrated. Examples of such a compound having an oxazolinyl group and / or a derivative of an oxazolinyl group include 2-amino-2-
Oxazoline, 2-phenylamino-2-oxazoline, 2-amino-5-methyl-2-oxazoline, 2-
Amino-4,5-cyclotetramethylene-2-oxazoline, 2-amino-4,5-diphenyl-2-oxazoline, 2-amino-5-chloromethyl-2-oxazoline, 2-amino-5-oxymethyl-2 -Oxazoline, 2-mercapto-2-oxazoline and the like,
By using the compound instead of the chain length terminating agent or in combination with the chain length terminating agent, an oxazolinyl group and / or a derivative of the oxazolinyl group can be incorporated into the molecule of the polyurethane resin. Further, the oxazolinyl group and / or the derivative of the oxazolinyl group can be incorporated into the molecule of the polyurethane resin by reacting the compound after synthesizing the polyurethane resin.

The printing ink binder of the present invention is
The oxazolinyl group and / or the derivative of the oxazolinyl group is not limited to those introduced into the polyurethane resin by the above-mentioned method, and particularly, those having an oxazolinyl group and / or a derivative of the oxazolinyl group in the polyurethane resin are particularly preferable. Can be used without restrictions.

The oxazolinyl group and / or the derivative of the oxazolinyl group incorporated in the polyurethane resin undergoes a cross-linking reaction after a drying step after printing, so that a conventional printing ink binder cannot completely solve the problem. It is considered that it is possible to improve the boil resistance, retort resistance, etc. of the pattern printing ink.

The content of the oxazolinyl group and / or the derivative of the oxazolinyl group in the polyurethane resin is 1 × 10 ^-6 to 1 × 10 per 1 g of the solid content of the polyurethane resin.
It is preferably within the range of about ^-3 gram equivalent. When the content is less than 1 × 10 ^-6 gram equivalent, the adhesiveness to a polypropylene film and the like in one liquid and the boiling resistance are insufficient, and conversely, it is more than 1 × 10 ^-3 gram equivalent. In that case, the viscosity stability over time of the solution tends to decrease, which is not preferable.

As a method for producing the polyurethane resin of the present invention, first, a polymer polyol component and a diisocyanate compound are reacted under an excess of isocyanate groups,
A two-step method in which a prepolymer having an isocyanate group at both ends of a high molecular weight polyol is prepared, and then this is reacted with a chain extender and optionally a chain length terminating agent in a suitable solvent, and a high molecular weight polyol component, Although any one-step method in which a diisocyanate compound, a chain extender and, if necessary, a polymerization terminator are reacted at once in a suitable solvent can be adopted, the former method is preferable for the purpose of obtaining a uniform polymer solution. .. In these production methods, the solvent used is usually an aromatic solvent such as benzene, toluene, xylene, etc. which is well known as a solvent for printing inks; an ester solvent such as ethyl acetate, butyl acetate; methanol, ethanol, etc. Alcoholic solvents such as isopropanol and n-butanol; acetone, methyl ethyl ketone,
Examples thereof include ketone solvents such as methyl isobutyl ketone and mixtures of two or more thereof.

When the polyurethane resin used in the present invention is produced by the two-step method, the conditions for reacting the high molecular weight polyol component and the diisocyanate compound are not limited, except that they are in excess of isocyanate. It is preferable to react so that the groups are in an equivalent ratio range of about 1 / 1.2 to 1/3. Further, the conditions for reacting the obtained prepolymer with a chain extender and, if necessary, a chain length terminating agent are as follows when the free isocyanate group at the end of the prepolymer is 1 equivalent,
The total equivalent of active hydrogen capable of reacting with the isocyanate group in the chain extender is preferably within a range of about 0.5 to 2.0 equivalents (particularly, in the case where the active hydrogen is an amino group, 0.
It should be in the range of 5 to 1.3 equivalents). If the amount of active hydrogen is less than 0.5 equivalent, the drying property, blocking resistance, and film strength are insufficient, and if the amount of active hydrogen exceeds 2.0 equivalents, the chain extender remains unreacted. It remains, and odor tends to remain after printing.

The number average molecular weight of the polyurethane resin obtained as described above is preferably in the range of about 5,000 to 100,000. When the molecular weight is less than 5,000, the printing ink using this as a binder has poor drying property, blocking resistance, film strength, oil resistance, etc.
On the other hand, when it exceeds 100,000, the viscosity of the polyurethane resin solution tends to increase and the gloss of the printing ink tends to decrease.

The concentration of resin solids in the polyurethane resin solution obtained as described above is not particularly limited and is appropriately determined in consideration of workability at the time of printing and is usually 15 to 60% by weight. The viscosity is usually 50 to 10,000 cP / 2.
It is practically preferable to set it to 5 ° C.

To produce a printing ink composition using the polyurethane resin of the present invention, a colorant and a solvent are added to the polyurethane resin, and if necessary, a surfactant and a wax for improving ink fluidity and surface film. May be appropriately mixed and kneaded by using an ordinary ink manufacturing device such as a ball mill, an attritor, or a sand mill. Further, nitrocellulose, vinyl chloride-vinyl acetate copolymer, polyamide, acrylic resin, chlorinated polypropylene and the like may be added within the range not departing from the performance of the present invention.

[0025]

EXAMPLES The present invention will be described in detail below with reference to production examples, examples and comparative examples, but the present invention is not limited to these examples. In the examples, all parts and% are by weight unless otherwise specified.

Production Example 1 A round-bottomed flask equipped with a stirrer, a thermometer and a nitrogen gas inlet tube was charged with 1000 parts of poly (1,2-propylene adipate) glycol having a molecular weight of 2000 and 222 parts of isophorone diisocyanate, and under a nitrogen stream. Was reacted at 100 ° C. for 6 hours to form a prepolymer having a free isocyanate value of 3.36%, and 815 parts of methyl ethyl ketone was added thereto to obtain a uniform solution of urethane prepolymer. Then, 2037 parts of the above urethane prepolymer solution was added in the presence of a mixture consisting of 74.2 parts of isophorone diamine, 9.0 parts of 2-amino-2-oxazoline, 1215 parts of methyl ethyl ketone, and 1015 parts of isopropyl alcohol, and added at 50 ° C. And reacted for 3 hours. The polyurethane resin solution A thus obtained had a resin solid content concentration of 30% and a viscosity of 520 cP / 25 ° C. The number average molecular weight of the polyurethane resin was 25,000.

Production Example 2 Poly (1,2-propylene adipate) glycol 1000 having a molecular weight of 2000 was placed in the same reactor as in Production Example 1.
And 222 parts of isophorone diisocyanate were charged and reacted at 100 ° C. for 6 hours under a nitrogen stream to form a prepolymer having a free isocyanate value of 3.36%. To this, 815 parts of methyl ethyl ketone was added to prepare a uniform solution of a urethane prepolymer. Then isophorone diamine 74.2
Part, di-n-butylamine 13.3 parts, 2-amino-
2037 parts of the urethane prepolymer solution was added in the presence of a mixture of 0.4 part of 4,5-diphenyl-2-oxazoline, 1223 parts of methyl ethyl ketone, and 1019 parts of isopropyl alcohol, and the mixture was reacted at 50 ° C. for 3 hours. The polyurethane resin solution B thus obtained had a resin solid content concentration of 30% and a viscosity of 650 cP / 25 ° C. The number average molecular weight of the polyurethane resin is 25
It was 000.

Production Example 3 A reactor similar to that of Production Example 1 was charged with 1000 parts of poly (butylene adipate) glycol having a molecular weight of 2000 and 222 parts of isophorone diisocyanate, and reacted at 100 ° C. for 6 hours under a nitrogen stream to obtain a free isocyanate value of 3 .4
A 0% prepolymer was prepared, and 815 parts of methyl ethyl ketone was added thereto to prepare a uniform solution of the urethane prepolymer. Then, 49.3 parts of isophoronediamine, 14.5 parts of 2-hydroxyethylethylenediamine, 15.1 parts of di-n-butylamine, 2-amino-5-methyl-2-
Oxazoline 1.3 parts, methyl ethyl ketone 198 parts,
1013 parts of toluene and 10 of isopropyl alcohol
2037 parts of the urethane prepolymer solution was added in the presence of a mixture of 13 parts, and the mixture was reacted at 50 ° C. for 3 hours. The polyurethane resin solution C thus obtained had a resin solid content concentration of 30% and a viscosity of 820 cP / 25 ° C. The number average molecular weight of the polyurethane resin is 2000.
It was 0.

Production Example 4 A reactor similar to that of Production Example 1 was charged with 1000 parts of poly (butylene adipate) glycol having a molecular weight of 2000 and 222 parts of isophorone diisocyanate, and the mixture was reacted at 100 ° C. for 6 hours under a nitrogen stream to give a free isocyanate value of 3 .4
A 0% prepolymer was prepared, and 815 parts of methyl ethyl ketone was added thereto to prepare a uniform solution of the urethane prepolymer. Then, 72.9 parts of isophorone diamine, 15.2 parts of 2-amino-5-oxymethyl-2-oxazoline,
2037 parts of the above urethane prepolymer solution was added in the presence of a mixture of 204 parts of methyl ethyl ketone, 1019 parts of toluene, and 1019 parts of isopropyl alcohol, and the mixture was reacted at 50 ° C. for 3 hours. The polyurethane resin solution D thus obtained had a resin solid content concentration of 30% and a viscosity of 730 cP / 25 ° C. The number average molecular weight of the polyurethane resin was 20,000.

Production Example 5 A reactor similar to that of Production Example 1 was charged with 1000 parts of polyoxytetramethylene glycol having a molecular weight of 1000 and 333 parts of isophorone diisocyanate, and the mixture was placed under a nitrogen stream for 10 times.
The reaction was carried out at 0 ° C for 10 hours to give a free isocyanate value of 3.10.
% Prepolymer with 8% methyl ethyl ketone
89 parts were added to obtain a uniform solution of urethane prepolymer. Then, the above urethane prepolymer solution 2222 in the presence of a mixture of 53.1 parts of isophorone diamine, 50.3 parts of 2-amino-4,5-cyclotetramethylene-2-oxazoline, 1345 parts of methyl ethyl ketone and 1117 parts of isopropyl alcohol. Add 5 parts
The reaction was carried out at 0 ° C for 3 hours. The polyurethane resin solution E thus obtained had a resin solid content concentration of 30% and a viscosity of 10
It was 0 cP / 25 ° C. The number average molecular weight of the polyurethane resin was 8,000.

Production Example 6 Poly (1,2-propylene adipate) glycol 1000 having a molecular weight of 2000 was placed in the same reactor as in Production Example 1.
And 222 parts of isophorone diisocyanate were charged and reacted at 100 ° C. for 6 hours under a nitrogen stream to form a prepolymer having a free isocyanate value of 3.36%. To this, 815 parts of methyl ethyl ketone was added to prepare a uniform solution of a urethane prepolymer. Then isophorone diamine 74.2
Part, di-n-butylamine 13.5 parts, methyl ethyl ketone 1222 parts and isopropyl alcohol 1019 parts in the presence of a mixture of the above urethane prepolymer solution 2037 parts and reacted at 50 ° C. for 3 hours. The polyurethane resin solution F thus obtained had a resin solid content concentration of 30% and a viscosity of 580 cP / 25 ° C. The number average molecular weight of the polyurethane resin was 25,000.

Production Example 7 A reaction apparatus similar to that of Production Example 1 was charged with 1000 parts of poly (butylene adipate) glycol having a molecular weight of 2000 and 222 parts of isophorone diisocyanate and reacted at 100 ° C. for 6 hours under a nitrogen stream to give a free isocyanate value of 3 .4
A 0% prepolymer was prepared, and 815 parts of methyl ethyl ketone was added thereto to prepare a uniform solution of the urethane prepolymer. Then, 49.3 parts of isophoronediamine, 14.5 parts of 2-hydroxyethylethylenediamine, 16.8 parts of di-n-butylamine, 198 parts of methyl ethyl ketone,
1013 parts of toluene and 10 of isopropyl alcohol
2037 parts of the urethane prepolymer solution was added in the presence of a mixture of 13 parts, and the mixture was reacted at 50 ° C. for 3 hours. The polyurethane resin solution G thus obtained had a resin solid content concentration of 30% and a viscosity of 790 cP / 25 ° C. The number average molecular weight of the polyurethane resin is 2000.
It was 0.

Examples 1-5, Comparative Examples 1-3 Titanium white (rutile type) 30 parts, Polyurethane resin solutions A-G 50 parts obtained in Production Examples 1-7, Toluene 10 parts,
A mixture having a composition of 10 parts of isopropyl alcohol was kneaded with a paint shaker to prepare a white printing ink. To the obtained white printing ink, 35 parts of toluene and 15 parts of isopropyl alcohol were further added to adjust the viscosity, and eight white inks shown in Table 1 were produced. The white ink of Comparative Example 3 is a two-component ink obtained by further adding 2 parts of isophorone disocyanate to the white ink obtained in Comparative Example 1. These eight white printing inks were applied to a discharge surface of a corona discharge treated nylon film (NY) having a thickness of 15 μm and a polyethylene terephthalate (PET) thickness of 11 μm by a simple gravure printing machine equipped with a gravure plate having a plate depth of 30 μm. Printing on one side and drying at 40 to 50 ° C gave a printed film. Then, a polyurethane adhesive having a solid content of 25% was applied and dried at a coating amount of 3 g / m ² on the printing surface of the obtained printing film, and then a 60 μm polyethylene film was dry laminated with a laminator to obtain a laminated film. It was The laminate strength (adhesive strength) of the thus obtained laminate film and the suitability for boiling at 100 ° C. were evaluated. The evaluation results are shown in Table 1.

Boil Suitability (1) Evaluation by Change in Appearance of Film The change in appearance was observed after the laminated film was boiled at 100 ° C. for 30 minutes. ○ ----- There is no abnormality in the film. × −−−−− A part of the film is delaminated or blisters are generated. (2) Change due to laminating strength (adhesive strength) After laminating film was boiled at 100 ° C for 30 minutes, it was cut into a width of 15 mm and a peeling tester was used to speed 300 mm
The T-type peel strength was measured in / min and compared with the strength before boiling. (Unit: g / 15mm)

[0035]

[Table 1]

[0036]

According to the present invention, it has excellent adhesiveness to various plastic films such as polyester, nylon film, polyethylene and polypropylene as a material to be printed, and has excellent boil resistance and storage stability. ,
The great effect that a binder for printing inks that can be used as a one-pack type printing ink composition can be obtained.

Claims (2)

[Claims] 1. A binder for a printing ink containing a polyurethane resin as a main component, which is obtained by reacting a polymer polyol, a diisocyanate compound, a chain extender, and optionally a chain length terminating agent, wherein the polyurethane resin is an oxazolinyl group and / or Also, a binder for a printing ink, which has a derivative of an oxazolinyl group. 2. The total amount of oxazolinyl groups and / or derivatives of oxazolinyl groups in the polyurethane resin is 1 × 10 ⁻⁶ to 1 × 10 per 1 g of the solid content of the polyurethane resin.
^-The binder for printing ink according to claim 1, which is contained in an amount of ^-3 gram equivalent.