JP2874452B2 - Printing ink composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is particularly useful as a coating composition for printing ink compositions, and more particularly, for coating various plastic films, plastic sheets or molded articles of synthetic resins.
The present invention relates to a solvent-based printing ink composition having excellent adhesion to a substrate such as nylon, a one-pack type, and having excellent resistance to boiling and retort.

[0002]

2. Description of the Related Art Solvent-based printing ink compositions used for plastics, especially for plastic films such as polypropylene, polyester, nylon, etc., are one-pack type inks containing a linear polyurethane resin soluble in an organic solvent as a main binder. And a two-pack type having a mixture of a linear polyurethane resin and a polyisocyanate compound soluble in an organic solvent as a main binder, and are used depending on the type and use of a printing medium. I have. Among these, one-pack type printing ink compositions have good adhesion to plastics and suitability for lamination to plastic films, but are not suitable for applications requiring high resistance such as boil sterilization and retort sterilization. There was a drawback that it could not cope sufficiently.

[0003] In addition, although the two-pack type can sufficiently cope with applications requiring high resistance, a polyisocyanate compound is added to a component containing a linear polyurethane resin and mixed immediately before use from the viewpoint of storage stability. However, there are drawbacks in that the operation is complicated, that the remaining meat lacks stability, and that it is difficult to reuse the remaining meat. In order to improve these drawbacks, various one-part inks having boiling and retort suitability have been proposed in recent years. However, storage stability of the ink, print suitability, anti-blocking property, general-purpose use for various films have been proposed. Two-component type that combines a one-component type ink and a polyisocyanate-based curing agent depending on the application, because it does not have the performance required for industrial printing inks, such as properties such as properties, boiling, retort suitability, etc. At present, ink is used properly.

[0004]

The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, have found that a polyurethane resin and a compound having at least two carbodiimide groups in a molecule are used as a main binder. Solvent-based printing inks have excellent adhesion to plastic films such as polyester, nylon, and polypropylene, have boil and retort suitability, and have excellent storage stability. Reached.

[0005]

That is, the present invention provides a polyurethane resin soluble in an organic solvent and a polycarbodiimide compound containing at least two carbodiimide groups represented by the general formula (1) in a molecule. Provided is a solvent-based printing ink composition serving as a main binder.

R _1- (N = C = NR ₂ ) _n -N = C = NR ₁ General formula (1)

(Wherein R ₁ and R ₂ are each independently
Alkyl, cycloalkyl, aryl, aralkyl, alkaryl, or heterocyclic which may have a substituent;
Represents the above integer. )

The mixing ratio of the polyurethane resin to the polycarbodiimide compound having at least two carbodiimide groups represented by the general formula (1) in the molecule is from 1.0 × 10 ^-4 to 5.0 × 10 ⁴ g per 1 g of the solid content of the polyurethane resin. ^It is preferred to use a polycarbodiimide compound within a range corresponding to ^-3 gram equivalent carbodiimide groups. Content is 1.0 × 10
If it is less than ^-4 gram equivalent, it is difficult to obtain physical properties such as boil resistance and retort resistance, and if it is more than 5.0 × 10 ^-3 gram equivalent, there is a problem in storage stability of the printing ink. Does not show stable performance as a liquid ink.

As the polycarbodiimide compound, known methods described in JP-A-59-187029, for example, a mono-, di-, or tri-isocyanate compound can be prepared by using a suitable catalyst such as 3-methyl A substance obtained by a method of heating in the presence of 1-phenyl-2-phosphorate-1-oxide to convert an isocyanate group into a carbodiimidate by a condensation reaction accompanied by removal of carbon dioxide can be used. The organic diisocyanate compound which is a raw material for synthesizing the carbodiimide compound is an aromatic diisocyanate, an aliphatic diisocyanate, an alicyclic diisocyanate, or a mixture thereof, for example, 1,5-naphthylene diisocyanate, 4,4-diphenylmethane diisocyanate,
4-diphenyldimethylmethane diisocyanate, 4,4-dibenzyl isocyanate, dialkyl diphenyl methane diisocyanate, tetraalkyl diphenyl methane diisocyanate, 1,3-phenylene diisocyanate, 1,
4-phenylene diisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, Examples include dicyclohexylmethane-4,4-diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, methylcyclohexane diisocyanate, m-tetramethylxylylene diisocyanate, and dimeryl diisocyanate.
Also, in order to adjust the carbodiimide group concentration in the molecule,
Organic monoisocyanate compounds such as phenyl isocyanate and butyl isocyanate are used.

As the polyurethane resin, a polyurethane resin usually used as a binder for printing ink can be effectively used and is not particularly limited, but the number average molecular weight is preferably in the range of 5,000 to 150,000. When the number average molecular weight is less than 5,000, the printing ink using this as a binder is inferior in drying property, blocking resistance, etc.,
It is difficult to obtain physical properties such as film strength, boiling resistance and retort properties. On the other hand, when it exceeds 150,000, the viscosity of the polyurethane resin solution increases, which is not preferable in terms of storage stability and printability of the ink.

Also, hydroxyl groups,
Amino group, may have various functional groups such as carboxyl group, especially when using a polyurethane resin having a carboxyl group as a binder, because it reacts with the carbodiimide group in the polycarbodiimide compound to be mixed, other It shows a more specific behavior than when a polyurethane resin having a functional group or having no reactivity with a carbodiimide group is used. That is, the carbodiimide group equivalent of the polycarbodiimide compound is excessive relative to the carboxyl group equivalent in the polyurethane resin, and within a range in which the viscosity of the printing ink used by mixing the same is not significantly increased,
When a printing ink obtained by mixing a polyurethane resin having a carboxyl group and a polycarbodiimide compound is used, a printed matter having particularly excellent heat resistance and oil resistance can be obtained by the reaction between the carboxyl group and the carbodiimide group.

The amount of carboxyl groups that may remain in the polyurethane resin varies depending on the carbodiimide group equivalent of the polycarbodiimide compound to be mixed, but the acid value of the polyurethane resin is preferably 0.1 to 30 KOHmg / g. If the amount of carboxyl groups in the polyurethane resin is too large, the reaction between the carboxyl groups and the carbodiimide groups may occur in a printing ink solution, resulting in thickening or gelling during ink production and storage before use. This is not preferred in terms of storage stability, and is not preferred because the carbodiimide group is consumed and the effect of the present invention is reduced or lost.

The method for producing the polyurethane resin is not particularly limited. For example, a polymer polyol and a diisocyanate compound are reacted in an excess ratio of isocyanate groups, and a prepolymer having isocyanate groups at both ends of the polymer polyol. There is a two-stage method in which a polymer (preferably, a free isocyanate value of 0.5 to 10%) is prepared, and then this is reacted with a chain extender and, if necessary, a reaction terminator in an appropriate solvent. The two-stage method is a preferable production method in that a uniform polymer solution is easily obtained.

The conditions for reacting the high molecular polyol with the diisocyanate compound are not particularly limited, except that the isocyanate group is excessive, but the equivalent ratio of hydroxyl group / isocyanate group is in the range of 1 / 1.2 to 1/3. Is preferably within the range. Further, the conditions for reacting the obtained prepolymer with a chain extender and, if necessary, a reaction terminator are not particularly limited, but 1 equivalent of a free isocyanate group having both ends of the prepolymer is used. In this case, the total equivalent of the amino groups in the chain extender and the reaction terminator is preferably in the range of 0.5 to 1.30. The total equivalent of amino groups is 0.5
If it is less than 1, the drying property, blocking resistance, and film strength are not sufficient, and if it is more than 1.30, the chain extender and the reaction terminator remain unreacted, and odor tends to remain on printed matter.

[0015] Specific examples of the high molecular polyol include:
For example, polyether polyols such as polymers or copolymers such as ethylene oxide, propylene oxide, and tetrahydrofuran; ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol,
4-butanediol, neopentyl glycol, pentanediol, hexanediol, octanediol, 1,4-
Saturated and unsaturated low molecular weight glycols such as butynediol, diethylene glycol, triethylene glycol, and dipropylene glycol; and alkyl glycidyl ethers such as n-butyl glycidyl ether and 2-ethylhexyl glycidyl ether; and monomers such as versatic acid glycidyl ester Carboxylic acid glycidyl esters and adipic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid,
Polyester polyols obtained by dehydrating and condensing dibasic acids such as malonic acid, glutaric acid, pimelic acid, speric acid, azelaic acid, sebacic acid, dimer acid or anhydrides thereof; ring-opening polymerization of cyclic ester compounds Polyester polyols obtained; other polycarbonate polyols, polybutadiene glycols,
Various known polymer polyols generally used in the production of polyurethane, such as glycols obtained by adding ethylene oxide or propylene oxide to bisphenol A, may be mentioned.

[0016] Of these high molecular polyols,
When a polymer polyol obtained from a glycol and a dibasic acid is used, up to 5 mol% of the glycol can be replaced with the following various polyols. That is, for example, glycerin, trimethylolpropane,
Trimethylolethane, 1,2,6-hexanetriol, 1,
It may be replaced by a polyol such as 2,4-butanetriol, sorbitol, pentaerythritol and the like.

The molecular weight of the high molecular polyol is appropriately determined in consideration of the solubility, drying properties, blocking resistance and the like of the obtained polyurethane resin, and is usually preferably in the range of 500 to 3000, more preferably 700 to 3000. A range of 2500 is preferred. If the molecular weight is less than 500, the printability tends to be inferior due to the decrease in solubility, and if it exceeds 3000, the drying property and the anti-blocking property tend to decrease. These polymer polyols may be used alone or in combination of two or more.

Further, within the range not deviating from the performance of the polyurethane resin used in the present invention, a part of the high molecular polyol is replaced with low molecular polyols, for example, various low molecular polyols used for producing the high molecular polyol. In this case, the amount of the low-molecular polyol used is preferably 20% by weight or less, more preferably 10% by weight or less. When the amount of the low-molecular polyol used exceeds 20% by weight, the solubility in a diluting solvent and the adhesion of the obtained printing ink composition to a plastic film are reduced. Also, especially when you want to introduce a carboxyl group into the polyurethane resin,
Polyester polyols obtained by ring-opening polymerization of a cyclic ester compound with dimethylolpropionic acid or the like may be used as the high molecular polyol, or dimethylolpropionic acid or the like may be used as the low molecular polyol.

As the isocyanate compound, aromatic,
Various known 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,
Typical examples thereof include 1,3-bis (isocyanatomethyl) cyclohexane, methylcyclohexanediisocyanate, m-tetramethylxylylene diisocyanate, and dimer isocyanate obtained by converting a carboxyl group of dimer acid into an isocyanate group.

As the chain extender, various known amines can be used. For example, ethylenediamine, propylenediamine, hexamethylenediamine, triethylenetetramine, diethylenetriamine, isophoronediamine, dicyclohexylmethane-4,4′-diamine and the like can be mentioned. Others, 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-
Diamines having a hydroxyl group in the molecule such as hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, and dimerdiamine in which a carboxyl group of dimer acid is converted to an amino group And the like are also typical examples.

Further, a reaction terminator may be used.
Examples of such a reaction terminator include dialkylamines such as di-n-butylamine and alcohols such as ethanol and isopropyl alcohol. Furthermore, when it is desired to introduce a carboxyl group into the polyurethane resin, an amino acid such as glycine or L-alanine can be used as a reaction terminator. As the solvent used in the production method, usually, well-known solvents for printing inks, benzene, toluene, aromatic solvents such as xylene, methanol, ethanol, isopropanol, alcoholic solvents such as n-butanol Solvents include ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone, and ester solvents such as ethyl acetate and butyl acetate, and these may be used alone or in a mixture of two or more.

In the case of producing a printing ink, various pigments and the above-mentioned solvent are added to the above-mentioned polyurethane resin and polycarbodiimide compound, and additives such as an anti-blocking agent and a plasticizer, and if necessary, the ink fluidity and dispersibility. Surfactants for improvement, or nitrified cotton having compatibility with the polyurethane resin, chlorinated polyethylene,
Chlorinated polypropylene, chlorinated polyolefins such as chlorinated ethylene / propylene, chlorsulfonated polyolefins, ethylene / vinyl acetate copolymers, or chlorinated or chlorsulfonated products thereof, maleic acid resins, vinyl chloride / vinyl acetate copolymers, A resin such as polyurethane is used in combination and kneaded using a usual printing ink production apparatus such as a ball mill, an attritor, and a sand mill.

[0023]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In the examples, “parts” means “parts by weight” and “%” means “% by weight”. [Production Example 1] In a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube, the molecular weight obtained from adipic acid and 3-methyl-1,5-pentanediol was 2,000.
Of polyester diol and 22 parts of isophorone diisocyanate were reacted at 85 ° C. for 6 hours under a nitrogen stream. Next, isophorone diamine 8.2 parts, di-n-butylamine 0.78 parts, toluene 12.4 parts, methyl ethyl ketone
12.4 parts and 57 parts of isopropyl alcohol were added and reacted at 50 ° C. for 3 hours with stirring to obtain a polyurethane resin solution (A) having a solid content of 30%, a viscosity at 25 ° C. of 350 cps and a molecular weight of 48,000.

Production Example 2 A polyurethane resin solution (B) having a solid content of 30% and a viscosity of 1300 cps at 25 ° C. was obtained from the following raw materials in the same manner as in Production Example 1. Polycaprolactone glycol (average molecular weight 2,000) 100 parts Isophorone diisocyanate 18 parts Toluene 97 parts Isophorone diamine 6 parts Di-n-butylamine 0.5 parts Methyl ethyl ketone 97 parts Isopropyl alcohol 97 parts

Production Example 3 A polyurethane resin solution (C) having a solid content of 30%, a viscosity at 25 ° C. of 800 cps and having a carboxyl group in the molecule was obtained from the following raw materials in the same manner as in Production Example 1. The acid value of the polyurethane resin is 7 KOHm
g / g. Polycaprolactone glycol (average molecular weight: 2,000) 100 parts Dimethylolpropionic acid 2.5 parts Isophorone diisocyanate 31 parts Toluene 113 parts Isophorone diamine 11 parts Di-n-butylamine 1 part Methyl ethyl ketone 113 parts Isopropyl alcohol 113 parts

[Production Example 4] A polyurethane resin solution (D) having a solid content of 30% and a viscosity of 700 cps at 25 ° C and having a carboxyl group in the molecule was obtained from the following raw materials in the same manner as in Production Example 1. The acid value of the polyurethane resin is 41 KOH
mg / g. Polycaprolactone glycol (average molecular weight: 2,000) 100 parts Dimethylolpropionic acid 20 parts Isophorone diisocyanate 67 parts Toluene 159 parts Isophorone diamine 15 parts Di-n-butylamine 2.6 parts Methyl ethyl ketone 159 parts Isopropyl alcohol 159 parts

[Example 1] Polyurethane resin solution (A)
40 parts, an ethyl acetate solution of a polycarbodiimide compound containing hexamethylene diisocyanate and butyl isocyanate as main raw materials (E) [degree of polymerization 3, solid content 50%] 5
, A mixture of 30 parts of titanium oxide, 15 parts of toluene and 10 parts of methyl ethyl ketone was kneaded to prepare a white printing ink. The obtained printing ink was put in a 500 ml glass sample bottle, left at 40 ° C. for 1 week, and then evaluated for storage stability. Table 1 shows the results. …: No increase in viscosity or gelation is observed as compared to immediately after production. Δ: No gelation, but an increase in viscosity is observed as compared to immediately after production. ×: Gelling as compared to immediately after production.

Further, the viscosity of the obtained printing ink was adjusted with a mixed solvent of toluene, methyl ethyl ketone and isopropyl alcohol (weight ratio: 60:30:10), and the printing plate depth was 35 μm.
m Print on corona-treated polyester film (PET) and corona-treated nylon film (NY) with a gravure proofing machine equipped with a m-gravure plate, and dry at 40 ° C to 50 ° C.
Printed matter was obtained. About the obtained printed matter, heat resistance, adhesiveness, extrusion lamination strength, dry lamination strength,
Boil suitability and retort suitability were evaluated. Table 1 shows the results. The evaluation was performed by the following test method.

1) Heat resistance Pressure was applied with a heat seal bar (2 kg / cm ² , 1) while the ink surface of the PET print was in contact with a 9 μ aluminum foil.
Seconds), the ink surface and the aluminum foil were immediately peeled off, and the heat sealing temperature when the ink surface could be peeled off without resistance was determined according to the following criteria. 5: At 200 ° C, the ink surface and the aluminum foil peel off without resistance. 4: At 180 ° C, the ink surface and the aluminum foil peel off without resistance. 3: At 160 ° C, the ink surface and the aluminum foil peel off without resistance. 2: At 140 ° C, the ink surface and the aluminum foil peel off without resistance. 1: The ink surface is removed on aluminum foil at 120 ° C or peel resistance is high.

2) Adhesion After the printed matter was allowed to stand for one day, a cellophane tape was stuck on the printed surface, and the appearance of the printed film when it was rapidly peeled was visually judged. The criteria were as follows. A: The printed film did not come off at all. …: 80% or more of the printed film remained on the film. Δ: 50% to 80% of the print film remained on the film. X: 50% or less of the printed film remained on the film.

3) Extrusion (EL) laminating strength The above printed matter was laminated with molten polyethylene by an extruding laminator using an isocyanate anchor coating agent, and aged at 40 ° C. for 2 days. Was cut to a width of 15 mm, and the T-peel strength was measured. 4) Dry (DL) laminating strength A CPP (unstretched polypropylene) film is laminated by a dry laminating machine using a urethane-based adhesive on the printed matter, aged at 40 ° C. for 3 days, and then subjected to the same method as the extrusion laminating strength. The peel strength was measured.

5) Suitability for boil and retort After dry lamination of the above-mentioned NY printed matter, the laminate is made into a bag, a mixture of water / salad oil is put as the contents, and the contents are sealed. After heating at 120 ° C. for 30 minutes for the retort suitability, the presence or absence of floating of the lamination was visually judged by the appearance. The criteria were as follows. …: There is no lami floating. Δ: Delamination was found in a very small portion, or blisters were generated, albeit slightly. X: Delamination occurred on the entire surface.

Example 2 Polyurethane resin solution (B)
40 parts of a polycarbodiimide compound containing hexamethylene diisocyanate and butyl isocyanate as main raw materials in ethyl acetate (F) [degree of polymerization 9, solid content 50%] 6
, A mixture of 30 parts of titanium oxide, 15 parts of toluene and 9 parts of methyl ethyl ketone was kneaded to prepare a white printing ink. Table 1 shows the results of evaluating the storage stability of the ink in the same manner as in Example 1, and further performing printing to evaluate the physical properties of the printed matter.

Example 3 Polyurethane resin solution (B)
Was replaced with a polyurethane resin solution (C), a white printing ink was prepared in the same manner as in Example 2, and the storage stability and physical properties of the printed matter were evaluated. Table 1 shows the results.

Comparative Example 1 Polyurethane Resin Solution (A)
A mixture of 40 parts, 30 parts of titanium oxide, 15 parts of toluene and 15 parts of methyl ethyl ketone was kneaded to prepare a white printing ink. Table 1 shows the results of evaluating the storage stability of the ink and the physical properties of the printed matter in the same manner as in Example 1. Comparative Example 2 40 parts of a polyurethane resin solution (B), 0.4 parts of a polycarbodiimide compound solution (E), and 30 parts of titanium oxide
, A mixture of 15 parts of toluene and 14.6 parts of methyl ethyl ketone was kneaded to prepare a white printing ink. Table 1 shows the results of evaluating the storage stability of the ink and the physical properties of the printed matter in the same manner as in Example 1.

Comparative Example 3 Polyurethane Resin Solution (C)
A mixture of 40 parts, 28 parts of a polycarbodiimide compound solution (F), 30 parts of titanium oxide and 2 parts of methyl ethyl ketone was kneaded to prepare a white printing ink. Table 1 shows the results of evaluating the storage stability of the ink and the physical properties of the printed matter in the same manner as in Example 1. [Comparative Example 4] 40 parts of a polyurethane resin solution (D), 5 parts of a polycarbodiimide compound solution (E), 30 parts of titanium oxide,
A mixture of 15 parts of toluene and 10 parts of methyl ethyl ketone was kneaded to prepare a white printing ink.The resulting ink had a high viscosity of 3000 cps and gelled after storage at 40 ° C for 1 day, and a stable printing ink was obtained. Could not be obtained.

[0037]

[Table 1]

[0038]

According to the present invention, it has excellent one-part adhesiveness to various plastic films such as polyester, nylon, polyethylene, and polypropylene used as a printing material, storage stability, and lamination processing. The present invention can provide a printing ink composition having excellent properties such as suitability, boilability, and retort suitability.

Claims (2)

(57) [Claims] 1. A solvent-based printing ink composition comprising a polyurethane resin soluble in an organic solvent and a polycarbodiimide compound having at least two carbodiimide groups represented by the following general formula (1) in a molecule as a main binder. Stuff. R _1- (N = C = NR ₂ ) _n -N = C = NR ₁ General formula (1) (wherein R ₁ and R ₂ each independently have a substituent Good alkyl, cycloalkyl, aryl, aralkyl, alkaryl, heterocyclic, and n represents an integer of 1 or more.) 2. A polyurethane resin having a solid content of 1.0 ×
The solvent-based printing ink composition according to claim 1, wherein the polycarbodiimide compound is used within a range corresponding to ^{10-4 to} 5.0 x ^10-3 gram equivalent of carbodiimide group.