JP3301201B2 - Easy solvent recovery printing ink composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an almost single solvent-based easily recoverable printing ink composition which is suitably used for flexible packaging gravure.

[0002]

2. Description of the Related Art In recent years, the destruction of the ozone layer in the stratosphere,
Problems related to air pollution, such as damage to agricultural products and destruction of forest resources due to acid rain in the lower sphere, and adverse effects on the human body due to photochemical oxidants, are becoming more serious. In particular,
In the gravure printing industry, which uses large amounts of organic solvents, there is a need to respond to hydrocarbon emission regulations in local governments, and to respond to the recent amendments to the Fire Service Law and the Occupational Safety and Health Law. Interest is growing.

For solvent recovery, a single solvent ink is preferable. Among polyurethane resins having no urea bond, those which dissolve in a ketone or ester single solvent are commercially available. However, these polyurethane resins are generally low in fluidity, color development, adhesiveness, etc. for versatile inks for gravure printing for soft packaging using various types of pigments, and are industrially stable. I can not use it.

In general, a urea bond is introduced into a polyurethane resin skeleton in order to improve the performance such as fluidity, color development and adhesiveness. However, a polyurethane resin having a urea bond is a ketone or ester resin. It does not dissolve in a single solvent, and it is essential to use a polar solvent such as alcohol. However, the presence of a large amount of alcohol is disadvantageous in that it is not preferable for solvent recovery (especially steam desorption) in terms of solvent separation, wastewater treatment, and cost because the alcohol is dissolved in water.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a printing ink composition which is almost a single solvent and which can easily recover a solvent.

[0006]

That is, the present invention relates to urine
In a printing ink composition using a polyurethane resin having a hydrogen bond as a binder, the solvent comprises 89.5 to 95.5% by weight of an ester solvent, 0.5 to 5.0% by weight of water, and 10.0% by weight or less of an alcoholic solvent. The present invention provides an easily solvent-recoverable printing ink composition.

The printing ink composition of the present invention uses a small amount of water in combination with an ester solvent and has a low alcohol content, so that the solvent recovery is excellent. Examples of the ester solvent include ethyl acetate, isopropyl acetate, butyl acetate, and isobutyl acetate. The amount of water in the total amount of the solvent is 0.5 to 5.0% by weight, particularly preferably 3.0 to 4.
5% by weight. If the amount of water is less than 0.5% by weight, the required amount of the alcohol solvent increases, and the amount of water becomes 5.0% by weight.
If the amount is larger, the stability, fluidity and color development of the obtained ink will be poor.

As alcohol solvents, methanol,
Examples include ethanol, isopropyl alcohol, and n-propanol. The amount of the alcohol-based solvent in the total amount of the solvent is 10% by weight or less, and the smaller the amount, the better the polyurethane resin can be dissolved. When the amount of the alcohol-based solvent exceeds 10% by weight, the solvent recoverability becomes poor. Water and an alcohol-based solvent are added at the time of synthesizing the polyurethane resin (when elongating the chain or after elongating the chain) and / or at the time of preparing the ink.

The polyurethane resin used as the binder is not particularly limited, but is obtained, for example, by chain-extending a prepolymer having a terminal isocyanate group by reacting a polymer polyol with an excess of a diisocyanate compound. Things. As the polymer polyol for obtaining the polyurethane resin, various types generally known as a polymer polyol component of polyurethane can be used. For example, polyether polyols such as polymers or copolymers of ethylene oxide, propylene oxide, tetrahydrofuran and the like: ethylene glycol, diethylene glycol, triethylene glycol,
1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1,5-pentanediol, 1,6- Hexanediol, octanediol, 1,
Various known saturated and unsaturated low molecular weight glycols such as 4-butynediol and dipropylene glycol or alkyl glycidyl ethers such as n-butyl glycidyl ether and 2-ethylhexyl glycidyl ether, and monocarboxylic acids such as glycidyl versatate Glycidyl acid esters, adibic acid, maleic acid, fumaric acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid,
Polyester polyols obtained by dehydrating and condensing dibasic acids such as azelaic acid, sebacic acid and suberic acid or acid anhydrides and dimer acids corresponding thereto: polyester polyols obtained by ring-opening polymerization of cyclic ester compounds Class: Other polycarbonate polyols, polybutadiene glycols, glycols obtained by adding ethylene oxide or propylene oxide to bisphenol A, and the like.

[0010] In the case of a high molecular polyol obtained from a glycol and a dibasic acid among the above high molecular polyols, up to 5 mol% of the glycol can be replaced by the following various polyols. For example, glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, 1,2,4-butanetriol, sorbitol, bentaerythritol and the like can be mentioned. 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, and is usually about 700 to 5,000, preferably about 10 to about 5000.
It is good to be in the range of 00-4000. If the molecular weight is less than 700, the printability tends to decrease as the solubility decreases, and if it exceeds 5,000, the drying property and the blocking resistance tend to decrease.

As the diisocyanate compound, 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, methylcyclohexanediisocyanate, m- Tetramethyl xylylene diisocyanate and dimers - dimer diisocyanate which a carboxyl group of the acid was converted into an isocyanate group as a representative example.

The above polymer polyol is reacted with the diisocyanate compound at a ratio of an excess of isocyanate groups, and a prepolymer having isocyanate groups at both ends of the polymer polyol (preferably a free isocyanate value
Adjust 0.5 ~ 10%). The conditions for reacting the polymer polyol with the diisocyanate compound are not particularly limited except that the isocyanate group is excessive,
It is preferable that the equivalent ratio of the isocyanate groups is in the range of 1 / 1.2 to 1/3. A polyurethane resin is obtained by extending the chain of the obtained prepolymer with a chain extender. When or after the chain is extended with a chain extender, a reaction terminator may be used, if necessary.

The chain elongation is carried out in a mixed solvent comprising 89.5 to 95.5% by weight of an ester solvent, 0.5 to 5.0% by weight of water and 10.0% by weight or less of an alcoholic solvent.
This is preferable because a polyurethane resin having a urea bond can be stably synthesized. When reacting the prepolymer with a chain extender and, if necessary, a reaction terminator, one free isocyanate group having both ends of the prepolymer is used.
When the equivalents are used, the total equivalent of the amino groups in the chain extender and the reaction terminator is preferably in the range of 0.5 to 1.3. If the total equivalent of amino groups is less than 0.5, the drying property, blocking resistance, and film strength are not sufficient, and if it exceeds 1.3, the chain extender and the reaction terminator remain unreacted, and the printed matter has an odor. It becomes easy to remain.

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. In addition, 2-hydroxyethylethylenediamine, di-2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, etc. Representative examples thereof include diamines having a hydroxyl group and dimer diamine obtained by converting a carboxyl group of a dimer acid into an amino group. Examples of the reaction terminator include dialkylamines such as di-n-butylamine.

The molecular weight of the polyurethane resin obtained as described above is preferably in the range of 5000 to 100,000. If the molecular weight is less than 5000, the drying properties of the printing ink using this as a binder, blocking resistance, film strength and oil resistance are poor, and if it exceeds 100000, the viscosity of the polyurethane resin solution may increase. However, the gloss of the printing ink tends to decrease. The resin solid component concentration of the polyurethane resin is not particularly limited, and is appropriately determined in consideration of workability at the time of printing and the like. Practically, the resin solid component concentration is 15 to 60% by weight, and the viscosity is 50 to 100,000 cps (25 ° C).
It is preferable that

When producing a printing ink composition, various pigments, ester solvents, water and alcohol solvents are added to the polyurethane resin, and additives such as an anti-blocking agent and a plasticizer are added to the polyurethane resin if necessary. And surfactants to improve dispersibility, or resins compatible with polyurethane resins, in a range that does not cause thickening and gelation over time, and can be used for normal printing such as ball mill, attritor, and sand mill. Kneading is performed using an ink manufacturing apparatus.

Examples of the resin which can be used in combination include nitrified cotton, chlorinated polyethylene, chlorinated polypropylene, chlorinated polyolefins such as chlorinated ethylene / propylene, chlorosulfonated polyolefin, ethylene / vinyl acetate copolymer or chlorinated or chlorsulfone thereof. Compound, maleic acid resin, vinyl chloride / vinyl acetate copolymer and the like. When producing a printing ink using the obtained polyurethane resin solution by combining water and an alcohol-based solvent during the synthesis of the polyurethane resin (when the chain is extended or after the chain is extended), printing is not limited. It is not necessary to add water and alcoholic solvents during ink production.

[0018]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. Parts and% in Examples and Comparative Examples represent parts by weight and% by weight. Example 1 A four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube was charged with 1,000 parts of polycaprolactone diol having a molecular weight of 2,000 and 223 parts of isophorone diisocyanate. The reaction was performed for 6 hours. Then, the mixture was cooled to 50 ° C, 80 parts of isophoronediamine, 9.6 parts of di-n-butylamine, 3020 parts of ethyl acetate and 46 parts of water were added, and the mixture was reacted under stirring at 50 ° C for 3 hours. A polyurethane resin solution (A) having a viscosity of 5000 cps at 25 ° C. and a molecular weight of 40,000 was obtained. Next, a mixture of 40 parts of the polyurethane resin solution (A), 30 parts of titanium oxide, 29.5 parts of ethyl acetate and 0.5 part of water was kneaded to prepare a white printing ink (a).

[Example 2] Polyurethane resin solution (A) 40
, 30 parts of titanium oxide, 24.9 parts of ethyl acetate, 4.6 parts of isopropyl alcohol (hereinafter referred to as IPA) and 0.5 part of water were kneaded to prepare a white printing ink (b).

Example 3 The same reactor as in Example 1 was charged with 1000 parts of polycaprolactone diol having a molecular weight of 2,000 and 233 parts of isophorone diisocyanate, and reacted at 90 ° C. for 6 hours under a nitrogen stream. Then, this is 50 ℃
And 80 parts of isophoronediamine, 9.6 parts of di-n-butylamine, 2802 parts of ethyl acetate, 131 parts of IPA and water
Add 131 parts and react at 50 ° C for 3 hours with stirring.
A polyurethane resin solution (B) having a viscosity of 900 cps at 30 ° C. and a molecular weight of 40,000 at 25 ° C. was obtained. Next, 40 parts of a polyurethane resin solution (B), 30 parts of titanium oxide, 27.4 parts of ethyl acetate, IP
A mixture of 1.3 parts of A and 1.3 parts of water was ground to prepare a white printing ink (c).

Comparative Example 1 The same reactor as in Example 1 was charged with 1211 parts of polycaprolactone diol having a molecular weight of 2,000 and 102 parts of isophorone diisocyanate, and reacted at 90 ° C. for 6 hours under a nitrogen stream. Then, this is 50 ℃
After cooling, 3064 parts of ethyl acetate was added and stirred to obtain a polyurethane resin solution (C) having a solid content of 30%, a viscosity at 25 ° C of 500 cps and a molecular weight of 4,000. Next, a mixture of 40 parts of the polyurethane resin solution (C), 30 parts of titanium oxide and 30 parts of ethyl acetate was kneaded to prepare a white printing ink (d).

Comparative Example 2 The same reactor as in Example 1 was charged with 1120 parts of polycaprolactone diol having a molecular weight of 2000 and 156.2 parts of isophorone diisocyanate, and reacted at 90 ° C. for 6 hours under a nitrogen stream. Then, add this to 50
C., 39.4 parts of di-n-butylamine and 3064 parts of ethyl acetate were added and reacted at 50.degree. C. for 3 hours with stirring. A polyurethane resin solution having a solid content of 30%, a viscosity of 600 cps at 25.degree. D) was obtained. Next, a mixture of 40 parts of the polyurethane resin solution (D), 30 parts of titanium oxide and 30 parts of ethyl acetate was kneaded to prepare a white printing ink (e).

Comparative Example 3 The same reactor as in Example 1 was charged with 1,000 parts of polycaprolactone diol having a molecular weight of 2,000 and 223 parts of isophorone diisocyanate, and reacted at 90 ° C. for 6 hours under a nitrogen stream. Then, this is 50 ℃
Then, 80 parts of isophoronediamine, 9.6 parts of di-n-butylamine, 2926 parts of ethyl acetate and 138 parts of IPA were added, and the mixture was reacted at 50 ° C. for 3 hours with stirring.
A polyurethane resin solution (E) having a viscosity of 50000 cps and a molecular weight of 40,000 was obtained. Next, polyurethane resin solution (E) 40
Parts, titanium oxide 30 parts, ethyl acetate 28.7 parts and IPA
1.3 parts of the mixture was ground to prepare a white printing ink (f).

Comparative Example 4 Polyurethane Resin Solution (E) 40
Parts, 30 parts of titanium oxide, 13.9 parts of ethyl acetate and IPA1
6.1 parts of the mixture was ground to prepare a white printing ink (g). [Comparative Example 5] 40 parts of a polyurethane resin solution (E), 30 parts of titanium oxide, 24.6 parts of ethyl acetate, 1.3 parts of IPA and 4.1 parts of water
Part of the mixture was ground to prepare a white printing ink (h).

The resulting ink was evaluated for its stability over time, fluidity, coloring and solvent recovery. Table 1 shows the evaluation results. The evaluation was based on the following method. (1) Stability over time The obtained white printing ink was placed in a 200 ml glass sample bottle, and the storage stability after one week at 40 ° C. was evaluated. The judgment values of the evaluation result are as follows. : No increase in viscosity or gelation is observed compared to immediately after production. Δ: Gelling does not occur as compared to immediately after production, but an increase in viscosity is observed. ×: Gelling compared to immediately after production. (2) Flowability The flow state of the ink was visually determined. The judgment values of the evaluation result are as follows. ○… Excellent △… Normal × …… Poor

(3) Color-forming properties The white printing ink was applied to the treated surface of a corona-treated polyester film (“Ester E5100” manufactured by Toyobo Co., Ltd., 15 μm in thickness) with a Meyer bar # 4, and the appearance and density of the coated product were determined. , From the viewpoint of transparency. The judgment values of the evaluation result are as follows. : Excellent △: normal ×: inferior (4) Solvent recovery The evaluation was made based on the amount of alcohol contained in the ink. ◎… very good ○… excellent △… normal ×… poor-…… Not evaluated due to poor ink-forming suitability

[0027]

[Table 1]

[0028]

According to the present invention, a printing ink composition having excellent stability, fluidity, coloring property, adhesiveness and the like, and an almost single solvent-based easy-solvent recovery printing ink can be obtained.

Claims (2)

(57) [Claims] 1. A printing ink composition comprising a polyurethane resin having a urea bond as a binder, wherein the solvent is 89.5 to
It is composed of 95.5% by weight of an ester solvent, 0.5 to 5.0% by weight of water, and 10.0% by weight or less of an alcoholic solvent.
Easy-to-solvent-recoverable printing ink composition. 2. A prepolymer having a terminal isocyanate group obtained by reacting a high molecular polyol with an excess of a diisocyanate compound is mixed with 89.5 to 95.5% by weight of an ester solvent, 0.5 to 5.0% by weight of water and 10.0% by weight. 請 characterized by a polyurethane resin obtained by chain extension in a mixed solvent consisting of an alcohol solvent and a binder
The printing ink composition according to claim 1, wherein the solvent is easily recovered.