JP2003041175A - Binder for printing ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a binder for printing ink, excellent in re-solubility and color tone reproducibility of ink in a solvent for ink not containing toluene and suitable for printing of various plastic films. SOLUTION: This binder for printing ink of a solvent system not containing toluene comprises a polyurethane resin which is soluble in a mixed solvent of ethyl acetate (a) with isopropyl alcohol (b) in (0-25):(100-75) weight ratio of the component (a) to the component (b). The polyurethane resin is obtained by reacting a polyesterpolyol composed of a dimer acid which is a polymeric fatty acid containing a 36C dicarboxylic acid obtained by dimerizing a 18C unsaturated monocarboxylic acid as a main component and a glycol component and having 700-4,000 number-average molecular weight with a diisocyanate compound and a chain extender as components.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing ink binder useful as a solvent-free special gravure ink binder containing no toluene.

[0002]

2. Description of the Related Art Conventionally, solvents such as toluene, methyl ethyl ketone (MEK) and ethyl acetate have been mixed and used as solvents for printing inks for plastic films. Among these, toluene is inexpensive and has a relatively high boiling point and a high dissolving power, so it is suitable for suppressing the drying of the ink on the gravure plate at the time of printing and preventing the plate clogging of the cell. Has been used as the main solvent of A polyurethane resin using 3-methylpentane adipate diol as a binder having good resolubility in a printing ink containing toluene (see, for example, Japanese Patent Application Laid-Open No. Sho 6-96
3-161065) is known.

[0003]

However, in recent years,
The revision of the Occupational Safety and Health Act strengthened the regulation of the environmental concentration of toluene, which made it necessary to improve the printing work environment.Moreover, since toluene has a relatively high boiling point, it tends to remain in the printed matter in particular. After the implementation of the PL method, it was necessary to reduce the residual solvent, and there was a great demand for solvent-based printing inks that did not contain toluene. In the case of solvents such as MEK and ethyl acetate excluding toluene, printing ink using conventional polyester-based polyurethane resin as a binder causes the ink remaining in the gravure plate cells to remain in the ink pan because the solvent dries quickly. There was a problem that the ink was dried by the time it came into contact with the new ink, it did not re-dissolve sufficiently, and plate clogging occurred, making it impossible to print on a plate with a shallow depth. Also, MEK,
When changing to ethyl acetate type solvent, in conventional polyester type polyurethane resin, these solvents have larger dissolving power of polyurethane resin than toluene, so when different types of color inks are overprinted, the ink film printed earlier There is a problem in that the ink printed after is melted to cause color transfer, resulting in poor color reproduction.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventor uses a polyester polyol using dimer acid, which is a specific polymerized fatty acid, as a polymer diol component of a polyurethane resin. At the same time, the polyurethane resin was mixed with a mixed solvent of ethyl acetate (a) and isopropyl alcohol (b) (a):
(B) = 0 to 25: 100 to 75 (mass ratio) by adjusting so as to dissolve, excellent in redissolvability and color tone reproducibility of the ink, even in the solvent for ink that does not contain toluene, various The inventors have found that a printing ink binder suitable for printing a plastic film or the like can be obtained, and completed the present invention.

That is, the present invention comprises a dimer acid and a glycol component which are polymer fatty acids containing, as a main component, a dicarboxylic acid having a carbon number of 36, which is obtained by dimerizing an unsaturated monocarboxylic acid having a carbon number of 18, and is composed of Average molecular weight is 7
A polyurethane resin obtained by reacting a polyester polyol (A) of 0 to 4000, a diisocyanate compound (B) and a chain extender (C) as constituents, wherein the polyurethane resin is ethyl acetate (a) and isopropyl alcohol. For the mixed solvent of (b),
(A): (b) = 0 to 25: It relates to a solvent-based binder for a printing ink which does not contain toluene and is dissolved in a range of 100 to 75 (mass ratio).

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the glycol component constituting the polyester polyol (A) is ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl- 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3-
Examples include various known saturated and unsaturated low molecular weight glycols such as methyl-1,5-pentanediol, 1,6-hexanediol, octanediol, 1,4-butynediol, and dipropylene glycol.

In the present invention, in addition to the polyester polyol (A), a conventionally known polymer polyol generally known for polyurethane resins may be used in combination. For example, polyether polyols such as polymers or copolymers of ethylene oxide, propylene oxide, tetrahydrofuran, etc .; ethylene glycol, diethylene glycol,
Triethylene glycol, 1,2-propanediol,
1,3-propanediol, 2-methyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1,5-pentanediol, 1,6-
Hexanediol, octanediol, 1,4-butynediol, dipropylene glycol, and other known saturated and unsaturated low-molecular-weight glycols, n-butylglycidyl ether, 2-ethylhexylglycidyl ether, and other alkylglycidyl ethers, versars Glycidyl esters of monocarboxylic acids such as tic acid glycidyl ester, dimer diol obtained by reducing dimer acid, adipic acid, maleic acid, fumaric acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, oxalic acid , Dicarboxylic acids such as malonic acid, glutaric acid, pimelic acid, azelaic acid, sebacic acid and suberic acid, and their corresponding acid anhydrides, polyester polyols obtained by dehydration condensation with dimer acid, cyclic ester compounds Ring-opening polymerization Polyester polyols are,
Polymer polyols such as polycarbonate polyols, polybutadiene glycols, and glycols obtained by adding ethylene oxide or propylene oxide to bisphenol A are mentioned.

In the present invention, the polyester polyol (A) is preferably 10 to 40 mass% in the total polymer polyol. When the ratio of (A) is less than 10% by mass, color transfer occurs and the color reproducibility is poor, and when it exceeds 40% by mass, the redissolvability tends to be poor.

In the present invention, the number average molecular weight of the polyester polyol (A) needs to be 700 to 4000. When the number average molecular weight is less than 700, the printability deteriorates as the solubility decreases. On the other hand, when it exceeds 4000, the drying property and blocking resistance are deteriorated.

In the present invention, as the diisocyanate compound (B), 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 diisocyanate, 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'-
Representative examples thereof include diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, methylcyclohexane diisocyanate, m-tetramethylxylylene diisocyanate, and dimerisocyanate obtained by converting the carboxyl group of dimer acid into an isocyanate group.

In the present invention, various known chain extenders 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, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2
-Hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine and other diamines having a hydroxyl group in the molecule, various known low-molecular glycols listed in the section of the description of the polyester polyol, and dimer acid carboxyl group Representative examples thereof include dimer diamines converted into amino groups. Furthermore, a chain length terminator can be used in combination if necessary.
Examples of the terminator include monoalcohols (methanol, propanol, butanol, 2-ethylhexanol, etc.), monoamines [monomers having 2 to 8 carbon atoms or dialkylamines (butylamine, dibutylamine, etc.), monoamines having 2 to 6 carbon atoms, or Dialkanolamine (monoethanolamine, diethanolamine, propanolamine, etc.)] and the like.

In the present invention, the polyurethane resin is (a) :( b) = 0 to 25: 100 to 75 with respect to a mixed solvent of ethyl acetate (a) and isopropyl alcohol (b).
It must dissolve in the range of (mass ratio).
A polyurethane resin in which the ratio of (a) is more than 25 and is soluble has poor re-solubility and printability is deteriorated.

In the present invention, the method for producing the polyurethane resin is not particularly limited, and the one-shot method in which the components are reacted at once or the multi-step method in which the components are reacted stepwise [for example, a diisocyanate compound and a part of an active hydrogen compound are reacted To form an isocyanate group-terminated prepolymer, and then react the mixture by adding the rest of the active hydrogen compound and further reacting] to produce the polymer. The multi-step method is preferable because it is easy to control the functional group.

When the polyurethane resin used in the present invention is produced by a multi-step method, the conditions for reacting the high molecular weight polyol component and the polyisocyanate compound are not limited, except that the isocyanate is in excess, but the active hydrogen group is not limited. / Isocyanate group is an equivalent ratio of 1 / 1.5 to 1 /
The reaction is preferably carried out within the range of 2. Also,
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 terminal of the prepolymer is 1 equivalent. The total equivalent of active hydrogen capable of reacting with the isocyanate group is preferably in the range of 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). When the amount of active hydrogen is less than 0.5 equivalent, the drying property, blocking resistance and film strength are not sufficient, and when the amount of active hydrogen exceeds 2.0 equivalents, the chain extender remains unreacted. It remains, and odor tends to remain after printing.

In the above reaction, in order to accelerate the reaction, if necessary, a catalyst used in a usual urethane reaction [amine catalyst (triethylamine, N-ethylmorpholine, triethylenediamine, etc.), tin catalyst (dibutyltin dilaurylate, dioctyl) is used. Tin dilaurate,
Tin octylate), titanium-based catalysts (tetrabutyl titanate, etc.)] and the like. The amount of the catalyst used is usually 0.1% by mass or less based on the polyurethane resin.

Solvents used in these production methods include alcohol solvents such as methanol, ethanol and isopropanol, ketone solvents such as acetone, MEK and methyl isobutyl ketone, ester solvents such as ethyl acetate and butyl acetate. These are used alone or as a mixture of two or more kinds.

In the present invention, the number average molecular weight of the polyurethane resin is usually in the range of 4,000 to 30,000. If the number average molecular weight is less than 4000,
The drying property, blocking resistance, film strength, etc. of the printing ink using this as a vehicle tend to decrease, while when it exceeds 30,000, the viscosity of the polyurethane resin increases and the gloss of the printing ink tends to decrease. Become. Further, the resin solid content concentration of the polyurethane resin is not particularly limited, but may be appropriately determined in consideration of workability at the time of printing, and is usually 15 to 60% by mass, and the viscosity is 50 to 1%.
It is practically preferable to adjust to the range of 00000 mPa · s / 25 ° C. Further, in the present invention, the following resins may be used in combination with the polyurethane resin which is the main component of the present invention as an auxiliary component, if necessary. For example, polyurethane resins other than the above, polyamide, nitrocellulose, polyacrylic acid ester, polyvinyl chloride, vinyl chloride / vinyl acetate copolymer, chlorinated polypropylene, rosin resin, ketone resin and the like can be mentioned.

In the binder of the present invention thus obtained,
A colorant, a solvent, and if necessary, a surfactant, a wax, and other additives for improving the ink fluidity and the ink surface film are appropriately blended, and an ordinary ink manufacturing apparatus such as a ball mill, an attritor, or a sand mill is used. A printing ink composition can be produced by kneading and kneading. The content of the binder of the present invention in the printing ink composition is such that the resin solid content in the printing ink composition is 3 to 2.
It is preferable that the compounding amount be 0% by mass.

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. Parts and% are based on mass.

Production Example 1 (Synthesis of Polyurethane Resin A) A number average molecular weight obtained by condensing dimer acid (dimer amount 80%) and diethylene glycol in a round bottom flask equipped with a stirrer, a thermometer and a nitrogen gas inlet tube. 300 parts of 1400 polyester polyol and 700 poly (ethylene neopentyl adipate) diol having a number average molecular weight of 3000
And 179.7 parts of isophorone diisocyanate were charged and reacted at 110 ° C. for 6 hours under a nitrogen stream to produce a prepolymer having a free isocyanate content of 2.57%, and then 1964 parts of ethyl acetate, 755 parts of MEK and 302 parts of isopropyl alcohol were added. To obtain a uniform solution of urethane prepolymer. Then isophorone diamine 74.8
Parts, 48.6 parts of poly (methylpentane maleate) diol having an average molecular weight of 770 and 4.7 parts of isopropanolamine were added, and the mixture was reacted at 70 ° C. for 8 hours. The polyurethane resin thus obtained (hereinafter referred to as polyurethane resin A) has a resin solid content concentration of 30% and a viscosity of 8
It was 20 mPa · s / 25 ° C. Also, resin solids 1
The amount of active hydrogen (amino group) per g is 1.2 x 10-4.
It was a gram equivalent, and the mass ratio of ethyl acetate (a): isopropyl alcohol (b) was dissolved in a mixed solvent of 25:75.

Production Example 2 (Synthesis of Polyurethane Resin B) Polyester polyol 30 having a number average molecular weight of 1400 obtained by condensing dimer acid (dimer content 80%) and diethylene glycol in the same round bottom flask as in Production Example 1.
0 parts and 700 parts of poly (ethylene neopentyl adipate) diol having a number average molecular weight of 3000 and 179.7 parts of isophorone diisocyanate were charged, and 110 parts were prepared under a nitrogen stream.
Reaction at 6 ℃ for 6 hours Free isocyanate content 2.57%
After producing the prepolymer of 2), 2387 parts of ethyl acetate and 597 parts of isopropyl alcohol were added to obtain a uniform solution of the urethane prepolymer. Next, 65.5 parts of isophorone diamine, 42.5 parts of poly (methylpentane maleate) diol having an average molecular weight of 770 and 4.1 parts of isopropanol amine were added, and then the mixture was reacted at 70 ° C. for 8 hours. The polyurethane resin thus obtained (hereinafter referred to as polyurethane resin B) has a resin solid content concentration of 30%,
The viscosity was 1100 mPa · s / 25 ° C. Further, the amount of active hydrogen (amino group) per 1 g of resin solid content is 1.3.
The mass ratio of ethyl acetate (a): isopropyl alcohol (b) was dissolved in a mixed solvent of 25:75.

Production Example 3 (Synthesis of Polyurethane Resin C) A polyester polyol 50 having a number average molecular weight of 1400 obtained by condensing dimer acid (dimer content 80%) and diethylene glycol in the same round bottom flask as in Production Example 1.
Parts and 950 parts of poly (ethylene neopentyl adipate) diol having a number average molecular weight of 3000 and 156.2 parts of isophorone diisocyanate were charged, and the mixture was heated at 110 ° C. under a nitrogen stream.
After reacting for 6 hours with a prepolymer having a free isocyanate content of 2.56%, 1888 parts of ethyl acetate, M
726 parts of EK and 291 parts of isopropyl alcohol were added to obtain a uniform solution of urethane prepolymer. Next, 52.4 parts of isophorone diamine, 34.0 parts of poly (methylpentane maleate) diol having an average molecular weight of 770 and 3.3 parts of isopropanol amine were added, and then 70 ° C.
And reacted for 8 hours. The polyurethane resin thus obtained (hereinafter referred to as polyurethane resin C) had a resin solid content concentration of 30% and a viscosity of 1125 mPa · s / 25 ° C. The amount of active hydrogen (amino group) per 1 g of resin solid content was 1.1 × 10 −4 gram equivalent, and the mass ratio of ethyl acetate (a): isopropyl alcohol (b) was 25:75. Dissolved in solvent.

Production Example 4 (Synthesis of Polyurethane Resin D) A polyester polyol 70 having a number average molecular weight of 1400 obtained by condensing dimer acid (dimer content 80%) and diethylene glycol in the same round bottom flask as in Production Example 1.
0 parts and 300 parts of poly (ethylene neopentyl adipate) diol having a number average molecular weight of 3000 and 222 parts of isophorone diisocyanate were charged and reacted under a nitrogen stream at 110 ° C. for 6 hours to prepare a prepolymer having a free isocyanate content of 2.75%. Later, ethyl acetate 2074 parts, ME
K798 parts and 319 parts of isopropyl alcohol were added to prepare a uniform solution of urethane prepolymer. Then, 83.3 parts of isophorone diamine, 75.8 parts of poly (methylpentane maleate) diol having an average molecular weight of 770 and 7.4 parts of isopropanol amine were added, and then 70 ° C.
And reacted for 8 hours. The polyurethane resin thus obtained (hereinafter referred to as polyurethane resin D) had a resin solid content concentration of 30% and a viscosity of 950 mPa · s / 25 ° C. Also, active hydrogen (amino group) per 1 g of resin solids
Is 1.1 × 10 −4 gram equivalent, and the mass ratio of ethyl acetate (a): isopropyl alcohol (b) is
It was dissolved in a mixed solvent of 30:70.

Production Example 5 (Synthesis of Polyurethane Resin E) A number average molecular weight of 300 was placed in the same round bottom flask as in Production Example 1.
0 poly (methylpentane adipate) diol 100
Charge 0 parts and 148 parts of isophorone diisocyanate,
After reacting under a nitrogen stream at 110 ° C. for 6 hours to produce a prepolymer having a free isocyanate content of 2.44%, 1411 parts of ethyl acetate, 705 parts of MEK and 705 parts of isopropyl alcohol were added to obtain a uniform solution of a urethane prepolymer. Then add 61 parts of isophorone diamine,
Then, the mixture was reacted at 70 ° C. for 6 hours. The polyurethane resin thus obtained (hereinafter referred to as polyurethane resin E)
Has a resin solid content concentration of 30% and a viscosity of 1410 mPa.
It was s / 25 ° C. The amount of active hydrogen (amino group) per 1 g of resin solid content is 0.7 × 10 −4 gram equivalent, and the mass ratio of ethyl acetate (a): isopropyl alcohol (b) is 35:65. Dissolved in solvent.

Examples 1 to 2 and Comparative Examples 1 to 3 In Examples 1 and Comparative Examples 1 to 3, 30 parts of titanium white (rutile type, manufactured by Ishihara Sangyo Co., Ltd.), polyurethanes of Production Examples 1 and 3 to 5 were used. A white original ink was prepared by kneading a mixture of 50 parts of resin, 10 parts of ethyl acetate, 5 parts of MEK and 5 parts of isopropyl alcohol with a paint shaker. To 100 parts of the white original ink, 20 parts of ethyl acetate, 15 parts of MEK and 15 parts of isopropyl alcohol were added to adjust the viscosity to prepare a 4-point white printing ink. In Example 2, 30 parts of titanium white (rutile type, manufactured by Ishihara Sangyo Co., Ltd.), 50 parts of the binder resin of Production Example 2, 10 parts of ethyl acetate and 10 parts of isopropyl alcohol were kneaded with a paint shaker, respectively. A white original ink was prepared. To 100 parts of the white original ink, 35 parts of ethyl acetate and 15 parts of isopropyl alcohol were added to adjust the viscosity to prepare a white printing ink for one point.

[0025] The obtained 5 points of white printing ink were applied with a gravure printing machine (rotary coater, RK Print Coat Instruments Co., Ltd.) to a corona discharge treated nylon film (NY) having a thickness of 15 µm and the thickness of the discharge treated surface. 11 μm polyethylene terephthalate film (PE
It was printed on one side of T) and dried at 80 ° C. to obtain a printed film. The printed film obtained was subjected to the following tests.

Adhesiveness After leaving the above printing film for 24 hours, a cellophane tape was attached to the printing surface, and the appearance of the printed film when peeled off rapidly at an angle of 90 ° was observed and evaluated. The evaluation results are shown in Table 1. ----- More than 80% of the printed film remained on the film. Δ --- 50 to 80% of the printed film remained on the film. X --- 50% or less of the printed film remained on the film.

Blocking resistance: The printed film was bent so that the printed surface was on the inside, a load of 200 gf / cm2 was applied, and the adhered state of the printed surface was observed after standing at 40 ° C for 24 hours. evaluated. The evaluation results are shown in Table 1. ◯ −−−− 0% to less than 20% of the contact area is attached. [Delta] -------- There is adhesion of 20% or more and less than 50% of the contact area. × −−−− 50% or more of the contact area was attached.

Pigment dispersibility and printability The pigment dispersibility and printability were evaluated by the color forming property, plate clogging property and color tone reproducibility. The evaluation results are shown in Table 1. Coloring property: The transparency and density of the printed surface were visually judged. Plate clogging property: Printing was performed with a gravure plate, and a missing print pattern due to cell clogging was visually determined. Color tone reproducibility: Ethyl acetate was coated on the printed surface with a bar coater, and the degree of dissolution of the white ink in ethyl acetate was visually determined. The evaluation criteria are as follows. ○ ----- Those with good suitability for each. △ ---- Inadequate individual suitability. × −−−− Each suitability is extremely poor.

[0029]

[Table 1]

[0030]

INDUSTRIAL APPLICABILITY According to the present invention, a binder for printing ink, which can be used for printing various plastic films such as polyester, nylon, polyethylene and polypropylene, and is excellent in pigment dispersibility, ink resolubility, color tone reproducibility and printability. And a printing ink composition using the same can be provided. That is, the binder for a printing ink of the present invention simply comprises a polyurethane resin containing 40% by mass or more of the polyester polyol (A) as shown in Comparative Example 2 and a conventional polyester-based polyurethane resin as shown in Comparative Example 3. With solvent-based printing inks such as MEK and ethyl acetate, which excludes toluene, the solvent remains dry quickly, and the ink remaining in the gravure plate cells dries until it comes into contact with the new ink in the ink pan. It solves the problem that printing will not be possible with a shallow plate because it does not dissolve and plate clogging occurs, and as shown in the examples, it is a solvent-based printing ink that does not contain toluene, and the redissolvability and color reproducibility of the ink. It provides excellent technology for printing various plastic films.

Claims (2)

[Claims] 1. A dimer acid, which is a polymer fatty acid containing a dicarboxylic acid having 36 carbon atoms as a main component, which is obtained by dimerizing an unsaturated monocarboxylic acid having 18 carbon atoms, and a glycol component, and has a number average molecular weight of 1. A polyurethane resin obtained by reacting 700 to 4000 polyester polyol (A), diisocyanate compound (B) and chain extender (C) as constituents, wherein the polyurethane resin is ethyl acetate (a) and isopropyl alcohol. (A): (b) = 0 to the mixed solvent of (b)
A solvent-based binder for a printing ink that does not contain toluene and that dissolves in the range of 25: 100 to 75 (mass ratio). 2. The binder for a printing ink according to claim 1, wherein the proportion of the polyester polyol (A) is 10 to 40% by mass based on the total polymer polyol.