JPH01308470A - Composition for printing ink - Google Patents

Abstract

PURPOSE:To obtain the title composition excelling in nonstickiness, water resistance, boiling resistance, retorting resistance, oil resistance, etc., and showing excellent adhesiveness to a film such as a PP film, by using a polyurethane resin synthesized under specified conditions as the main binder. CONSTITUTION:A hydroxyl-terminated polymer-diol (A) which is preferably a polyester-diol of an average MW of 1,000-3,000 is reacted with an organic diisocyanate compound (B) which is preferably an aliphatic or alicyclic diisocyanate in a molar ratio of (A) to (B) of 1:1.2-1.8 to synthesize an insocyanate-terminated propolymer, and this prepolymer is reacted with a chain extender (B) (e.g., isophoronediamine) which is a low-molecular compound having a specified amount (e.g., at least two) active hydrogen atoms to obtain an organic solvent-soluble polyurethane resin of a number-average MW of 10,000-70,000. This resin is used as the main binder.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a composition for printing ink. More specifically, the present invention relates to a printing ink composition that has excellent boil resistance, retort resistance, oil resistance, and adhesion resistance, and has very good adhesion to various plastic films such as polyester, nylon, and polypropylene.

(Prior art) In general, polyester-based polyurethane has superior adhesion to various adherends compared to polyether-based polyurethane. However, conventional polyester-based polyurethane is superior to certain films, such as nylon and polyester, depending on its composition. However, other types of films, such as polyolefins such as polypropylene and polyethylene, have insufficient adhesion and are disadvantageous in terms of management because it is complicated to select a vehicle for ink depending on the type of film.

Furthermore, polyester films and nylon films are often used as packaging materials for foods that undergo boil sterilization or retort sterilization processes after food packaging, and the printing ink vehicles used for them are naturally boil resistant, retort resistant, and oil resistant. However, there is no printing ink composition that can satisfy all of these requirements, and there is a need for a high-performance ink with improved laminate strength.

As mentioned above, in the current situation where inks are selected appropriately depending on the type of film used, not only printing ink manufacturers but also printing companies are forced to complicate quality control, inventory management, etc. of these inks. The reality is that

(Problem to be solved by the invention) The purpose of the present invention is to improve the boiling resistance of a printing substrate.

It has excellent retort resistance and adhesion resistance, and has excellent adhesion to polypropylene, polyester, and nylon films, especially to polypropylene film, and An object of the present invention is to provide a printing ink composition with excellent oil resistance.

Another object of the present invention is to provide a printing ink composition suitable for packaging retort foods, etc. (Means for Solving the Problems) According to the present invention, the above object is achieved by In a printing ink composition containing as a main binder component an organic solvent-soluble polyurethane resin obtained by reacting an isocyanate and a chain extender, the polyurethane resin has (5) a terminal hydroxyl group and an average molecular weight of 1000 to 3;
000 polymeric diol, (6) organic diisocyanate compound and (Q chain extender), 11
The molar ratio of (6) and (b) and (mon) is 1:1.2 to 1.8
A prepolymer having terminal isocyanate groups is synthesized by reacting at a ratio of 0.0, and then the molar ratio to (A) is 0.
The number average molecular weight obtained by adding (6) and 0 to this prepolymer and reacting is 3 to 1.0.
This is achieved by using a printing ink composition characterized by a polyurethane resin of 0,000 to 70,000.

As the polymer diol (6) having a number average molecular weight of 00 to 3000 used in the present invention, island molecular diols known in the polyurethane industry can be used. Examples include polyether diol, polyester diol, polycarbonate diol, and hydroxyl group-containing diene polymer.

Among the polyether diols, polyoxytetramethylene diol, polyoxypropylene diol, or modified products thereof are preferred. These are cyclic ethers such as propylene oxide and tetrahydrofuran.
Therefore, it is obtained.

Polyester diols include aliphatic, alicyclic or aromatic dicarboxylic acids having 4 to 20 carbon atoms and 2 to 2 carbon atoms.
An example is one obtained from a diol of 0. Examples of aliphatic dicarboxylic acids used here include glutaric acid, adipic acid, succinic acid, maleic acid, pimelic acid, superric acid, azelaic acid, and sepatic acid, and examples of alicyclic dicarboxylic acids include cyclohexane. Dicarboxylic acids, etc.
Examples of aromatic dicarboxylic acids include phthalic acid, terephthalic acid, and isophthalic acid. In addition, the diol used at this time is ethylene glycol, 1.4
-Butanediol, 1,6-hexane glycol% 1
．． 9-nonanediol, 2-methyl-1,8-octanediol, diethylene glycol, propylene glycol, 3-methyl-1,5-bentanediol, etc. are used.

The method for producing the polyester dionyl used in the present invention is not particularly limited, and known polyester condensation means can be applied. That is, a diol mixture and a dicarboxylic acid or an ester-forming derivative thereof are charged in a desired ratio to perform esterification or transesterification, and the reaction product thus obtained is further subjected to a polycondensation reaction at high temperature and under high vacuum. By doing so, a polyester diol having a desired molecular weight can be produced. In addition to the above polyester diols, polyester diols obtained by ring-opening polymerization of cyclic ester compounds such as ε-caprolactone and β-methyl-δ-valerolactone can also be used.

Examples of polycarbonate diol include 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,4-butanediol, 1,5-bentanediol, 1,6-hexanediol, 3-methyl- 1,5
-bentanediol, 1,10-decanediol, cyclohexanedimethanol, and other diols synthesized by reaction with various carbonate compounds can be exemplified.

The method for producing the polycarbonate diol used in the present invention is not particularly limited, and known methods can be applied.

Next, a hydroxyl group-containing diene polymer is a liquid diene polymer having a hydroxyl group at the end of the molecule. These liquid diene polymers include polymers obtained by homopolymerizing diene monomers having from 4 to 12 carbon atoms, and furthermore, polymers obtained by homopolymerizing diene monomers having from 4 to 12 carbon atoms, and also from these diene monomers and α-olefinic addition polymerizable monomers from 2 to 22 carbon atoms. A copolymer with is preferred. Furthermore, to these liquid diene polymers, those modified by adding unsaturated carboxylic acids or derivatives thereof such as anhydrous ruin may also be used.Specifically, butadiene polymers, isoprene polymers, etc. In addition to homopolymers such as polymers, examples include copolymers such as butadiene-isoprene copolymer, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer, and butadiene-2-nibruhexyl acrylate copolymer. I can do it.

Particularly preferred polymeric diols are polyester diols and polycarbonate diols in terms of adhesiveness and boiling resistance. In terms of cost and performance, the most preferred polymeric diol is polyester diol.

The molecular weight of these polymer diols is 1000 to 3000
If the molecular weight is less than 1,000, the solubility in a diluting solvent decreases, resulting in poor printability and poor adhesion. On the other hand, if the molecular weight exceeds 3000, the adhesion, drying properties and blocking resistance are insufficient.

Examples of the organic diisocyanates used in the present invention include diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-)17 diisocyanate, phenylene diylene anor), and 1,5-naphthyl diisocyanate. Diisocyanate, 3,3'-dichloro-4,4'
- Aromatic diisocyanates such as diphenylmethane diisocyanate, xylylene diisocyanate, and toluylene diisocyanate.

Examples include aliphatic or alicyclic diisocyanates such as hexamethylene diisocyanate, inphorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and hydrogenated xylylene diisocyanate. The organic diisocyanate may be used alone or as a mixture.Due to problems with retort resistance, stickiness resistance, adhesion, and toxicity, aliphatic or alicyclic diisocyanates are preferred. Among them, diisocyanates such as hexamethylene diisocyanate, inphorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and hydrogenated xylylene diisocyanate are particularly useful in the synthesis of polyurethanes. Low molecular weight compounds having the above active hydrogen atoms are usually used as chain extenders, but
Chain extenders other than these active hydrogen atom compounds can also be used in the present invention. Representative examples of these active hydrogen atom-containing compounds include ethylene glycol, butanediol, propylene glycol, 1゜6-
Hexanediol, 1,9-nonanediol, 1,4-
Bis(β-hydroxyethoxy)benzene, 1,4-cyclohexanediol, bis(β-hydroxyethyl)
Diols such as terephthalate and xylene glycol, water, hydrazine, ethylenediamine, propylenediamine, xylylenediamine, inphoronediamine, trimethylhexamethylenediamine, 4,4'-dicyclohexylmethanediamine, piperazine, phenylenediamine, tolylenediamine , adipic acid dihydrazide, isophthalic acid dihydrazide, etc., and these compounds may be used alone or in combination.

The polyurethane resin in the present invention further includes, as necessary,
-valent low-molecular alcohols, low-molecular amines, and the like can also be used as modifying agents.

All of the above-mentioned polyurethane raw materials are known, and polyurethanes obtained from the raw materials used in the present invention are also known. However, regarding poly-9-rethane for use as a print-in binder as in the present invention, there is no mention of any special polymerization method as defined in the present invention. The revolutionary effects brought about by the present invention are not obtained simply by using these compounds as raw materials, but by adopting the specific polymerization method defined in the present invention. This is achieved for the first time.

To explain in more detail the polymerization method of the present invention and its effects, firstly, in the present invention, the average molecular
(A): (average molar ratio of 1:1.2 to 1)
．． 8 to 8 until the terminal hydroxyl group of (A) is substantially no longer present in the reaction system to synthesize a prepolymer having a terminal incyanate, and then, after dissolving this prepolymer in a solvent, Add K(A) to this solution
It is obtained by adding and reacting an organic diisocyanate (B) with a molar ratio of 0.3 to 1.0 and a chain extender (q. As a specific method for this, the prepolymer obtained is The molar ratio to (6) is 0.3 to 1.0
A method in which polyurethane is obtained by further adding (B), and then adding (q), or (a method in which a predetermined amount of Q is added, and then the entire amount of (B) to be added is added, and the above molar ratio The shortfall (B) from 0.3 to 1.0 and (
A method may be used in which polyurethane having the same molar ratio is finally obtained by appropriately adding q alternately.

Conventionally, methods for synthesizing polyurethane for printing in Φ include a method of polymerizing compounds (A), (B) and (q) all at once, or a method in which the entire amount of (^ and (B) is first charged into a reaction system and reacted. (The method of polymerizing by adding Ole is known as a typical method, but if polyurethane is synthesized using such a polymerization method, the object of the present invention is not achieved at all. However, the polymerization method of the present invention If the method is adopted, boiling resistance and retort resistance during synthesis of greborimer (A)
: The molar ratio of (13) is preferably in the range of 1:1.2 to 1:IL8, more preferably 1:1.3 to 1.
: The range is 1.6. If this ratio is smaller than 1:1.2, oil resistance and solution stability will decrease;
．． If it is larger than 8, boil resistance, retort resistance, and oil resistance will be impaired.

In addition, in the present invention, (B
) is preferably in the range of 0.3 to 1.0,
It is preferably 0.4 to 0.8. This ratio is 0.3
If it is too small, boil resistance, retort resistance, and oil resistance will be insufficient, while if it is too large, adhesion, solution stability, and solvent resolubility will be poor.

The number average molecular weight of the polyurethane obtained in this way is 1
A value in the range of 0,000 to 70,000 is preferred. It is preferably in the range of 15,000 to 50,000. If the number average molecular weight is less than 10,000, the surface strength, non-adhesiveness, water resistance, oil resistance, etc. of the printed matter will be poor;
If it is larger than 0,000, the viscosity of the polyurethane solution in an organic solvent is high, which impedes its handling as a printing ink vehicle, and the adhesive performance is greatly reduced.

In the present invention, a coloring agent such as a pigment, a solvent, a surfactant for improving ink fluidity and modifying a surface film, and other additives are appropriately blended into the polyurethane solution, and a ball mill, The printing ink composition can be manufactured by kneading using a common ink manufacturing apparatus such as an attriter or a sand mill.

The printing ink composition thus obtained exhibits excellent adhesion to films of polypropylene, polyethylene, polyester, nylon, etc., and improves the surface strength of printed matter.
It has excellent properties such as non-adhesion, water resistance, boil resistance, retort resistance, oil resistance, acid resistance, and alkali resistance. If the composition of the present invention is made into a two-component ink using a wrinkle irrecyanate curing agent if desired, durability such as boiling resistance, retort resistance, heat resistance, bit oiliness, etc. can be further improved. The polyisocyanate curing agent used here is a trifunctional or higher functional polyisocyanate, such as 1 mol of trimethylolpropane and 1.6-hexamethylene diisocyanate, tolylene diisocyanate, inphoron diisocyanate, etc. Triisocyanates synthesized from 3 moles of diisocyanate such as isocyanate are preferred.

Note that the printing ink composition obtained in the present invention does not substantially contain active isocyanate groups in the solution, and is fundamentally different from a two-component printing ink.

However, the printing ink composition obtained according to the present invention does not have problems such as pot life that two-component printing inks have.

As described above, the printing ink composition of the present invention can be used as a one-component type or a two-component type, and both have superior adhesive performance, boil resistance, retort resistance, oil resistance, etc. compared to conventional ones. It is useful.

Furthermore, the printing ink composition of the present invention may contain other polymers such as nitrocellulose, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyamide, and acrylic acid ester polymer, if necessary.

(Example) Next, the present invention will be specifically explained with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Parts in Examples and Comparative Examples refer to parts by weight unless otherwise specified.

(Polyurethane solution synthesis example 1) An equimolar mixture of 2-methyl-1,8-octanediol (MOD) and 1,9-nonanediol (ND) and adipic acid (AD) had an average molecular weight of about 2000. 200 parts (0.1 mol) of polyester diol and 33.3 parts (0.15 mol) of inphorone diisocyanate (IPDI)
mol) was placed in a round bottom flask equipped with a stirrer and a thermometer and mixed uniformly. The mixture was then reacted at 100° C. for 8 hours to obtain a prepolymer having isocyanate groups at both ends. 390 parts of methyl ethyl ketone (MgK) was added thereto and dissolved uniformly, and then 1 part (0.05 mol) of IPD was added thereto. Then inphorondiamine (IPDA) 15
．． A chain extender solution containing 5 m (0.09 x mol) dissolved in 213 parts of isopropanol (IPA) was added to carry out a chain extension reaction.

The obtained polyurethane resin solution had a solid content concentration of 30% and a viscosity of 12p (25°C). The number average molecular weight of this polyurethane was 19,800.

This polyurethane is called pu-A.

Following the same procedure, the solid content concentration is 3 with the preparation composition shown below.
A polytalethane solution pu-B-puG was synthesized.

Table IKt shows the results obtained along with various measured physical property values.
Reminder.

pu-B Mui0 Mixed diol of D and ND (MOD:ND molar ratio = Q, 55:Q, 35) and AD, resulting in an average molecular weight of approximately Hayabusa IPDA l 5.2
(0,089Mo#) MEK 4
04 parts IPA 218 parts u-C 3-methylbentanediol (MPD) and AD and polyester diol with an average molecular weight of about 2000 2
00 parts (0.1 mol) IPDA 14.8 parts (
0.87 mol) MEK a a
6 parts IPA 208 parts u-D Poly(methylvalerolactone) glycol [Labole L manufactured by Kuraray: average molecular weight approx. 2000] 200 parts (0.1
mole) 4.4-dicyclohexylmethanediamine 18.5 parts (
o, oss mole) MEK 398 part IP person
215 parts u-E poly(caprolactone) glycol [Polylite F manufactured by Dainippon Ink: average molecular weight approximately 20003200 parts (0.1
mole) 4.4-dicyclohexylmethane diisocyanate IP
DA l & 6 copies (0,
092 mol) MEK 406 parts IPA 219 parts uF Polycarbonate diol with an average molecular weight of about 2000 obtained from equimolar mixed diol of MOD and ND and diphenyl carbonate 200 parts (0.1
mole) IPDA 14
．． 5th part (0,085 sols) MEK
393 parts IPA 212 parts u-G Mixed diol of MOD and ND (MOD:ND molar ratio =
0.3 : 0.7'') 200 parts (0.1 mol) of polycarbonate diol with an average molecular weight of about 2000 obtained from todiphenyl carbonate 14.6 parts (0.1 mol) of IPDA (5 mol of 0.08°C) MEK
403 parts IPA 217 parts (
Polyurethane synthesis example 2) Poly(caprolactone) glycol [Polylite F manufactured by Dainippon Ink: average molecular weight approximately 2000] 200 parts (0.1
mol) and 44.4 parts (0.2 mol) of IPDI were placed in the same flask as in Synthesis Example 1 and mixed thoroughly.

The mixture was then reacted at 120° C. for 4 hours to obtain a prepolymer having isocyanate groups at both ends. MEK 39 for this
After dissolving 3 parts of IPDA uniformly, add 14.6 parts of IPDA (0.
A chain extender solution containing 086 mol) dissolved in 212 parts of ingropanol was added to carry out a chain extension reaction.

The obtained polycrethane resin solution had a solid content concentration of 30% and a viscosity of Lop (25° C.). The number average molecular weight of this polyurethane was 17,100. This polyurethane is called pu-H.

Following the same procedure, the solid content concentration is 3 with the preparation composition shown below.
0-polyurethane solutions pu-I and pu-J were synthesized. Table I shows the results obtained along with various measured physical property values.
K summarized.

pu-I Polyester diol with an average molecular weight of about 2000 obtained from MPD and AD 200 parts (0.1 mol) IPDI 44.4 parts (
0.2 mol) IPDA
14.5 parts C0,085 mol) MEK
393 part IP person 211
Part u-J Poly(methylvalerolactone) glycol [Labole L manufactured by Kuraray: average molecular weight approximately 2000] 200 parts (0,1
mole) IPDI 44.4 parts (
0.2 mol) IPDA
14.5 parts (0,085 mol) MEK
393 part IP person
PU-E and PU obtained as above in 211 parts
-H) It is clear that the obtained polyurethane has better heat resistance than that obtained by the conventional method.

Examples 1 to 7 and Comparative Examples 1 to 3 Polyurethane solutions pu-A to pu-J obtained in Synthesis Examples
After adjusting the solid content concentration of Yoshi polyurethane to 30%, each raw material with the following composition was placed in a small ball mill and kneaded for 24 hours to obtain a printing ink.

Poly9 urethane solution (concentration 30%) 100 parts Titanium oxide (Bankyo Sangyo Thai Bake R-550) 75
Part Methyl Ethyl Ketone 65 parts Isoptetrapanol 35 parts These printing inks were printed on nylon film and polyester film using a gravure printing machine.

Drying was performed at 50°C for 20 hours.

Next, the following tests were conducted on the obtained round printed matter, and the results are shown in Table 1.

(1) Adhesiveness Adhesive tape Nichiban Cellotape ■φ300) was applied to the printed surface, the cellophane tape was peeled off, and the condition of the printed surface was observed during running, and the judgment was made as follows.

Items where the printed surface is not removed by the adhesive tape at all...◎(
2) Resistance to curling The sample was folded so that the printed side was on the inside (it was tightly tightened with a chair and left overnight in an air bath kept at 40°C, then spread out again, and the resistance at that time was judged intuitively). Na.

There was no resistance at all...
・・・Good item with very little resistance ・・・・・・
＼Those who have resisted eating or 3018
1011. Poor and difficult to peel (8) Boiling resistance The printed matter was immersed in boiling water at 100°C for 60 minutes, and the surface condition of the printed matter was then observed.

The printed surface is as perfect as it was before dipping.
・○ Items with slight changes in the printed surface ・・・・・・
Δ Items where the entire printed surface peels off...
... × (A) Retort resistance The printed matter was immersed in hot water at 125° C. for 30 minutes, and the surface state of the printed matter was observed after that.

The printed surface is as perfect as it was before dipping.
・◎If you rub the printing surface too hard, the coating will be damaged...
...Δ(6) Oil-resistant printed matter was immersed in soybean oil for 2 days, and the surface condition of the printed surface was then observed.

The printed surface is as perfect as it was before dipping. ◎ If the printed surface is rubbed too hard, the paint film will be partially damaged. °・○ (6
) Alkali Resistance 54 A printed matter was immersed in an aqueous NaOH solution for 2 days, and the surface condition of the printed matter was then observed.

The printed surface is as perfect as it was before dipping °・◎ If the printed surface is rubbed too hard, some parts of the coating will be damaged... ○ Part of the printed surface will peel off ... Δ The entire printed surface will peel off Items to be stored... It also has excellent properties and alkali resistance. 1+ Adhesion resistance is also good.

This makes it very useful as a printing ink binder for packaging such as cilantro food.

[Brief explanation of the drawing]

FIG. 1 is a complex elastic modulus temperature distribution curve of polyurethane used in Examples and Comparative Examples of the present invention. Patent applicant RiRa Shi Co., Ltd.

Claims (1)

[Claims] (1) In a printing ink composition containing as a main binder an organic solvent-soluble polyurethane resin obtained by reacting a polymeric diol, an organic diisocyanate, and a chain extender, the polyurethane resin is attached to the (A) terminal When synthesizing from a polymeric diol having an average molecular weight of 1,000 to 3,000 having a hydroxyl group, (B) an organic diisocyanate compound, and (C) a chain extender, first (A) and (B) are
):(B) in a molar ratio of 1:1.2 to 1.8 to synthesize a prepolymer having terminal isocyanate groups, and then reacted in a molar ratio of (A) to 0.3 to 1. 0 (B) and (C) are added to this prepolymer,
The number average molecular weight obtained by the reaction is 1000.
1. A printing ink composition characterized by being a polyurethane resin having a molecular weight of 0 to 70,000.