JP2534309B2 - Printing ink composition - Google Patents

Description

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

(Prior Art) In general, polyester-based polyurethane has better adhesion to various adherends than polyether-based polyurethane. However, conventional polyester-based polyurethanes exhibit excellent adhesion to specific films, such as nylon and polyester, depending on their composition, but lack adhesion to other types of films, such as polyolefins such as polypropylene and polyethylene. There is a disadvantage in management because of the complexity of selecting an ink vehicle depending on the type of the ink.

Furthermore, polyester films and nylon films are often used as packaging materials for foods that have undergone a boil sterilization and retort sterilization process after food packaging, and the vehicle for printing inks used for these is naturally boil resistance, retort resistance, and oil resistance. However, there is no printing ink composition that is required to have alkali resistance, but there is no printing ink composition that can satisfy all of these requirements, and a high-performance ink having improved laminate strength is desired.

As mentioned above, there is a situation in which ink is properly selected and used depending on the type of film used, and printing ink manufacturers as well as printing companies are forced to make complicated such as quality control and inventory control of these inks. Is the reality.

(Problems to be Solved by the Invention) The object of the present invention is excellent in boil resistance, retort resistance and tack resistance as an object to be printed, and excellent in any film of polypropylene, polyester, and nylon film. It is an object of the present invention to provide a printing ink composition having adhesiveness, particularly excellent adhesion to a polyester film, and excellent oil resistance and alkali resistance.

Another object of the present invention is to provide a printing ink composition suitable for packaging retort foods and the like.

(Means for Solving the Problems) According to the present invention, the above object is printing using a polyurethane resin soluble in an organic solvent obtained by reacting a polymer diol, an organic diisocyanate and a chain extender as a main binder component. In the ink composition, the polymer diol component of the polyurethane resin has the following structural units (I) and / or (II) as units based on diol, -O- (CH _{2) 9} molar ratio of -O- (II) units (I) / (II) is 0/100 to 100/0, wherein a unit based on the dicarboxylic acid (Wherein R is an alkylene group having 4 to 12 carbon atoms and which may be branched) and a structural unit (III) represented by the formula (In the formula, Ar represents an arylene group having 6 to 10 carbon atoms) and the structural unit (IV) is represented by structural unit (III) / structural unit (I
V) is achieved by using a printing ink composition characterized by containing a polyester diol having a number average molecular weight of 500 to 4000 in a molar ratio of 1/9 to 9/1 as a main component. .

The polyester diol in the present invention contains 2-methyl-1,8-octanediol (I) and / or
Or, in addition to 1,9-nonanediol (II), 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,10-decane It does not matter even if it contains a small amount of diol, etc., but these other diols are 50 mol% in the diol component.
It is preferably used at less than.

In the dicarboxylic acid component used for producing the polyester diol, examples of the aliphatic dicarboxylic acid represented by HOOCRCOOH (R is an alkylene group having 4 to 12 carbon atoms and which may be branched) include adipic acid and
Pimelic acid, suberic acid, azelaic acid, sebacic acid,
Dodecanedioic acid and the like can be mentioned.

Also Examples of the aromatic dicarboxylic acid represented by (in the formula, Ar is an arylene group having 6 to 10 carbon atoms) include phthalic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and a mixture thereof at any ratio. More preferred are terephthalic acid and isophthalic acid. Further, as the above aromatic dicarboxylic acid, its alkyl ester compound can also be used.

The molar ratio of structural unit (III) / structural unit (IV) is 1/9 to 9 /
It is important to be in the range of 1 to achieve the effect of the present invention, more preferably 1/3 to 4/1, optimally 1/2 to 3
It is desirable to be in / 1. When the molar ratio is less than 1/9, flexibility and low temperature flexibility are insufficient, and when it is more than 9/1, retort resistance, oil resistance and alkali resistance are poor.

The method for producing the polyester diol used in the present invention is not particularly limited, and known polyester condensation means can be applied. For example, a diol mixture and a dicarboxylic acid mixture are charged at a desired ratio for esterification or transesterification, and the reaction product thus obtained is further subjected to polycondensation reaction at high temperature and high vacuum in the presence of a polycondensation catalyst. As a result, a polyester diol having a desired molecular weight can be produced.

The molecular weight of these polyester diols is 500-400
It is 0, preferably in the range of 600 to 3000. Molecular weight 500
If it is less than the above range, the solubility in the diluting solvent is lowered, so that the printability is poor and the adhesiveness is also lowered. On the other hand, when the molecular weight exceeds 4000, it is insufficient in terms of drying property and blocking resistance.

As the organic diisocyanate used in the present invention,
For example diphenyl methane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, phenylene diisocyanate, 1,5-naphthylene diisocyanate, 3,3'-dichloro-4,4'-diphenyl methane diisocyanate Aromatic diisocyanates such as xylylene diisocyanate and toluylene diisocyanate, and aliphatic or alicyclic diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate and hydrogenated xylylene diisocyanate. The organic diisocyanates may be used alone or in a mixture. Retort resistance, tack resistance, adhesiveness,
More preferable from the problem of toxicity are aliphatic or alicyclic diisocyanates, especially hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, diisocyanate such as hydrogenated xylylene diisocyanate. Is.

Further, in the synthesis of polyurethane, a low molecular weight compound having two or more active hydrogen atoms is usually used as a chain extender, but these active hydrogen atom compounds can also be used in the present invention. As typical examples of these active hydrogen atom-containing compounds, for example, ethylene glycol, butanediol, propylene glycol, 1,6-hexanediol, 1,9-nonanediol, 1,4-bis (β
-Hydroxyethoxy) benzene, 1,4-cyclohexanediol, bis (β-hydroxyethyl) terephthalate, xylene glycol and other diols, water, hydrazine, ethylenediamine, propylenediamine, xylylenediamine, isophoronediamine, piperazine, phenylene Examples thereof include diamine, tolylenediamine, adipic acid dihydrazide, and isophthalic acid dihydrazide. These compounds may be used alone or in combination.
Further, if necessary, a monohydric low molecular weight alcohol, a low molecular weight amine or the like can be used as a modifier.

A known urethanization reaction technique is used as an operation method for obtaining polyurethane. For example, a polyol and a low molecular weight compound having an active hydrogen atom are mixed, and an organic diisocyanate compound is added and reacted in a solvent such as ethyl acetate, toluene, methyl ethyl ketone, or acetone, or the polyol and the organic diisocyanate are previously mixed with, for example, 60 The reaction is carried out at a temperature of up to 120 ° C. to obtain a prepolymer of the terminal isocyanate, and the above solvent is added and dissolved therein, and then a method of chain-extending with the above low-molecular compound to obtain polyurethane is adopted. At this time, if necessary, a monohydric low-molecular alcohol, a low-molecular amine or the like may be used as a modifier to control the molecular weight.

The number average molecular weight of the polyurethane thus obtained is
The range of 5,000 to 70,000 is preferable. A more preferable molecular weight is in the range of 8,000 to 50,000. If the number average molecular weight is too small, the surface strength, non-adhesiveness, water resistance, oil resistance, etc. of the printed matter will be poor, while if the molecular weight is too large, the viscosity of the organic solvent solution of polyurethane will be high and the printing ink vehicle As a result, the handling performance will be hindered, and the adhesive performance will be significantly reduced.

Further important in the printing ink composition of the present invention, in the polyurethane solution, a colorant such as a pigment, a solvent,
If necessary, appropriately mix a surfactant for improving the fluidity of the ink and modifying the surface film, and other additives, and knead using a usual ink manufacturing device such as a ball mill, attritor, or side mill. A printing ink can be produced by the method.

The printing ink thus obtained exhibits excellent adhesiveness to films such as polyester, nylon and polypropylene, and has excellent surface strength, non-adhesiveness, water resistance, oil resistance, acid resistance, alkali resistance, etc. A two-component ink having excellent various properties and further using a polyisocyanate-based curing agent will further improve durability such as boil resistance, retort resistance, heat resistance and oil resistance.

Examples of the polyisocyanate-based curing agent used in the two-component ink include 1 mol of trimethylolpropane and 1,6
-Hexamethylene diisocyanate, tolylene diisocyanate, isophorone diisocyanate, and other triisocyanates synthesized from 3 moles of diisocyanate are preferable. As described above, the printing ink composition of the present invention can be used as either a one-component type or a two-component type, and both of them are excellent in adhesion performance, boil resistance, retort resistance, etc., and are useful as compared with conventional ones. . Further, in the production of the printing ink composition of the present invention, if necessary, nitrocellulose,
It is permissible to mix polymers such as polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyamide, and acrylic acid ester-based polymers.

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

The compounds used are indicated by abbreviations, but the relationship between abbreviations and compounds is as follows.

(Synthesis of polyester diol) Adipic acid 657g, isophthalic acid 747g, 2 in 5 reactors
-Methyl-1,8-octanediol (616 g) and 1,9-nonanediol (1144 g) were charged, and the produced water was distilled while the temperature was raised from 150 ° C to 220 ° C over 1 hour. After distilling out about 300g of water, add 500mg of tetraisopropyl titanate and 150mmHg
The water that was still formed was distilled off while reducing the pressure to -100 mmHg. After the acid value was reduced to 0.2 KOHmg / g, the pressure was reduced to 0.5 mmHg and the excess glycol was distilled off to give a hydroxyl value of 56 KOHmg / g and an acid value of 0.1.
A polyester having hydroxyl groups at both ends and having a KOH mg / g and a number average molecular weight of about 2000 was obtained. (Abbreviated as polyester diol A) Polyester diols shown in Table 1 were synthesized with the same formulation. (B ~ J) Example 1 200 parts of the polyester diol (A) shown in Table 1 and 44.4 parts of isophorone diisocyanate were charged into a round bottom flask equipped with a stirrer and a thermometer, mixed uniformly, and reacted at 100 ° C. for 4 hours to terminate the reaction. A prepolymer having an isocyanate group was obtained. To this, 390 parts of methyl ethyl ketone was added and uniformly dissolved, and then a chain extender solution prepared by dissolving 14.5 parts of isophoronediamine in 213 parts of isopropanol was added to carry out a chain extension reaction. A solution was obtained (Polyurethane A). The number average molecular weight of this polyurethane was 16,500.

Examples 2 to 7 and Comparative Example 3 The amount (molar ratio) of polyester polyol / organic diisocyanate / chain extender used was 1.0 / 2.0 / as in Example 1.
Example 1 except that the composition was 0.85 and the types of polyester polyol and organic diisocyanate were changed to the compositions shown in Table 2.
A polyurethane solution was synthesized according to the same formulation.

(Preparation method of printing ink) Polyurethane solution (concentration 30%) 100 parts Titanium oxide (Ishihara Sangyo Taipaque R-550) 75 parts Ethyl acetate 50 parts Isopropanol 50 parts Kneading the above raw materials in a small ball mill for 24 hours and printing ink Obtained. These printing inks were printed on a nylon film and a polyester film with a gravure printing machine. It was dried at 50 ° C. for 20 hours.

Next, the printed matter obtained was subjected to the following tests, and the results are shown in Table 2.

(1) Adhesive Adhesive tape (Nichiban Cello Tape # 300) on the printed surface
The state of the printed surface when the adhesive tape was peeled off was observed and judged as follows.

Printed surface that cannot be taken on the adhesive tape side at all …… ◎ Part of the printed surface taken on the adhesive tape side …… ○ If the entire printed surface is taken on the adhesive tape side …… × (2) Resistance Blotting property The durable blotting property is to fold each printed material so that the printed surface is on the inside and squeeze it well with a vise, and then reopen the sample left in the air bath maintained at 40 ° C for one day and judge the resistance at that time. Those having no resistance were judged to be good, those having a slight resistance were judged to be good, and those having a clear resistance or those in a state where peeling was difficult were judged to be defective.

(3) Boil resistance The printed matter was immersed in boiling water at 100 ° C. for 60 minutes, and then the surface state of the printed matter was observed.

The printed surface is the same as it was before immersion. ◎ ◎ The printed surface has a slight change …… ○ The printed surface is peeled off …… × (4) Retort resistance Printed in hot water of 125 ℃ Was dipped for 30 minutes, and the surface condition of the printed material was observed.

The printing surface is completely the same as the immersion surface .... ◎ The printing surface loses a little gloss .... ○ The coating film is damaged when the printing surface is rubbed strongly. △ The printing surface is peeled off. ... × (5) Oil resistance The printed matter was dipped in soybean oil for 2 days, and then the surface condition of the printed surface was observed.

The printed surface is the same as it was before dipping. ◎◎ The coating is partially damaged when the printed surface is rubbed strongly. ○ (6) Alkali resistance 5% NaOH aqueous solution penetrates the printed material for 2 days, then printed material The surface condition was observed.

The printed surface is the same as it was before immersion. ◎ ◎ The coating film is damaged if the printed surface is rubbed strongly. ○ The printed surface is partially peeled …… △ The printed surface is completely peeled …… × (Effects of the Invention) The printing ink composition of the present invention exhibits excellent adhesiveness to various non-absorbent substrates, particularly polyester film, and further has resistance to boil, retort, oil and alkali. Excel. Also, the adhesion resistance is good.

This makes it very useful as a printing ink binder for packaging retort foods and the like.

Claims (1)

(57) [Claims] 1. A printing ink composition having a polyurethane resin as a main binder, which is soluble in an organic solvent, obtained by reacting a polymeric diol, an organic diisocyanate and a chain extender, and the polymeric diol component is based on the diol. It has the following structural units (I) and / or (II) as a unit, -O- (CH _{2) 9} molar ratio of -O- (II) units (I) / (II) is 0/100 to 100/0, wherein a unit based on the dicarboxylic acid (Wherein R is an alkylene group having 4 to 12 carbon atoms and which may be branched) and a structural unit (III) represented by the formula (In the formula, Ar is an arylene group having 6 to 10 carbon atoms) and the structural unit (IV) is represented by structural unit (III) / structural unit (IV)
Number average molecular weight 500 contained in the ratio of 1/9 to 9/1 in the molar ratio of
A printing ink composition, characterized in that it comprises ˜4000 polyester diols as a main component.