JPH0662907B2 - Binder for printing ink - Google Patents

Description

The present invention relates to a binder for printing ink.

(Problems to be solved by conventional techniques / inventions) In recent years, with the diversification of packaged items and the sophistication of packaging technology,
Various plastic films have been developed as a packaging material, and one suitable for a packaged item has been appropriately selected and used. By the way, when a plastic film is used as a packaging material, it is printed for decoration or surface protection of the plastic film.
Printing inks for such printing are required to have high performance such as good adhesion to various plastic films.

Polyurethane is often used as a binder for printing inks used for such printing inks that have been conventionally used. In general, printing inks using polyurethane as a binder have excellent adhesive strength alone to polyester films and nylon films, but since the adhesive strength to general-purpose films such as polyethylene film and polypropylene film is insufficient, polyethylene film When printing on a polypropylene film or a polypropylene film, a two-component reactive ink in which a polyisocyanate compound is mixed with polyurethane is used to supplement the adhesive force.

However, the two-component reactive ink has a disadvantage that it needs to be mixed with a curing agent immediately before printing, is inconvenient to handle, and has various practical limitations in terms of pot life (pot life). Therefore, in this field, various researches and developments have been carried out on polyurethane which has good adhesiveness to various plastic films, and which can be used as a binder for a one-component ink that does not need to contain a polyisocyanate compound, There is some improvement in terms of adhesion. However, for example, when the one-pack ink is used for printing a plastic film used as a packaging base material subjected to a boil sterilization, a retort sterilization step, and the like after packaging food,
Such printed matter still has a problem that the boil resistance and the retort resistance (hereinafter referred to as boil resistance) are inferior. Therefore, since it is difficult to use the one-pack type ink in the field where the boil resistance is required, the two-pack reactive ink in which the polyisocyanate compound is blended still occupies the mainstream although it has the drawbacks as described above. Is the current situation.

(Means for Solving the Problems) The present inventors have solved the problems as described above and have excellent adhesiveness and boil resistance to various plastic films such as polyester, nylon, polyethylene, and polypropylene as printed materials. As a result of extensive studies for the purpose of providing a binder for liquid type printing inks, when the epoxy-modified polyurethane having a specific amount of epoxy groups obtained by a specific method is used as a binder for printing inks, the above-mentioned problems occur. The inventors have found that they can be solved, and have completed the present invention.

That is, the present invention provides a polymer polyol, a diisocyanate compound and a chain to the polyurethane consisting of extenders, further epoxy groups per resin solids 1g 1.0 × 10 ^{- 6} ~2.0
× 10 ^{- 4} relates to a printing ink binder, characterized in that so that gram equivalent by reacting 1,2-epoxy alcohols containing mainly epoxy-modified polyurethane obtained by.

The binder for a printing ink of the present invention is an epoxy-modified polyurethane modified with 1,2-epoxy alcohol, and an epoxy group is introduced at the terminal of the epoxy-modified polyurethane.

Examples of 1,2-epoxy alcohols include glycidol, its derivatives, and monoglycidyl ethers of diols synthesized from epichlorohydrin and diols. Specific examples include ethylene glycol monoglycidyl ether and butanediol monoglycidyl ether. , Hexanediol monoglycidyl ether and the like.

Further, the epoxy group content 1.0 resin solids per 1g of epoxy-modified polyurethane obtained is × 10 of ^{- 6} to 2.0 ×
10 ^- is preferably a ^four gram equivalent. More preferably
^{1.0 × 10 - 5 ~1.0 × 10} - is ⁴ gram equivalent. The content is 1.0 × 10 ^{- 6} gram equivalent adhesion to polypropylene film and the like in the case of a one-pack type when less than such resistance boiling resistance tends to deteriorate, also 2.0 × 1
0 ^{- 4} when more than gram equivalent tend to decrease over time stability of viscosity of the polyurethane solution (binder).

Next, other constituent components of the epoxy-modified polyurethane of the present invention will be described. First, as the polymer polyol component, polyether polyols such as polymers or copolymers of ethylene oxide, propylene oxide, tetrahydrofuran, etc .; ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1, 3-butanediol, 1,4-
Saturated or unsaturated of butanediol, neopentyl glycol, pentanediol, 3-methyl-1,5-bentanediol, hexanediol, octanediol, 1,4-butynediol, diethylene glycol, triethylene glycol, dipropylene glycol, etc. Low molecular weight glycol component and adipic acid, phthalic anhydride, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid,
Polyester polyols obtained by dehydration condensation of dibasic acids such as oxalic acid, malonic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid and sebacic acid, or the corresponding dibasic acid components of acid anhydrides; cyclic Polyester polyols obtained by ring-opening polymerization of ester compounds; other polycarbonate polyols, polybutadiene glycols, glycols obtained by adding ethylene oxide or propylene oxide to bisphenol A, and various other known substances generally used for polyurethane production Polymer polyols of

Among the above, in the case of a polymer polyol obtained from a glycol component and a dibasic acid component, up to 5 mol% of the glycol component can be substituted with the following various polyols. That is, for example, glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, 1,2,4-butanetriol, pentaerythritol,
Examples thereof include sorbitol.

Furthermore, within the range not deviating from the performance of the polyurethane of the present invention, a part of the high molecular weight polyol component can be used by substituting it with a low molecular weight polyol, and the amount used in the normal polyol component is 20% by weight. % Or less, preferably
It is set to 10% by weight or less. Examples of the low molecular weight polyols include various low molecular weight polyols used for producing the high molecular weight polyols. When the use ratio of the low molecular weight polyol exceeds 20% by weight, the adhesiveness of the obtained printing ink composition to a plastic film and the solubility to a diluting solvent tend to decrease, which is not preferable.

The molecular weights of the various polymer polyols described above are appropriately determined in consideration of the solubility, drying property, blocking resistance and the like of the obtained polyurethane resin, and it is usually preferable to be in the range of 500 to 3000. If the molecular weight is less than 500, the printability tends to be poor due to the decrease in solubility, while if it exceeds 3,000, the drying property and blocking resistance tend to deteriorate.

As the diisocyanate compound, aromatic, aliphatic or alicyclic isocyanates can be used. Specifically, 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, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, cyclohexane-1,4- Representative examples thereof include diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, methylcyclohexane diisocyanate and m-tetramethylxylylene diisocyanate.

Furthermore, the epoxy-modified polyurethane of the present invention requires the use of a chain extender. That is, when the chain extender is not used, the physical properties of the film are not sufficient and the tackiness becomes strong, and the drying property and blocking resistance of the printing ink are remarkably lowered. Examples of the chain extender include ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, dicyclohexylmethane-4,
Polyamines such as 4'-diamine, 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-
It is possible to use diamines having a hydroxyl group in the molecule such as 2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine and di-2-hydroxypropylethylenediamine, and the low-molecular-weight glycols described in the above-mentioned polymer polyol section. .

Furthermore, a chain length terminating agent may be used if necessary, and examples of the chain length terminating agent include dialkylamines such as di-n-butylamine and alcohols such as ethanol and isopropyl alcohol.

The epoxy-modified urethane of the present invention is a polymer polyol,
It is produced by a method of reacting a polyurethane containing a terminal isocyanate group composed of a diisocyanate compound and a chain extender with 1,2-epoxy alcohol.

In the production of a polyurethane containing a terminal isocyanate group, first, a polymer polyol component and a diisocyanate compound are reacted under conditions of excess isocyanate groups, and a prepolymer having an isocyanate group at both ends of the polymer polyol (preferably an isocyanate content 0.5
~ 10%) and then reacting it with a chain extender in a suitable solvent, and optionally a chain length terminating agent, as well as a polymeric polyol component, a diisocyanate compound, a chain extender and the required Depending on the situation, any one-step method in which the chain-length terminating agent is reacted at once in a suitable solvent can be adopted, but the two-step method is preferred because a uniform polymer solution is easily obtained.

When producing a polyurethane containing a terminal isocyanate group used in the present invention by a two-step method, the conditions for reacting the polymer polyol component and the diisocyanate compound,
There is no particular limitation except that the amount of the isocyanate group is excessive, but it is preferable to react the hydroxyl group / isocyanate group in an equivalent ratio of 1 / 1.2 to 1/3. The conditions for reacting the obtained prepolymer with a chain extender and optionally a polymerization terminator are also not particularly limited, but the free isocyanate group at both ends of the prepolymer is 1 equivalent. In this case, the total equivalent of active hydrogen capable of reacting with the isocyanate group in the chain extender is preferably within the range of 0.5 to 0.99 equivalent. If the active hydrogen is less than 0.5 equivalents, the drying property, blocking resistance, and film strength are not sufficient, and if the active hydrogen is more than 0.99 equivalents, it is necessary to react with 1,2-epoxy alcohol. The required isocyanate groups become insufficient, and the boiling resistance and the like decrease.

Then, 1,2-epoxy alcohol may be charged and reacted with the terminal isocyanate group-containing polyurethane so that the gram equivalent of epoxy groups of the obtained epoxy-modified polyurethane falls within the above range.

In these production methods, the solvent used is usually
Benzene, which is well known as a solvent for printing inks,
Aromatic solvents such as toluene and xylene; Ester solvents such as ethyl acetate and butyl acetate; Alcohol solvents such as methanol, ethanol, isopropanol, n-butanol; Ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone One of these or a mixture of two or more thereof is appropriately selected and used.

The number average molecular weight of the polyurethane resin of the present invention obtained as described above is preferably in the range of 5,000 to 100,000. When the number average molecular weight is less than 5000, the drying property of the printing ink using this as a vehicle, blocking resistance,
The film strength, oil resistance, etc. tend to decrease, while 100,000
Polyurethane resin solution (binder)
The viscosity of the ink increases and the gloss of the printing ink tends to decrease. The concentration of the resin solid content of the polyurethane resin solution 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 weight, and the viscosity is 50 to 10%.
It is practically preferable to adjust it in the range of 0000 cP / 25 ° C.

Further, in the present invention, in addition to polyurethane which is the main component of the present invention, the following resins may be used in combination as a binder of the present invention as an auxiliary component, if necessary. Examples thereof include polyurethanes, polyamides, nitrocellulose, polyacrylic acid esters, copolymers of polyvinyl chloride and vinyl acetate, rosin-based resins, and ketone resins other than those of the present invention.

A colorant, a solvent, a surfactant for improving ink fluidity and an ink surface film, if necessary, a wax, and other additives are appropriately blended in the binder of the present invention, and a usual ball mill, attritor, sand mill or the like is used. A printing ink composition can be produced by kneading with an ink producing device. The amount of the binder of the present invention in the printing ink composition is preferably such that the resin solid content in the printing ink composition is 3 to 20% by weight.

Hereinafter, the present invention will be described in detail with reference to production examples, examples and comparative examples, but the present invention is not limited to these examples.

Production Example 1 Poly (1,2-propylene adipate) having a molecular weight of 2000 was placed in a round bottom flask equipped with a stirrer, a thermometer and a nitrogen gas inlet tube.
1000 parts of glycol and 222 parts of isophorone diisocyanate were charged and reacted at 100 ° C for 6 hours under a nitrogen stream to produce a prepolymer having a free isocyanate content of 3.36%. Then, 815 parts of methyl ethyl ketone was added thereto to prepare a uniform solution of urethane prepolymer. And Then, a mixture of 77.6 parts of isophorone diamine and 1214 parts of methyl ethyl ketone was added to the urethane prepolymer and kept at 50 ° C. for 3 hours. After incubating, add 4.8 parts of glycidol and add another 7
React at 0 ° C for 5 hours, then isopropyl alcohol 101
The reaction was terminated by adding 5 parts. The polyurethane resin solution thus obtained (hereinafter referred to as resin solution A) had a resin solid content concentration of 30% and a viscosity of 820 cP / 25 ° C. The number average molecular weight of the polyurethane resin was 38,000.

Production Example 2 A round bottom flask equipped with a stirrer, a thermometer and a nitrogen gas introduction tube was charged with 1000 parts of poly (ε-caprolactone) glycol having a molecular weight of 1000 and 333 parts of isophorone diisocyanate, and reacted at 100 ° C. for 6 hours under a nitrogen stream. Then, a prepolymer having a free isocyanate content of 3.10% was produced, and then 815 parts of methyl ethyl ketone was added thereto to prepare a uniform solution of the urethane prepolymer. Then isophorone diamine
A mixture of 65.6 parts and 1385 parts of methyl ethyl ketone was added to the urethane prepolymer and kept at 50 ° C. for 3 hours. After keeping warm, add 15.7 parts of glycidol and further 70 ℃
Then, the reaction was terminated by adding 1100 parts of isopropyl alcohol. The polyurethane resin solution thus obtained (hereinafter referred to as resin solution B) had a resin solid content concentration of 30% and a viscosity of 480 cP / 25 ° C. The number average molecular weight of the polyurethane resin was 13,000.

Production Example 3 A round bottom flask equipped with a stirrer, a thermometer and a nitrogen gas introduction tube was charged with 1000 parts of poly (ε-caprolactone) glycol having a molecular weight of 3000 and 185 parts of isophorone diisocyanate, and reacted at 100 ° C. for 6 hours under a nitrogen stream. After producing a prepolymer having a free isocyanate content of 3.44%, 815 parts of methyl ethyl ketone was added thereto to obtain a uniform solution of urethane prepolymer. Then isophorone diamine
71.7 parts, dibutylamine 16.2 parts, methyl ethyl ketone 11
A mixture of 65 parts was added to the urethane prepolymer and kept at 50 ° C. for 3 hours. After maintaining the temperature, 0.1 part of glycidol was added and further reacted at 70 ° C. for 5 hours, and then 990 parts of isopropyl alcohol was added to terminate the reaction. The polyurethane resin solution thus obtained (hereinafter referred to as resin solution C) had a resin solid content concentration of 30% and a viscosity of 1000 cP / 25 ° C. The number average molecular weight of the polyurethane resin is 2000
It was 0.

Production Example 4 Poly (1,2-propylene adipate) having a molecular weight of 2000 was placed in a round bottom flask equipped with a stirrer, a thermometer and a nitrogen gas inlet tube.
1000 parts of glycol and 222 parts of isophorone diisocyanate were charged and reacted at 100 ° C for 6 hours under a nitrogen stream to produce a prepolymer having a free isocyanate content of 3.34%, and then 815 parts of methyl ethyl ketone was added thereto to prepare a uniform solution of urethane prepolymer. And Next, the urethane prepolymer was added to a mixture consisting of 77.0 parts of isophoronediamine, 8.4 parts of dibutylamine, 1017 parts of isopropyl alcohol, and 1219 parts of methyl ethyl ketone, and the mixture was kept at 50 ° C. for 3 hours. The polyurethane resin solution thus obtained (hereinafter referred to as resin solution D) had a resin solid content concentration of 30% and a viscosity of 700 cP / 25 ° C. The number average molecular weight of the polyurethane resin was 36,000.

Production Example 5 A round bottom flask equipped with a stirrer, a thermometer and a nitrogen gas inlet tube was charged with 1000 parts of poly (ε-caprolactone) glycol having a molecular weight of 1000 and 333 parts of isophorone diisocyanate, and reacted at 100 ° C. for 6 hours under a nitrogen stream. Then, after producing a prepolymer having a free isocyanate content of 3.10%, 937 parts of methyl ethyl ketone was added thereto to prepare a uniform solution of the urethane prepolymer. Then, 72.8 parts of glycidol was added and further reacted at 70 ° C. for 5 hours, and then 469 parts of isopropyl alcohol was added to complete the reaction. The polyurethane resin solution thus obtained (hereinafter referred to as resin solution E) had a resin solid content concentration of 50% and a viscosity of 500 cP / 25 ° C. The number average molecular weight of polyurethane resin is 3200.
Met.

Production Example 6 A round bottom flask equipped with a stirrer, a thermometer and a nitrogen gas inlet tube was charged with 1000 parts of poly (ε-caprolactone) glycol having a molecular weight of 3000 and 81.4 parts of isophorone diisocyanate, and reacted at 150 ° C. for 6 hours under a nitrogen stream. After producing a prepolymer having a free isocyanate content of 0.23%, 1689 parts of methyl ethyl ketone was added thereto to prepare a uniform solution of urethane prepolymer. Then, 4.4 parts of glycidol was added, and the reaction was further performed at 70 ° C. for 5 hours, and then 845 parts of isopropyl alcohol was added to complete the reaction. The polyurethane resin solution thus obtained (hereinafter referred to as resin solution F) had a resin solid content concentration of 30% and a viscosity of 280 cP / 25 ° C. The number average molecular weight of the polyurethane resin is 4200.
It was 0.

Examples 1 to 3 and Comparative Examples 1 to 4 Titanium white (rutile type) 30 parts Polyurethane resin solution obtained in Preparation Examples 1 to 50 parts Toluene 10 parts Isopropyl alcohol 10 parts Mixtures of composition respectively with paint shaker A white printing ink was prepared by kneading. Obtained mixture 10
To 0 parts, toluene 35 parts and isopropyl alcohol 15
Then, 7 parts of white printing ink as shown in Table 1 were prepared by adding parts. The white printing ink of Comparative Example 4 is a two-component printing ink obtained by further adding 2 parts of isophorone diisocyanate to those obtained in Comparative Example 1.

The 7 white printing inks obtained were applied with a simple gravure printing machine equipped with a gravure plate with a plate depth of 30 μm to a thickness of 15 μm.
m corona discharge treated nylon film (NY) discharge treated surface and 11 μm thick polyethylene terephthalate (PET)
Was printed on one side and dried at 40 to 50 ° C. to obtain a printed film.

Then, the solid content of 25% on the printing surface of the obtained printing film
After applying and drying the polyurethane adhesive of (3) at a coating amount of 3 g / m ^2, a 60 μm polyethylene film was dry laminated with a laminator to obtain a laminated film. The thus obtained laminate film was evaluated for blocking resistance, laminate strength (adhesive strength) and suitability for boiling at 100 ° C. The evaluation results are shown in Table 1.

The functional group content in Table 1 is the gram equivalent of epoxy groups per 1 g of polyurethane resin solids.

Blocking resistance Overlapping the printing surfaces of printing films, temperature 40 ℃, humidity
The ink was peeled off after being held at 80% and a pressure of 1 kg / cm ² for 3 hours, and the degree of ink peeling was observed and evaluated.

○: The ink on the printed surface does not come off at all.

△: A part of the ink on the printed surface comes off.

×: 50% or more of the ink on the printed surface comes off.

Boilability (1) Evaluation by change in appearance of film Laminated film was observed for change in appearance after boiling at 100 ° C for 30 minutes.

○: There is nothing wrong with the film.

△: Is a small part of the film delaminated?
Or there are few blister but they are occurring.

×: A part of the film is delaminated or blisters occur.

(2) Change due to laminating strength (adhesive strength) 15m after laminating the laminated film at 100 ℃ for 30 minutes
The T-type peel strength was measured with a peel tester at a speed of 300 mm / min and compared with the strength before boil. (Unit: g / 15m
m) Effect of the Invention A one-pack type printing ink using the binder for a printing ink of the present invention has excellent blocking resistance, adhesion to various plastic films such as polyester, nylon film, polyethylene, and polypropylene, which are print targets,
It has the effect of exhibiting boil resistance and the like.

Claims (1)

[Claims] 1. A polymeric polyol, a diisocyanate compound and a chain to the polyurethane consisting of extenders, further resin solids 1g per epoxy group ^{1.0 × 10 - 6 ~2.0 × 10} -
^A binder for a printing ink, which mainly contains epoxy-modified polyurethane obtained by reacting 1,2-epoxy alcohol so as to have a weight of ⁴ grams.