JPWO2015068412A1 - Binder for printing ink, laminate ink composition for soft packaging, and printed matter - Google Patents

Abstract

A printing ink binder comprising a polyethylene glycol (hereinafter referred to as PEG) -containing polyurethane resin and a vinyl chloride-vinyl acetate copolymer resin, wherein the PEG-containing polyurethane resin is at least (A) a polyester having a number average molecular weight of 1000 to 6000. It is obtained by reacting a polyol, (B) PEG, (C) a diisocyanate compound, and (D) a chain extender. On the other hand, the binder for printing inks which is the range of 1-40 mass parts.

Description

  The present invention relates to a binder for printing ink, a laminate ink composition for soft packaging, and a printed matter.

  In recent years, plastic films have been used in various fields as packaging materials. Printing on such a plastic film is performed by gravure printing or flexographic printing. With the diversification of packaging base materials, the performance required for printing inks and coating agents used for decoration or surface protection is becoming increasingly sophisticated.

  For example, a printing ink for plastic films needs to have excellent printability, adhesion, blocking resistance, and gloss for a wide variety of films. Furthermore, in the field of food packaging containers, ink is not in direct contact with the contents, and sanitary laminated packaging containers are used.

  In general, there are the following two methods for laminating. That is, an ink is printed using various plastic films as a printing substrate, an extrusion laminating method in which molten polyolefin or the like is laminated on the printing surface via an anchor coating agent, and a plastic film is laminated on the printing surface via an adhesive. This is a dry laminating method.

  Therefore, the ink used in the laminating method must adhere well to printing substrates such as various plastic films, and must have excellent adhesion to the laminated plastic film, printability, and laminate strength. In addition, for the purpose of sterilizing the contents, if boil or retort treatment is applied to wrap the whole packaging container laminated in hot water, suitability for boil and retort that does not cause laminating float or wrinkle during treatment Is required.

  Since most of the above ink performance mainly depends on the performance of the binder resin, various binder resins are used depending on the required performance. Generally, a polyurethane resin is used as a binder resin for laminating ink (see Patent Documents 1 to 3).

JP 2010-270215 A JP 2010-270216 A Japanese Patent No. 4882206

  Generally, a polyurethane resin with a molecular urethane bond concentration as high as possible is used as the binder resin for laminating inks. However, when the urethane bond concentration increases, the ink boil and retort suitability tends to be poor, and methyl ethyl ketone The solubility in solvents such as ethyl acetate, isopropyl alcohol, etc. decreases, and when these solvents are used, printing of the image area is caused by the phenomenon that the solid matter of ink accumulates in the plate, which is called plate clogging. There is a problem that a defect occurs (decrease in printability).

  On the other hand, in inks using aromatic organic solvents such as toluene, the polyurethane resin skeleton is hardened to improve blocking resistance. By adding chlorinated PP (polypropylene), boil / retort suitability, laminate strength, An ink having good printability, adhesion and anti-blocking properties can be obtained. However, from the viewpoint of the working environment, the use of aromatic organic solvents and organic solvents that do not contain ketone organic solvents such as methyl ethyl ketone is being promoted (such as non-tolueneization). In addition, with these polyurethane resins alone, it has been difficult for inks obtained with organic solvents not containing aromatic organic solvents to meet a wide variety of film requirements.

  An object of the present invention is to provide a printing ink binder for obtaining an ink excellent in printability, laminate strength and boil / retort property. Moreover, it is providing the laminate ink composition for soft packaging which uses the binder for printing inks, and its printed matter.

  As a result of intensive studies, the present inventors have found that polyethylene glycol (hereinafter referred to as “PEG”) is used as a binder for printing inks in laminate inks for soft packaging even when organic solvents that do not contain aromatic organic solvents are used. It has been found that containing a polyurethane resin and a vinyl chloride / vinyl acetate copolymer resin as components is effective in solving the problem. The present invention has been completed based on such findings.

  The present invention is a printing ink binder comprising PEG-containing polyurethane resin and vinyl chloride vinyl acetate copolymer resin as components, wherein the PEG-containing polyurethane resin is at least (A) a polyester polyol having a number average molecular weight of 1000 to 6000, (B) is obtained by reacting PEG, (C) diisocyanate compound and (D) chain extender, and (B) the content ratio of PEG is 100 parts by mass of PEG-containing polyurethane resin, It is related with the binder for printing inks which is the range of 1-40 mass parts. By using PEG-containing polyurethane resin and vinyl chloride vinyl acetate copolymer resin as components, effects such as improved printability can be obtained. Further, when the content ratio of PEG is within the above range, effects such as improvement in suitability for boil / retort and printability can be obtained.

  Moreover, this invention relates to said binder for printing inks whose number average molecular weights of (B) PEG are 200-4000. (B) When the number average molecular weight of PEG is within the above range, effects such as improvement in laminate strength can be obtained.

  The present invention also relates to the printing ink binder described above, wherein the PEG-containing polyurethane resin is obtained by reacting dimethylolpropionic acid. Further, by using a dimethylolpropionic acid (hereinafter referred to as DMPA) -containing polyurethane resin as a component, effects such as improvement in laminate strength and suitability for boil and retort can be obtained.

  The present invention also relates to a laminate ink composition for soft packaging comprising the above-mentioned printing ink binder, colorant and organic solvent as components.

  The present invention also relates to the above-mentioned laminate ink composition for soft packaging, wherein the organic solvent does not contain an aromatic organic solvent or a ketone organic solvent. The printing ink binder of the present invention is particularly suitable for a laminate ink composition for soft packaging that does not use an aromatic organic solvent or a ketone organic solvent, but uses an aromatic organic solvent or a ketone organic solvent. It can also be used in laminated ink compositions for soft packaging, and exhibits excellent properties.

  Moreover, this invention relates to the printed matter formed by printing said laminated ink composition for soft packaging.

  According to the present invention, it is possible to provide a printing ink binder for obtaining an ink excellent in printability, laminate strength and boil / retort suitability.

Hereinafter, embodiments of the present invention will be described in detail.
The binder for printing ink of the present invention is a binder for printing ink comprising a PEG-containing polyurethane resin and a vinyl chloride vinyl acetate copolymer resin as components, and the PEG-containing polyurethane resin is at least (A) a number average molecular weight of 1000 to 6000. Polyester polyol, (B) PEG, (C) a diisocyanate compound, and (D) a chain extender, and (B) the content ratio of PEG is 100 masses of PEG-containing polyurethane resin. It is the range of 1-40 mass parts with respect to a part.

  Examples of the diol component constituting the (A) polyester polyol used in the present invention include ethylene glycol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, triethylene glycol, 1- or 2-methyl. -1,3-butylene glycol, 1- or 2-methyl-1,4-pentylene glycol, 2,4-diethyl-1,5-pentanediol, tripropylene glycol, 1,2-propylene glycol, 1,3 -Butanediol, 1-, 2- or 3-methyl-1,5-pentanediol, 2-methyl-1,3-propanediol, bisphenol A ethylene oxide, propylene oxide, ethylene propylene oxide and other alkylene oxides Addendum, Neopen Glycol, butyl ethyl propanediol. Of these, particularly preferred are 3-methyl-1,5-pentanediol and neopentyl glycol.

  The following polyfunctional polyols can be used for some of the diol components. Examples of the polyfunctional polyol include glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, 1,2,4-butanol, sorbitol, pentaerythritol and the like. It is done.

  Examples of the dicarboxylic acid constituting the polyester polyol include adipic acid, succinic acid, sebacic acid, azelaic acid, fumaric acid, maleic acid, terephthalic acid, isophthalic acid and the like, and mixtures of two or more thereof. Of these, particularly preferred are adipic acid and sebacic acid. Also included are the anhydrides of the dicarboxylic acids and esterified products of lower alcohols having 1 to 5 carbon atoms.

  The (A) polyester polyol in the present invention is obtained by a method similar to a conventionally known polyester production method. For example, a polyester polyol can be obtained by dehydrating and condensing the diol component and the dicarboxylic acid or acid anhydride.

  The polyester polyol (A) used in the present invention has a number average molecular weight of 1000 to 6000. If the number average molecular weight is less than 1000, the urethane bond concentration in the molecule is high, and the boil and retort suitability of the ink tends to be poor, and methyl ethyl ketone. And solubility in solvents such as ethyl acetate and isopropyl alcohol tends to be lowered. On the other hand, when the number average molecular weight exceeds 6000, the urethane bond concentration in the molecule is lowered, and the adhesiveness, the laminate strength, and the blocking resistance are liable to be lowered. The number average molecular weight of the polyester polyol is preferably 1500 to 5000, and more preferably 2000 to 4000. The number average molecular weight can be measured by gel permeation chromatography (GPC) (in terms of standard polystyrene).

  (B) PEG used in the present invention preferably has a number average molecular weight of 200 to 4000, more preferably 400 to 3000, and still more preferably 500 to 2000. When the number average molecular weight is 200 to 4000, effects such as improvement in laminate strength can be obtained.

  It is the range of 1-40 mass parts with respect to 100 mass parts of PEG containing polyurethane resins, Preferably it is 2-30 mass parts, More preferably, it is 3-20 mass parts. (B) When the content ratio of PEG is in the range of 1 to 40 parts by mass, effects such as improvement in boil / retort suitability and printability can be obtained.

  The diisocyanate compound (C) used in the present invention includes alicyclic diisocyanates such as isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, 1,4-cyclohexane diisocyanate, methylcyclohexylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate. Fragrances such as aliphatic diisocyanates such as dodecamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, tolylene diisocyanate, xylylene diisocyanate, α, α, α ′, α′-tetramethylxylylene diisocyanate Examples thereof include aliphatic diisocyanates and modified products of these diisocyanate compounds. These polyisocyanate compounds may be used alone or in combination of two or more. Of these, alicyclic diisocyanates are preferred, and isophorone diisocyanate (IPDI) is particularly preferred.

  The PEG-containing polyurethane resin used in the present invention is preferably further reacted with a low molecular diol. As the low molecular diol, dimethylolpropionic acid (DMPA) is particularly preferable. The content of dimethylolpropionic acid (DMPA) is preferably in the range of 0.01 to 5 parts by mass, more preferably 0.05 to 4 parts by mass with respect to 100 parts by mass of the PEG-containing polyurethane resin. More preferably, it is 0.1 to 3 parts by mass. By using dimethylolpropionic acid as a component, effects such as improvement in laminate strength and suitability for boil and retort can be obtained.

  As the (D) chain extender used in the present invention, various known ones can be used. For example, ethylenediamine, propylenediamine, hexamethylenediamine, triethylenetetramine, diethylenetriamine, isophoronediamine, dicyclohexylmethane-4,4′-diamine, dimer diamine and the like can be mentioned. Other molecules such as 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, etc. Diamines having a hydroxyl group therein, neopentyl glycol, butylethylpropanediol, ethylene glycol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, triethylene glycol, 1- or 2-methyl -1,3-butylene glycol, 1- or 2-methyl-1,4-pentylene glycol, 2,4-diethyl-1,5-pentanediol, tripropylene glycol, Diols such as ethylene glycol, 1,2-propylene glycol, 1,3-butanediol, 1-, 2- or 3-methyl-1,5-pentanediol, 2-methyl-1,3-propanediol And alkylene oxide adducts such as ethylene oxide, propylene oxide and ethylene propylene oxide of bisphenol A, and other diols. Of these, isophoronediamine is particularly preferred.

  Other chain extenders include diols having a tertiary amine structure such as methyldiethanolamine, methyldiisopropanolamine, phenyldiisopropanolamine, 4-methylphenyldiisopropanolamine, 4-methylphenyldiethanolamine, and 2 A mixture of more than one type can be mentioned.

  Furthermore, in the present invention, a chain elongation terminator can be used as necessary. Examples of chain elongation terminators include monoalcohols (methanol, propanol, butanol, 2-ethylhexanol, etc.), monoamines (mono- or dialkylamines having 2 to 8 carbon atoms (butylamine, dibutylamine, etc.), mono-monomers having 2 to 6 carbon atoms. Or dialkanolamine (monoethanolamine, diethanolamine, propanolamine, isopropanolamine, etc.)] and the like.

  The PEG-containing polyurethane resin used in the present invention is a conventionally known method such as JP-A-62-153366, JP-A-62-153367, JP-A-1-236289, JP-A-2-64173. No. 2, JP-A-2-64174, JP-A-2-64175 and the like.

  Specifically, polypropylene glycol and a combination polyol and a diisocyanate compound are reacted in an excess ratio of isocyanate groups to obtain a prepolymer of a terminal isocyanate group, and the resulting prepolymer is placed in a suitable solvent, that is, non-toluene. Ester solvents such as ethyl acetate, propyl acetate, butyl acetate, etc .; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone; methanol, ethanol, isopropyl alcohol, n-butanol, etc. Alcohol solvents; hydrocarbon solvents such as methylcyclohexane and ethylcyclohexane; or a mixed solvent such as a two-stage method of reacting with a chain extender and / or endblocker, or polypropylene glycol Lumpur and combination polyol, diisocyanate compound, a chain extender and (or) endblocker is produced by one-step process of reacting at a time in a suitable solvent of the above.

  The binder for printing ink of the present invention comprises a PEG-containing polyurethane resin and a vinyl chloride vinyl acetate copolymer resin as components, and the blending ratio is vinyl chloride vinyl acetate copolymer resin / PEG-containing polyurethane resin by mass ratio = 1/2. It is preferably ~ 9. By setting it within this range, effects such as improved printability can be obtained.

  The vinyl chloride vinyl acetate copolymer resin having a hydroxyl group used in the present invention can be obtained by two kinds of methods. One is obtained by copolymerizing vinyl chloride monomer, vinyl acetate monomer and vinyl alcohol in appropriate proportions. The other is obtained by copolymerizing vinyl chloride and vinyl acetate and then partially saponifying vinyl acetate. In the vinyl chloride vinyl acetate copolymer resin having a hydroxyl group, the properties of the resin film and the resin dissolution behavior are determined by the monomer ratio of vinyl chloride, vinyl acetate and vinyl alcohol. That is, vinyl chloride imparts toughness and hardness of the resin coating, vinyl acetate imparts adhesion and flexibility, and vinyl alcohol imparts good solubility in polar solvents.

  To the binder for printing ink of the present invention obtained as described above, a colorant, an organic solvent, and, if necessary, a surfactant, wax, and other additives for improving the ink fluidity and the ink surface film. A laminating ink composition for soft packaging (printing ink) can be produced by appropriately blending and kneading using a normal ink production apparatus such as a ball mill, an attritor or a sand mill. In addition, the compounding quantity of the binder of this invention in the laminating ink composition for soft packaging (printing ink) is 3-20 mass% in the resin solid content in the laminating ink composition for soft packaging (printing ink). It is preferable to blend in.

  As an organic solvent used for a laminating ink composition for soft packaging (printing ink), it is preferable not to include an aromatic organic solvent or a ketone organic solvent from the point of use environment, for example, methanol, ethanol, isopropanol, Examples include alcohol solvents such as n-propanol and methoxypropanol, and ester solvents such as ethyl acetate, n-propyl acetate, isopropyl acetate and butyl acetate, and these are used alone or as a mixture of two or more.

  The laminate ink composition for soft packaging of the present invention is suitable as a printing ink for a plastic film as a packaging material, and printing on such a plastic film may be performed by gravure printing or flexographic printing, which are generally performed. . And, for example, an extrusion laminating method in which various plastic films are used as printing bases, ink (laminated ink composition for soft packaging) is printed, and molten polyolefin is laminated on the printed surface via an anchor coat agent, or A dry laminate process is performed in which a plastic film is laminated on the printing surface via an adhesive to produce a printed matter.

  EXAMPLES Hereinafter, although the suitable Example of this invention is described, this invention is not limited to these Examples. Hereinafter, “part” represents “part by mass”, and “%” represents “% by mass”.

Synthesis Example 1 (Synthesis of polyurethane resin a)
In a round bottom flask equipped with a stirrer, a thermometer and a nitrogen gas introduction tube, 295 parts of polyester polyol (adipate of 3-methyl-1,5-pentanediol) having a number average molecular weight of 3000 as component (A), (B) As a component, 5 parts of polyethylene glycol having a number average molecular weight of 400 and 49.3 parts of isophorone diisocyanate (IPDI) as a component (C) were charged and reacted at 105 ° C. for 6 hours under a nitrogen stream to obtain an isocyanate group content of 2.67%. After producing the prepolymer, 233 parts of ethyl acetate was added to make a uniform solution of the urethane prepolymer. Subsequently, 582 parts of the urethane prepolymer solution was added to a mixture comprising 20 parts of isophoronediamine (IPDA), 1.7 parts of di-n-butylamine (DBA), 373 parts of ethyl acetate and 260 parts of isopropyl alcohol as component (D). Then, the reaction was carried out at 60 ° C. for 3 hours. The polyurethane resin thus obtained (hereinafter referred to as polyurethane resin a) had a resin solid content concentration of 30% by mass, a viscosity of 500 mPa · s (25 ° C.), and an amine value of 0.8 mgKOH / g.

(Synthesis Examples 2 to 13)
Using the raw materials shown in Tables 1 and 2, polyurethane resin solutions b to m were obtained in the same manner as in Synthesis Example 1.

(Examples 1-10 and Comparative Examples 1-3)
Regarding color pigment dispersibility, 28 parts of polyurethane resin of Synthesis Examples 1 to 13, 10 parts of vinyl chloride vinyl acetate copolymer resin (15% solution in ethyl acetate), 10 parts of cyanine blue, mixed solvent ethyl acetate / isopropyl A laminated ink composition for soft wrapping composed of 52 parts of alcohol = 7/3 (mass ratio) was dispersed for 3 hours using a pigment disperser (paint shaker), and then mixed with Zahn Cup No. 1 using a mixed solvent. 3 was adjusted to 15 seconds, and the laminated ink composition for soft packaging was evaluated for the following (1) color pigment dispersibility.

  Moreover, 35 parts of polyurethane resins of Synthesis Examples 1 to 13, 10 parts of vinyl chloride vinyl acetate copolymer resin (15% solution in ethyl acetate), 35 parts of titanium white, mixed solvent ethyl acetate / isopropyl alcohol = 7/3 (Mass ratio) A laminate ink composition for soft packaging having a composition of 20 parts was dispersed for 1 hour using a pigment disperser (paint shaker), and Zahn Cup No. The viscosity was adjusted using the above-mentioned solvent so as to be 15 seconds at 3 and the following (2) to (7) were evaluated and evaluated for the laminated ink composition for soft packaging. The above results are summarized in Tables 3-4.

(1) Color pigment dispersibility A polyethylene terephthalate film (abbreviated as PET film) is printed using the ink (cyanine blue) described above to produce a printed film, and the state of the coating film of the printed matter is determined by visual observation. did. The evaluation criteria are as follows.
“Good”: No uneven color on the coating film and good pigment dispersion.
“Δ”: Some color unevenness in the coating film and pigment dispersion is slightly inferior.
“X”: Color unevenness occurs in the coating film, and pigment dispersion is inferior.

(2) Printability The state of a print pattern printed with a small gravure printing tester using the ink (titanium white) described above, that is, the state of a plate doctor being cut, and a print pattern related to cell clogging Missing was determined by visual observation. The evaluation criteria are as follows.
“○”: Good printability.
“△”: Insufficient printability.
“×”: Very poor printability.

(3) Dry (DL) laminating strength A dry laminating machine using urethane adhesive on the ink surface of the printed matter obtained by printing the above ink (titanium white) on a PET film or nylon film (abbreviated as NY film) A CPP (unstretched polypropylene) film was laminated, and after aging at 40 ° C. for 2 days, the sample was cut to a width of 15 mm on the third day after lamination, and the 180 ° peel strength was measured.

(4) Boil suitability test After applying an isocyanate adhesive on the ink surface of a printed material obtained by printing the ink (titanium white) described above on a PET film or nylon film (abbreviated as NY film), 60 μm by a dry laminating machine. The unstretched polyethylene film was laminated to obtain a laminated product. The laminated product was made into a bag, a water / oil mixture was sealed inside, sealed, heated in 95 ° C. hot water for 30 minutes, and the floating state of the laminated product was observed to evaluate the boil suitability.
“O”: The laminated product does not float at all.
“△”: A part of the laminate processed product that is partially lifted.
“×”: A float occurred on the entire surface of the laminated product.

(5) Retort suitability test After applying an isocyanate adhesive to the ink surface of the printed matter obtained by printing the ink (titanium white) described above on a PET film or NY film, a 60 μm unstretched polypropylene film was applied by a dry laminating machine. Lamination was performed to obtain a laminated product. This laminated product is made into a bag, sealed with a water / oil mixture inside, heated in pressurized hot water at 120 ° C for 30 minutes, and evaluated for retort suitability by observing the floating state of the laminated product. did.
“O”: The laminated product does not float at all.
“△”: A part of the laminate processed product that is partially lifted.
“×”: A float occurred on the entire surface of the laminated product.

(6) Adhesion Printing was performed on the PET film using the ink (titanium white) described above. The print film was allowed to stand for 24 hours, and then a cellophane tape was affixed to the print surface, and the coating state of the print surface when it was rapidly peeled off was observed and evaluated.
“◯”: 80% or more of the printed film remains on the film.
“Δ”: 50 to 80% of the printed film remains on the film.
“×”: 50% or less of the printed film remains on the film.

(7) Blocking resistance Printing was performed on the PET film using the ink (titanium white) described above to produce a printed film. The printed surface of the printed film was overlapped, and the adhesion state of the printed surface after standing at 40 ° C. with a load of 4 × 10 ⁵ Pa for 15 hours was observed.
“◯”: There is adhesion of 0% to less than 20% of the contact area.
“Δ”: There is adhesion of 20% to less than 50% of the contact area.
“×”: There is adhesion of 50% or more of the contact area.

  As shown in Tables 3 to 4, Comparative Examples 1 to 3 in which the content ratio of (B) PEG is not in the range of 1 to 40 parts by mass with respect to 100 parts by mass of the PEG-containing polyurethane resin are color pigment dispersibility, Printability, boilability, retort suitability, adhesion, and blocking resistance are all poor. On the other hand, Examples 1 to 10 using a polyurethane resin as a binder in which the content ratio of (B) PEG is in the range of 1 to 40 parts by mass with respect to 100 parts by mass of the PEG-containing polyurethane resin are color pigment dispersibility. It can be seen that the printability, boilability, retortability, adhesiveness, and blocking resistance are all excellent. Therefore, the ink using the binder for printing ink of the present invention has good color pigment dispersibility and excellent solubility in a solvent without using an aromatic organic solvent or a ketone organic solvent. Suppressing and printing defects in the image area do not occur. Moreover, since the binder for printing inks of this invention is excellent in printability, and also excellent in boil and retort suitability, it is very useful as a binder for printing inks used for food packaging containers and the like.

Claims (6)

  A binder for printing ink comprising a polyethylene glycol (hereinafter referred to as “PEG”)-containing polyurethane resin and a vinyl chloride-vinyl acetate copolymer resin, wherein the PEG-containing polyurethane resin has at least (A) a number average molecular weight of 1000 to 6000. It is obtained by reacting a polyester polyol, (B) PEG, (C) a diisocyanate compound, and (D) a chain extender, and (B) the content ratio of PEG is 100 parts by mass of a PEG-containing polyurethane resin. The binder for printing ink which is the range of 1-40 mass parts with respect to.   (B) The binder for printing inks of Claim 1 whose number average molecular weights of PEG are 200-4000.   The printing ink binder according to claim 1, wherein the PEG-containing polyurethane resin is obtained by reacting dimethylolpropionic acid.   A laminate ink composition for soft packaging comprising the binder for printing ink according to any one of claims 1 to 3, a colorant and an organic solvent as components.   The laminate ink composition for soft packaging according to claim 4, wherein the organic solvent does not contain an aromatic organic solvent or a ketone organic solvent.   A printed matter obtained by printing the laminate ink composition for soft packaging according to claim 4 or 5.