JP4687071B2 - High density yellow ink for laminating with excellent migration resistance - Google Patents

Description

  The present invention relates to a yellow ink for laminating, a laminate laminate obtained by bonding a film coated with the ink and a sealant, and a laminate packaging material produced by processing the laminate laminate.

Gravure inks and flexographic inks are widely used for the purpose of imparting cosmetic properties and functionality to a printing medium. In the case where a gravure and flexographic printed substrate is used as a packaging material, particularly a food packaging material, it is generally subjected to a laminating process. In this case, various printed materials and laminating processes are used depending on the type of contents and the purpose of use.
Printing inks used for laminate packaging materials are required to have adhesiveness to films, blocking resistance, migration resistance, light resistance, and heat resistance, but migration resistance, light resistance, and heat resistance depend on the characteristics of the contained colorant. Because of this, the colorant that can be used is limited depending on the application.

CI pigment yellow 14 is widely used as a colorant for laminating yellow ink because of its excellent density and cost. CI Pigment Yellow 14 for gravure ink uses a pigment containing a polar coupler component to improve dispersibility, so water resistance is slightly inferior, and migration resistance is sufficient for retort applications. Is not available and its use is limited to snack and boil applications only. For this reason, CI pigment yellows 155, 180, and 83, which have excellent migration resistance, are used for retort applications. However, these pigments have lower coloring power than CI pigment yellow 14, so that the color reproducibility of printed matter can be reduced. There is a problem that the concentration is not sufficient. In order to improve the density, increasing the pigment content in the ink results in high viscosity and poor fluidity. Decreasing the resin content in the ink to lower the viscosity decreases the coating properties of the ink, such as laminate strength. There's a problem. Further, since an increase in pigment content also causes an increase in cost, it is not an effective means for solving the lack of ink density.
Japanese Patent Laid-Open No. 06-345988

  An object of the present invention is to provide a high-concentration yellow ink for laminating excellent in migration resistance.

That is, the present invention is at least one selected from CI Pigment Yellow 155 and 180, a laminate for yellow ink containing CI Pigment Yellow 83 and polyurethane resins,
At least one selected from CI Pigment Yellow 155 and 180;
CI Pigment Yellow 83 and
The weight ratio is in the range of 100: 40 to 100: 3
It is related with the yellow ink for lamination which is .

  Furthermore, the present invention relates to a laminate laminate obtained by applying the above yellow ink for laminating to a film and bonding it to a sealant via an adhesive, and a laminate packaging material produced by processing the laminate laminate.

  According to the present invention, it is possible to provide an excellent yellow ink for laminating having both migration resistance and concentration.

  The present invention will be described in detail. “Ink” used in the following description means “printing ink”. “Part” means “part by weight”.

  The present invention is a yellow ink for laminating comprising a polyurethane resin as a main binder, which contains, as a colorant, a mixture of two or more kinds of yellow pigments having excellent migration resistance and different color tones. The idea of the present invention is excellent in migration resistance by itself, but among yellow pigments with insufficient concentration, by mixing at least two kinds of yellow pigments with a green color tone and reddish yellow pigments, The problem is to greatly improve the concentration.

  Specific yellow pigments used in the yellow ink for laminating of the present invention include C.I. Pigment Yellow 155 and 180 as greenish yellow pigments having excellent migration resistance. Pigment Yellow 155 is a Shizuazo yellow pigment, and Pigment Yellow 180 is a benzimidazolone yellow pigment, all of which are generally excellent in light resistance, solvent resistance, water resistance, acid resistance, and alkali resistance. Pigment. C.I. Pigment Yellow 83 is an example of a reddish yellow pigment having excellent migration resistance. Pigment Yellow 83 is a disazo pigment, and is generally a pigment excellent in solvent resistance, water resistance, acid resistance, and alkali resistance.

Specific structure of the laminate for yellow ink of the present invention contains at least one kind and CI Pigment Yellow 8 3 is selected from CI Pigment Yellow 155 and 180.

Furthermore, at least one kind selected from the group consisting of CI Pigment Yellow 155 and 180, and CI Pigment Yellow 83 100: 40 to 100: preferably in a weight ratio of 3. If the ratio of CI pigment yellow 83 is higher than this range, the redness becomes too strong, and if it is lower, the effect of improving the density is small.

  The total pigment content in the yellow ink for laminating of the present invention is preferably 4 to 15% by weight, more preferably about 6 to 13% by weight. When the total pigment content is less than 4% by weight, the concentration is low, and when it exceeds 15% by weight, the viscosity of the ink increases.

  The polyurethane resin in the yellow ink for laminating of the present invention may be a conventionally known method, for example, 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, a 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 used in a suitable solvent, that is, for non-toluene gravure ink. Ester solvents such as ethyl acetate, propyl acetate, and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; alcohol solvents such as methanol, ethanol, isopropyl alcohol, and n-butanol; Hydrocarbon solvents such as methylcyclohexane and ethylcyclohexane; or a mixed solvent of these two-stage processes in which they are reacted with a chain extender and / or end-capping agent, or polypropylene glycol and a combination polyol, diiso Aneto 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. Among these methods, it is preferable to use a two-stage method in order to obtain a uniform polyurethane resin. Moreover, when producing a polyurethane resin by a two-stage method, it is preferable to make it react so that the sum (equivalent ratio) of the amino group of a chain extender and / or terminal blocker may become a ratio of 1 / 0.9-1.3. If the equivalent ratio of isocyanate group to amino group is less than 1 / 1.3, the chain extender and / or end-capping agent will remain unreacted, the polyurethane resin will turn yellow, and odor will occur after printing. Sometimes.

  The weight average molecular weight of the polyurethane resin thus obtained is preferably in the range of 15,000 to 100,000. When the weight average molecular weight of the polyurethane resin is less than 15,000, there is a tendency that the blocking resistance of the ink composition obtained, the strength of the printed film, the oil resistance, and the like tend to be low. The viscosity of the resulting ink composition tends to increase, and the gloss of the printed film tends to decrease.

  The content of the polyurethane resin in the yellow ink for laminating of the present invention is 4% by weight or more with respect to the total weight of the ink, from the viewpoint of sufficient adhesion of the ink to the printing medium, at an appropriate ink viscosity or during ink production. -25 weight% or less is preferable from a viewpoint of the work efficiency at the time of printing, and also the range of 6-15 weight% is preferable.

The present invention, at least one selected from the group consisting of CI Pigment Yellow 155 and 180, C .I. Is a laminate for yellow ink to contain Pigment Yellow 83 and the polyurethane resin as an essential component, and further required as an ink Therefore, a combination resin, an organic solvent, and the like can be included. In addition, extender pigments, pigment dispersants, leveling agents, antifoaming agents, waxes, plasticizers, infrared absorbers, ultraviolet absorbers, fragrances, flame retardants, and the like can be included as necessary.

  Further, in order to disperse the pigment stably in the ink, it is possible to disperse the polyurethane resin alone, but it is also possible to use a dispersant in order to disperse the pigment more stably. As the dispersant, anionic, nonionic, cationic, amphoteric surfactants can be used. For example, a comb-structure polymer compound obtained by adding polyester to polyethyleneimine, or an alkylamine derivative of an α-olefin maleic acid polymer may be used. Specific examples include Solsperz series (ZENECA), Ajisper series (Ajinomoto), and homogenol series (Kao). Further, BYK series (Bicchemi), EFKA series (EFKA), and the like can be used as appropriate. The dispersant is preferably contained in the ink in an amount of 0.05% by weight or more based on the total weight of the ink from the viewpoint of the storage stability of the ink and 5% by weight or less from the viewpoint of the suitability for lamination. .1 to 2% by weight.

  Examples other than the polyurethane resin used in combination with the ink of the present invention as needed include vinyl chloride-vinyl acetate copolymer resin, chlorinated polypropylene resin, ethylene-vinyl acetate copolymer resin, vinyl acetate resin, polyamide resin, Acrylic resin, polyester resin, alkyd resin, polyvinyl chloride resin, rosin resin, rosin modified maleic acid resin, ketone resin, cyclized rubber, chlorinated rubber, butyral, petroleum resin and the like can be mentioned. The combined resins can be used alone or in admixture of two or more. The content of the combined resin is preferably 1 to 25% by weight, more preferably 2 to 15% by weight, based on the total weight of the ink.

  The ink of the present invention can be produced by dissolving and / or dispersing a resin, a colorant and the like in an organic solvent. Specifically, it is possible to produce a pigment dispersion in which a pigment is dispersed in an organic solvent with a polyurethane resin, and to produce an ink by blending the obtained pigment dispersion with other compounds as necessary. it can.

The particle size distribution of the pigment in the pigment dispersion is adjusted by appropriately adjusting the size of the grinding media of the disperser, the filling rate of the grinding media, the dispersion treatment time, the discharge speed of the pigment dispersion, the viscosity of the pigment dispersion, and the like. be able to. As a disperser, generally used, for example, a roller mill, a ball mill, a pebble mill, an attritor, a sand mill and the like can be used.
In the case where bubbles or unexpectedly large particles are included in the ink, it is preferably removed by filtration or the like in order to reduce the quality of the printed matter. A conventionally well-known filter can be used.

The ink viscosity produced by the above method is in the range of 10 mPa · s or more from the viewpoint of preventing the pigment from settling and being appropriately dispersed, and 1000 mPa · s or less from the viewpoint of workability efficiency during ink production or printing. preferable. In addition, the said viscosity is a viscosity measured at 25 degreeC with the Tokimec B-type viscometer.
The viscosity of the ink can be adjusted by appropriately selecting the type and amount of raw materials used, for example, a polyurethane resin, a colorant, an organic solvent, and the like. The viscosity of the ink can also be adjusted by adjusting the particle size and particle size distribution of the pigment in the ink.

[Example]
The present invention will be described in detail by the following examples, but the present invention is not limited to these examples.
The ratio “%” means all weight percentages.

[Example 1] CI pigment yellow 155: 10%, CI pigment yellow 83: 1%, urethane resin solution (solid content 30%): 45%, MEK: 44%
[Example 2] CI pigment yellow 180: 10%, CI pigment yellow 83: 1%, urethane resin solution (solid content 30%): 45%, MEK: 44%
[Example 3] CI Pigment Yellow 155: 5%, CI Pigment Yellow 180: 5%, CI Pigment Yellow 83: 1%, Urethane Resin Solution (solid content 30%): 45%, MEK: 44%
[ Reference Example 4] CI pigment yellow 155: 10.8%, CI pigment yellow 83: 0.2%, urethane resin solution (solid content 30%): 45%, MEK: 44%
[ Reference Example 5] CI pigment yellow 155: 7.5%, CI pigment yellow 83: 3.5%, urethane resin solution (solid content 30%): 45%, MEK: 44%
[Comparative Example 1] CI Pigment Yellow 14: 11%, urethane resin solution (solid content 30%): 45%, MEK: 44%
[Comparative Example 2] CI Pigment Yellow 155: 11%, urethane resin solution (solid content 30%): 45%, MEK: 44%
[Comparative Example 3] CI Pigment Yellow 180: 11%, urethane resin solution (solid content 30%): 45%, MEK: 44%

[Ink evaluation] The viscosity of the obtained yellow ink was diluted with a mixed solvent of methyl ethyl ketone, ethyl acetate and isopropyl alcohol (weight ratio: 40:40:20), and then 16 seconds (25 ° C.) with Zahn cup # 3 (manufactured by Rai Co., Ltd.). ), Printed on a corona-treated nylon film (trade name Emblem ON, thickness 15 μm, manufactured by Unitika Ltd.) using a gravure proofing machine equipped with a 35 μm gravure plate and dried at 40-50 ° C. The printed matter of yellow ink was subjected to reflection density measurement and migration resistance test. The results are shown in Table 1. The evaluation was performed by the following test method.

[Measurement of Reflection Density] The printed surface of the yellow ink print and the standard white plate were overlapped, and the reflection density was measured with a 408 reflection densitometer (X-RITE) from the non-printed surface side. A reflection density of 1.5 or higher was set to a practical level, and the judgment criteria were as follows.
O: Sufficient concentration Δ: Practical concentration.
X: The concentration is insufficient.

[Miggle Shawn Resistance Test] Using urethane adhesive (TM595 / CAT-RT56: Toyo Morton Co., Ltd.) on yellow ink printed matter, a laminate made by laminating a CPP (unstretched polypropylene) film with a dry laminating machine was made into a bag. Then, water was added as a content, and after sealing and heating at 120 ° C. for 30 minutes, the migration of the pigment to the PET film and the CPP film was visually determined. The determination criteria were as follows.
○: Coloring on the film is not seen. Δ: Coloring on the film is seen somewhat. ×: Coloring on the film is seen. Only ○ is judged to be practical.

The results of evaluating the examples, reference examples and comparative examples are shown in Table 1.

Claims (3)

At least one selected from CI Pigment Yellow 155 and 180, a yellow ink for laminate containing CI Pigment Yellow 83 and polyurethane resins,
At least one selected from CI Pigment Yellow 155 and 180;
CI Pigment Yellow 83 and
The weight ratio is in the range of 100: 40 to 100: 3
The yellow ink for laminating. The laminate for yellow ink of claim 1 Symbol placement on the film was coated, laminated stack formed by bonding the sealant through an adhesive. A laminate packaging material produced by processing the laminate laminate according to claim 2 .