JP2997587B2 - Aqueous printing ink composition for lamination - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based printing ink composition for laminating, and more particularly to a printing method for a paper product such as a paper bag or a kraft tape, followed by laminating.
An object of the present invention is to provide an aqueous printing ink composition for lamination having excellent lamination suitability.

[0002]

2. Description of the Related Art After printing water-based printing ink on paper products for packaging, for example, handbags, paper containers such as soaps, packaging papers, and kraft tapes, the durability, moisture-proofness, and adhesive properties of the adhesives are increased. In order to impart releasability, the printing surface is subjected to extrusion lamination using an olefin polymer such as polyethylene which is hot-melted. Since these paper products have irregularities on the paper surface and can be expected to have an anchoring effect, a method of directly laminating the polymer without applying anything to the printing surface has been used so that the work is simple and inexpensive. Have been. Therefore, as the performance of the ink used, the adhesiveness to the polymer is further required.

Conventionally, as a binder resin for aqueous printing inks, an aqueous alkali solution of a natural or modified resin of shellac, casein, or rosin maleic acid has been used. Acrylic resin, styrene / acrylic resin, styrene / maleic acid resin, styrene / acrylic /
Alkaline aqueous solutions of various copolymer resins such as maleic acid resins have come to be mainly used, and various water-dispersible resins such as acrylics and styrenes have also been used in combination with the above water-soluble copolymer resins. . All of these binder resins have poor adhesion to the polymer for lamination, but as the aqueous printing ink for lamination, an ink containing a large amount of shellac, which has the highest adhesiveness to the polymer, is used. Was.

[0004]

As the binder resin of the aqueous printing ink for lamination, shellac is used among resins commonly used in aqueous printing inks, but the adhesiveness with the polymer for lamination is low. It is not sufficient, and there is a problem that the polymer does not adhere to the surface of the printed matter even if the laminating process is performed, or if the polymer is once adhered, it is easily peeled off with a small stress. Further, since the adhesive applied to the kraft tape or the like is solvent-based, there is a problem that the solvent migrates through the paper layer to the ink surface after application, and causes lamination. The present invention is intended to solve such a problem.

[0005]

That is, the present invention relates to a water-dispersible polyolefin resin having an average particle diameter of 1.0 μm or less in an aqueous printing ink composition for lamination mainly comprising a colorant and an aqueous binder resin. The present invention relates to an aqueous printing ink composition for lamination, characterized in that the printing ink has a solid content of 10% by weight or more. Hereinafter, the aqueous printing ink composition for lamination according to the present invention will be described in detail. First, as the colorant, dyes, inorganic, organic, and extender pigments generally used in aqueous inks can be used.

[0006] As the aqueous binder resin, generally used alkali-soluble resin binders and water-dispersible binders can be used. As the alkali-soluble resin, a resin having an acid value in the range of 50 to 250 can be used. Specifically, shellac, natural or modified resins such as rosin-modified maleic acid, acrylic acid, methacrylic acid, unsaturated carboxylic acid monomers such as maleic acid and its ester or amide compound, styrene, α-methylstyrene, vinyl toluene and the like Copolymer resins obtained from monomers having an unsaturated bond, such as styrene compounds, fatty acid vinyl ester compounds such as vinyl acetate, and other various vinyl compounds can be used. These copolymer resins are
From the viewpoint of the fluidity and stability of the ink and the blocking resistance of the printed matter, the molecular weight is 5,000 to 100,0.
Within the range of 00, the softening point must be 40 ° C. or higher. Examples of the alkali for making these resins water-soluble include organic amines such as monoethanolamine, triethanolamine and morpholine, and inorganic alkalis such as aqueous ammonia and alkali metal hydroxide.

The water-dispersible resin used in combination with the alkali-soluble binder resin includes acrylic acid,
Unsaturated bonds such as unsaturated carboxylic acids such as methacrylic acid and maleic acid and esters or amide compounds thereof, styrene compounds such as styrene, α-methylstyrene and vinyltoluene, fatty acid vinyl ester compounds such as vinyl acetate, and various other vinyl compounds A monomer obtained by emulsion polymerization of a monomer having the following formula can be used. As the polyolefin resin according to the present invention, low density homopolymers or copolymers of ethylene and propylene are particularly preferable, and those having an average particle size of 1.0 μm or less can be used. When the average particle diameter is larger than 1.0 μm, good lamination strength cannot be obtained. As the amount of the polyolefin resin, 10% by weight or more based on the total amount of the aqueous ink can be appropriately added and mixed according to the use conditions and composition of the ink. If the amount is less than 10% by weight, the desired lamination strength cannot be obtained.

A method of adding a polyethylene resin wax for imparting friction resistance and slipperiness of the ink has been conventionally known. However, in order to perform the function as a wax, it is necessary that the wax particles partially protrude from the surface of the dried ink film. Therefore, compared to the present invention, the wax must have a very large particle size. The amount of wax added is at most 2% by weight in the ink. Since these waxes have a large particle size, even if they are dried in a mixed state with a binder resin, a layered and uniform film is not formed, and a large amount of the wax causes embrittlement of the ink film itself. Thus, the polyolefin resin of the present invention and polyethylene wax,
The average particle diameter and the amount of addition are completely different, and they differ in the functions and applications.

In addition to the above-mentioned colorants, aqueous binder resins and polyethylene resins, various additives can be used as required. That is, an antifoaming agent, a water-miscible solvent, a plasticizer, a crosslinking agent, and the like can be appropriately used. To produce the aqueous printing ink composition according to the present invention, a colorant in the aqueous binder resin,
It can be carried out according to a conventional method by mixing a polyethylene resin and, if necessary, an additive. As for the addition of the polyethylene resin, it may be added at the stage of producing the ink or mixed at a later stage at the stage of preparing the ink. After printing the aqueous printing ink composition for lamination on paper as a printing medium, a good printed product can be obtained by a usual laminating method. That is, a printed product having excellent lamination strength can be obtained only by directly applying a molten polymer without applying an anchor coat agent to the ink printing surface.

Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

【Example】

Production example of water-dispersible polyethylene resin Polyethylene resin (oxidized polyethylene wax)
60 parts by weight and 10 to 17 parts by weight of an emulsifier (polyoxyethylene nonylphenyl ether) are added to the resin at a temperature of 2
The mixture was mixed and dissolved at a temperature higher by 0 ° C. After dissolution, the carboxyl group in the resin was neutralized with a base, and 23-30 parts by weight of hot water (90-100 ° C) was added with stirring. 150
After stirring for 1 hour while adjusting the stirring strength while raising the temperature to ° C., the mixture was immediately quenched to obtain a water-dispersible polyethylene resin having a solid content of 60% by weight and an average particle size (see Table 1). Synthesis example of water-soluble resin varnish Acrylic resin (acid value 18) having a monomer composition of methacrylic acid 32% by weight, methyl methacrylate 23% by weight, butyl acrylate 25% by weight, and styrene 20% by weight.
(0, molecular weight: 40,000) 30.0% by weight, 7.1% by weight of 28% aqueous ammonia, and 62.9% by weight of water were dissolved by heating at 90 ° C. to synthesize a water-soluble resin varnish. Production example of aqueous base ink A blue aqueous base ink having the following composition was produced by a bead mill by a conventional method. Cyanine blue 30.0% by weight Water-soluble resin varnish 50.0% by weight Antifoam 0.4% by weight Water 17.6% by weight

Production Examples of Aqueous Ink Composition (Examples 1 to 8)
A water-dispersible polyethylene resin, a water-soluble resin varnish, an antifoaming agent and water were added and mixed so as to have a solid content shown in Table 1, and aqueous ink compositions of Examples 1 to 8 were produced by a conventional method. (Comparative Examples 1 to 7) 30% by weight of the aqueous base ink,
Water-dispersible polyethylene resin, water-soluble shellac resin varnish, polyethylene wax dispersion, water-soluble resin varnish,
An antifoaming agent and water were added and mixed so as to have a solid content shown in Table 1, and aqueous ink compositions of Comparative Examples 1 to 7 were produced by a conventional method. Here, as the water-dispersible polyethylene resin having each average particle diameter (see Table 1), those obtained according to Production Examples were used. The water-soluble shellac resin varnish is obtained by neutralizing shellac resin in ammonia water to solubilize it, and solidifying the solid content of 3%.
The one adjusted to 0% by weight was used. The polyethylene wax dispersion used had an average particle diameter of 3 μm and a solid content of 40% by weight.

(Comparative Test) Examples 1 to 8 and Comparative Example 1
Using the aqueous ink compositions obtained in Nos. 1 to 7, fluidity, on-machine viscosity stability, laminate strength, and solvent immersion test were performed. The test method and evaluation method were as shown below. The test results are shown in Table 2. Test method and evaluation method Fluidity test method Using a B-type viscometer, use a No. 2 rotor at 60 rpm and 30 rpm.
Measure the ink viscosity at the time of rpm, 30rpm / 60r
The fluidity is determined from the viscosity ratio of pm. Evaluation method A: Viscosity ratio less than 1.20 B: Viscosity ratio 1.20 or more to less than 1.70 C: Viscosity ratio 1.70 or more

2. On-press viscosity stability test method The test ink was diluted with water until the outflow time was 12 seconds (Rigoux cup # 4), and was set on a Shinko flexo printing machine.
After an idle operation for 3 hours at ambient temperature and normal humidity at a speed of 1 minute, the ink viscosity was measured. Evaluation method A: Outflow seconds less than 18 seconds B: Outflow seconds 18 seconds or more to less than 30 seconds C: Outflow seconds 30 seconds or more Laminating strength test method After the test ink was spread on a kraft paper (kraft clupak paper) with a hand proofer, a 20 μm film thickness of 340 ° C. molten polyethylene (Sumikacene L705 Sumitomo Chemical) was applied using a modern machine laminating machine. Laminated on the painted surface. The width of the obtained laminate is 2
The sheet was cut to 0 mm, and the peel strength at the time of peeling at a peel rate of 300 mm / min was measured. Evaluation method A: Peel strength 250 g / 20 mm or more B: Peel strength 150 g / 20 mm or more to 250 g / 2
Less than 0 mm C: Peel strength less than 150 g / 20 mm

4. Solvent immersion test Test method The laminate obtained at the time of the laminate strength test is used, and the state of lamination floating when immersed in toluene is confirmed. Evaluation method A: Lami floating is not observed even after 90 minutes after immersion. B: Lami floating is observed within 90 minutes after 30 minutes after immersion. C: Lami floating is observed within 30 minutes after immersion.

[Table 1]

[Table 2]

[0015]

According to the present invention, an aqueous laminating printing ink composition containing a polyolefin resin can obtain a laminate having high lamination strength and excellent solvent resistance while maintaining good fluidity and printability. be able to.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C09D 11/00-11/20

Claims (4)

(57) [Claims] 1. An aqueous printing ink composition for lamination mainly comprising a colorant and an aqueous binder resin, wherein a water-dispersible polyolefin resin having an average particle size of 1.0 μm or less is contained in the printing ink composition in a solid content of 10%. A water-based printing ink composition for laminates, characterized in that the composition contains at least 10% by weight. 2. The aqueous printing ink composition for lamination according to claim 1, wherein the polyolefin resin is a polyethylene resin. 3. A laminating method for applying a hot-melted polyolefin resin to the surface of a printed material obtained by using the aqueous printing ink composition for lamination according to claim 1. 4. A printed product obtained by laminating by the processing method according to claim 3.