JPS5915461A - Water-base printing ink composition - Google Patents

Abstract

PURPOSE:To provide the titled compsn. excellent in adhesion and printability, by employing as a vehicle component a resin solution prepared by adding ammonia or an amine to a particular acrylic copolymer dissolved in an aqueous medium. CONSTITUTION:1-10wt% carboxyl group-contg. vinyl monomer (e.g., acrylic acid), 3-40wt% vinyl monomer having in the molecule polyalkylene oxide group of the formula (wherein R is H, methyl; n is 2-50) [e.g., polyethylene glycol mono(meth)acrylate], 0-30wt% vinyl monomer having an OH group [e.g., 2- hydroxyethyl (meth)acrylate], and other vinyl monomer copolymerizable therewith are subjected to soln. polymn. in the presence of a polymn. initiator to yield an acrylic copolymer. Said copolymer is neutralized by adding ammonia or an amine, and dissolved in an aqueous medium to yield a resin soln. as a vehicle component. Colorants, fillers, etc. are incorporated in said resin soln.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water-based printing ink composition, which has excellent adhesion particularly to corona discharge treated polyolefin films,
The present invention also relates to an ink composition suitable for lamination processing.

Traditionally, polyolefin films have been widely used as food packaging materials due to their excellent hygiene, heat-sealability, and low cost.
It is used.

However, polyolefin films lack adhesion to printing inks due to their poor polarity. Therefore, the adhesion can be improved by kneading fillers into the polyolefin in advance or by applying corona discharge treatment to the film surface. In particular, corona discharge treatment is the most advantageous in terms of cost.

° As printing inks used for corona discharge treated polyolefin films, organic solvent-based inks such as nitrified cotton/polyamide-based, nitrated cotton/maleic acid resin-based, nitrated cotton/polyurethane-based, and chlorinated polypropylene-based inks are used. In addition, organic solvents such as hydrocarbons, esters, and ketones are added to dissolve the resin, resulting in problems with residual solvents, hygiene issues, and the release of organic solvents into the atmosphere. There are problems such as volatilization, and water-based printing inks are desired from the viewpoint of resource and energy conservation, and some are being put into practical use.

Conventional vehicles for water-based printing inks include shellac, rosin-modified maleic acid resin, styrene/acrylic acid resin, acrylic ester-acrylic acid resin, hydroxyethyl cellulose, and water-soluble polyester. Printing ink adheres to expensive modified polyolefin films, but relatively inexpensive corona discharge-treated polyolefin films have poor adhesion and lack printability, such as plate clogging and plate fogging in gravure printing, and problems with printed matter. There are problems such as lack of printing effects such as gloss and lack of stability during ink storage.

In addition, back-printed composite films such as polyguthypylene film (OPP)/printing ink/adhesive/polypropylene film (CPP) have traditionally been used as transparent flexible packaging materials for ramen noodles, sweets, etc. Most of the films are processed by dry lamination or extrusion lamination such as polyethylene film, coloring material/printing ink/anchor coating agent/polyethylene melt coating, and currently there are no water-based printing inks that can withstand this processing. It is.

The present invention was completed as a result of intensive research to solve the above-mentioned problems, and the first purpose is to obtain a water-based printing ink with excellent printing effects and printability. The objective is to obtain a water-based printing ink that has sufficient adhesive strength for corona discharge treated polyolefin films.
A third objective is to obtain a water-based printing ink that is resistant to lamination.゛That is, the present invention provides a carboxyl group-containing vinyl monomer (1) with 1-10 polymers! :%, the following formula% formula% in the molecule) (However, in the formula, R is a hydrogen atom or a methyl group, and n is 2
Indicates an integer between ~50. ) Vinyl monomer containing a polyalkylene oxide group represented by ■) 3 to 40% by weight, vinyl monomer (C) containing other hydroxyl groups 0 to 40% by weight
Ammonia or amine is added to an acrylic copolymer obtained by solution polymerizing a monomer mixture consisting of 30% by weight and the balance consists of other copolymerizable vinyl monomers (D), and the resin solution dissolved in an aqueous medium is used as a vehicle component. The present invention provides an aqueous printing ink composition.

Carboxyl group-containing vinyl monomer (A
) include acrylic acid, methacrylic acid, itaconic acid,
Crotonic acid, etc., 1 to IO wt%, preferably 3
It is used in a range of 7% by weight. If the amount used is too small, it will be difficult to water-solubilize, and if the amount is too large, the adhesive strength during extrusion lamination will decrease.

For sulvinyl monomers containing polyalkylene oxide groups in the molecule, polyethylene L/7 glycol mono(
meth)acrylate, polypropylene glycol mono(
meth)acrylate, N-(polyoxyalkylene)-
Examples include (meth)acrylamide or alkyl etherified products thereof, and those in which n in the general formula is 2 to 50, preferably 4 to 25, are used, and the amount used is 3 to 50.
40% by weight, preferably 5 to 25%, which causes a decrease in printing effect and lamination suitability, and if it is too large, no increase in effect can be expected and the cost is undesirable.

Examples of the vinyl monomer C) containing a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and the amount used is 0 to 30% by weight, preferably 1 to 20 parts by weight. range. If too much is used, the flexibility of the ink film will decrease,
Although the adhesive strength will be insufficient when laminated, it is preferable to use an amount equal to or higher than the IM amount since the adhesive strength increases due to the reaction with the adhesive (urethane type) during dry lamination.

Other copolymerizable vinyl monomers (D) include (meth)acrylic acid alkyl esters having an alkyl group having 1 to 8 carbon atoms, such as methyl (meth)acrylate;
Ethyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, 2
-Ethylhexyl (meth)acrylate, styrene, vinyltoluene, vinyl acetate, N-methylol (meth)acrylamide, and the like.

In the present invention, the solution polymerization of the monomer mixture described above may be carried out by a method known per se. For example, 180-propyl alcohol- kfxt (D Polymerize in an organic solvent.

The amines necessary for neutralizing the obtained acrylic copolymer include dimethylethanolamine, diethylethanolamine, and morpholine, and then, if necessary, part of the organic solvent during polymerization is distilled off. Dissolve the resin in an aqueous medium.

The vinyl monomer (containing a polyalkylene oxide group used in the present invention) has also been attempted to be used as an emulsifier during emulsion polymerization, but if such an emulsion is used as a vehicle for aqueous printing ink, it may cause plate clogging. becomes. On the other hand, the present invention differs in that the molecular weight is relatively small because it is solution polymerized, and it is used as a resin solution, so that there is no deterioration in printing suitability such as plate clogging.

The aqueous printing ink composition according to the present invention can be prepared by adding colorants such as pigments, fillers, and other necessary additives, as is known in the art.
Obtained by grinding.

This printing ink can be applied to paper, plastic, metal boxes, etc., but when applied to corona discharge treated polyolefin films and lamination processing, it exhibits superior effects compared to known water-based inks. .

be.

The present invention will be explained in more detail below using specific examples. The middle part of the example shows parts by weight.

Example 1 ~ Equipped with a stirrer, a thermometer, and a nitrogen gas introduction pipe FC 47
Loflask K, 1so-7” Lobil Alcohol 150
The mixture was heated to 83°C in a trench and maintained at this temperature.

Then, the monomer mixture and polymerization initiator 4 shown in Table 1 were added.
After adding the same amount dropwise over 2 hours, the reaction was continued for an additional 3 hours. After that, 136 parts of ammonia water and water shown in Table 1 were added, azeotropically distilled off a part of the 1So-propyl alcohol, and then water/1so-propyl alcohol 8/2 (8/2) was added.
A vehicle with a resin solid content (40% by weight) was obtained.

Next, using each of the obtained vehicles, each printing ink was kneaded in a conventional manner according to the following formulation, and Zahn cup ≠ 3
diluted with a mixed solvent of water and ethyl alcohol in equal amounts for 17 seconds (at 25°C) and gravure printed on a corona discharge treated polypropylene film (Torefan $2535, part name manufactured by Toshi ■) to determine inkability and adhesion. The strength, bending resistance, and printing effect were tested 24 hours after printing, and the results are shown in Table 2.

Vehicle 45 industrial ethyl alcohol 20 water
1Oiso-propyl alcohol 1O In addition, each printed matter was treated with a polyethyleneimine anchor coat leg agent and then extrusion coated with polyethylene, and each printed matter was coated with an adhesive (Toyo Morton Ki Atcoat,
After coating the polyethylene film (trade name), dry lamination was performed on the polyethylene film, and the strength was measured after aging at 40° C. for 2 days. The results are shown in Table 2.

Suitability for making ink is determined by fluidity, adhesion is determined by the peeling strength of cellophane adhesive tape, bending resistance is determined by the peeling state when the print is rubbed, and printing effect is determined by the gradation reproducibility of the printed material and the ink. Judgments were made based on the state of color development.

Table 2 patent applicant Toyo Ink Manufacturing Co., Ltd.

Claims (1)

[Scope of Claims] 1 Carboxyl group-containing vinyl hexamer (A) 1-1
0% by weight, 3-40% by weight of a vinyl monomer containing a polyalkylene oxide group represented by the following formula (wherein R is a hydrogen atom or a methyl group, and n is an integer from 2 to 50) in the molecule. Ammonia or A water-based ink composition containing, as a vehicle component, a resin solution to which an amine is added and dissolved in an aqueous medium.