JPS6123825B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a varnish for printing ink, particularly to a varnish for solution-type gravure printing ink having excellent pigment dispersibility. The essential conditions for a resin used in a varnish for graphia printing ink are that it has good solubility in a solvent, good dispersibility of pigments, and stability of the printing ink. Further, the dry film is required to have good adhesion to the substrate to be printed, especially plastic film, chemical resistance and blocking resistance. Traditionally, varnishes for graphia printing inks have been made by dissolving polyamides, nitrocellulose, vinyl chloride/vinyl acetate copolymers, acrylic polymers, rubber-based modified products, etc. in various solvents. However, the above required performance is not completely satisfied. Among these, acrylic polymers have excellent chemical resistance and light resistance when dried, and are easy to impart blocking resistance, and have excellent adhesion to plastic films, especially polyvinyl chloride, but they also It has poor dispersibility compared to other resins, and improvements in this point have been desired. As a result of intensive research by the present inventors in order to improve the drawbacks of the above-mentioned acrylic polymers, we found that (a) monomers capable of radical polymerization having an amino group, an amide group, or a quaternary ammonium base in the molecule of 0.5~ 10 parts by weight, (b) 0.5 to 0.5 parts by weight of a monomer capable of radical polymerization having a sulfonic acid group or sulfonic acid group in the molecule
10 parts by weight, and (c) 99 to 80 parts by weight of another monomer capable of radical copolymerization, an ink varnish containing the resulting copolymer as a resin component has good pigment dispersibility, It has also been found that acrylic polymers have excellent light resistance and chemical resistance. In the present invention, (a) radically polymerizable monomers having an amino group, an amide group, or a quaternary ammonium base in the molecule include, for example, aminoethyl acrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, Acrylic monomers having amino groups such as tertiary-butylaminoethyl acrylate, aminoethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, tertiary-butylaminoethyl methacrylate, and their hydrochloric acid, sulfuric acid, acetic acid, etc. salt, acrylamide, N-methylolacrylamide, N・N-dimethylacrylamide, N-methoxymethylacrylamide, N-ethoxymethylacrylamide, N-n
-butoxymethylacrylamide, methacrylamide, N-methylolmethacrylamide, diacetone acrylamide, hydroxymethyldiacentone acrylamide, acryloylmorpholine, N-methoxymethylmethacrylamide, N-
Monomers with amide groups such as n-butoxymethylmethacrylamide and N-vinylpyrrolidone; aromatic vinyl monomers such as vinylpyridine, methylvinylpyridine, ethylvinylpyridine, vinylimidazole, methylvinylimidazole, ethylvinylimidazole, and vinylpyrimidine; and their salts such as hydrochloric acid and sulfuric acid, as well as 2-hydroxy-3-methacryloxypropyltrimethylammonium chloride, methyl chloride quaternized product of dimethylaminoethyl methacrylate, methyl bromide quaternized product of diethylaminoethyl methacrylate, etc. Quaternary ammonium salts can also be used. In the present invention, (b) monomers capable of radical polymerization having a sulfonic acid group or sulfonic acid group in the molecule include sulfonic acids such as sulfoethyl acrylate, sulfopropyl acrylate, sulfoethyl methacrylate, and sulfopropyl methacrylate. Acrylic monomers having groups and their amines or metal salts, vinylsulfonic acid and its amines or metal salts, p-styrenesulfonic acid and its amines or metal salts, allylsulfonates, methallylsulfonates, etc. be. Also 2-acrylamide-
2-Methylpropanesulfonic acid and its amine or metal salt are monomers that share an amide group and a sulfonic acid group in the molecule. A radically polymerizable monomer having (a) an amino group, an amide group, or a quaternary ammonium base in the molecule, and (b) a radically polymerizable monomer having a sulfonic acid group or sulfonic acid group in the molecule. It is necessary to use each monomer in an amount of 0.5 to 10% by weight based on the total monomers. If it is less than 0.5% by weight, the pigment dispersibility will be poor, and if it is more than 10% by weight, the water resistance of the dried film will be poor. In the present invention, (c) other monomers capable of radical polymerization include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate,
Acrylic esters such as decyl acrylate, methacrylic esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, octyl methacrylate, decyl methacrylate, stearyl methacrylate, styrene, α- methylstyrene,
Styrenic derivatives such as vinyl toluene and styrene chloride, vinyl alcohol derivatives such as vinyl acetate, vinyl propionate, vinyl valerate, and vinyl versatate are used as main ingredients, and other unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, and maleic acid are used. It is also possible to use monomers having hydroxyl groups such as acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and hydroxypropyl methacrylate. These monomers are used in an amount of 80 to 99% by weight of the total monomers, and the combination of various monomers can be selected so that the resin coating obtained from them has a glass transition point in the range of 0°C to 70°C. preferable. If the temperature is lower than 0° C., if printing materials are left stacked one on top of the other, a so-called blocking phenomenon occurs in which the printed surfaces adhere to each other, making it unusable. 70
If the temperature is higher than .degree. C., the adhesion to the substrate, especially plastic film, is poor, and the dry ink film is unable to respond to the expansion and contraction of the film due to poor flexibility. The ability to freely change the glass transition point and adjust the hardness of the resin in accordance with the printing material is also a major advantage of the printing ink varnish according to the present invention. In the present invention, the method of copolymerizing with various monomers selected from (a), (b), and (c) as described above includes:
A common method is radical polymerization in an organic solvent. The organic solvents used here include aliphatic alcohols such as methanol, ethanol, propanol, and butanol, aromatic hydrocarbons such as toluene and xylene, and alicyclic carbons such as cyclohexane, methylcyclohexane, dimethylcyclohexane, and ethylcyclohexane. Examples include hydrogens, ketones such as acetone, methyl ethyl ketone, diethyl ketone, and methyl isobutyl ketone, and esters such as methyl acetate and ethyl acetate. Also methyl cellosolve, ethyl cellosolve, cellosolve acetate,
Organic solvents with relatively high boiling points such as diacetone alcohol and butyl acetate can also be used. These organic solvents should be selected depending on the purpose and application of the printing ink. You can get something that can be dissolved in. For example, when printing on extremely thin polyvinyl chloride film of 50μ or less used for packaging objects, in addition to the adhesion of the printing ink to the film, the printed ink must be dried at low temperatures and in a short time. . In addition, so-called strong solvents that dissolve polyvinyl chloride can hardly be used in the printing process because they swell the film, and for such applications, inks containing low-boiling alcohol as the main solvent have been desired. The copolymer used in the printing ink according to the present invention has an amino group,
Because it has hydrophilic or relatively hydrophilic groups such as amide groups, quaternary ammonium bases, sulfonic acid groups, and sulfonic acid groups, it has good solubility in highly hydrophilic low-boiling alcohols, and is suitable for the above uses. is particularly suitable. As described above, the copolymer used in the present invention has good pigment dispersibility and the hardness of the resin can be easily changed, so that adhesion to a printing medium and blocking resistance can be obtained at the same time. In addition, it is easy to create a composition that dissolves in a solvent suitable for the printing material.
It is an excellent varnish for gravure inks. Examples will be specifically described below. All parts indicate parts by weight. Example 1 A varnish was obtained by polymerizing monomers in a four-necked flask equipped with a stirrer, a thermometer, and a nitrogen gas inlet using the following recipe and operating method. Formula 1 Methyl methacrylate 30 2 n-butyl methacrylate 30 3 Ethyl acrylate 30 4 Sulfoethyl methacrylate sodium salt 8 5 N-n-butoxymethylacrylamide 2 6 sec-butanol 50 7 Ethanol 50 8 Methyl acetate 46 9 Benzoyl oxide 4 Procedure: Pour the entire amount of the recipe into the four-necked flask and heat to reflux temperature, and cool when the nonvolatile content reaches 39% or more. The glass transition point of the obtained resin was 30°C, and the dispersibility of the phthalocyanine blue pigment was good.
A more stable printing ink was obtained. In addition, when the ink obtained here was printed on 30μ polyvinyl chloride film, it showed good adhesion.
It also showed good results in anti-blocking tests. Comparative Example 1 When sulfoethyl sodium methacrylate or N-n-butoxymethylacrylamide was excluded from the formulation of Example 1, the pigment dispersibility was poor. Examples 2 to 4, Comparative Example 2 Varnishes were obtained in the same manner as in Example 1, but with different monomer compositions. The resulting varnish was made into an ink in the same manner as in Example 1, and the pigment dispersibility, ink stability, adhesion to polyvinyl chloride film, and blocking resistance of printed matter were examined. Table 1 shows the monomer composition, glass transition point, and performance results. Test method Pigment dispersibility: 15 parts of phthalocyanine blue pigment, ink varnish according to the invention (40% non-volatile content) 25
sec-butanol/ethanol/methyl acetate = 1.1.1 (weight ratio) mixed solvent of 60 parts was ground in an attritor for 30 minutes, and the dispersion state of the pigment was judged with a grind gauge. Stability of ink: The ink obtained in the pigment dispersibility test was placed in a 30 cm long test tube, left for one month, and then the sedimentation property of the pigment was examined. Blocking resistance: Each printing ink was printed on a 30μ polyvinyl chloride film using a gravure printing machine with a depth of 30μ, and the printed surface was overlapped with an unprinted polyvinyl chloride film at 40℃, 0.5Kg/cm ² , relative Pressure bonding was carried out at a temperature of 85%. It did not wear off after 24 hours and was judged based on the condition of the printed surface. Adhesion to polyvinyl chloride: In the blocking resistance test, a 1.5 cm wide cellophane adhesive tape was attached to the printed film, and the condition of the printed surface was judged when it was peeled off. 【table】

Claims (1)

[Claims] 1 (a) An amino group, an amide group, or 4
(b) 0.5 to 10 parts by weight of a monomer capable of radical polymerization having a sulfonic acid group or a sulfonic acid group in the molecule;
and (c) 99 to 80 parts by weight of another monomer capable of radical copolymerization, as a resin component. 2. The varnish for printing ink according to claim 1, wherein the polymer has a glass transition point within the range of 0°C to 70°C.