JPS62236875A - Dispersing agent for ink preparation - Google Patents

Abstract

PURPOSE:To obtain the titled dispersing agent which gives an ink having excellent long-term stability, drying characteristics, gloss, etc., by using a salt of a copolymer of a monomer selected from among isobutylene, styrene, and acrylic acid with maleic acid (anhydride) as principal component. CONSTITUTION:A copolymer which consists of at least one kind of monomer unit (A) selected from among isobutylene, styrene and acrylic acid (ester) units, and a maleic acid (anhydride) unit (B) [except a styrene/maleic acid (anhydride) copolymer] is prepared. Examples of the copolymer include a maleic acid/ isobutylene copolymer, a maleic acid/acrylic acid copolymer, and a maleic acid/acrylic acid/styrene copolymer. Then, a salt of this copolymer is used as principal component, and if necessary, a solvent such as water is mixed therewith, thus giving an objective dispersing agent for ink preparation.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a dispersant for ink preparation, and more specifically, it provides an ink with excellent storage stability and good ink gloss when printed. This invention relates to a dispersant for ink preparation.

[Prior art and its problems 1 Ink is prepared mainly using a binder that binds a colorant, a colorant, and a solvent as main ingredients. From the viewpoint of toxicity and flammability during ink preparation or printing, so-called water-based inks have come to be widely used instead of organic solvents and water. A water-soluble resin is used as a dispersant for preparing this water-based ink, and a salt of a styrene-maleic anhydride copolymer is known as such a resin.

Although ink prepared using the salt of this copolymer as a dispersant has excellent drying properties and abrasion resistance when printed, it lacks storage stability and has poor gloss when printed. There were drawbacks.

[Purpose of the invention] This invention has been made based on the above circumstances.

That is, an object of the present invention is to provide a dispersant for ink preparation that eliminates the above-mentioned drawbacks, provides an ink with excellent storage stability, and also provides an ink with good gloss and abrasion resistance when printed. It is to be.

[Means for Solving the Problems] The gist of the present invention for solving the problems described above is to provide at least one seven-unit compound selected from the group consisting of isobutylene units, styrene units, and acrylic acid or ester units thereof. and maleic acid and/or maleic anhydride units as constituent units (excluding copolymers of styrene and maleic acid and/or maleic anhydride). This is a dispersant for ink preparation.

More specifically, this ink preparation dispersant includes a copolymer of maleic acid and/or maleic anhydride and isobutylene, a copolymer of maleic acid and/or maleic anhydride, and acrylic acid or an ester thereof. copolymer, maleic acid and/or
or a copolymer of maleic anhydride, imbutylene, and acrylic acid or its ester, a copolymer of maleic acid and/or maleic anhydride, acrylic acid or its ester, and styrene, and maleic acid and/or maleic anhydride. Examples include salts of acids and imbutylene, and copolymers of styrene and acrylic acid or esters thereof. Moreover, this dispersant for ink preparation has a salt of a mixture of two or more selected from the group consisting of the above copolymers, or a mixture of two or more selected from the group consisting of salts of each of the above copolymers. It may be something.

The inbutylene unit can be represented by the following general formula (1).

H3-(--CH2-C-ichi CH3...(1) The styrene unit can be represented by the following general formula (2).

...-(2) The acrylic acid ester unit has the following general formula % (However, R is a hydrogen atom or a lower alkyl group, and preferably R is a methyl group.) The maleic anhydride unit has the following general formula %. However, the copolymer of the present invention may contain a maleic anhydride unit at the end of the molecule in a bonding manner as shown in the following general formula (5).

(However, X is another seven unit.) The maleic acid unit can be represented by the general formula (6).

Such a copolymer having 1,000 units can be synthesized, for example, as follows.

That is, when inbutylene is used as one of the seven polymers, first, predetermined amounts of each copolymerizable monomer except isobutylene are charged into a reaction vessel, and the reaction vessel is cooled and sufficiently degassed. Next, a predetermined amount of inbutylene is added and a copolymerization reaction is carried out while stirring. At this time, the reaction temperature is usually 30 to 200°C, preferably 45 to 20°C.
It is 0°C.

The reaction time is usually 0.5 to 20 hours, preferably 1 to 10 hours.

In this copolymerization reaction, a solvent, a catalyst such as a polymerization initiator or promoter, and a molecular weight regulator can be used as necessary.

Examples of the solvent include benzene, toluene, xylene, ethylbenzene, propylbenzene, cumene, n
-Butylbenzene, t-butylbenzene, hexylbenzene, chlorobenzene, dichlorobenzene, bromobenzene, hexane, heptane, octane, decane, cyclohexane, methylcyclohexane, ethylcyclohexane, decalin, dichloroethane, chloroform, butyl chloride, acetone, ethyl methyl ketone , acetophenone, cyclopentanone, cyclohexanone, dibutyl ether, dioxane, tetrahydrofuran, methanol,
Mention may be made of various compounds such as ethanol, propatool, butanol, cyclohexanol, acetonitrile, propionitrile, nitromethane, nitroethane, N,N-dimethylformamide, dimethylsulfoxide. These compounds can be used singly or as a mixture of two or more.

Among these solvents, for example, ethylbenzene, cumene, n-butylbenzene, mixtures thereof, acetonitrile, nitromethane, nitroethane, methyl ethyl ketone, acetone, N,N-dimethylformamide, dimethyl sulfoxide, and the like can be suitably used.

As the catalyst, various common polymerization initiators can be used, and examples of suitable ones include organic peroxides such as benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, and dicumyl peroxide. and organic diazo compounds such as azobisisobutyronitrile. Alternatively, a method of promoting the polymerization reaction by irradiation with light or radiation may also be used.

As the molecular weight regulator, for example, various known molecular weight regulators that can be used in radical polymerization of olefins, vinyl compounds, etc. can be used.

Further, the copolymer according to the present invention usually has a number average molecular weight of 500 to 400,000, and preferably a number average molecular weight of 1,000 to 200,000. If the number average molecular weight is less than 500, the effect of improving the dispersibility of the colorant, ie, organic or inorganic pigment particles, cannot be expected, and the production of this copolymer may become difficult. Also,
If the number average molecular weight is greater than 400,000, the viscosity becomes extremely high when used as an alkaline aqueous solution, making it impossible to uniformly disperse the inorganic pigment and resulting in poor productivity.

Further, in the copolymer of the present invention, even if the number average molecular weight is within the above range, the content of maleic acid units is preferably 5 to 60 mol%, particularly 10 to 50 mol%. This copolymer requires the presence of maleic acid and/or maleic anhydride units, and if the content is less than the above range, the number of polar groups will decrease and the dispersibility of the pigment may become unsatisfactory. Moreover, if the content exceeds the above range, synthesis of the copolymer may become extremely difficult.

The copolymer is neutralized with an alkali to form a copolymer salt.

Examples of the alkali include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; inorganic and organic ammonium hydroxides; and alkali metal carbonates such as sodium carbonate, potassium carbonate, and sodium hydrogen carbonate. ; ammonium carbonate; alkali metal salts of carboxylic acids or phenols such as sodium acetate, sodium oxalate, and sodium phenoxide; ammonia, urea, thiourea, and organic amines. These alkalis may be used in combination of two or more. Among these, sodium hydroxide, potassium hydroxide, sodium carbonate, ammonium hydroxide, ammonia, sodium acetate, urea, thiourea, organic amines and the like are preferred.

Then, the neutralization treatment can be carried out, for example, by directly blowing ammonia gas into the copolymerization reaction product liquid obtained by performing the copolymerization reaction in the solvent, or by combining the copolymerization reaction product liquid with an aqueous alkali solution that dissolves the alkali. This can be done by mixing.

The temperature during the neutralization treatment is, for example, 20 to 150°C, and the neutralization treatment time is usually set to 0.5 to 10 hours.

Regardless of whether the temperature and time of neutralization treatment are as described above or not, in short, neutralization treatment is carried out at a level where the degree of neutralization is 0.10 to 1.00. good.

That is, even if the salt of the copolymer in this invention is partially salt and the remainder is carboxylic acid and/or carboxylic acid anhydride,
A portion may be a salt and the remainder may be an ester, a carboxylic acid, and/or a carboxylic acid anhydride.

The neutralized product liquid obtained by neutralizing the copolymer with the alkali as described above contains the salt of the copolymer.

The neutralization product solution can be used as it is, or the ink can be prepared by adjusting the concentration of the salt of the copolymer in the solution and the alkali concentration in the solution by various methods such as removing a part of the solvent. It can be used as a dispersant. Further, the salt of the copolymer may be separated and recovered by removing the solvent and the like from the neutralization product liquid, and may be subjected to purification treatment such as washing as necessary. This recovered salt of the copolymer is
It can be used as a dispersant for ink preparation either as it is or by dissolving or blending it in a solvent such as water or water containing a small amount of alcohol.

That is, by the method described above, a dispersant for ink preparation consisting of a salt of the copolymer can be obtained.

This dispersant for ink preparation can be suitably used, for example, as a dispersant for printing ink.

In other words, a dispersant for ink preparation made of a salt of this copolymer has good colorant binding properties, and an ink prepared using a salt of this copolymer as a dispersant has good drying properties when printed. In addition to being excellent in basic properties such as abrasion resistance, the ink also has excellent properties such as good gloss and high storage stability of the ink itself.

The dispersant for ink preparation made of the salt of the copolymer can be used as an ink or an ink composition by adding a binder, a colorant, a solvent, and, if necessary, various auxiliary agents.

The binder is not particularly limited as long as it can be used for water-based ink, and for example,
Styrene, an acrylic resin containing carboxyl groups, obtained by copolymerizing acrylic esters, methacrylic esters, etc. with acrylic acid, methacrylic acid, itaconic acid, etc., and then neutralizing it with basic substances such as ammonia and amines to make it water-soluble. A carboxyl group-containing acrylic resin with improved colorant dispersibility, drying properties, and gloss by copolymerizing
Drying and abrasion resistant M-ton product made by copolymerizing ether monomers such as ethyl cellosolve acrylate White I Each
+? +1. GI and Sノ II/ jt □Now J1 section 7
Styrene-maleic acid resin obtained by copolymerizing styrene and maleic anhydride, maleic anhydride half ester, or maleic acid, styrene-acrylic resin obtained by copolymerizing styrene and acrylic acid Acid resins, maleated rosins obtained by reacting rosins with maleic anhydride, acid anhydrides such as acid anhydrides, and polyhydric alcohols such as neopentyl glycol, which have an acid value of Examples include polyester resins with a molecular weight of about 50 to 100 and about 3,000 to 15,000, and polyamide resins made water-soluble by increasing the acid value.

Among these various binders, at least one monomer selected from the group consisting of isobutylene, styrene, and acrylic acid or its ester; and at least one monomer selected from the group consisting of maleic acid, maleic acid ester, maleic acid half ester, and maleic anhydride. A copolymer obtained by copolymerizing at least one type of shielding material or a salt thereof is preferred, and a copolymer of styrene and alkyl maleate monoester or a salt thereof is particularly preferred, and a copolymer thereof having an acid value of 70
〜200 mgKOH/g, and the molecular weight is 4000〜
A copolymer of 15,000 styrene and an alkyl maleate monoester is preferred.

As the coloring agent, ink dyes such as ordinary dyes for water-based inks, organic pigments, inorganic pigments, and mixtures thereof in arbitrary proportions can be used. However, organic pigments and inorganic pigments for printing inks are usually preferably used.

Examples of the inorganic pigments include zinc oxide, calcium carbonate, barium sulfate, zinc white, lithopone, titanium dioxide, titanium white, chromium yellow, cadmium yellow, nickel titanium yellow, red iron oxide, mica-like iron oxide, lead white, and red lead. , silver vermilion, ultramarine (milory blue, Prussian blue), deep blue (ultramarine), cobalt oxide, titanium dioxide-coated mica,
Strontium chromate, titanium yellow, titanium black, zinc chromate, iron black, molybdenum red,
Molybdenum white, molybdenum orange, litharge,
Emerald green, Guiney green, cobalt blue, mercury cadmium sulfide, ultramarine, mineral fast yellow, cadmobon, navels yellow (antimony yellow)
, yellow iron oxide, chromium oxide, zinc yellow, carbon black, lead sulfate, lead molybdate, cadmium carbonate,
Examples include lead sulfide, zinc sulfide, cadmium sulfide, and mercury sulfide.

As the organic pigment, azo pigments, phthalocyanine pigments, etc. can be used. Specifically, for example, Banza Yellow, Benzidine Yellow, Permanent Yellow, Palcan First Yellow, Suren Yellow, Permanent Red, Benzidine Yellow, etc. Din Orange, Palkan Orange, Pig Orange 17, Threnpril Orange, Rose Red, Permanent Carmine, Permanent Bordeaux, Brill First Scarlet, Piglet 23, Palkan Fire Red, Pyrazolone Red, Watching Red, Lysole Red, Lake Red, Helio Red, Lake Bordeaux, Pon Maroon Dark, Toluidine Red, Quinacridone Red, Chromophthal Red, Pig Violet 23, Dioxazine Violet, Victoria Pure Blue Lake, Victoria Blue Lake, Pig Blue 15, Pig Blue 16, Pig Blue 17, Diamond Green Lake , copper phthalocyanine green, copper phthalocyanine blue, pig green B, green gold, diamond black, etc.

The solvent is preferably water or a mixture of water and alcohol.

Alcohols include lower alcohols such as methanol, ethanol, propatool, isopropyl alcohol,
Alternatively, a mixture of these in arbitrary proportions can be mentioned.

The mixing ratio of water and alcohol in the solvent is 1 part water and 1 part water.
The amount of alcohol per 00 parts by volume is usually 30 parts by volume or less, preferably 5 parts by volume or less.

Note that the solvent may contain the alkali or components in the neutralized organism.

The auxiliary agents include desiccants, antioxidants, drying inhibitors, concentration adjusting agents such as toners and tints, varnishes such as Victoria, compounds, special varnishes, gel varnishes, and diluted varnishes, and fluidity adjusting agents such as surfactants. Examples include pharmaceutical preparations. As the varnish, linseed oil varnish is preferably used.

The blending ratio of the binder and the auxiliary agent can be set to various values depending on the purpose. For example, when used as an adjunct to linseed oil varnish,
The linseed oil-containing varnish may be used in an amount of 5 to 20 parts by weight per 100 parts by weight of the binder.

The blending ratio of each component forming the ink containing the dispersant for ink preparation is that the colorant is usually 10 to 500 parts by weight, preferably 50 to 200 parts by weight, with respect to 100 parts by weight of the binder. The solvent is usually 10 to 10
00 parts by weight, preferably 200 to 700 parts by weight,
The amount of this dispersant for ink preparation is usually 1 to 30 parts by weight, preferably 3 to 20 parts by weight.

There are no particular restrictions on the order or method of blending the ink preparation dispersant made of the salt of the copolymer, the binder, the colorant, the solvent, and if necessary the auxiliary agent, but for example, , the following method can be suitably used.

That is, a pigment slurry is prepared by mixing a coloring agent such as the organic and/or inorganic pigment, the solvent, and a binder. The pigment slurry and this dispersant for ink preparation are blended to produce a slurry composition in which the colorant such as the organic and/or inorganic pigment is uniformly dispersed, that is, a colorant-containing composition for ink preparation. The ink can be obtained by blending such a composition with an auxiliary agent such as linseed oil varnish if necessary, heating and melting it in a molten kettle, cooling it, and kneading it in a commonly used kneading machine such as a ball mill. .

This dispersant for ink preparation can be suitably used in printing inks such as gravure ink, flexographic ink, screen ink, flat plate ink, letterpress ink, and concave plate ink.

The ink prepared as described above has excellent storage stability, good drying properties and gloss when printed, and high abrasion resistance.

[Effect of the invention] According to this invention, the ink itself has excellent stability over time,
It is possible to provide a novel dispersant for ink preparation that can provide an excellent ink with good properties such as drying properties, abrasion resistance, and gloss when printed.

In particular, this dispersant for ink preparation improves the storage stability of the ink itself and improves printing performance compared to conventional dispersants for ink preparation consisting of salts of copolymers of styrene and maleic acid and/or maleic anhydride. It can improve the gloss and abrasion resistance of the printed surface.

[Example] Next, examples and comparative examples of the present invention will be shown.

(Examples 1 to 6, Comparative Example 1) Preparation of binder In a three-ring flask, 4 BOcc of xylene and 1 cc of styrene were added.
04g, maleic acid n-propyl half ester 148g and benzoyl peroxide 0.8g,
The copolymerization reaction was carried out at ℃ for 2 hours.

After the polymerization was completed, the product was poured into water to obtain a copolymer.

The number average molecular weight of this copolymer is 6400 and the acid value is 171.
It was mgKOH/g.

Neutralize this copolymer with aqueous ammonia (degree of neutralization = 1) L,
A 20% by weight aqueous solution was prepared.

6. Preparation of dispersant using this aqueous solution as a binder.
A copolymerization reaction of the type shown in Table 1, acetonitrile 4ElOcc as a solvent, and benzoyl peroxide O and Eg as catalysts was carried out at 110°C for 2 hours while stirring at 400 rpm. I did it. Note that when using imbutylene as a monomer, first, other monomers other than imbutylene are charged into the autoclave, and the autoclave is cooled to -10°C and the inside of the autoclave is sufficiently degassed. A copolymerization reaction was carried out in the same manner as described above.

After the copolymerization reaction was completed, the copolymerization reaction product was poured into water to precipitate a copolymer, which was collected to obtain a copolymer.

Number average molecular weight, amount of inbutylene (mole ratio), amount of styrene (mole ratio), amount of methyl acrylate (
Table 1 shows the amount of maleic anhydride (mole) and the amount of maleic anhydride (mole ratio).

Thereafter, an amount of ammonium hydroxide aqueous solution (ammonium water) was added to the copolymer to give a neutralization degree of 1 to make the concentration 20% by weight, and a neutralization reaction was carried out at 80°C for 6 hours. A dispersant that is a salt of a polymer was prepared.

Preparation of ink and evaluation thereof Pigment (
Lake Red) 2'0 parts by weight, solvent (water) 40 parts by weight,
6 parts by weight of the divergent agent obtained in the above Preparation Example were added and milled in a ball mill at 25°C for 10 hours to prepare an ink.

The storage stability of the obtained ink, and the gloss and drying properties when the ink was spread on water-repellent liner paper were evaluated using the following methods.

Evaluation method Evaluation and criteria for ink storage stability: After being left at 25°C for 24 hours, viscosity increase of less than 20%...Good Viscosity increase of 20% or more...Poor Gloss: Placed in an oven at 200°C for 3 seconds Gloss value after injection [Glossmeter GM-3M (Murakami Color Research New Co., Ltd.), measured value at a specular reflection angle of 60°C] Abrasion resistance: Mix Carporundum (120-200 mesh) with compressed air and pour it from the nozzle. The paint was sprayed onto the painted surface and the degree of damage to the painted surface was visually observed and evaluated.

Drying property: Evaluated by finger touch method after placing in an oven at 200°C for 3 seconds.

-24 In Table 1, IB, ST, AM, and MA mean the structural units of isobutylene, styrene, methyl acrylate, and Malayan anhydride, respectively.

Claims (1)

[Claims] (1) A copolymer whose constituent units are at least one monomer unit selected from the group consisting of isobutylene units, styrene units, and acrylic acid or ester units thereof, and maleic acid and/or maleic anhydride units (with the exception of styrene units). and maleic acid and/or maleic anhydride (excluding copolymers of maleic acid and/or maleic anhydride).