JP2013049788A - Non-aqueous pigment ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-aqueous pigment ink with preferable storage stability and a high printing density.SOLUTION: The non-aqueous pigment ink includes (A) an alkyl (meth)acrylate copolymer having 2.5-25 mass% of a carbocyclic ring part with respect to the entire copolymer and 0.05 mass% or less of a nitrogen-containing group part with respect to the entire copolymer, (B) an alkyl (meth)acrylate copolymer having 0.5-5.0 mass% of a nitrogen-containing group part with respect to the entire copolymer and 1.0 mass% or less of a carbocyclic ring part with respect to the entire copolymer, (C) a pigment, and (D) an organic solvent.

Description

  The present invention relates to a non-aqueous pigment ink.

  The ink coloring materials used in inkjet recording systems are broadly divided into those using pigments and those using dyes, but they have excellent light resistance, weather resistance and water resistance necessary for high-quality printing. Therefore, there is a tendency for inks using pigments as color materials to increase.

  In terms of the solvent, the ink is large and can be divided into a water-based ink and a non-water-based ink. Non-water-based inks that do not use water as the solvent for ink, such as solvent-based inks mainly composed of volatile solvents and oil-based inks mainly composed of non-volatile solvents, have better drying properties and printability than water-based inks. Is also excellent.

  In non-aqueous type inks, a pigment dispersant that dissolves in a solvent is generally used. This pigment dispersant enhances the affinity between the solvent and the pigment. Therefore, when the solvent penetrates into the recording paper, the pigment also enters the recording paper. There is a tendency to be drawn. As a result, the print density is lowered and the showthrough is likely to occur.

  Therefore, a non-aqueous pigment ink using non-aqueous resin dispersed fine particles having pigment dispersing ability as a dispersant has been proposed (Patent Document 1). In Patent Document 1, an acrylic polymer containing an alkyl (meth) alkylate unit having an alkyl group having 12 or more carbon atoms and a (meth) acrylate unit having a urethane group is used as a pigment dispersant. The present invention provides a non-aqueous pigment ink that suppresses show-through and increases printing density and has excellent storage stability.

  On the other hand, in order to obtain better ink storage stability, there is a method of enhancing the ink-based pigment dispersibility by enhancing the adsorption action between the dispersant and the pigment. However, if the adsorbing action between the dispersant and the pigment is too strong, the printing density may decrease after printing because the pigment penetrates into the recording medium while adsorbed on the dispersant.

JP 2010-1452 A

  An object of the present invention is to provide a non-aqueous pigment ink having good storage stability and high printing density.

  In one aspect, the present invention has a carbocyclic portion of 2.5% by mass to 25% by mass with respect to the entire copolymer, and the nitrogen-containing base is 0.05% by mass or less with respect to the entire copolymer. Alkyl (meth) acrylate copolymer (A), having 0.5% to 5.0% by mass of nitrogen-containing base with respect to the whole copolymer, and 1.0% of carbocyclic ring with respect to the whole copolymer. It is a non-aqueous pigment ink containing an alkyl (meth) acrylate copolymer (B), a pigment (C), and an organic solvent (D) that is not more than mass%.

  According to the present invention, it is possible to provide a non-aqueous pigment ink having good storage stability and high printing density.

  Hereinafter, although the embodiment concerning the present invention is described, the illustration in this embodiment does not limit the present invention.

  A non-aqueous pigment ink according to an embodiment of the present invention (hereinafter sometimes simply referred to as “ink”) has a carbon ring part of 2.5% by mass to 25% by mass with respect to the entire copolymer, Alkyl (meth) acrylate copolymer (A) (hereinafter sometimes simply referred to as “copolymer (A)”) having a nitrogen-containing base of 0.05% by mass or less based on the whole polymer, An alkyl (meth) acrylate copolymer having a nitrogen-containing base of 0.5% by mass to 5.0% by mass in the entire coalescence and having a carbocyclic part of 1.0% by mass or less based on the whole copolymer ( B) (hereinafter sometimes simply referred to as “copolymer (B)”), pigment (C), and organic solvent (D). Thereby, an ink having high storage stability and high printing density can be obtained. Here, “(meth) acrylate” means acrylate and methacrylate (hereinafter the same).

  Carbon black used in non-aqueous pigment inks forms a crystallite by overlapping a network plane with a continuous carbon six-membered ring structure, and the crystallites gather to form particles. Therefore, in consideration of the adsorption action (interaction) with the carbon black surface, it is desirable that the pigment dispersant has a carbocycle rather than an aliphatic hydrocarbon so as to be easily adsorbed on the carbon black surface. In addition, there are functional groups such as carboxyl groups on the surface of acidic carbon black, and considering the adsorption action with these, as a pigment dispersant, basic nitrogen is used so that it can be easily adsorbed on the surface of carbon black. It is desirable to have a containing group.

  As the strength of the adsorption action with the carbon black surface, the intermolecular interaction by the carbon ring part is weaker than the acid-base interaction by the nitrogen-containing base part. In the ink of this embodiment, the strength of this adsorption action is used to stabilize the pigment dispersion system by the action of both adsorption actions so that the balance of the pigment dispersion system on the recording medium is lost after printing. Thus, it is possible to prevent a decrease in printing density.

  That is, after the ink is printed on the recording medium, the copolymer (A) having a carbon ring portion having a six-membered ring surface of carbon black and an adsorbing action is obtained from the pigment in the process of losing the balance of the pigment dispersion system. It is separated and penetrates into the recording medium together with the organic solvent. The copolymer (B) having a nitrogen-containing group adsorbed by acidic carbon black and acid-base interaction maintains the adsorbed state with the carbon black, but has a copolymer (A ) Decreases, the viscosity of the ink increases, and it tends to remain on the surface of the recording medium together with carbon black. This increases the printing density on the surface of the recording medium.

  On the other hand, a copolymer having a carbocyclic part and a nitrogen-containing base part in one molecule has a strong adsorbing action on the surface of carbon black and good pigment dispersibility in the ink. On the surface of the medium, the copolymer may permeate into the recording medium while adsorbed on the carbon black, and the print density on the surface of the recording medium may decrease due to the back-through.

  In the above description, carbon black has been described, but the same effect can be obtained as long as the pigment can have an adsorption action with the carbocyclic portion and the nitrogen-containing base portion.

  The alkyl (meth) acrylate copolymer (A) has a carbon ring part of 2.5% by mass to 25% by mass with respect to the whole copolymer, and the nitrogen-containing base part is 0.05% by mass with respect to the whole copolymer. % Or less.

  The carbocyclic part may have a substituted or unsubstituted aromatic hydrocarbon group and / or a substituted or unsubstituted alicyclic hydrocarbon group, and may be monocyclic and / or polycyclic, It is preferable that carbon number is 5-20. Examples of the aromatic hydrocarbon group include a phenyl group, a bidenyl group, a terphenyl group, a toluyl group, a chlorophenyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, a biphenylenyl group, a fluorenyl group, and the like. it can. Examples of the alicyclic hydrocarbon group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptanyl group, a cyclooctanyl group, a benzoquinolyl group, and the like, and derivatives thereof. These may be used alone or in combination. Preferably, it is a C6-C14 aromatic hydrocarbon group, and a phenyl group, a naphthyl group, and derivatives thereof can be used. In particular, when the pigment is carbon black, the aromatic hydrocarbon group is desirable because it has a similar structure to the six-membered ring of carbon black and is more easily adsorbed.

  The carbocyclic moiety is 2.5% by mass to 25% by mass, preferably 5% by mass to 22% by mass, and more preferably 7.5% by mass to 20% by mass with respect to the entire copolymer. is there. Adsorption to the surface of carbon black is effective when it is 2.5% by mass or more, and solubility can be increased even in a low-polarity solvent when it is 25% by mass or less.

  Here, the mass proportion of the carbocyclic moiety can be determined from the proportion of the mass of the monomer having a carbocyclic ring with respect to the total amount of monomers used for synthesis during synthesis of the copolymer (hereinafter the same).

  Further, from the viewpoint of dispersibility of the pigment in the ink, the carbocyclic moiety is preferably contained at 0.05 mmol / g to 1.0 mmol / g, more preferably 0.15 mmol / g, relative to 1 g of the pigment. -1.0 mmol / g.

  The nitrogen-containing base part has a functional group containing nitrogen, and examples thereof include an amino group, a cyano group, a nitrile group, an amide group, a urethane bond, and the like, and combinations thereof.

  The nitrogen-containing base is 0.05% by mass or less, preferably 0.01% by mass or less, based on the entire copolymer. More preferably, it is substantially not contained. For example, a copolymer synthesized without using a monomer having a nitrogen-containing base can be used.

  Here, the mass ratio of the nitrogen-containing base can be determined from the ratio of the mass of the monomer having a nitrogen-containing group with respect to the total amount of monomers used in the synthesis during synthesis of the copolymer (the same applies hereinafter).

  The copolymer (A) preferably has a weight average molecular weight measured by GPC of 5,000 to 30,000, more preferably 8,000 to 20,000. When the molecular weight is equal to or higher than the lower limit value, the storage stability can be improved, and when the molecular weight is equal to or lower than the upper limit value, the ink can be reduced in viscosity, and the ink jet ink can improve the ejection stability.

  The content of the copolymer (A) in the ink is preferably 1% by weight or more, more preferably 2% by weight or more in terms of solid content, from the viewpoint of ensuring pigment dispersibility in the ink. preferable. On the other hand, if the content of the copolymer (A) is too high, not only the viscosity of the ink is increased, but also the storage stability under a high temperature environment may be deteriorated. Or less, more preferably 15% by weight or less, and still more preferably 3 to 10% by weight.

  The alkyl (meth) acrylate copolymer (B) has a nitrogen-containing base part of 0.5% by mass to 5.0% by mass with respect to the whole copolymer, and the carbocyclic part is 1. 0% by mass or less.

  The nitrogen-containing group part can have a functional group containing nitrogen, for example, an amino group, a cyano group, a nitrile group, an amide group, a urethane bond, and the like, and combinations thereof can be used. And at least one selected from a group, a cyano group, a nitrile group, an amide group, and a urethane bond.

  The nitrogen-containing base is 0.5% by mass to 5.0% by mass, and preferably 1.0% by mass to 2.5% by mass with respect to the entire copolymer. The content of 0.5% by mass or more is effective for the dispersion of the pigment, and the content of 5.0% by mass or less can prevent the pigment from penetrating into the recording medium.

  Further, from the viewpoint of dispersibility of the pigment on the recording medium, the nitrogen-containing base is preferably contained at 0.2 mmol / g to 1.0 mmol / g, more preferably 0.35 mmol / g, with respect to 1 g of the pigment. g to 0.85 mmol / g.

  Examples of the carbocyclic portion include those described for the copolymer (A).

  A carbocyclic part is 1.0 mass% or less with respect to the whole copolymer, Preferably it is 0.1 mass%. More preferably, it is substantially not contained. For example, a copolymer synthesized without using a monomer having a carbocyclic moiety can be used.

  The copolymer (B) preferably has a weight average molecular weight measured by GPC of 5000 to 20,000, more preferably 8000 to 15,000. When the molecular weight is equal to or higher than the lower limit value, the storage stability can be improved, and when the molecular weight is equal to or lower than the upper limit value, the ink can be reduced in viscosity, and the ink jet ink can improve the ejection stability.

  The content of the copolymer (B) in the ink is preferably 1% by weight or more, more preferably 2% by weight or more in terms of solid content, from the viewpoint of securing the pigment dispersibility in the ink. preferable. On the other hand, if the content of the copolymer (B) is too high, not only the viscosity of the ink is increased, but also the storage stability in a high temperature environment may be deteriorated. Or less, more preferably 15% by weight or less, and still more preferably 3 to 10% by weight.

  The alkyl group contained in each of the copolymer (A) and the copolymer (B) is not particularly limited, but the copolymer (A) and / or the copolymer (B) has an alkyl group having 12 to 25 carbon atoms. It is preferable to have. This alkyl group is excellent in affinity with (D) organic solvent described later. Examples of the alkyl group include dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosanyl group, henicosanyl group, docosanyl group, isododecyl group, and isooctadecyl group. These may have branches. Moreover, these multiple types may be included.

  The total amount of the copolymer (A) and the copolymer (B) is preferably 1% by mass to 20% by mass, more preferably 2% by mass to 12% by mass, and still more preferably with respect to the whole ink. Is 2% by mass to 10% by mass. When it is 1% by mass or more, it is effective for the storage stability of the ink, and when it is 20% by mass or less, the viscosity of the ink can be made relatively low.

  The total amount of the copolymer (A) and the copolymer (B) with respect to the mass of the pigment is 0.1 to 1.5 from the viewpoint of securing pigment dispersibility, assuming that the mass of the pigment is 1 in terms of solid content. It is preferable that there is, more preferably 0.2 to 1.2.

  The mass ratio of the copolymer (A) and the copolymer (B) is preferably 1: 0.5 to 1: 3, more preferably 1: 0.8 to 1: 2.

  The mass ratio of the carbocyclic moiety contained in the copolymer (A) and the nitrogen-containing base moiety contained in the copolymer (B) is preferably 1: 0.5 to 1: 3, more preferably 1: 0.8 to 1: 2. If the copolymer (A) has too many carbocyclic moieties, the viscosity of the ink will increase, and if the copolymer (B) has too many nitrogen-containing bases, the ink concentration on the surface of the recording medium will be low. A range is preferred.

  Next, a method for synthesizing the copolymers (A) and (B) will be described.

  The copolymer (A) can be obtained by radical polymerization of a (meth) acrylate containing a carbon ring and an alkyl (meth) acrylate. At this time, it is preferable to use an alkyl (meth) acrylate having an alkyl group having 12 to 25 carbon atoms as the alkyl (meth) acrylate.

  The copolymer (B) is a nitrogen-containing group as one of monomers to be copolymerized with the alkyl (meth) acrylate ester in the synthesis of the copolymer (A) in the first stage reaction. Radical polymerization was performed using a reactive (meth) acrylate having a functional group capable of reacting with the compound, and a compound having a nitrogen-containing group and an alcoholic hydroxyl group was obtained in the first stage in the second stage reaction. It can be obtained by reacting with a copolymer.

  Examples of the alkyl (meth) acrylate having a carbocycle include cyclohexyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, phthalic acid (meth) acrylate, and the like. Which can be used alone or in combination.

  Examples of the alkyl (meth) acrylate having an alkyl group having 12 to 25 carbon atoms include lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, isolauryl (meth) acrylate, Mention may be made of isostearyl (meth) acrylates, which may be used alone or in combination.

  Preferred examples of the functional group capable of reacting with the nitrogen-containing group in the reactive (meth) acrylate include a glycidyl group, a vinyl group, and a (meth) acryloyl group.

  Examples of the (meth) acrylic monomer having a glycidyl group include glycidyl (meth) acrylate, glycidyl ether of hydroxyalkyl (meth) acrylate, such as 4-hydroxybutyl acrylate glycidyl ether, and 3,4-epoxycyclohexylmethyl. A (meth) acrylate etc. can be mentioned. These reactive (meth) acrylates can be used alone or in combination. Of these, glycidyl methacrylate is preferred.

  The monomer mixture can contain monomers other than the above-mentioned monomers that can be copolymerized with the monomer, as long as the effects of the present invention are not impaired. Examples of this monomer include styrene monomers such as styrene and α-methylstyrene; vinyl ether polymers such as vinyl acetate, vinyl benzoate, and butyl vinyl ether; maleic acid esters, fumaric acid esters, acrylonitrile, methacrylonitrile, Examples include α-olefins. Further, alkyl (meth) acrylates having an alkyl chain length of less than 12 carbons such as 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, tert-octyl (meth) acrylate, and the like can also be used. These can be used alone or in combination of two or more.

  In the synthesis of the copolymer (A), in the monomer mixture, the (meth) acrylate having a carbocycle is preferably contained at 5% by mass to 22% by mass, more preferably 7.5% by mass to 20% by mass. %.

  Moreover, in the synthesis | combination of a copolymer (A), it is preferable that an alkyl (meth) acrylate is contained by 20 mass%-80 mass% in a monomer mixture, More preferably, it is 30 mass%-65 mass%. .

  Moreover, in the synthesis | combination of a copolymer (A), it is preferable that another monomer is 40 mass% or less in a monomer mixture, More preferably, it is 30 mass% or less.

  In the synthesis of the copolymer (B), the monomer mixture preferably contains 20 to 80% by mass of alkyl (meth) acrylate, more preferably 30 to 65% by mass.

  Moreover, in the synthesis | combination of a copolymer (B), it is preferable that a reactive (meth) acrylate is contained by 5 mass%-40 mass% in a monomer mixture, More preferably, it is 10 mass%-35 mass%. is there.

  Moreover, in the synthesis | combination of a copolymer (B), it is preferable that another monomer is 30 mass% or less in a monomer mixture, More preferably, it is 20 mass% or less.

  Hereinafter, as an example of the synthesis method of the copolymers (A) and (B) of the present embodiment, the copolymer (A) is synthesized in the first-stage reaction, and the obtained copolymer (A) is obtained. A method for synthesizing the copolymer (B) having an amino group in the second-stage reaction will be described.

  The first-stage radical polymerization is preferably performed in an organic solvent (D) described later. In order to adjust the molecular weight, it is effective to use a chain transfer agent together during the polymerization. Examples of the chain transfer agent include thiols such as n-butyl mercaptan, lauryl mercaptan, stearyl mercaptan, and cyclohexyl mercaptan.

  Examples of the polymerization initiator include azo compounds such as AIBN (azobisisobutyronitrile), t-butylperoxybenzoate, t-butylperoxy-2-ethylhexanoate (perbutyl O, manufactured by NOF Corporation), and the like. Known thermal polymerization initiators such as oxides can be used. In addition, a photopolymerization initiator that generates radicals upon irradiation with active energy rays can be used. As a polymerization solvent used for solution polymerization, for example, a petroleum solvent (aroma free (AF) system) or the like can be used. As the polymerization solvent, it is preferable to select one or more kinds of solvents (described later) that can be used as they are as a non-aqueous solvent for the ink. In the polymerization reaction, other commonly used polymerization inhibitors, polymerization accelerators, dispersants and the like can also be added to the reaction system.

  Examples of the compound having a nitrogen-containing group and an alcoholic hydroxyl group used in the second-stage reaction include an alcohol having an amino group, and an amino alcohol is preferably used. Examples of amino alcohols include monool amines having 2 to 10 carbon atoms, such as monomethylethanolamine, diol amines having 4 to 20 carbon atoms, such as diethanolamine, diisopropanolamine, and mixtures thereof. A dialkanolamine having a number of 4 to 20 is preferred. The amino alcohol is preferably reacted at 0.05 to 1 molar equivalent, more preferably at 0.1 to 1 molar equivalent, relative to 1 mol of the glycidyl group.

  The reaction in the second stage can be carried out by adding amino alcohol to the copolymer solution obtained in the first stage, and heating while stirring while aerated with an inert gas.

The ink of this embodiment contains a pigment (C). The pigment may be arbitrary, and preferably, a pigment for black ink is used in that the effect of the present embodiment is more remarkable. Examples of pigments include carbon blacks such as furnace black, lamp black, acetylene black and channel black; metals or metal oxides such as copper, iron and titanium oxide; organic pigments such as orthonitroaniline black Can do. These may be used alone or in any mixture. In that the resulting higher print density, dibutyl phthalate as measured according to JIS K6221 (DBP) oil absorption is 80cm ³ / 100g~140cm ³ / 100g, and the nitrogen adsorption specific surface area measured in accordance with JIS K6217 is 100 m ² / g A carbon black pigment of ˜200 m ² / g is preferred.

  The average particle diameter of the pigment is preferably 300 nm or less, more preferably 150 nm or less, and even more preferably 100 nm or less from the viewpoint of ejection stability and storage stability. Here, the average particle diameter of the pigment can be measured by a dynamic light scattering particle size distribution analyzer LB-500 (manufactured by Horiba, Ltd.) or the like.

  The pigment content in the ink composition is usually 0.01 to 20% by weight, preferably 1 to 15% by weight from the viewpoint of printing density and ink viscosity, and preferably 5 to 10% by weight. Even more preferred.

  The ink of this embodiment contains an organic solvent (D). Here, the organic solvent is a nonpolar organic solvent or a polar organic solvent, and is a solvent having a 50% distillation point of 150 ° C. or higher. The 50% distillation point means a temperature at which 50% by weight of a solvent is volatilized, which is measured according to JIS K0066 “Testing method for distillation of chemical products”. From the viewpoint of safety, the 50% distillation point of the organic solvent is preferably 160 ° C. or higher, and more preferably 230 ° C. or higher.

  For example, preferred examples of the nonpolar organic solvent include aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents and the like. Examples of the aliphatic hydrocarbon solvent and alicyclic hydrocarbon solvent include, for example, “Teclean N-16, Teclean N-20, Teclean N-22, Nisseki Naphthezol L, Nissho Naphthezol M, manufactured by Nippon Petroleum Corporation. Nisseki Naphthezol H, No. 0 Solvent L, No. 0 Solvent M, No. 0 Solvent H, Nisseki Isosol 300, Nisseki Isosol 400, AF-4, AF-5, AF-6, AF-7 ", manufactured by Exxon “Isopar G, Isopar H, Isopar L, Isopar M, Exxsol D40, Exxsol D80, Exxsol D100, Exxsol D130, Exxsol D140”, “Normal Paraffin H” manufactured by Japan Energy, etc. are preferable. Preferred examples of the aromatic hydrocarbon solvent include “Nisseki Clean Sol G” (alkylbenzene) manufactured by Nippon Petroleum Corporation, “Solvesso 200” manufactured by Exxon, and the like.

  As the polar organic solvent, ester solvents, alcohol solvents, higher fatty acid solvents, ether solvents, and mixed solvents thereof can be used. For example, selected from the group consisting of an ester solvent that is an ester of a higher fatty acid having 8 to 20 carbon atoms and an alcohol having 1 to 24 carbon atoms, a higher alcohol having 8 to 24 carbon atoms, and a higher fatty acid having 8 to 20 carbon atoms. One or more of them can be preferably used.

More specifically, as polar organic solvents, methyl laurate, isopropyl laurate, isopropyl myristate, isooctyl myristate, isopropyl palmitate, isostearyl palmitate, methyl oleate, ethyl oleate, isopropyl oleate, butyl oleate , Methyl linoleate, isobutyl linoleate, ethyl linoleate, isopropyl isostearate, soybean oil methyl, soybean oil isobutyl, tall oil methyl, tall oil isobutyl, diisopropyl adipate, diisopropyl sebacate, diethyl sebacate, propylene glycol monocaprate Ester solvents such as trimethylolpropane tri-2-ethylhexanoate and glyceryl tri-2-ethylhexanoate; isomyristyl alcohol, isopalmityl Alcohol solvents such as alcohol, isostearyl alcohol, oleyl alcohol, hexyl decanol, octyldodecanol, and decyltetradecanol; higher grades such as nonanoic acid, isononanoic acid, isomyristic acid, hexadecanoic acid, isopalmitic acid, oleic acid, and isostearic acid Preferred examples include fatty acid solvents; ether solvents such as diethyl glycol monobutyl ether, ethylene glycol monobutyl ether, propylene glycol monobutyl ether, and propylene glycol dibutyl ether.
These organic solvents can be used alone or in combination of two or more.

  The ink of this embodiment can contain arbitrary components as long as the effects of the present invention are not impaired. For example, as resins other than the copolymers (A) and (B), acrylic resins, styrene-acrylic resins, styrene-maleic resins, rosin resins, rosin ester resins, ethylene-vinyl acetate resins , Petroleum resin, coumarone indene resin, terpene phenol resin, phenol resin, urethane resin, melamine resin, urea resin, epoxy resin, cellulose resin, vinyl chloride resin, xylene resin, alkyd resin, aliphatic carbonization Hydrogen resin, butyral resin, maleic acid resin, fumaric acid resin, hydroxyl group-containing carboxylic acid ester, salt of long chain polyaminoamide and high molecular weight acid ester, salt of high molecular weight polycarboxylic acid, salt of long chain polyaminoamide and polar acid ester , High molecular weight unsaturated acid ester, polymer copolymer, modified polyurethane, modified polyacrylate , Polyether ester type anionic activator, naphthalenesulfonic acid formalin condensate salt, aromatic sulfonic acid formalin condensate salt, polyoxyethylene alkyl phosphate ester, polyoxyethylene nonylphenyl ether, polyester polyamine, stearylamine acetate Etc. can be included.

  A nozzle clogging preventive agent, an antioxidant, a conductivity adjusting agent, a viscosity adjusting agent, a surface tension adjusting agent, an oxygen absorbent and the like can be appropriately added. These types are not particularly limited, and those used in the field can be used.

  The ink according to the present embodiment is used to disperse the copolymer (A), the copolymer (B), the pigment (C), the organic solvent (D), and optional components at once or in a disperser such as a bead mill. In addition, it is obtained by stirring and mixing, and if desired, filtering through a membrane filter or the like.

  The suitable range of the viscosity of the ink varies depending on the nozzle diameter of the ejection head of the inkjet recording system, the ejection environment, and the like, but in general, it is preferably 5 to 30 mPa · s at 23 ° C., and preferably 5 to 15 mPa · s. Is more preferable, and is most preferably about 10 mPa · s. Here, the viscosity represents a value at 10 Pa when the shear stress is increased from 0 Pa at a rate of 0.1 Pa / s at 23 ° C.

  The non-aqueous pigment ink of this embodiment is preferably printed by an ink jet recording method. As an inkjet recording method, any method such as a piezo method, an electrostatic method, or a thermal method may be used. When an ink jet recording apparatus is used, ink is ejected from an ink jet head based on a digital signal, and the ejected ink droplets are attached to a recording medium. A line head method can also be used as the ink jet recording method, and the line head ink jet recording method enables printing at a high printing speed.

  The recording medium is not particularly limited, and the thickness of the ink absorbing layer is larger than that of plain paper, high-quality plain paper, inkjet (IJ) paper, IJ matte paper, coated paper in which an ink absorbing solution is coated on the recording medium, and coated paper. Can be used for thin coated paper, glossy paper (photo glossy paper), special paper, cloth, etc.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. Hereinafter, “mass%” is simply referred to as “%”.

<Adjustment of copolymers 1 to 4>
Table 1 shows monomers contained in the copolymers 1 to 4. Copolymers 1 to 4 are used for adjusting the following copolymers B-1 to B-4.

  In a 500 ml four-necked flask, 156.4 g of IOP (isooctyl palmitate, manufactured by Nikko Chemicals Co., Ltd., hereinafter the same) was charged, and the temperature was raised to 120 ° C. while aerated with nitrogen gas. Next, while maintaining the temperature at 120 ° C., VMA 80 g, GMA 20 g, and perbutyl O (t-butylperoxy 2-ethylhexanoate, manufactured by NOF Corporation, the same shall apply hereinafter) 3.8 g The mixture was added dropwise over 3 hours. Thereafter, 0.2 g of perbutyl O was added after 1 hour and 2 hours while maintaining the temperature at 120 ° C. Further, aging was performed at 120 ° C. for 1 hour to obtain a solution of copolymer 1 having a solid content of 40%.

  In the preparation of copolymer 1, a solution of copolymer 2 having a solid content of 40% was obtained in the same manner except that VMA 68 g and GMA 32 g were used instead of VMA 80 g and GMA 20 g.

  In the preparation of copolymer 1, a solution of copolymer 3 having a solid content of 40% was obtained in the same manner except that VMA 68 g, GMA 32 g, and perbutyl O 2.0 g were used instead of VMA 80 g and GMA 20 g and perbutyl O 3.8 g. .

  In the preparation of the copolymer 1, a solution of copolymer 4 having a solid content of 40% was obtained in the same manner except that VMA 68 g, GMA 32 g, and perbutyl O 5.0 g were used instead of VMA 80 g, GMA 20 g, and perbutyl O 3.8 g. .

<Adjustment of Copolymers A-1 to A-5>
Table 2 shows monomers contained in the copolymers A-1 to A-5.

  In the preparation of copolymer 1, a solution of copolymer A-1 having a solid content of 40% was obtained in the same manner except that VMA 40 g, GMA 20 g, and CHMA 40 g were used instead of VMA 80 g and GMA 20 g.

  In the preparation of copolymer 1, a solution of copolymer A-2 having a solid content of 40% was obtained in the same manner except that VMA 60 g, GMA 20 g, and BnMA 20 g were used instead of VMA 80 g and GMA 20 g.

  In the preparation of copolymer 1, a solution of copolymer A-3 having a solid content of 40% was obtained in the same manner except that VMA 40 g, GMA 20 g, and BnMA 40 g were used instead of VMA 80 g and GMA 20 g.

  In the preparation of copolymer 1, 40% solid content was obtained in the same manner except that VMA 40 g, GMA 20 g, and BnMA 40 g were used instead of VMA 80 g and GMA 20 g, and perbutyl O 5.4 g was used instead of perbutyl O 3.8 g. A solution of polymer A-4 was obtained.

  In the preparation of the copolymer 1, VMA 40 g, GMA 20 g, and BnMA 40 g were used instead of MA 80 g and GMA 20 g, and perbutyl O 1.8 g was used instead of perbutyl O 3.8 g. A solution of polymer A-5 was obtained.

<Adjustment of copolymers B-1 to B-4, AB>
Table 3 shows monomers contained in the copolymers B-1 to B-4 and AB.

  A 500 mL four-necked flask was charged with 15 g of IOP, 250 g of the above copolymer 1 solution (solid content: 100 g), and 10 g of diethanolamine, and heated to 110 ° C. while aerated with nitrogen gas and stirred. The mixture was kept at 110 ° C. for 2 hours to complete the reaction between the glycidyl group and diethanolamine and cooled to obtain a copolymer B-1 solution having a solid content of 40%.

  In the preparation of the copolymer B-1, IOP 33g, a solution of the copolymer 2 instead of the copolymer 1 solution 250g (solid content 100g) was used, and the same conditions except that diethanolamine 22g was used. A solution of copolymer B-2 having a solid content of 40% was obtained.

  In the preparation of the copolymer B-1, the conditions other than using 33 g of IOP 33 g and 250 g of the copolymer 3 solution (solid content 100 g) instead of the solution of the copolymer 1 and using 22 g of diethanolamine were the same. A solution of copolymer B-3 having a solid content of 40% was obtained.

  In the preparation of the copolymer B-1, the conditions except that IOP 33 g and the solution of the copolymer 4 were used instead of the copolymer 1 solution 250 g (solid content 100 g) and diethanolamine 22 g were used, A solution of copolymer B-4 having a solid content of 40% was obtained.

  In the preparation of the copolymer B-1, a copolymer having a solid content of 40% was prepared in the same manner except that a solution of the copolymer A-2 (250 g of solid content) was used instead of the solution of the copolymer 1. A solution of coalescence AB was obtained.

<Details of copolymer>
The details of the copolymers A-1 to A-5, B-1 to B-4, and AB are shown in Table 4.

Details of the monomers used in the preparation of each copolymer are as follows.
VMA: behenyl methacrylate, MW; 339, carbon number of alkyl group 22, 22 manufactured by NOF Corporation GMA: glycidyl methacrylate, MW; 142, manufactured by Wako Pure Chemical Industries, Ltd. CHMA: cyclohexyl methacrylate, MW; 182.5, Wako Pure BnMA: Benzyl methacrylate, MW; 176.5, manufactured by Wako Pure Chemical Industries, Ltd. DEA: Diethanolamine, MW: 105.1, manufactured by Wako Pure Chemical Industries, Ltd.

<Ink adjustment>
Inks were prepared with the formulations shown in Tables 5 and 6.
In Example 1, 2.63 g of the copolymer A-3 solution (solid content: 1.05 g), 2.63 g of the copolymer B-2 solution (solid content: 1.05 g), 3.5 g of pigment (Carbon black, MA-7 manufactured by Mitsubishi Chemical Corporation), 14.00 g of IOP, and 12.25 g of AF-4 (naphthenic solvent, manufactured by Nippon Oil Co., Ltd.) were mixed, and zirconia beads (diameter 0. 0) were mixed. 5 mm), and dispersed for 120 minutes by a rocking mill (RMO5S type, manufactured by Seiwa Giken Co., Ltd.). After dispersion, the zirconia beads were removed, and the particles were filtered through 3.0 μm and 0.8 μm membrane filters in order to remove dust and coarse particles, thereby obtaining an ink.

  In Examples 2 to 8 and Comparative Examples 1 to 3, inks were prepared in the same manner as in Example 1 except that the formulations shown in Tables 5 and 6 were used.

<Evaluation>
Using each of the inks described above, the surface density, penetration, and storage stability were evaluated. The results are shown in Tables 5 and 6.

(Table concentration)
Each ink described above is loaded into ORPHISX 9050 (manufactured by Riso Kagaku Kogyo Co., Ltd.), and a solid image is printed at 300 × 300 dpi on plain paper (ideal paper thin mouth, manufactured by Riso Kagaku Kogyo Co., Ltd.), thereby evaluating the print density. did. The surface OD value of the obtained solid image was measured using an optical densitometer (RD920, manufactured by Macbeth Co.) and evaluated according to the following criteria. The ORPHISX 9050 is a system that uses a line-type inkjet head and conveys paper in the sub-scanning direction orthogonal to the main scanning direction (the direction in which the nozzles are arranged) to perform printing.
AA: 1.10 or more A: 1.05 or more and less than 1.10 B: 1.0 or more and less than 1.05 C: Less than 1.0

(Betrayal)
A solid image was printed in the same manner as the evaluation of the above table density, and the back surface OD value of the obtained solid image was measured using an optical densitometer (RD920, manufactured by Macbeth Co., Ltd.) and evaluated according to the following criteria. The strikethrough is evaluated as better as the back surface OD value is lower.
AA: Less than 0.21 A: 0.21 or more and less than 0.24 B: 0.24 or more and less than 0.27 C: 0.27 or more

(Storage stability (70 ° C, 4 weeks))
After measuring the initial viscosity of each ink described above, each ink was put in a sealed container and allowed to stand in an environment of 70 ° C. for 4 weeks. Thereafter, the viscosity of the ink was measured, and the rate of change in viscosity ([(after 4 weeks Viscosity value × 100) / (initial viscosity value)] − 100 (%)) was determined and evaluated according to the following criteria. The viscosity of the ink is a viscosity at 10 Pa when the shear stress is increased from 0 Pa at a rate of 0.1 Pa / s at 23 ° C., and is a stress-controlled rheometer RS75 (cone angle: 1 °, diameter: 60 mm) manufactured by Harke. It was measured.
A: Viscosity change rate is less than ± 5% A: Viscosity change rate is ± 5% or more and less than ± 10% B: Viscosity change rate is ± 10% or more and less than ± 20% C: Viscosity change rate is ± 20% or more

  As shown in Tables 5 and 6, the ink of each example includes both a copolymer containing a carbocyclic ring and a copolymer containing a nitrogen-containing group, and the surface concentration and the strikethrough are good together with the storage stability. It was.

  In Examples 1, 2, and 4, the copolymers A-3, 1, and 5 were used, and the carbocyclic portion content and the weight average molecular weight of the copolymer (A) were more appropriate. The strikethrough and storage stability were better.

  In Example 3, the weight average molecular weight of the copolymer A-4 was relatively small, and the storage stability was slightly lowered. In Example 5, the weight average molecular weight of the copolymer B-3 was relatively large, and the breakthrough was slightly reduced. In Example 6, the weight average molecular weight of the copolymer B-4 was relatively small, and the storage stability was slightly lowered. In Example 7, the content of the copolymer A-2 was relatively small, and the surface concentration and the back-through were slightly reduced. In Example 8, the amine group content of the copolymer B-1 was relatively small, and the storage stability was lowered.

  In Comparative Example 1, a copolymer containing both a benzene ring and an amine group in one molecule was included, and the surface concentration and the strike-through decreased. In Comparative Example 2, only the copolymer containing a benzene ring was included, and the surface concentration and storage stability were lowered. In Comparative Example 3, only the copolymer containing an amine group was contained, and the surface concentration and the strikethrough were lowered.

Claims (9)

  Alkyl (meth) acrylate copolymer having a carbocyclic portion of 2.5% by mass to 25% by mass with respect to the entire copolymer, and having a nitrogen-containing base of 0.05% by mass or less with respect to the entire copolymer. (A), an alkyl (having a nitrogen-containing base of 0.5% by mass to 5.0% by mass relative to the entire copolymer, and having a carbocyclic moiety of 1.0% by mass or less based on the entire copolymer; A non-aqueous pigment ink comprising a (meth) acrylate copolymer (B), a pigment (C), and an organic solvent (D).   The non-aqueous pigment ink according to claim 1, wherein the carbocyclic portion includes a substituted or unsubstituted aromatic hydrocarbon group and / or a substituted or unsubstituted alicyclic hydrocarbon group.   The non-aqueous pigment ink according to claim 1, wherein the nitrogen-containing base portion includes at least one selected from an amino group, a cyano group, a nitrile group, an amide group, and a urethane bond.   The carbocyclic part of the said alkyl (meth) alkylate copolymer (A) is 0.05 mmol / g-1.0 mmol / g with respect to 1 g of pigments (C), The any one of Claim 1 to 3 The non-aqueous pigment ink described in 1.   5. The nitrogen-containing base part of the alkyl (meth) alkylate copolymer (B) is 0.2 mmol / g to 1.0 mmol / g with respect to 1 g of the pigment (C). The non-aqueous pigment ink described in 1.   At least one of the alkyl (meth) alkylate copolymer (A) and the alkyl (meth) alkylate copolymer (B) has an alkyl group having 12 to 25 carbon atoms. The non-aqueous pigment ink according to any one of the above.   The non-aqueous pigment ink according to any one of claims 1 to 6, wherein the alkyl (meth) alkylate copolymer (A) has a weight average molecular weight of 5,000 to 30,000.   The non-aqueous pigment ink according to any one of claims 1 to 7, wherein the alkyl (meth) alkylate copolymer (B) has a weight average molecular weight of 5,000 to 20,000.   The total amount of the alkyl (meth) alkylate copolymer (A) and the alkyl (meth) alkylate copolymer (B) is 1% by mass to 20% by mass with respect to the entire ink. The non-aqueous pigment ink according to any one of 8.