JP2018053052A - Resin for oily inkjet ink, oily inkjet ink and manufacturing method of urethane-modified (meth)acryl polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin for oily inkjet ink improving ink storage stability and reducing by-product amount from the resin.SOLUTION: There is provided a (meth)acrylic polymer, which is a resin for oily inkjet ink having an urethane bond as a side chain, a unit A having an alkyl group having carbon atoms of 8 to 18, a unit B in which the urethane bond is introduced by a reaction of amino alcohol and polyvalent isocyanate with a base point which is a functional group reactive with an amino group, a unit C having a β-diketone group and/or β-keto acid ester group and a unit D having an alkylene oxide group represented by -(R-O)-, where R is an alkylene group having 1 to 4 carbon atoms.SELECTED DRAWING: None

Description

  The present invention relates to a resin for oil-based inkjet ink, an oil-based inkjet ink containing the resin, and a method for producing a urethane-modified (meth) acrylic polymer.

Resin dispersants are widely used to disperse particulate matter in non-aqueous solvents. For example, in the ink field, it has been studied to improve the storage stability of ink by stably dispersing a coloring material such as a pigment in a non-aqueous solvent using a resin dispersant.
Even in a system having a relatively low ink viscosity, such as an inkjet ink, it is desirable to stably disperse a pigment in a non-aqueous solvent. On the other hand, if a large amount of a resin dispersant is used to stably disperse the pigment, the ink viscosity becomes high and may not be suitable depending on the printing method.
In addition, if an attempt is made to increase the affinity between the pigment and the non-aqueous solvent by the resin dispersant, the pigment and the non-aqueous solvent are difficult to separate on the paper after printing, and the pigment penetrates into the paper together with the non-aqueous solvent. There may be a phenomenon of strikethrough.

Patent Document 1 discloses a non-aqueous pigment ink containing an acrylic polymer containing an alkyl (meth) acrylate unit having an alkyl group having 12 or more carbon atoms and a (meth) acrylate unit having a urethane group.
While the acrylic polymer of Patent Document 1 is excellent in dispersion stability in a solvent, it can prevent the pigment from penetrating into the inside of the paper by increasing the detachability between the pigment and the solvent on the paper surface. .
Since the acrylic polymer of Patent Document 1 has a long-chain alkyl group, the alkyl (meth) acrylate has excellent affinity with a non-aqueous solvent, and can improve the dispersion stability in the non-aqueous solvent. Moreover, the (meth) acrylate unit which has a urethane group of patent document 1 can surround a pigment by having a urethane group which has high polarity and adsorbs a pigment. And since the (meth) acrylate unit which has a urethane group of patent document 1 has high polarity and low solubility with respect to a non-aqueous solvent, it can improve the detachability of a non-aqueous solvent and a pigment after printing.

JP 2010-1452 A

As a method for introducing a urethane bond as a side chain into an acrylic polymer, an acrylic polymer is polymerized from a monomer mixture, and an isocyanate compound and a polyol are reacted with a functional group capable of reacting with an amino group in the acrylic polymer. The compound is reacted.
By-products may be generated at the stage of reacting the isocyanate compound and the polyol compound with the acrylic polymer, which may be a problem. This by-product may also be mixed into the ink.

  An object of the present invention is to provide an oil-based inkjet ink resin, an oil-based inkjet ink, and a method for producing the resin that improve ink storage stability and reduce the amount of by-products from the resin.

The gist of the present invention is as follows.
(1) A (meth) acrylic polymer having a urethane bond as a side chain, which is a unit having an alkyl group having 8 to 18 carbon atoms, a functional group capable of reacting with an amino group, and an amino alcohol and a polyvalent isocyanate. Unit B into which a urethane bond has been introduced by the reaction with, unit C having a β-diketone group and / or β-keto acid ester group, and — (R—O) — (wherein R has 1 to 4 carbon atoms) The resin for oil-based inkjet inks which has the unit D which has the alkylene oxide group represented by this.
(2) The resin for oil-based inkjet ink according to (1), wherein the unit D includes a unit derived from a (meth) acrylic monomer having an ethylene oxide group represented by the following general formula (1).
^{_{CH 2 = CR 1 -COO- (C}} 2 H 4 O) n -R 2 (1)
(In General Formula (1), R ¹ is a hydrogen atom or a methyl group, R ² is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aromatic ring-containing group having 6 to 10 carbon atoms, and n is It is an integer from 2 to 20.)
(3) The unit B is a reaction between an amino alcohol and a polyvalent isocyanate based on a unit derived from a (meth) acrylic monomer having a functional group capable of reacting with an amino group represented by the following general formula (2). Resin for oil-based inkjet inks as described in (1) or 2) containing the unit by which the urethane bond was introduce | transduced by.
^{_{CH 2 = CR 3 -COO-R}} 4 (2)
(In the general formula (2), R ³ is a hydrogen atom or a methyl group, and R ⁴ is a functional group capable of reacting with an amino group.)

(4) The mass ratio of the main chain of the (meth) acrylic polymer to the urethane bond part introduced into the (meth) acrylic polymer is 60:40 to 99: 1 (1) to (3 ) Resin for oil-based inkjet ink in any one of.
(5) Any of (1) to (4), wherein the functional group capable of reacting with the amino group of the unit B is at least one selected from a glycidyl group, a vinyl group, and a (meth) acryloyl group. A resin for oil-based ink-jet inks as described above.
(6) An oil-based inkjet ink comprising the oil-based inkjet ink resin according to any one of (1) to (5).

(7) a unit A having an alkyl group having 8 to 18 carbon atoms, a unit B having a functional group capable of reacting with an amino group, a unit C having a β-diketone group and / or a β-keto ester group, and-( R—O) — (wherein R is an alkylene group having 1 to 4 carbon atoms), a (meth) acrylic polymer having a unit D having an alkylene oxide group, an amino alcohol, and a polyvalent A method for producing a urethane-modified (meth) acrylic polymer, wherein a urethane bond is introduced into the (meth) acrylic polymer by reacting with an isocyanate compound.
(8) The urethane-modified (meth) acrylic polymer according to (7), wherein a fatty acid bismuth salt having a fatty acid moiety having 5 to 18 carbon atoms is added in the step of introducing a urethane bond into the (meth) acrylic polymer. Manufacturing method.
(9) Production of urethane-modified (meth) acrylic polymer according to (7) or (8), wherein a fatty acid having 8 to 18 carbon atoms is added in the step of introducing a urethane bond into the (meth) acrylic polymer. Method.

  According to the present invention, there are provided an oil-based inkjet ink resin, an oil-based inkjet ink, and a method for producing the resin that improve ink storage stability and reduce the amount of by-products from the resin.

Hereinafter, the resin for oil-based inkjet ink according to the present invention will be described using an embodiment.
The oil-based inkjet resin according to the present embodiment is a (meth) acrylic polymer having a urethane bond as a side chain, and is based on a unit A having an alkyl group having 8 to 18 carbon atoms and a functional group capable of reacting with an amino group. A unit B in which a urethane bond is introduced by the reaction of an amino alcohol and a polyvalent isocyanate, a unit C having a β-diketone group and / or a β-keto ester group, and — (RO) — (wherein R is an alkylene group having 1 to 4 carbon atoms), and has a unit D having an alkylene oxide group represented by:
According to this embodiment, an oil-based inkjet resin (hereinafter simply referred to as urethane) that improves the storage stability of oil-based inkjet ink (hereinafter sometimes simply referred to as “ink”) and reduces the amount of by-products from the resin. Sometimes referred to as a modified polymer).
In the present invention, (meth) acrylate means acrylate or methacrylate. The (meth) acrylic polymer means a polymer having an acrylate-derived unit, a methacrylate-derived unit, or a combination thereof.

Since the urethane-modified polymer according to the present embodiment has an alkyl group having 8 to 18 carbon atoms, the affinity for the non-aqueous solvent can be increased, and the urethane-modified polymer can be dispersed or dissolved in the non-aqueous solvent. Moreover, the urethane-modified polymer according to the present embodiment improves the affinity for the pigment and facilitates adsorption to the pigment by introducing a urethane bond into the side chain. Thus, in the urethane-modified polymer, the alkyl group is oriented in the solvent and the urethane bond portion is oriented in the pigment, so that the pigment can be stably dispersed in the non-aqueous solvent.
In addition, since the urethane bond part is highly polar, its solubility in non-aqueous solvents is low, and after printing, the releasability between the non-aqueous solvent and the pigment is increased on the paper surface, so that the pigment and paper together with the non-aqueous solvent. It is possible to prevent the penetration phenomenon from occurring inside.

When a by-product is generated in the polymerization of the urethane-modified polymer, the by-product is insoluble in the polymerization solvent and may settle if left standing. This sediment can be removed by a filter or centrifugal separation, but the removal efficiency is very poor due to the high viscosity of the resin itself.
In addition, the sediment causes a clogged pipe in a urethane-modified polymer or an ink production line including the urethane-modified polymer.
When a pigment is dispersed using a urethane-modified polymer containing a by-product, there is a problem that the screen inside the disperser is clogged and the dispersion efficiency is lowered.

In the polymerization of a urethane-modified polymer, insoluble by-products include, among raw materials, a monomer having a functional group capable of reacting with an amino group, a monomer having a β-diketone group and / or a β-keto ester group, an amino alcohol, It is thought that highly polar monomers such as polyvalent isocyanate reacted.
Therefore, in the present invention, by using a monomer having an alkylene oxide group together with these raw materials, the amount of by-products can be reduced in the polymerization of the urethane-modified polymer. As a result, the amount of by-products from the resin can be reduced without impairing the effect of ink storage stability of the urethane-modified polymer.

  The (meth) acrylic polymer (urethane-modified polymer) having a urethane bond as a side chain according to this embodiment is a unit A having an alkyl group having 8 to 18 carbon atoms, an amino alcohol based on a functional group capable of reacting with an amino group. Unit B into which a urethane bond has been introduced by the reaction of polyisocyanate with polyisocyanate, unit C having β-diketone group and / or β-keto ester group, and — (RO) — (wherein R is carbon A unit D having an alkylene oxide group represented by formula (1-4).

  This urethane-modified polymer includes a unit A having an alkyl group having 8 to 18 carbon atoms, a unit B ′ having a functional group capable of reacting with an amino group, a unit C having a β-diketone group and / or a β-keto ester group. And a (meth) acrylic polymer having a unit D having an alkylene oxide group represented by-(RO)-(wherein R is an alkylene group having 1 to 4 carbon atoms) It may be referred to as a trunk polymer.), An amino alcohol, and a polyvalent isocyanate compound are reacted to introduce a urethane bond into the (meth) acrylic polymer.

The alkyl group of unit A of the trunk polymer remains as it is in the final urethane-modified polymer and exhibits solvent affinity.
In the urethane-modified polymer, the unit A has 8 or more carbon atoms in the alkyl group, so that the affinity for non-aqueous solvents, particularly hydrocarbon non-polar solvents, can be increased. Can be dispersed or dissolved stably. When the solubility of the urethane-modified polymer is lowered, the urethane-modified polymer may become cloudy in a non-aqueous solvent and the viscosity may increase.
When the carbon number of the alkyl group of the unit A is 18 or less, the urethane-modified polymer can be dispersed or dissolved in a liquid state or a non-aqueous solvent at room temperature. When this carbon number is 19 or more, the urethane-modified polymer may solidify particularly at low temperatures.

  The functional group capable of reacting with the amino group of the backbone polymer unit B ′ serves as a base point for introducing a urethane bond. In the urethane-modified polymer, a unit B in which a urethane bond is introduced by a reaction between an amino alcohol and a polyvalent isocyanate is based on a functional group capable of reacting with an amino group.

By including the unit C having a β-diketone group and / or a β-keto acid ester group in the urethane-modified polymer, the viscosity of the urethane-modified polymer-containing liquid can be lowered. For example, when selecting an ink solvent, restrictions based on the viscosity value of the solvent itself are reduced, and the range of selection of a non-aqueous solvent can be expanded. In addition, when blending a fixing resin or an additive as necessary, the allowable range of ink viscosity increase by the blended components is widened, and the degree of freedom of ink formulation can be expanded.
A part of the β-diketone group and / or β-ketoester group of the unit C may react with a polyvalent isocyanate to form a urethane bond, while the remaining part is a β-diketone group and / Or remains in the urethane-modified polymer as β-keto acid ester groups.

  By containing the unit D having an alkylene oxide group in the urethane-modified polymer, the amount of by-products from the resin can be reduced. One factor is that when the monomers constituting each of the units A, B, and C are mixed and polymerized, the monomers constituting the unit D are included so that the monomers can be mixed more uniformly. This is because the reaction between the monomers is promoted to suppress the generation of unreacted monomers that do not contribute to the reaction. Some of the unreacted monomer may react with aminoalcohol and polyisocyanate in the subsequent urethanization reaction and be produced as an insoluble by-product.

The alkyl group having 8 to 18 carbon atoms of the unit A may be either a straight chain or a branched chain.
Examples of the alkyl group having 8 to 18 carbon atoms include octyl group (2-ethylhexyl group), isooctyl group, nonyl group, decyl group, dodecyl group (lauryl group), tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, Examples include heptadecyl group, octadecyl group, hexadecyl group (palmityl group), octadecyl group (stearyl group) and the like. These may be contained alone or in a plurality of types in one molecule.

Examples of the functional group capable of reacting with the amino group of the unit B include a glycidyl group, a vinyl group, and a (meth) acryloyl group.
As the unit B, for example, based on a unit derived from a (meth) acrylic monomer having a functional group capable of reacting with an amino group represented by the following general formula (2), a reaction between an amino alcohol and a polyvalent isocyanate is used. It is a unit in which the urethane bond is introduced.
_{^{CH 2 = CR 3 -COO-R}} 4 (2)
In the general formula (2), R ³ is a hydrogen atom or a methyl group.
R ⁴ is a functional group capable of reacting with an amino group, and examples thereof include a glycidyl group, a vinyl group, a (meth) acryloyl group, or a functional group containing one or more of these.

For example, in the above formula (2), when R ⁴ is a glycidyl group, it reacts with amino alcohol to open an epoxy group, and amino alcohol is added to the trunk polymer.
R ^a —COO—CH ₂ —CH (OH) —CH ₂ —N (R ^b OH) _p R ^c _2-p
Here, R ^a is a trunk polymer moiety, R ^b and R ^c are each independently an arbitrary alkyl group, and p is 1 or 2.
Then, the hydroxy group of the added amino alcohol and the polyvalent isocyanate react to introduce a urethane bond.

  Examples of the β-diketone group of the unit C include an acetoacetyl group and a propionacetyl group. Examples of the β-keto acid ester group of the unit C include an acetoacetoxy group and a propionacetoxy group.

The alkylene oxide group of unit D is represented by — (R—O) —, where R is an alkylene group having 1 to 4 carbon atoms. Preferably, the alkylene oxide group of unit D is represented by — (R—O) _n —, wherein R is an alkylene group having 1 to 4 carbon atoms, and n is preferably an integer of 2 to 20, Preferably, n is an integer of 2-10.
Specifically, as the alkylene oxide group of the unit D, a methylene oxide group, an ethylene oxide group, a propylene oxide group, a butylene oxide group, or a combination thereof can be used. Among these, an ethylene oxide group and a propylene oxide group can be preferably used.
As for the alkylene oxide group of the unit D, two or more alkylene oxide groups may be bonded to each other in the urethane-modified polymer.

The unit D is, for example, a unit derived from a (meth) acrylic polymer having an ethylene oxide group represented by the following general formula (1).
^{_{CH 2 = CR 1 -COO- (C}} 2 H 4 O) n -R 2 (1)
In the general formula (1), R ¹ is a hydrogen atom or a methyl group.
R ² is preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aromatic ring-containing group having 6 to 10 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, still more preferably. Is an alkyl group having 1 to 6 carbon atoms. By R ² is an alkyl group, it is possible to suppress the reactivity with a polyvalent isocyanate, to prevent the formation of by-products.
n is preferably an integer of 2 to 20, more preferably an integer of 2 to 10. When n is 20 or less, fluidity can be ensured in the monomer state and the polymerizability can be improved.

  The urethane-modified polymer preferably contains a plurality of units A. The plurality of units A may be composed of one type of functional group from among the functional groups described above, or may be composed of two or more different functional groups. The same applies to the units B, C and D.

The unit A is preferably contained in an amount of 30% by mass or more, more preferably 40 to 95% by mass, and still more preferably 50 to 90% by mass with respect to all units of the urethane-modified polymer.
The unit B is preferably 1 to 30% by mass and more preferably 3 to 25% by mass with respect to all units of the urethane-modified polymer.
The unit C is preferably 50% by mass or less and more preferably 1 to 40% by mass with respect to all units of the urethane-modified polymer.
The unit D is preferably 50% by mass or less and more preferably 1 to 40% by mass with respect to all units of the urethane-modified polymer.

In the urethane-modified polymer, the mass ratio “unit C: unit D” between the unit C and the unit D is preferably 10:90 to 90:10, more preferably 30:70 to 70:30.
The weight average molecular weight (Mw) of the trunk polymer is preferably from 6000 to 80000, more preferably from 7000 to 70000, and even more preferably from 8000 to 50000.

Preferably, the trunk polymer has a (meth) acrylic polymer as a main chain, and has the following side chain on a carbon atom of the main chain.
-CO-O-R ^{A
-CO-O-R B}
-CO-O- ^RC
-CO-O- ^RD
Here, ^RA is an alkyl group having 8 to 18 carbon atoms.
R ^B is a functional group capable of reacting with an amino group.
R ^C is a β-diketone group and / or a β-keto acid ester group.
R ^D is an alkylene oxide group.

The trunk polymer can be produced by copolymerizing a monomer mixture containing the following monomers.
Alkyl (meth) acrylate having an alkyl group having 8 to 18 carbon atoms;
Reactive (meth) acrylate having a functional group capable of reacting with an amino group;
Monomer having a β-diketone group and / or a β-keto acid ester group;
Monomer having an alkylene oxide group;

  Examples of the monomer A include palmityl (meth) acrylate (C16), isocetyl (meth) acrylate (C16), dodecyl (meth) methacrylate (C12), 2-ethylhexyl (meth) acrylate (C8), and stearyl (meth) acrylate. (C18), isostearyl (meth) acrylate (C18), isodecyl (meth) acrylate (C10), nonyl (meth) acrylate (C9), isooctyl (meth) acrylate (C8), tridecyl (meth) acrylate (C13), etc. Can be mentioned.

  As the monomer B, for example, a (meth) acrylate having a glycidyl group such as glycidyl (meth) acrylate; a vinyl group such as vinyl (meth) acrylate, 2- (2-vinyloxyethoxy) ethyl (meth) acrylate ( (Meth) acrylate; (meth) acrylate having a (meth) acryloyl group such as dipropylene glycol di (meth) acrylate and 1,6-hexanediol di (meth) acrylate.

  Preferred examples of the monomer C include (meth) acrylates and (meth) acrylamides containing a β-diketone group and / or a β-keto acid ester group in the ester chain. More specifically, examples include acetoacetoxyalkyl (meth) acrylates such as acetoacetoxyethyl (meth) acrylate; hexadione (meth) acrylates; acetoacetoxyalkyl (meth) acrylamides such as acetoacetoxyethyl (meth) acrylamide, and the like. .

  By including the monomer C, it is possible to introduce a functional group having an ionic group into the trunk polymer. In general, when an ionic group is introduced into a non-polar solvent having a low polarity, the viscosity of the ink is increased. However, the increase in viscosity can be suppressed by the presence of the monomer C. This also contributes to electrostatic aggregation and fixing of the ink when the ink lands on the recording medium, and as a result, it is possible to improve the print density and suppress the back-through.

As the monomer D, for example,
Polyethylene glycol mono (meth) acrylate,
Polypropylene glycol mono (meth) acrylate,
Polyethylene glycol propylene glycol mono (meth) acrylate,
Polyethylene glycol tetramethylene glycol mono (meth) acrylate,
Propylene glycol polybutylene glycol mono (meth) acrylate,
Octoxy polyethylene glycol polypropylene glycol (meth) acrylate,
Lauroxy polyethylene glycol (meth) acrylate,
Phenoxypolyethylene glycol (meth) acrylate,
Phenoxy polyethylene glycol polypropylene glycol (meth) acrylate etc. can be mentioned.
The number of repeating units n of the alkylene oxide group of the polyalkylene glycol moiety is preferably 2 to 20, more preferably 2 to 10.
Monomers A, B, C and D described above can be used alone or in combination of two or more.

  In addition to the monomers A, B, C and D described above, other monomers may be used as long as the effects of the present invention are not impaired. Other monomers include, for example, 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; -Olefin; Alkyl (meth) acrylates having an alkyl group with less than 8 carbon atoms may be mentioned.

In the production process of the trunk polymer, a monomer mixture containing the monomers A, B, C and D described above is prepared.
What is necessary is just to adjust the compounding quantity of the monomers A, B, C, and D in a monomer mixture so that it may become the ratio of the unit A of the above-mentioned (meth) acrylic polymer, the unit B, the unit C, and the unit D.

The polarities of the monomers are, in order from the lowest, alkyl (meth) acrylate A having an alkyl group having 8 to 18 carbon atoms <reactive (meth) acrylate B having a functional group capable of reacting with an amino group <β-diketone group and / or Or it tends to be a monomer C having a β-keto acid ester group.
Monomers that are easily dissolved in the polymerization solvent by themselves are monomer A and monomer B, and monomer C is dissolved in the polymerization solvent by using monomer B as a dissolution aid.
By adding the monomer D having an alkylene oxide group to this, the solubility of the monomer C is further improved, and a uniform monomer mixture can be produced. By using this monomer mixture, the subsequent urethanation reaction proceeds uniformly, and the amount of by-products can be reduced. Moreover, it can prevent that an unreacted monomer remains.
In particular, the (meth) acrylate having an alkylene oxide group tends to be soluble in the polymerization solvent and to be less polar than the monomer C having a β-diketone group and / or a β-keto ester group.

The monomer mixture described above can be polymerized by known radical copolymerization. The reaction system is preferably carried out by solution polymerization or dispersion polymerization.
In the polymerization reaction, a polymerization initiator, a chain transfer agent, a polymerization inhibitor, a polymerization accelerator, a dispersant and the like can be appropriately added to the reaction system in order to adjust the reaction rate.
Examples of the polymerization initiator include azo compounds such as AIBN (azobisisobutyronitrile); t-butylperoxybenzoate, t-butylperoxy-2-ethylhexanoate (Perbutyl O, manufactured by NOF Corporation), etc. Thermal polymerization initiators such as peroxides can be used. In addition, a photopolymerization initiator that generates radicals upon irradiation with active energy rays can be used.
Moreover, the molecular weight of the (meth) acrylic polymer obtained can be adjusted by using a chain transfer agent together in a reaction system. As the chain transfer agent, for example, thiols such as n-butyl mercaptan, lauryl mercaptan, stearyl mercaptan, and cyclohexyl mercaptan can be preferably used.

  The polymerization solvent (reaction solvent) used for the solution polymerization is not particularly limited, but is preferably one that can disperse or dissolve the resin obtained by polymerization. Moreover, when using resin for an ink, it is preferable to select suitably a polymerization solvent from the nonaqueous solvents of the ink mentioned later so that a polymerization solvent may be used as a nonaqueous solvent of an ink as it is.

  In this embodiment, the above-mentioned (meth) acrylic polymer (backbone polymer), amino alcohol, and polyvalent isocyanate compound are reacted to introduce a urethane bond into the backbone polymer. This reaction may be referred to as a urethanization reaction.

In the urethanization reaction, first, the amino group of the amino alcohol reacts and bonds to the functional group capable of reacting with the amino group of the unit B of the trunk polymer. Next, the isocyanate group (R ¹ N═C═O) of the polyvalent isocyanate compound undergoes an addition reaction to the hydroxy group of the amino alcohol as shown in the following formula. As a result, a urethane bond (—NH—CO—O—) is introduced, and the structure of the carbamate ester (R ¹ NHCOOR) is obtained.
(R ¹ N═C═O) + (R—OH) → R—OCONHR ¹
Here, R—OH represents an amino alcohol portion bonded to a reactive functional group of the (meth) acrylic polymer.
By the above, the urethane bond which acts as a pigment adsorption group is introduced with respect to the trunk polymer which does not have pigment adsorption ability.

Examples of amino alcohols include monomethylethanolamine, diethanolamine, and diisopropanolamine. Among them, since the number of urethane bonds formed by providing two hydroxy groups can be increased, dialkanolamine (secondary) represented by the general formula (HOR) ₂ NH (R is a divalent hydrocarbon group) Alkanolamine) is preferable. These amino alcohols can be used alone or in combination of two or more.

  This amino alcohol is preferably reacted at 0.05 to 1 molar equivalent from the viewpoint of introducing an appropriate amount of urethane bond to the functional group capable of reacting with the amino group of the unit B. It is more preferable to make it react by 1 molar equivalent. When the amino alcohol is less than 1 molar equivalent, an unreacted functional group remains in the unit B, but the remaining functional group is considered to act as an adsorbing group for the pigment.

Examples of the polyvalent isocyanate compound include aliphatic compounds such as 1,6-diisocyanate hexane, 1,3-bis (isocyanatemethyl) benzene, 1,3-bis (isocyanatemethyl) cyclohexane, 1,5-naphthalene diisocyanate, and fats. A cyclic type and an aromatic type are mentioned, and multiple types can also be used.
In order to prevent unreacted raw materials from remaining when introducing a urethane bond by reaction with a hydroxy group, the polyvalent isocyanate compound is approximately equivalent to a hydroxy group contained in the charged raw material (0.98 to 0.98 to (1.02 molar equivalent) is preferable.

In the above reaction, it is also preferable to add a polyhydric alcohol and react the polyhydric alcohol with the polyvalent isocyanate compound. By adding a polyhydric alcohol, formation of a urethane bond is repeated, and a polyurethane side chain that becomes a more polar side chain can be obtained.
Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, dipropylene glycol, 1,3 propanediol, polyethylene glycol, polypropylene glycol and the like, and a plurality of types can be used.
The polyhydric alcohol is also important for controlling the polarity of the resin. If the resin polarity becomes extremely large, the pigment dispersibility, the ink viscosity is lowered, and the ink storage stability is impaired. Therefore, the polyhydric alcohol can be reacted at 0 to 20 molar equivalents with respect to the amino alcohol. The reaction is preferably carried out at 0.05 to 10 molar equivalents.

  The mass ratio between the main chain (trunk polymer) of the urethane-modified polymer and the introduced urethane bond (branch or branch polymer) is preferably 60:40 to 99: 1, and 70:30 to 99: 1. It is more preferable that The mass of the main chain of the urethane-modified polymer is the total mass of the monomers used for the copolymerization, and the mass of the introduced urethane bond is the mass of the amino alcohol and polyvalent isocyanate compound used for the reaction. When alcohol is used, this is also the total mass.

A catalyst can be used in the urethanization reaction.
Examples of the catalyst include a tin-based catalyst such as dibutyltin dilaurate, a titanium-based catalyst such as titanium tetra-2-ethylhexoxide, a zirconium-based catalyst such as zirconium tetraacetylacetonate, and a zinc-based catalyst such as zinc naphthenate, A bismuth-based catalyst or the like can be used.

Especially, in a urethanation reaction, fatty acid bismuth salt can be used preferably as a catalyst. It is preferable to use a fatty acid together with a fatty acid bismuth salt.
Conventionally, tin-based catalysts have been widely used in urethanization reactions. However, from the viewpoint of environmental conservation, a tin-based catalyst is not suitable, so an alternative catalyst is required.
As a result of examining various catalysts from the viewpoint of safety and further examining the reaction rate and by-products, fatty acid bismuth salts can be preferably used as the catalyst for the urethanization reaction. Further, in the urethanization reaction, the amount of such a by-product can be effectively reduced by using a fatty acid together with the fatty acid bismuth salt for the by-product generated when the fatty acid bismuth salt is used.
Furthermore, since the tin-based catalyst has high reactivity, not only the main reaction but also the side reaction proceeds, and a by-product may be easily generated. On the other hand, by combining the fatty acid bismuth salt and the fatty acid, when the reaction proceeds slowly and the main reaction proceeds, the side reaction hardly occurs and the amount of by-products can be reduced.
The fatty acid bismuth salt is suitable for the urethanization reaction of the present embodiment in terms of the size of the element and the structure of the compound coordinated with the electron density compared to titanium, zirconium and zinc-based catalysts. In addition, the fatty acid part of the fatty acid bismuth salt increases the solubility in a non-aqueous solvent and allows the urethanization reaction to proceed more uniformly.

As the fatty acid bismuth salt, one in which three fatty acids are bonded to bismuth (III) can be used. The fatty acid moiety may be either saturated or unsaturated, but it is preferable to use a saturated fatty acid from the viewpoint of stability.
As a fatty-acid part, it is preferable that it is C5 or more, and it is more preferable that it is C8 or more. Thereby, the affinity with the alkyl group portion of the trunk polymer is increased, and the trunk polymer and the catalyst can be brought close to each other. If it does so, a catalyst can act locally in the reaction part of the amino alcohol part and polyvalent isocyanate of a trunk polymer, and a urethanation reaction can be accelerated | stimulated.
On the other hand, the fatty acid portion preferably has 18 or less carbon atoms, more preferably 10 or less. When the number of carbon atoms in the fatty acid portion of the fatty acid bismuth salt is increased, the affinity with the polymerization solvent may be reduced and may not contribute to the urethanization reaction. Further, by setting the number of carbon atoms to 18 or less, affinity with the alkyl group portion of the trunk polymer can be maintained.

Specific examples of the fatty acid bismuth salt include bismuth 2-ethylhexanoate (C8), bismuth neodecanoate (C10), bismuth octoate (C8), and bismuth neopentanoate (C5).
These fatty acid bismuth salts can be used alone or in combination of two or more.

The fatty acid bismuth salt is preferably blended in an amount of 1 part by mass or less, more preferably 0.8 parts by mass or less, and still more preferably 100 parts by mass (solid content) of (meth) acrylic polymer (trunk polymer). 0.5 parts by mass or less. Since the fatty acid bismuth salt remains as an impurity after the urethane-modified polymer is polymerized, the amount of the fatty acid bismuth salt is preferably small. In this embodiment, since the effect can be obtained even with a small amount of catalyst, the fatty acid bismuth salt is 0.50 parts by mass or less, further 0.45 parts by mass or less with respect to 100 parts by mass (solid content) of the trunk polymer. You may mix | blend.
On the other hand, the fatty acid bismuth salt may be blended in an amount of 0.01 parts by mass or more, particularly 0.05 parts by mass or more with respect to 100 parts by mass (solid content) of (meth) acrylic polymer (trunk polymer).

In the case of solution polymerization, the fatty acid bismuth salt is preferably blended at 0.30% by mass or less, more preferably 0.20% by mass or less, and still more preferably 0.15% by mass with respect to the total amount of the reaction system. It is as follows.
On the other hand, in the case of solution polymerization, the fatty acid bismuth salt is preferably blended at 0.01% by mass or more, more preferably 0.02% by mass or more, based on the total amount of the reaction system.

In the urethanization reaction, by using a fatty acid together with a fatty acid bismuth salt, the urethanization reaction can be promoted, the amount of by-products can be reduced, and the molecular weight of the urethane-modified polymer can be increased.
This is because the fatty acid structure is similar to the alkyl group part having 8 to 18 carbon atoms and the polymerization solvent contained in the trunk polymer, and thus the affinity between the trunk polymer and the fatty acid can be obtained. Furthermore, since the fatty acid structure is similar to the fatty acid portion of the fatty acid bismuth salt, the affinity between the fatty acid bismuth salt and the trunk polymer can be increased, and the reaction can be promoted.
As the reaction proceeds, monomers that do not contribute to the reaction are reduced, and generation of by-products can be suppressed. In addition, as the reaction proceeds, the urethanization reaction proceeds in a chain manner, the degree of polymerization is increased, and a high molecular weight polymer can be obtained.
Moreover, since an amine is contained in the reaction system of the trunk polymer, the functional group derived from the amine can be neutralized with a fatty acid, so that the urethanization reaction can proceed more efficiently.

The fatty acid may be either a saturated fatty acid or an unsaturated fatty acid, but is preferably a saturated fatty acid from the viewpoint of stability. The fatty acid may be either a straight chain fatty acid or a branched chain fatty acid.
The fatty acid preferably has 8 or more carbon atoms, more preferably 10 or more. When the fatty acid has 8 or more carbon atoms, the affinity with the alkyl group portion of the trunk polymer can be increased. If it does so, a catalyst can act locally because a fatty acid intervenes in a reaction part of an amino alcohol part and polyvalent isocyanate of a backbone polymer, and a urethanization reaction can be accelerated.
On the other hand, the fatty acid preferably has 18 or less carbon atoms, more preferably 16 or less. If the number of carbon atoms of the fatty acid is increased, the affinity with the polymerization solvent may be reduced and may not contribute to the urethanization reaction. Moreover, the affinity with the alkyl group part of the trunk polymer can be maintained by making the carbon number of the fatty acid 18 or less.
Examples of such fatty acids include isopalmitic acid (C16), octanoic acid (C8), stearic acid (C18), decanoic acid (C10), dodecanoic acid (C12), and the like.
These fatty acids can be used alone or in combination of two or more.

Fatty acids are preferably blended at a mass ratio of 0.8 or more, more preferably 1.0 or more, still more preferably 1.5 or more, and still more preferably 2. 0 or more. Thereby, the urethanization reaction can be promoted, and the amount of by-products can be further reduced.
On the other hand, since the fatty acid acts as an acid component after polymerizing the urethane-modified polymer, it is preferable that the amount of the fatty acid is small. The fatty acid is preferably blended at a mass ratio of 30 or less, more preferably 15 or less, with respect to the fatty acid bismuth salt 1. In order to reduce the blending amount of the fatty acid, the fatty acid can be blended at a mass ratio of 10 or less and further 7 or less with respect to the fatty acid bismuth salt 1.

  In the case of solution polymerization, the fatty acid is preferably 0.1% by mass or more, and may be 0.2% by mass or more, based on the total amount of the reaction system. On the other hand, in the case of solution polymerization, the fatty acid is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and 0.5% by mass or less, based on the total amount of the reaction system. Even the effect can be obtained.

It is preferable that the carbon number c1 of the alkyl group (8 to 18 carbon atoms) of the trunk polymer, the carbon number c2 of the fatty acid portion of the fatty acid bismuth salt, and the carbon number c3 of the fatty acid satisfy the following relationship.
When the fatty acid bismuth salt has a plurality of fatty acid moieties, the carbon number c2 is the carbon number of each fatty acid moiety. In this case, it is preferable that the carbon number c2 of each fatty acid part independently satisfies the following relationship.
c1> c3 ≧ c2

  In the present embodiment, the trunk polymer may be washed with a poor solvent after the step of obtaining the (meth) acrylic monomer (trunk polymer). This washing step is preferably performed before the urethanization reaction described above.

The weight average molecular weight (Mw) of the urethane-modified polymer is not particularly limited, but when used as an inkjet ink, it is preferably about 10,000 to 80,000 from the viewpoint of ink ejection properties, and is about 13,000 to 50,000. Is more preferable.
The glass transition temperature (Tg) of the urethane-modified polymer is preferably not higher than normal temperature, and more preferably 0 ° C. or lower. Thereby, when the ink is fixed on the recording medium, a film can be formed at room temperature.

  In the case of subjecting the urethane-modified polymer to solution polymerization, polymerization is performed so that the solid content of the trunk polymer is 15 to 60% by mass, and then the urethanization reaction is performed, so that the solid content of the urethane-modified polymer is 15 to 60% by mass. Can be polymerized. Within this range, the rate of polymerization and urethanization reaction can be easily controlled.

  The urethane-modified (meth) acrylic polymer according to this embodiment can be preferably used as a pigment dispersant. When a urethane-modified polymer is used as a pigment dispersant, it is preferably applied to oil-based ink.

  The urethane-modified polymer according to the present embodiment itself has a high pigment dispersibility, so that the blending amount can be reduced, and a pigment dispersant need not be added separately. As a result, it is possible to suppress adverse effects caused by the blending of pigment dispersants, which are usually polymer compounds, that is, increase in ink viscosity and decrease in storage stability, and in particular, improve ejection stability in inkjet recording systems. Can do. Furthermore, not only the storage stability under a normal use environment but also the storage stability under a high temperature environment condition can be ensured.

The oil-based ink includes at least a pigment and a non-aqueous solvent, and can further include a urethane-modified (meth) acrylic polymer as a pigment dispersant.
The urethane-modified polymer is preferably 0.1% by mass or more, and more preferably 2% by mass or more, from the viewpoint of ensuring pigment dispersibility with respect to the total amount of ink. On the other hand, when the content of the polymer is increased, not only the viscosity of the ink is increased, but also the storage stability in a high temperature environment may be lowered. Therefore, the urethane-modified polymer is preferably 20% by mass or less, and more preferably 10% by mass or less, based on the total amount of the ink.
In addition, the urethane-modified polymer is preferably 0.2 or more from the viewpoint of ensuring pigment dispersibility, assuming that the mass of the pigment is 1, and from the viewpoint of improving ink viscosity and avoiding ejection failure due to changes over time, 1 The following is preferable.

  As the non-aqueous solvent, any of a non-polar organic solvent and a polar organic solvent can be used. These may be used alone or in combination. In the present embodiment, it is preferable to use a water-insoluble organic solvent that does not uniformly mix with the same volume of water at 1 atm and 20 ° C. as the non-aqueous solvent.

Preferable examples of the nonpolar organic solvent include petroleum hydrocarbon solvents such as aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents.
Examples of the aliphatic hydrocarbon solvent and the alicyclic hydrocarbon solvent include non-aqueous solvents such as paraffinic, isoparaffinic, and naphthenic solvents, and commercially available products include 0 Solvent L, 0 Solvent M, 0 Solvent H, Cactus normal paraffin N-10, Cactus normal paraffin N-11, Cactus normal paraffin N-12, Cactus normal paraffin N-13, Cactus normal paraffin N-14, Cactus normal paraffin N-15H, Cactus normal paraffin YHNP Cactus normal paraffin SHNP, Isosol 300, Isosol 400, Teclean N-16, Teclean N-20, Teclean N-22, AF Solvent No. 4, AF Solvent No. 5, AF Solvent No. 6, AF Solvent No. 7, Futezol 160, Naphthezol 200, Naphthezol 220 (all manufactured by JX Nippon Oil & Energy Corporation); Isopar G, Isopar H, Isopar L, Isopar M, Exol D40, Exol D60, Exol D80, Exol D95, Exol D110, Exol D130 (Both manufactured by TonenGeneral Sekiyu KK) and the like can be preferably mentioned.
As the aromatic hydrocarbon solvent, grade alkene L, grade alkene 200P (all manufactured by JX Nippon Oil & Energy Corporation), Solvesso 100, Solvesso 150, Solvesso 200, Solvesso 200ND (all manufactured by TonenGeneral Sekiyu KK), etc. Can be preferably mentioned.
The distillation initial boiling point of the petroleum hydrocarbon solvent is preferably 100 ° C. or higher, more preferably 150 ° C. or higher, and even more preferably 200 ° C. or higher. The distillation initial boiling point can be measured in accordance with JIS K0066 “Method for Distillation Test of Chemical Products”.

Preferred examples of the polar organic solvent include fatty acid ester solvents, higher alcohol solvents, higher fatty acid solvents and the like.
For example, isononyl isononanoate, isodecyl isononanoate, methyl laurate, isopropyl laurate, hexyl laurate, isopropyl myristate, isopropyl palmitate, hexyl palmitate, isooctyl palmitate, isostearyl palmitate, methyl oleate, ethyl oleate , Isopropyl oleate, butyl oleate, hexyl oleate, methyl linoleate, ethyl linoleate, isobutyl linoleate, butyl stearate, hexyl stearate, isooctyl stearate, isopropyl isostearate, 2-octyldecyl pivalate, soybean oil Methyl, soybean oil isobutyl, tall oil methyl, tall oil isobutyl, etc., the number of carbon atoms in one molecule is 13 or more, preferably 16-30 fatty acid esters Agent;
Higher alcohol solvents having 6 or more, preferably 12 to 20 carbon atoms in one molecule, such as isomyristyl alcohol, isopalmityl alcohol, isostearyl alcohol, stearyl alcohol, oleyl alcohol, isoeicosyl alcohol, decyltetradecanol ;
Higher fatty acid solvents such as lauric acid, isomyristic acid, palmitic acid, isopalmitic acid, α-linolenic acid, linoleic acid, oleic acid, isostearic acid and the like having 12 or more carbon atoms, preferably 14-20 carbon atoms Is mentioned.
The boiling point of polar organic solvents such as fatty acid ester solvents, higher alcohol solvents and higher fatty acid solvents is preferably 150 ° C. or higher, more preferably 200 ° C. or higher, and further preferably 250 ° C. or higher. preferable. The non-aqueous solvent having a boiling point of 250 ° C. or higher includes non-aqueous solvents that do not exhibit a boiling point.

These non-aqueous solvents may be used alone or in combination of two or more as long as a single phase is formed. Moreover, you may include another organic solvent in the range which can form a single phase with the non-aqueous solvent to be used.
In the present embodiment, when a polymerization solvent is used in the production process of the urethane-modified (meth) acrylic polymer, a petroleum hydrocarbon solvent and a fatty acid ester solvent can be preferably used from the above non-aqueous solvents. Since higher alcohol solvents and higher fatty acid solvents have a considerable influence on the reaction system, it is preferable to limit the amount used as a polymerization solvent.
When blending a higher alcohol solvent and a higher fatty acid solvent with the oil-based ink, it is preferable to add them after preparing the urethane-modified (meth) acrylic polymer.

  As the pigment, organic pigments such as azo pigments, phthalocyanine pigments, polycyclic pigments, dyed lake pigments, and inorganic pigments such as carbon black and metal oxides can be used. Examples of the azo pigments include soluble azo lake pigments, insoluble azo pigments, and condensed azo pigments. Examples of phthalocyanine pigments include metal phthalocyanine pigments and metal-free phthalocyanine pigments. Polycyclic pigments include quinacridone pigments, perylene pigments, perinone pigments, isoindoline pigments, isoindolinone pigments, dioxysazine pigments, thioindigo pigments, anthraquinone pigments, quinophthalone pigments, metal complex pigments. And diketopyrrolopyrrole (DPP). Examples of carbon black include furnace carbon black, lamp black, acetylene black, and channel black. Examples of the metal oxide include titanium oxide and zinc oxide. These pigments may be used alone or in combination of two or more.

The average particle diameter of the pigment is preferably 300 nm or less, more preferably 200 nm or less, from the viewpoint of ejection stability and storage stability.
The pigment is usually 0.01 to 20% by mass with respect to the total amount of the ink, and preferably 1 to 15% by mass from the viewpoint of printing density and ink viscosity.

In order to stably disperse the pigment in the oil-based ink, the urethane-modified (meth) acrylic polymer according to the present embodiment can be used as a pigment dispersant.
Other pigment dispersants may be used in combination as long as the effects of the present invention are not impaired. As other pigment dispersants, any of an anionic dispersant, a cationic dispersant, and a nonionic dispersant may be used. In addition, as the other pigment dispersant, any of a high molecular weight compound and a low molecular weight compound (surfactant) may be used.

  From the viewpoint of color developability, a dye may be used in combination with the pigment. As the dye, those generally used in the technical field can be arbitrarily used. For example, basic dye, acid dye, direct dye, soluble vat dye, acid mordant dye, mordant dye, reactive dye, vat Examples thereof include dyes, sulfur dyes, metal complex dyes, and salt-forming dyes. You may use these individually or in combination of multiple types.

  In addition to the above components, the oil-based ink may contain various additives. As additives, nozzle clogging inhibitors, antioxidants, conductivity modifiers, viscosity modifiers, surface tension modifiers, oxygen absorbers, and the like can be appropriately added. These types are not particularly limited, and those used in the field can be used.

The oil-based ink can be prepared by an ordinary method. For example, all the components are put into a disperser such as a bead mill in a lump or divided and dispersed, and if desired, prepared by passing through a filter such as a membrane filter. it can.
In addition, the urethane-modified polymer may be produced in the form of a resin-containing liquid by solution polymerization as described above, and other components may be mixed or dispersed in the resin-containing liquid all at once or separately to prepare an oil-based ink. it can.

  The oil-based ink described above can be used as a general printing ink for ink jet printing, offset printing, stencil printing, gravure printing, electrophotographic printing, and the like. In particular, since the dispersion stability is good, it is preferably used as an inkjet ink.

  The viscosity of the inkjet 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. More preferably, it is 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 printing method using the inkjet ink is not particularly limited, and 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, it is preferable that the ink according to the present embodiment is ejected from the ink jet head based on a digital signal, and the ejected ink droplets are attached to the recording medium.

  In the present embodiment, the recording medium is not particularly limited, and printing paper such as plain paper, coated paper, special paper, cloth, inorganic sheet, film, OHP sheet, etc., and these are used as a base material and an adhesive layer on the back surface An adhesive sheet or the like provided with can be used. Among these, printing paper such as plain paper and coated paper can be preferably used from the viewpoint of ink permeability.

  Here, the plain paper is paper in which an ink receiving layer, a film layer, and the like are not formed on normal paper. Examples of plain paper include high quality paper, medium quality paper, PPC paper, reprinted paper, recycled paper, and the like. Plain paper is a paper in which ink easily penetrates because paper fibers having a thickness of several μm to several tens of μm form voids of several tens to several hundreds of μm.

  Further, as the coated paper, inkjet coated paper or so-called coated printing paper can be preferably used. Here, the coated printing paper is a printing paper conventionally used in letterpress printing, offset printing, gravure printing, etc., and has an inorganic pigment such as clay or calcium carbonate on the surface of high-quality paper or medium-quality paper. A printing paper provided with a coating layer by a paint containing a binder such as starch. Coated printing paper can be applied to fine coated paper, high-quality lightweight coated paper, medium-weight lightweight coated paper, high-quality coated paper, medium-quality coated paper, art paper, cast coated paper, etc., depending on the coating amount and coating method. being classified.

  Hereinafter, an embodiment of the present invention will be described. The present invention is not limited by the following examples. In the following description, “%” represents “mass%” unless otherwise specified.

<Ink preparation>
(Synthesis of trunk polymer)
Table 1 shows the formulation of the monomer mixture of the trunk polymers a to h.
Charge 126.5 g of isooctyl palmitate (Nikko Chemicals Co., Ltd.) to a 300 ml four-necked flask and heat to 110 ° C. with aeration and aeration of nitrogen gas, and add the monomer mixture of the formulation shown in Table 1 to this Further, 16.7 g of AF7 and 4 g of perbutyl O (t-butylperoxy 2-ethylhexaate (manufactured by NOF Corporation)) were added dropwise over 3 hours. Thereafter, while maintaining the temperature at 110 ° C., 0.2 g of perbutyl O was added after 1 hour and further heated for 1 hour. 12.7 g of isooctyl palmitate was added to obtain a stem polymer-containing liquid having a solid content of 40%.
The weight average molecular weight (GPC method, standard polystyrene conversion) of the obtained trunk polymer was 9000 to 12000.

Each component shown in Table 1 is as follows.
Palmityl-stearyl methacrylate: PSMA, manufactured by Kao Corporation.
2-ethylhexyl methacrylate: 2-EHA, manufactured by NOF Corporation.
Glycidyl methacrylate: GMA, manufactured by NOF Corporation.
2-acetoacetoxyethyl methacrylate: AAEM, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.
Methoxypolyethylene glycol methacrylate: n≈2, “trade name: Blemmer PME-100” manufactured by NOF Corporation, molecular weight of about 100.
Methoxypolyethylene glycol methacrylate: n≈4, “trade name: Blemmer PME-200” manufactured by NOF Corporation, molecular weight of about 200.
Methoxypolyethylene glycol methacrylate: n≈9, “trade name: Blemmer PME-400” manufactured by NOF Corporation, molecular weight of about 400.
The PSMA is a mixture of palmityl methacrylate and stearyl methacrylate.
N is the number of repeating units of ethylene glycol.

(Synthesis of urethane modified polymer)
Urethane bonds were introduced into the obtained trunk polymer to synthesize resins 1 to 9 as urethane-modified polymers.
The tops of Tables 2 and 3 show the formulations of urethane-modified polymers (resins 1-9).
According to the composition shown in each table, a mixture of diethanolamine and propylene glycol was added to the trunk polymer-containing liquid, and heated at 110 ° C. for 1 hour with aeration and stirring of nitrogen gas. Then, according to the composition shown in each table, a mixture of bismuth 2-ethylhexanoate and isopalmitic acid was added to this mixture, and then a mixture of diisocyanate and isooctyl palmitate was added dropwise over 1 hour. After dripping, it was made to react for 6 hours and the resin 1-9 of 40% of solid content was obtained.
Resins 7 to 9 were synthesized in the same manner except that the “mixture of bismuth 2-ethylhexanoate and isopalmitic acid” was changed to “dibutyltin dilaurate”.

Details of each component are as follows.
Diethanolamine: manufactured by Tokyo Chemical Industry Co., Ltd.
Propylene glycol: Wako Pure Chemical Industries, Ltd.
Bismuth 2-ethylhexanoate: Wako Pure Chemical Industries, Ltd.
Dibutyltin dilaurate: “L-101” manufactured by Tokyo Fine Chemical Co., Ltd.
Isopalmitic acid: manufactured by Tokyo Chemical Industry Co., Ltd.
Diisocyanate: 1,6-diisocyanate hexane, manufactured by Tokyo Chemical Industry Co., Ltd.
Isooctyl palmitate: manufactured by Nikko Chemicals Corporation.
AF7: “AF Solvent No. 7” manufactured by JX Nippon Oil & Energy Corporation, petroleum hydrocarbon solvent.

(Preparation of ink)
The lower part of Table 2 and Table 3 shows the formulation of each ink.
Using each of the resins 1 to 9, the ink raw materials were mixed according to the formulations shown in Tables 2 and 3, zirconia beads (diameter 0.5 mm) were added, and a rocking mill (Seiwa Giken Co., Ltd.) was used for 120 minutes. Distributed. 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, whereby ink was prepared.

Details of each component are as follows.
Carbon black: “NEROX500” manufactured by Evonik Japan.
Isooctyl palmitate: “IOP” manufactured by Nikko Chemicals Corporation.
Stearyl alcohol: manufactured by Higher Alcohol Industry Co., Ltd.
AF-4: “AF Solvent No. 4” manufactured by JX Nippon Oil & Energy Corporation; petroleum hydrocarbon solvent.

<Evaluation>
The following evaluation was performed about the obtained resin and ink. The results are shown in each table.

(Weight average molecular weight)
The weight average molecular weights of the resins 1 to 9 were measured using “GPC system” manufactured by Shimadzu Corporation. This gel permeation chromatography (GPC) can measure the molecular weight distribution of a synthetic polymer using a hydrophobic filler and a non-aqueous (organic solvent) mobile phase.
A styrene-divinylbenzene copolymer was used as the hydrophobic filler, and tetrahydrofuran was used as the organic solvent.
The measurement results were evaluated according to the following criteria.
A: The weight average molecular weight is 13,000 or more.
B: The weight average molecular weight is 10,000 or more and less than 13,000.
C: The weight average molecular weight is less than 10,000.

(By-product amount)
About the obtained resins 1-9, the amount of by-products in the resin-containing liquid was measured.
In the resin-containing liquid, the urethane-modified alkyl methacrylate is finely dispersed in the solvent, but the by-product is insoluble in the solvent and has a low dispersibility, so that it easily precipitates. Using this characteristic, predetermined centrifugation conditions were determined such that in the centrifugation of the resin-containing liquid, the urethane-modified alkyl methacrylate remained in the supernatant and the by-products settled. Under these centrifugation conditions, the resin-containing liquids of various resins 1 to 9 were centrifuged under the same conditions, the supernatant was removed, and the amount of sediment was measured. The mass ratio of the sedimentation amount was measured with respect to the total amount of the resin-containing liquid, and this was defined as the by-product amount. The amount of this by-product was evaluated according to the following criteria.
A: Less than 0.1%.
B: 0.1% or more and less than 0.3%.
C: 0.3% or more.

(Ink storage stability)
Each ink was put in a sealed container and left in an environment of 70 ° C. for 4 weeks. The ink viscosity before being left and the ink viscosity after being left were measured, and the rate of change in viscosity was determined from the following equation. This viscosity change rate was evaluated according to the following criteria.
The ink viscosity is the viscosity at 1000 s-1 when the shear rate is increased from 1 s-1 to 1000 s-1 at 23 ° C., and the rheometer MCR302 (Cone angle: 1 °, diameter: 50 mm) manufactured by Anton Paar Co., Ltd. Measured with
Viscosity change rate = [(viscosity after 4 weeks × 100) / (initial value of viscosity)] − 100 (%)
A: Viscosity change rate is less than 5%.
B: Viscosity change rate is 5% or more and less than 10%.
C: Viscosity change rate is 10% or more.
Each ink in the examples had an initial viscosity value in the range of 5 to 15 mPa · s.

(Catalyst, acid safety)
It was judged as a safety standard whether the catalyst and acid used in the synthesis of the resin are subject chemical substances under the PRTR system. The evaluation criteria are as follows.
A: Not applicable as a target chemical by PRTR system.
B: Corresponds to the target chemical substance under the PRTR system.

As shown in each table, in the inks of the examples, the amount of by-products of the resin can be suppressed to a small level, the ink storage stability is excellent, and the weight average molecular weight of the resin is within an appropriate range.
In Examples 1 to 3, various methoxypolyethylene glycol methacrylates were used, and good results were obtained.
Examples 4 and 5 were obtained by reducing the amount of methoxypolyethylene glycol methacrylate with respect to Examples 1 and 2, respectively, and were good results.
In Example 6, the amount of methoxypolyethylene glycol methacrylate was increased compared to Example 2, and each was a good result. In Example 6, although the amount of 2-acetoacetoxyethyl methacrylate was small and the ink storage stability was lowered, it was in a good range.
In Examples 1 to 6, a highly safe catalyst and acid were used, and good results could be obtained.
Example 7 was different from Example 1 in that a conventional tin-based catalyst was used, and although the amount of by-products of the resin was reduced, it was in a good range.

The polarities of the monomers are PSMA <LMA <GMA <AAEM in ascending order. Monomers that can be dissolved in the polymerization solvent alone are PSMA, LMA, and GMA. In AAEM, GMA became a dissolution aid and was dissolved in a synthetic solvent.
By adding methoxypolyethyleneglycol methacrylate (PME) to the monomer mixture, the solubility of AAEM is improved and a uniform monomer mixture solution is obtained. Therefore, the units derived from each monomer are uniformly arranged randomly in the trunk polymer, and then It is assumed that the urethanization reaction proceeds uniformly and by-products are reduced.
The PME used in the examples was soluble in the polymerization solvent and was less polar than AAEM.

In Comparative Example 1, methoxypolyethylene glycol methacrylate was not used, and the amount of resin by-products increased.
In Comparative Example 2, 2-acetoacetoxyethyl methacrylate was not used, the ink storage stability was lowered, and the amount of resin by-products was increased.

Claims (9)

A (meth) acrylic polymer having a urethane bond as a side chain,
Unit A having an alkyl group having 8 to 18 carbon atoms,
A unit B in which a urethane bond is introduced by a reaction between an amino alcohol and a polyvalent isocyanate based on a functional group capable of reacting with an amino group;
an alkylene oxide represented by a unit C having a β-diketone group and / or a β-keto ester group, and — (R—O) — (wherein R is an alkylene group having 1 to 4 carbon atoms). Having units D having groups,
Resin for oil-based inkjet ink. The resin for oil-based inkjet ink according to claim 1, wherein the unit D includes a unit derived from a (meth) acrylic monomer having an ethylene oxide group represented by the following general formula (1).
^{_{CH 2 = CR 1 -COO- (C}} 2 H 4 O) n -R 2 (1)
(In General Formula (1), R ¹ is a hydrogen atom or a methyl group, R ² is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aromatic ring-containing group having 6 to 10 carbon atoms, and n is It is an integer from 2 to 20.) The unit B is based on a unit derived from a (meth) acrylic monomer having a functional group capable of reacting with an amino group represented by the following general formula (2). The resin for oil-based inkjet ink according to claim 1, comprising a unit into which is introduced.
^{_{CH 2 = CR 3 -COO-R}} 4 (2)
(In the general formula (2), R ³ is a hydrogen atom or a methyl group, and R ⁴ is a functional group capable of reacting with an amino group.)   The mass ratio of the main chain of the (meth) acrylic polymer to the urethane bond part introduced into the (meth) acrylic polymer is 60:40 to 99: 1. The resin for oil-based inkjet inks as described in the item.   5. The functional group capable of reacting with the amino group of the unit B is at least one selected from a glycidyl group, a vinyl group, and a (meth) acryloyl group. Resin for oil-based inkjet ink.   The oil-based inkjet ink containing the resin for oil-based inkjet inks of any one of Claim 1 to 5. Unit A having an alkyl group having 8 to 18 carbon atoms,
Unit B having a functional group capable of reacting with an amino group,
an alkylene oxide represented by a unit C having a β-diketone group and / or a β-keto ester group, and — (R—O) — (wherein R is an alkylene group having 1 to 4 carbon atoms). A (meth) acrylic polymer having a unit D having a group;
Amino alcohol,
Reacting with a polyvalent isocyanate compound to introduce a urethane bond into the (meth) acrylic polymer;
A method for producing a urethane-modified (meth) acrylic polymer.   The method for producing a urethane-modified (meth) acrylic polymer according to claim 7, wherein a fatty acid bismuth salt having a fatty acid moiety having 5 to 18 carbon atoms is added in the step of introducing a urethane bond into the (meth) acrylic polymer. .   The method for producing a urethane-modified (meth) acrylic polymer according to claim 7 or 8, wherein a fatty acid having 8 to 18 carbon atoms is added in the step of introducing a urethane bond into the (meth) acrylic polymer.