JP2015089933A - Non-aqueous ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-aqueous ink with which discharge stability is ensured by suppressing wettability of a nozzle plate while maintaining power saving, satellite suppression, and improved printing density, and with which amine odor is reduced.SOLUTION: A non-aqueous ink includes a color material, a non-aqueous solvent, a non-aqueous resin, and a water-soluble resin, in which the water-soluble resin includes a functional group formed by converting an amino group into urea. The water-soluble resin is an amino group-containing water-soluble resin in which the amino group is converted into urea. As the amino group-containing water-soluble resin, a basic polymer electrolyte such as polyethyleneimine (PEI), polyvinylamine, polyvinyl pyridine or the like, or a derivative thereof can be mentioned.

Description

  The present invention relates to a non-aqueous ink, and more particularly to a non-aqueous ink suitable for use in an ink jet recording system.

  Inkjet recording is a method in which high-fluidity inkjet ink is ejected from fine head nozzles as ink particles, and an image is recorded on a recording medium placed opposite to the nozzle, enabling high-speed printing with low noise. Therefore, it has been spreading rapidly in recent years. As an ink used in such an ink jet recording system, a so-called non-aqueous ink in which a color material is finely dispersed in a water-insoluble solvent is known.

  In recent years, it has been desired to reduce the power consumption of devices such as printers as much as possible from the viewpoint of resource environment and energy saving, and the demand for power saving is increasing more and more in ink-jet printing in order to save power.

In an ink jet recording apparatus, pressure is applied to an ink chamber provided in an ink jet head, and ink in the ink chamber is ejected from a nozzle. However, since the viscosity of the ink increases in a low temperature environment, a desired amount of ink is ejected. For this reason, it is necessary to increase the drive voltage of the ink jet head, which increases power consumption. Further, if discharge is performed with a high driving voltage, satellites are likely to be generated. Satellites adhere to the recording medium and reduce the print quality. Therefore, conventionally, in a low temperature environment where satellites are likely to be generated, recording is started after performing a so-called warm-up operation for heating the inkjet head in order to ensure print quality. This warm-up operation also causes an increase in power consumption.
From the above, in order to suppress power consumption, it is conceivable to reduce the viscosity of ink in a low temperature environment. However, it is extremely effective to reduce the viscosity of ink as a means for that purpose. Although it is possible to reduce the viscosity of the ink by reducing the amount of the color material and the amount of powder in the ink, there is a problem that the print density is lowered and the image quality is lowered.

  In order to solve the above problems, for example, Patent Document 1 discloses a primary and / or 2 in one molecule chemically reacted to a dispersant by reacting with a pigment, a dispersant, and a reactive functional group of the dispersant. An ink using a colorant in which a water-soluble resin containing two or more primary amino groups is combined has been proposed. This ink has high storage stability, pigment dispersibility, and ejection stability that does not cause clogging at the nozzle portion. However, with the colorant described in Patent Document 1, it is necessary to increase the amount of the dispersant in order to stabilize the ink in a low temperature environment, and the viscosity cannot be lowered to such an extent that the satellite is suppressed. .

By the way, it is possible to reduce the viscosity of the ink by using a hydrocarbon-based high boiling point and low-viscosity nonpolar solvent (hereinafter simply referred to as a hydrocarbon-based nonpolar solvent). The use of a hydrocarbon-based non-polar solvent as the ink solvent changes the polarity of the ink solvent and may deteriorate the pigment dispersion stability. This is considered to be solved by changing the composition of the dispersant. . Patent Document 2 proposes a non-aqueous pigment ink containing water-insoluble resin-dispersed fine particles having pigment dispersing ability.
However, the water-insoluble resin-dispersed fine particles described in Patent Document 2 have a functional group (urethane group) that adsorbs to the pigment inside the hydrocarbon-based nonpolar solvent and has an affinity for the hydrocarbon-based nonpolar solvent. In this case, the water-insoluble resin-dispersed fine particles are difficult to adsorb on the pigment, and a sufficient amount of pigment dispersibility cannot be ensured with a small amount. For this reason, it is necessary to preliminarily prescribe a large amount of water-insoluble resin-dispersed fine particles for the pigment, which causes a problem that the ink viscosity increases. On the other hand, the pigment dispersibility needs to have good affinity between the hydrocarbon-based nonpolar solvent and the pigment. If the affinity is too high, the pigment disperses when the hydrocarbon-based nonpolar solvent penetrates into the recording medium. However, there is a tendency to be easily pulled into the recording medium. As a result, the print density is lowered and the show-through tends to occur.

JP 2008-19333 A JP 2010-1452 A

  In order to solve the above problems, the present applicant is a non-aqueous pigment ink containing a pigment, a non-aqueous solvent, a water-insoluble resin, and a water-soluble resin, and the water-insoluble resin has at least carbon number. An acrylic resin comprising a copolymer of a monomer mixture containing an alkyl (meth) acrylate (A) having 8 to 18 alkyl groups and a monomer (B) having a β-diketone group or β-keto ester group. A non-aqueous pigment ink was proposed (Japanese Patent Application No. 2012-151614). In general, pigment dispersants are in an equilibrium state by repeated adsorption and desorption on the pigment surface, and the ink system is stabilized. However, in the non-aqueous pigment ink, a water-insoluble resin as a pigment dispersant is added to the pigment surface. The ink can be stabilized. As a result, power saving, satellite suppression and printing density improvement can be achieved, while low temperature aptitude and pigment dispersion stability can be ensured, and at the same time, show-through can be suppressed and high printing density can be realized. Can do.

  However, when the non-aqueous pigment ink is a water-soluble resin containing an amino group such as polyethyleneimine as the water-soluble resin, the ink is highly wettable with respect to the nozzle plate used in the inkjet head. Bending may occur during ejection or non-ejection. Further, the ink adhering to the nozzle plate may be transferred to a printed material such as paper, and stains may occur. In addition, there is a problem of giving off an unpleasant amine odor, leaving room for improvement.

  The present invention has been made in view of the above-described conventional problems, and the problems thereof are discharge stability by suppressing wettability to the nozzle plate while maintaining power saving, satellite suppression, and print density improvement. It is an object of the present invention to provide a non-aqueous ink and a method for producing the same, which can secure the odor and further reduce the amine odor.

The present invention for solving the above problems is as follows.
(1) A non-aqueous ink containing a coloring material, a non-aqueous solvent, a non-aqueous resin, and a water-soluble resin,
The non-aqueous ink, wherein the water-soluble resin contains a functional group in which an amino group is uread.

(2) preparing a mixture containing a coloring material, a non-aqueous solvent, a non-aqueous resin, and a water-soluble resin containing an amino group; and a monoisocyanate compound having an alkyl group having 8 or more carbon atoms in the mixture. Adding and ureating the amino group of the water-soluble resin,
A method for producing a non-aqueous ink, comprising:

(3) a step of preparing a mixture containing a coloring material, a non-aqueous solvent, a non-aqueous resin, and a water-soluble resin containing an amino group;
Adding a monoisocyanate compound having a C8 alkyl group or a polyisocyanate compound to the mixture and ureating the amino group of the water-soluble resin; and reacting the isocyanate compound with the water-soluble resin. Removing the water-soluble resin insolubilized by
A method for producing a non-aqueous ink, comprising:

  According to the present invention, while maintaining power saving, satellite suppression, and printing density improvement, non-aqueous ink that can suppress the wettability to the nozzle plate to ensure ejection stability and further reduce amine odor and A manufacturing method thereof can be provided.

<Non-aqueous ink>
The non-aqueous ink of the present invention is a non-aqueous ink containing a coloring material, a non-aqueous solvent, a non-aqueous resin, and a water-soluble resin, wherein the water-soluble resin has a functional group in which an amino group is ureaated. It is characterized by including a group.
The non-aqueous ink of the present invention has the effects of the non-aqueous pigment ink proposed by the present applicant (Japanese Patent Application No. 2012-151614) (power saving, satellite suppression and printing density improvement, low temperature suitability and pigment dispersion stability, In this case, the amine odor is reduced while maintaining the discharge stability by suppressing the wettability to the nozzle plate.
Hereinafter, each component of the non-aqueous ink of the present invention will be described in detail.

[Color material]
Examples of the color material contained in the non-aqueous ink of the present invention include pigments and dyes. Each will be described below.

(Pigment)
The non-aqueous ink of the present invention may have any color, and examples of the pigment include organic pigments such as azo, phthalocyanine, dye, condensed polycyclic, nitro, and nitroso (brilliant carmine 6B, Lake red C, watching red, disazo yellow, hansa yellow, phthalocyanine blue, phthalocyanine green, alkali blue, aniline black, etc.); metals such as cobalt, iron, chromium, copper, zinc, lead, titanium, vanadium, manganese, nickel Metal oxides and sulfides, and inorganic pigments such as ocher, ultramarine, and bitumen, and carbon blacks such as furnace carbon black, lamp black, acetylene black, and channel black can be used. Any one of these pigments may be used alone, or two or more of these pigments may be used in combination.

  The content of the pigment in the non-aqueous ink of the present invention is usually 0.01 to 20% by mass, preferably 1 to 15% by mass from the viewpoint of printing density and ink viscosity, and 5 to 10% by mass. More preferably it is.

(dye)
As dyes, azo dyes, metal complex dyes, naphthol dyes, anthraquinone dyes, indigo dyes, carbonium dyes, quinoneimine dyes, xanthene dyes, cyanine dyes, quinoline dyes, nitro dyes, nitroso dyes, benzoquinone dyes, naphthoquinone dyes, phthalocyanine dyes, Mention may be made of oil-soluble dyes such as metal phthalocyanine dyes.
Any one of these dyes may be used alone, or two or more of these dyes may be used in combination.

  The content of the dye in the non-aqueous ink of the present invention is usually 0.01 to 10% by mass, preferably 0.3 to 5% by mass from the viewpoint of printing density and ink viscosity, 0.5 to More preferably, it is 3 mass%.

  The average particle diameter of the color material in the ink is preferably about 500 nm or less, more preferably 200 nm or less, and even more preferably 150 nm or less. On the other hand, the average particle diameter is preferably about 50 nm or more in order to prevent the print-through of the printed matter. Here, the average particle diameter of the coloring material is a volume-based value measured by a dynamic light scattering particle size distribution measuring apparatus LB-500 manufactured by Horiba, Ltd.

[Non-aqueous solvent]
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 of two or more as long as they form a single phase. From the viewpoint of lowering the viscosity, it is preferable to use a nonpolar organic solvent.
The content of the nonpolar organic solvent is preferably 20% by mass or more, more preferably 40% by mass or more, and further preferably 50% by mass or more with respect to the total mass of the ink solvent. When the content of the hydrocarbon-based nonpolar solvent is 20% by mass or more based on the total amount of the solvent, the viscosity can be sufficiently lowered.

  When the content of the nonpolar organic solvent is 50% by mass or more based on the total mass of the ink solvent, it is possible to obtain the effect of further reducing the ink viscosity and further improving the storage stability. When the content of the non-polar organic solvent is 50% by mass or more with respect to the total mass of the ink solvent, the water-soluble resin hardly collects in the ink solvent and gathers in the vicinity of the color material and strongly adheres to the surface of the color material. To adsorb. For this reason, not only can the viscosity of the solvent itself be lowered, but also the effect of lowering the viscosity by being able to reduce the amount of free resin in the solvent can be obtained, and the dispersion stability of the colorant can be further improved. Presumed to be possible.

  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 alicyclic hydrocarbon solvent include paraffinic, isoparaffinic, and naphthenic solvents. For example, what is sold with the following brand names is mentioned. Teclean N-16, Teclean N-20, Teclean N-22, Naphthezol L, Naphthezol M, Naphthezol H, No. 0 Solvent L, No. 0 Solvent M, No. 0 Solvent H, Isosol 300, Isosol 400, AF Solvent No. 4, AF Solvent No. 5, AF Solvent No. 6, and AF Solvent No. 7 (all manufactured by JX Nippon Oil & Energy Corporation); Isopar G, Isopar H, Isopar L, Isopar M, Exol D40, Exol D80, Exol D100, Exol D130 and Exol D140 (both manufactured by TonenGeneral Sekiyu KK). Examples of the aromatic hydrocarbon solvent include grade alkene L, grade alkene 200P (all manufactured by JX Nippon Oil & Energy Corporation), Solvesso 200 (manufactured by TonenGeneral Sekiyu KK), and the like.

  Preferable examples of the polar organic solvent include ester solvents, higher alcohol solvents, higher fatty acid solvents, and the like. For example, methyl laurate, isopropyl laurate, isopropyl 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, trimethylolpropane tri-2-ethylhexanoate, tri Ester solvent having 14 or more carbon atoms in one molecule such as glyceryl 2-ethylhexanoate; isomyristyl alcohol, isopalmityl alcohol, isostear Higher alcohol solvents with 8 or more carbon atoms in one molecule such as alcohol, oleyl alcohol, etc .; carbon in one molecule such as isononanoic acid, isomyristic acid, hexadecanoic acid, isopalmitic acid, oleic acid, isostearic acid And higher fatty acid solvents having a number of 9 or more.

[Non-aqueous resin]
The non-aqueous resin is a co-polymer of a monomer mixture containing an alkyl (meth) acrylate (A) having at least an alkyl group having 8 to 18 carbon atoms and a monomer (B) having a β-diketone group or β-keto ester group. acrylic resin comprising a polymer, an oil-modified alkyd resin and / or fatty acid-modified alkyd resin oil length iodine value consists more oils and / or fatty 100gI 2 _/ 100g is 50 mass% or more, and oil-modified polyester resin And / or a fatty acid-modified polyester resin, or an epoxy resin having an alkyl group having 8 to 18 carbon atoms. Among them, an acrylic resin made of the above-mentioned copolymer from the viewpoint of improving printing density and suppressing back-through. Is preferred.

  In the acrylic resin, since it contains an alkyl group having 8 to 18 carbon atoms, it is highly compatible with the non-aqueous solvent hydrocarbon non-polar solvent, and thus is dissolved in the non-aqueous solvent. By containing a β-diketone group or a β-keto ester group, the viscosity of the ink can be lowered, and the low-temperature suitability can be further improved. In addition, by suppressing the increase in viscosity, it contributes to electrostatic aggregation and fixing of the ink when the ink lands on the recording medium. As a result, the printing density is improved and the back-through is suppressed. be able to.

  In the acrylic resin, when the alkyl group has 19 or more carbon atoms, the water-insoluble resin tends to solidify at a low temperature and the low-temperature suitability may be deteriorated. On the other hand, when the number of carbon atoms is 7 or less, the compatibility with the hydrocarbon-based nonpolar solvent is lowered, and the coloring material cannot be stably dispersed, so that the storage stability is deteriorated and the viscosity of the ink is also reduced. It can be expensive. Further, in a low temperature environment, the ink viscosity is further increased, and the low temperature aptitude is deteriorated. The number of carbon atoms of the alkyl group is more preferably 12-18.

  The alkyl group having 8 to 18 carbon atoms may be linear or branched. Specifically, an octyl group, a nonyl group, a decyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, and the like may be mentioned, and these may include a plurality of types. .

  Examples of the β-diketone group constituting the functional group include acetoacetyl group and propionacetyl group as preferred examples. Examples of the β-keto acid ester group include acetoacetoxy group and propionacetoxy group as preferred examples. Can be mentioned.

The molecular weight (weight average molecular weight) of the acrylic resin is not particularly limited, but when used as an inkjet ink, it is preferably about 5000 to 50000, and preferably about 10,000 to 30000 from the viewpoint of ink ejection. Is more preferable.
The glass transition temperature (Tg) of the acrylic resin is preferably normal temperature or lower, and more preferably 0 ° C. or lower. Thereby, when the ink is fixed on the recording medium, the film formation can be promoted at room temperature.

  The alkyl (meth) acrylate (A) is an alkyl (meth) acrylate having an alkyl group having 8 to 18 carbon atoms, and forms the main chain of the acrylic resin together with the monomer (B). The alkyl group is a functional group of the main chain. Configure the group. Examples of the alkyl (meth) acrylate (A) include palmityl / stearyl methacrylate (C16 / C18), cetyl acrylate (C16), dodecyl methacrylate (C12), dodecyl acrylate (C12), 2-ethylhexyl methacrylate (C8), 2 -Ethylhexyl acrylate (C8) can be preferably mentioned. These can be used singly or appropriately mixed.

  The monomer (B) is a (meth) acrylate or (meth) acrylamide having a β-diketone group or a β-keto ester group, and forms the main chain of the acrylic resin together with the alkyl (meth) acrylate (A). -A diketone group or a β-keto ester group constitutes a functional group of the main chain. By including this monomer (B), the viscosity of the ink can be lowered, and the low-temperature suitability can be further improved. In addition, by suppressing the increase in viscosity, it contributes to electrostatic aggregation and fixing of the ink when the ink lands on the recording medium. As a result, the printing density is improved and the back-through is suppressed. be able to.

  Preferred examples of the monomer (B) include (meth) acrylates and (meth) acrylamides containing a β-diketone group or a β-keto acid ester group in the ester chain. More specifically, examples include acetoacetoxyalkyl (meth) acrylates such as acetoacetoxyethyl (meth) acrylate, acetoacetoxyalkyl (meth) acrylamides such as hexadione (meth) acrylate, acetoacetoxyethyl (meth) acrylamide, and the like. These may be used alone or in combination of two or more.

  In the monomer mixture (alkyl (meth) acrylate (A) and monomer (B)), the alkyl (meth) acrylate (A) is preferably contained in an amount of 30% by mass or more, and preferably 40 to 95% by mass. More preferably, it is 50-90 mass%. It is preferable that a monomer (B) is 3-30 mass%, and it is more preferable that it is 5-20 mass%.

  Each of the above monomers can be easily polymerized by known radical copolymerization. The reaction system is preferably carried out by solution polymerization or dispersion polymerization. In this case, in order to make the molecular weight of the acrylic resin after polymerization within the above preferred range, it is effective to use a chain transfer agent in combination 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), etc. Known 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. 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 (which will be described later) that can be used as they are as non-aqueous solvents for ink. In the polymerization reaction, other commonly used polymerization inhibitors, polymerization accelerators, dispersants and the like can also be added to the reaction system.

  The acrylic resin according to the present invention preferably has a comb structure having a urethane group as a side chain with respect to the main chain of the acrylic resin constituted by the alkyl (meth) acrylate (A) and the monomer (B). By the alkyl group having 8 to 18 carbon atoms of the alkyl (meth) acrylate (A), the affinity of the non-aqueous solvent described later with a hydrocarbon non-polar solvent is improved, and the solubility in the solvent is ensured. On the other hand, the coloring material can be adsorbed by the side chain of the urethane group to improve the storage stability.

  The side chain urethane group is a functional group capable of reacting with an amino group by using (meth) acrylate having a functional group capable of reacting with an amino group in addition to the alkyl (meth) acrylate (A) and the monomer (B). And an amino alcohol and a polyvalent isocyanate compound, which will be described later, can be introduced. Preferable examples of the functional group capable of reacting with an amino group include a glycidyl group, a vinyl group, and a (meth) acryloyl group.

  Examples of the (meth) acrylate having a glycidyl group include glycidyl (meth) acrylate, and examples of the (meth) acrylate having a vinyl group include vinyl (meth) acrylate and 2- (2-vinyloxyethoxy) ethyl (meth). An acrylate etc. are mentioned preferably. Examples of the (meth) acrylate having a (meth) acryloyl group include dipropylene glycol di (meth) acrylate and 1,6-hexanediol di (meth) acrylate. These (meth) acrylates may contain multiple types. In addition, (meth) acrylate having a functional group capable of reacting with these amino groups can be used even when a urethane group is not introduced.

An amino alcohol reacts with a functional group capable of reacting with an amino group and binds, and an isocyanate group (R ¹ N═C═O) of a polyvalent isocyanate compound is added to the hydroxy group of the amino alcohol as follows. Then, a urethane group (urethane bond) (carbamic acid ester: R ¹ NHCOOR) is introduced. Here, R- represents an amino alcohol part bonded to a functional group of the copolymer.
R ¹ N═C═O + R—OH → ROCONHR ¹
By the above, the urethane group which acts as an adsorbing group to the color material is introduced.

Examples of amino alcohols include monomethylethanolamine, diethanolamine, and diisopropanolamine. Among them, those having two hydroxy groups can increase the number of urethane groups to be formed, and therefore dialkanolamines (secondary) represented by the general formula (HOR) ₂ NH (R is a divalent hydrocarbon group). Alkanolamine) is preferable. These amino alcohols can also be used in combination of multiple types.

  From the viewpoint of introducing a urethane group, the amino alcohol is preferably reacted in an amount of 0.05 to 1 molar equivalent, relative to the functional group capable of reacting with the amino group of the (meth) acrylate. More preferably, the reaction is performed in an equivalent amount. When the amino alcohol is less than 1 molar equivalent, an unreacted functional group remains in the (meth) acrylate having a functional group capable of reacting with the amino group, but the remaining functional group is used as an adsorbing group to the colorant. It is thought to act.

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 the urethane group is introduced by the reaction with the hydroxy group, the polyvalent isocyanate compound is approximately equivalent to the hydroxy group contained in the charged raw material (0.98 to 0.98 to (1.02 molar equivalent) is preferable.

  The mass ratio of the copolymer part and the introduced urethane base part in the acrylic resin is preferably 80:20 to 99: 1, and more preferably 85:15 to 95: 5. The mass of the copolymer part in the acrylic resin is the total mass of the monomers used for the copolymerization, and the mass of the introduced urethane base is the total mass of the amino alcohol and polyvalent isocyanate compound used for the reaction. . Since the urethane base has a high adsorbing ability to the color material, it is considered that the higher the mass ratio of the urethane base, the higher the adsorption rate to the color material, but when the mass ratio is higher than 20, The compatibility of the colorant deteriorates and the amount of free water-insoluble resin increases, and the adsorption rate of the coloring material decreases.

[Water-soluble resin]
The water-soluble resin according to the present invention contains a functional group in which an amino group is ureated. Specifically, the water-soluble resin according to the present invention is one in which an amino group of a water-soluble resin containing an amino group used in the method for producing a non-aqueous ink according to the present invention to be described later is ureated.
A water-soluble resin containing an amino group can maintain power saving, satellite suppression, and improvement in printing density, but it is considered that a part thereof remains free in the solvent without adsorbing to the colorant. There is a concern that the presence of a small amount of the primary amino group or the secondary amino group of the water-soluble resin remaining in the solvent causes the water-soluble resin to adhere to the nozzle plate of the inkjet head and increase wettability. Therefore, in the present invention, the amino group of the water-soluble resin containing an amino group is uread to improve the wettability with respect to the nozzle plate while maintaining power saving, satellite suppression and printing density improvement. . Moreover, the amine odor can be reduced by ureating low molecular amines liberated in the solvent.
In addition, the water-soluble resin according to the present invention, that is, the water-soluble resin containing a functional group in which an amino group is ureated is a product in which a part of the amino group of the water-soluble resin containing an amino group is ureated, Details of the water-soluble resin will be described later.

(Content of each component)
The content of the non-aqueous resin with respect to the total amount of the ink is preferably 0.1% by mass or more, and more preferably 1% by mass or more from the viewpoint of ensuring dispersibility of the coloring material. On the other hand, if the content of the non-aqueous resin 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. It is more preferable that the amount is not more than mass%. That is, the content of the non-aqueous resin with respect to the total amount of the ink is more preferably 1 to 10% by mass, and further preferably 2 to 8% by mass.

  The content of the non-aqueous resin with respect to the color material is preferably 0.1 to 1.0 in terms of a mass ratio with respect to the color material from the viewpoint of ensuring storage stability. When the content of the non-aqueous resin with respect to the color material is too small as less than 0.1 by mass ratio with respect to the color material, or when it is too large with more than 1.0, it may be difficult to ensure storage stability.

  The content of the non-aqueous resin with respect to the water-soluble resin is preferably 0.1 to 20 and more preferably 0.4 to 10 by mass ratio. When the content of the non-aqueous resin is less than 0.1 or less than 20 by mass ratio with respect to the water-soluble resin containing amino groups, it may be difficult to ensure storage stability.

  The mass of the resin relative to the mass of the color material (the total amount of the non-aqueous resin and the water-soluble resin) is preferably 0.2 or more from the viewpoint of securing the effect of dispersibility of the color material, assuming that the mass of the color material is 1. From the viewpoint of improving the ink viscosity and avoiding poor discharge due to changes over time, it is preferably 1.5 or less.

  The content of the water-soluble resin containing an amino group is preferably 0.01 to 0.5, more preferably 0.05 to 0.3, and preferably 0.1 to 0 in terms of a mass ratio with respect to the coloring material. .2 is most preferred. The water-soluble resin containing amino groups is preferably contained in an amount of about 0.1 to 5% by mass, more preferably 0.5 to 1.5% by mass, based on the total amount of ink.

  The non-aqueous ink of the present invention may contain conventional additives in addition to the above components. Additives include surfactants such as anionic, cationic, amphoteric or nonionic surfactants, antioxidants such as dibutylhydroxytoluene, propyl gallate, tocopherol, butylhydroxyanisole, and nordihydroguaiare. And tic acid.

  The viscosity of the non-aqueous ink of the present invention is preferably 5 to 30 mPa · s at 23 ° C., although the suitability range varies depending on the nozzle diameter of the ejection head, the ejection environment, etc. in the case of an inkjet recording system. It is more preferably 5 to 15 mPa · s, and about 10 mPa · s is suitable for an inkjet recording apparatus. 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.

<Method for producing non-aqueous ink>
The non-aqueous ink of the present invention described above can be produced by the non-aqueous ink production method of the present invention described below.
The method for producing a non-aqueous ink according to the first aspect of the present invention includes a step of preparing and dispersing a mixture containing a coloring material, a non-aqueous solvent, a non-aqueous resin, and a water-soluble resin containing an amino group, and Adding a monoisocyanate compound having an alkyl group having 8 or more carbon atoms to the dispersion, and ureating the amino group of the water-soluble resin.
The method for producing a non-aqueous ink according to the second aspect of the present invention includes a step of preparing and dispersing a mixture containing a coloring material, a non-aqueous solvent, a non-aqueous resin, and a water-soluble resin containing an amino group, A step of adding a monoisocyanate compound having an alkyl group having less than 8 carbon atoms or a polyisocyanate compound to the dispersion to ureate an amino group of the water-soluble resin, and the isocyanate compound and the water-soluble resin. And a step of removing a water-soluble resin that is insolubilized by the reaction.
In any embodiment, the method for producing a non-aqueous ink according to the present invention includes urethanizing an amino group of a water-soluble resin having an amino group that is not adsorbed to a colorant and remains free in a solvent. Can improve the wettability. Moreover, the amine odor can be reduced by ureating low molecular amines liberated in the solvent.
Below, the 1st aspect and 2nd aspect of the manufacturing method of this invention are demonstrated sequentially.

<First aspect>
In this embodiment, a step of preparing and dispersing a mixture containing a coloring material, a non-aqueous solvent, a non-aqueous resin, and a water-soluble resin containing an amino group (hereinafter also referred to as “step A”), and the above. A step of adding a monoisocyanate compound having an alkyl group having 8 or more carbon atoms to the dispersion and ureating the amino group of the water-soluble resin (hereinafter also referred to as “step B1”).

[Step A]
In Step A, a mixture containing a coloring material, a non-aqueous solvent, a non-aqueous resin, and a water-soluble resin containing an amino group in a predetermined ratio is prepared, and the obtained mixture is sufficiently dispersed with a known disperser. To obtain a dispersion. Since these coloring material, non-aqueous solvent, and non-aqueous resin are the same as the coloring material, non-aqueous solvent, and non-aqueous resin described in the non-aqueous ink of the present invention described above, description thereof is omitted here. Only the water-soluble resin containing an amino group will be described.

(Water-soluble resin containing amino group)
Examples of the water-soluble resin containing an amino group include basic polymer electrolytes such as polyethyleneimine (PEI), polyvinylamine, and polyvinylpyridine, or derivatives thereof. Particularly, polyethyleneimine having a weight average molecular weight of 200 to 2000. Alternatively, modified polyethyleneimine obtained by addition reaction with polyethyleneimine having a weight average molecular weight of 200 to 2000 and either an acrylate ester or a vinyl compound can be suitably used. The modified polyethyleneimine has a ratio of 0.3 mol equivalent to less than 1 mol equivalent to the acrylic ester or vinyl compound when the total amine value of polyethyleneimine is 1 mol equivalent (hereinafter, simply referred to as modified polyethyleneimine). Is preferred). Here, the amine value is determined by the amine titration method (KOHmg / g) by (2) indicator titration method of JIS K-7237-1995 (total amine value test method for amine curing agent of epoxy resin), and the molecular weight of KOH is 56. It is calculated in terms of 11 mg / mmol.

  If the weight average molecular weight of the polyethyleneimine is less than 200, the effect of increasing the density with respect to plain paper is low, and if it is 2000 or more, the storage stability deteriorates depending on the storage environment. The weight-average molecular weight of polyethyleneimine is more preferably 300 to 1800 because the effect of increasing the concentration is great, the pour point is −5 ° C. or lower, and the storage stability at low temperatures is good. .

  As the polyethyleneimine, commercially available products can be used. For example, Epomin SP-006, Epomin SP-012, Epomin SP-018, Epomin SP-200 manufactured by Nippon Shokubai Co., Ltd. Lupasol FG, Lupasol manufactured by BASF Corporation G20 Waterfree, Lupasol PR8515, etc. can be mentioned preferably.

  In the modified polyethyleneimine, an acrylic acid ester and a vinyl compound may be used together. In this case, the ratio of the acrylic acid ester to the vinyl compound is 0.1 when the amine value of polyethyleneimine is 1 molar equivalent. 3 molar equivalents or more. When the amount is less than 0.3 molar equivalent, the effect of improving the ink repellency of the nozzle plate is weakened.

The mechanism for improving the ink repellency of the nozzle plate when modified polyethyleneimine is used is presumed as follows. That is, imino groups and amino groups (—NH, —NH ₂ ) present in inks using polyethyleneimine tend to adhere to the nozzle plate of the inkjet head. By using a modified polyethyleneimine obtained by Michael addition of an acrylate ester or vinyl compound to the imino group or amino group of polyethyleneimine, the ink repellency is increased and the wettability to the nozzle plate is improved.

Preferred examples of the acrylate ester include methyl acrylate, ethyl acrylate, t-butyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, and the like.
Preferable examples of the vinyl compound include vinyl halides such as acrylonitrile, vinyl chloride and vinyl fluoride, and vinyl acetate.

  The modified polyethyleneimine can be obtained by Michael addition of an acrylate ester or a vinyl compound to the imino group or amino group of polyethyleneimine. In detail, it is manufactured by dropping polyethyleneimine and an acrylic ester or vinyl compound into diethanolamine heated to 50 to 60 ° C. while stirring, and then maintaining at 50 to 60 ° C. for 1 to 3 hours. Can do.

  Even an acrylic resin that does not have a functional group with a high adsorbing ability to a coloring material such as a urethane group can be obtained by combining an acrylic resin having a β-diketone group or a β-keto ester group with a water-soluble resin. Combined use makes it possible to obtain a strong adsorbing ability to coloring materials. It is estimated that the dispersion of the color material can be stabilized by the interaction of the β-diketone group or β-keto acid ester group of the water-insoluble resin, the polar group of the water-soluble resin, and the color material. The Since the elimination of the water-insoluble resin from the coloring material is suppressed by the interaction between the β-diketone group or β-keto acid ester group, the polar group of the water-soluble resin, and the coloring material, the water-insoluble resin to be used As a result, the viscosity can be kept low while ensuring the dispersion stability of the coloring material, and the low temperature suitability can be improved.

  In addition, the comb-type acrylic resin having urethane groups as side chains increases the adsorptivity to the coloring material due to the urethane groups, but if the mass ratio of the urethane groups increases, the compatibility with the solvent deteriorates and the coloring material becomes The adsorption rate decreases, the amount of free water-insoluble resin increases, and the ink viscosity increases. However, when the comb-type acrylic resin having a urethane group as a side chain further has a β-diketone group or a β-keto acid ester group, a water-soluble resin can be used in combination with the coloring material. The action can be enhanced, the free water-insoluble resin can be reduced, and the ink viscosity can be lowered.

  Furthermore, the alkyl group having 8 to 18 carbon atoms of the acrylic resin improves the affinity of the non-aqueous solvent with the hydrocarbon non-polar solvent and ensures solubility in the solvent. If the affinity is too high, the coloring material tends to be drawn into the recording medium when the non-aqueous solvent penetrates into the recording medium. However, by combining the acrylic resin and the water-soluble resin, the dispersion stability of the coloring material is ensured even if the amount of the acrylic resin is suppressed, so the amount of the acrylic resin can be reduced. Infiltration is suppressed. As a result, show-through can be suppressed and a high print density can be realized.

In step A, a mixture containing a coloring material, a non-aqueous solvent, a non-aqueous resin, and a water-soluble resin containing an amino group is prepared. It is preferable that the ratio is the content of the coloring material, the non-aqueous solvent, the non-aqueous resin, and the water-soluble resin containing an amino group described in the water-based ink.
Moreover, there is no restriction | limiting in particular as a method of preparing a mixture, For example, a mixture can be prepared by preparing each component in a predetermined container and stirring suitably. Thereafter, the coloring material can be dispersed by using any dispersing means such as a ball mill and a bead mill, and if desired, it can be prepared by passing through a known filter such as a membrane filter. When polyethyleneimine is used as the water-soluble resin containing an amino group, polyethyleneimine is often slightly soluble or hardly soluble in general-purpose non-aqueous solvents. Therefore, it is desirable to use a device capable of applying a share such as a bead mill and mix in a state where the share is applied. When the water-soluble resin is soluble in the non-aqueous solvent to be used, such a share is unnecessary, but it is preferable to mix them under stirring.

[Step B1]
In step B1, a monoisocyanate compound having an alkyl group having 8 or more carbon atoms is added to the dispersion prepared in step A, and the amino group of the water-soluble resin is uread.

(Monoisocyanate compound having an alkyl group having 8 or more carbon atoms)
Examples of the alkyl group having 8 or more carbon atoms in the monoisocyanate compound include octyl group, nonyl group, dodecyl group, octadecyl group and the like. The alkyl group preferably has 8 to 18 carbon atoms, and the upper limit is 22.
Examples of the monoisocyanate compound include dodecyl isocyanate, octadecyl isocyanate, octyl isocyanate, nonyl isocyanate, hexadecyl isocyanate, behenyl isocyanate, etc. Among them, dodecyl isocyanate, octadecyl isocyanate and hexadecyl isocyanate are preferable.

In Step B1, the amino group of the water-soluble resin having an amino group is ureated by the monoisocyanate compound having an alkyl group having 8 or more carbon atoms. That is, the water-soluble resin contains a functional group in which some amino groups are ureated.
When the amino group of the water-soluble resin is ureated using a monoisocyanate compound, the amount of the monoisocyanate compound added is preferably an amount corresponding to 0.01 to 0.3 mol relative to the water-soluble resin. This is because the water-soluble resin that does not adsorb to the colorant and remains free in the solvent is uread, and a ratio corresponding to the free water-soluble resin is preferable. As reaction conditions, although it reacts also at normal temperature, since reaction is completed rapidly, it is preferable to heat at 50-60 degreeC.

<Second aspect>
In this embodiment, a step of preparing and dispersing a mixture containing a coloring material, a non-aqueous solvent, a non-aqueous resin, and a water-soluble resin containing an amino group (hereinafter also referred to as “step A”), the dispersion. Adding a monoisocyanate compound having an alkyl group having less than 8 carbon atoms or a polyisocyanate compound to the product, and ureating the amino group of the water-soluble resin (hereinafter also referred to as “step B2”), and the isocyanate A step of removing the water-soluble resin that is insolubilized by the reaction between the compound and the water-soluble resin (hereinafter also referred to as “step C”).
In addition, since the process A in this aspect is the same as the process A in a 1st aspect, description is abbreviate | omitted and the process B2 after is demonstrated below.

[Step B2]
In step B2, a monoisocyanate compound or polyisocyanate compound having an alkyl group having less than 8 carbon atoms is added to the mixture prepared in step A, and the amino group of the water-soluble resin is uread.

(Monoisocyanate compound having an alkyl group having less than 8 carbon atoms)
Examples of the alkyl group having less than 8 carbon atoms in the monoisocyanate compound include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. The alkyl group preferably has 1 to 6 carbon atoms.
Examples of the monoisocyanate compound include methyl isocyanate, ethyl isocyanate, butyl isocyanate, hexyl isocyanate, and the like. Among them, methyl isocyanate, ethyl isocyanate, and butyl isocyanate are preferable.

(Polyisocyanate compound)
Examples of the polyisocyanate compound include hexamethylene diisocyanate, tolylene diisocyanate, isophorone diisocyanate, isocyanurate type polyisocyanate (Duranate TSA-100, Duranate TSS-100 manufactured by Asahi Kasei Chemicals Corporation), biuret type polyisocyanate (Asahi Kasei Chemicals Corporation) Duranate 24A-100) and the like. Among them, hexamethylene diisocyanate and isocyanurate type polyisocyanate (Duranate TSA-100 manufactured by Asahi Kasei Chemicals Corporation) are preferable.

In step B2, the amino group of the water-soluble resin having an amino group is uread by a monoisocyanate compound having a C8 alkyl group or a polyisocyanate compound. In this embodiment, when some of the amino groups of the water-soluble resin are ureated by the isocyanate compound, the water-soluble resin that is not adsorbed to the colorant and remains free in the solvent becomes insoluble in the non-aqueous solvent and settles. To do.
When the amino group of the water-soluble resin is ureated using the monoisocyanate compound or polyisocyanate compound, the amount of the isocyanate compound added corresponds to 0.01 to 0.3 mol relative to the water-soluble resin. An amount is preferred. This is because the water-soluble resin that does not adsorb to the colorant and remains free in the solvent is uread, and a ratio corresponding to the free water-soluble resin is preferable. As reaction conditions, although it reacts also at normal temperature, since reaction is completed rapidly, it is preferable to heat at 50-60 degreeC.

[Step C]
In Step C, the water-soluble resin that is insolubilized by the reaction between the monoisocyanate compound or polyisocyanate compound having an alkyl group having less than 8 carbon atoms and the water-soluble resin is removed.
That is, in the process B2, as described above, the water-soluble resin that is not adsorbed by the colorant and remains free in the solvent becomes insoluble in the non-aqueous solvent by reacting with the isocyanate compound. In this step, the water-soluble resin is removed.
Examples of means for removing the insoluble water-soluble resin include filtering and centrifugation.

  In the production method of the present invention, other steps may be provided in any aspect, and other steps include a premixing step in step A, a dilution step, a heating step in step B, and a cooling step in step C. Etc.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

[Examples 1 to 13, Comparative Examples 1 to 9]
(Synthesis of resin solution a)
A four-necked flask was charged with AF Solvent No. 6 (naphthenic solvent; manufactured by JX Nippon Oil & Energy Corporation), and the temperature was raised to 110 ° C. while aerated with nitrogen gas and stirred. Next, while maintaining the temperature at 110 ° C., each monomer mixture having the composition shown in Table 1, AF Solvent No. 6, and perbutyl O (t-butylperoxy 2-ethylhexanoate; manufactured by NOF Corporation) Was added dropwise over 3 hours. Thereafter, perbutyl O was added in small amounts after 1 hour and 2 hours while maintaining at 110 ° C. Further, aging was performed at 110 ° C. for 1 hour and diluted with AF Solvent No. 6 to obtain a colorless and transparent resin solution a having a nonvolatile content of 50%. The weight average molecular weight (GPC method, standard polystyrene conversion) of the obtained resin solution was 12200.

(Synthesis of resin solution b)
As shown in Table 2, in a four-necked flask, the resin solution a obtained above (solid content 50% in AF Solvent No. 6 solvent), propylene glycol (Asahi Glass Co., Ltd.), diethanolamine (Corporation) Nippon Catalyst Co., Ltd.) was charged, and the temperature was raised to 110 ° C. while agitating with nitrogen gas. By maintaining at 110 ° C. for 1 hour, the reaction between the glycidyl group of the resin solution a and diethanolamine was completed. Thereafter, dibutyltin dilaurate was added as a catalyst, and a mixture of Takenate 600 (1,3-bis (isocyanatomethyl) cyclohexane, Mitsui Chemicals Polyurethane Co., Ltd.) and Exepal HL (hexyl laurate, manufactured by Kao Corporation) After the dropwise addition, the temperature was raised to 120 ° C. and reacted for 6 hours, followed by cooling to obtain a resin solution b having a solid content of 40%. The average molecular weight (GPC method, standard polystyrene conversion) was 22300.

(Preparation of non-aqueous ink)
In the proportions shown in Tables 3 to 5, the obtained non-aqueous resin, polyethyleneimine (Epomin SP-012 manufactured by Nippon Shokubai Co., Ltd.), pigment (carbon black, MA77 manufactured by Mitsubishi Chemical Corporation), and solvent for dispersion AF Solvent No. 6 and Exepearl HL were mixed, and the resulting preparation was sufficiently dispersed with a bead mill to prepare a pigment dispersion.
Next, as shown in Tables 3 to 5, an isocyanate compound was added, and the amino group of the remaining polyethyleneimine was ureated (Comparative Examples 7 to 9 only added an isocyanate compound). Thereafter, AF Solvent No. 6 and Exepearl HL are added as a viscosity adjusting solvent for dilution, and then the diluted solution is centrifuged, filtered through a 3 μm membrane filter to remove dust and coarse particles, and non-aqueous ink ( Hereinafter, this is simply referred to as “ink”.

  About the obtained ink, the average particle diameter and the viscosity of the ink were measured. The average particle size was measured with a dynamic light scattering particle size distribution device LB-500 manufactured by Horiba, Ltd. 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 Haake. It was measured.

(Evaluation method)
(Print density)
The obtained ink is loaded into an ink jet printer (Olfis X9050, manufactured by Riso Kagaku Kogyo Co., Ltd.). The paper type of the print setting is plain paper and the image quality is standard (300 x 300 dpi). The OD values of the front and back surfaces of a solid image printed on (Science Industrial Co., Ltd.) were measured using an optical densitometer (RD920, manufactured by Macbeth Co., Ltd.) and evaluated according to the following criteria. If the image density is high and the OD value on the back surface is low, it indicates that there is little show-through.
Print density (Table OD)
S: 1.20 or more A: 1.15 or more and less than 1.20 B: 1.10 or more and less than 1.15 C: 1.05 or more and less than 1.10 D: Less than 1.05 Print density (back OD)
S: 0.20 or less A: Over 0.20 or less 0.25 or less B: Over 0.25 or less 0.30 or less C: Over 0.30

(Ink storage stability (70 ° C))
Each ink was put in a sealed container and allowed to stand in an environment of 70 ° C. for 4 weeks. Thereafter, changes in the viscosity and average particle diameter of the ink were measured, and the measurement results were evaluated as follows. The viscosity and average particle diameter after standing were measured by the above methods.
Viscosity change rate:
[(Viscosity after 4 weeks × 100) / (initial value of viscosity)] − 100 (%)
Average particle size change rate:
[(Average particle diameter after 4 weeks × 100) / (initial value of average particle diameter)] − 100 (%)
S: The viscosity and the average particle diameter change rate of the color material are both less than ± 3% A: The viscosity and the average particle diameter change rate of the color material are either ± 3% or more and less than ± 5% B: The viscosity and the color material Either the average particle size change rate is ± 5% or more and less than ± 10% C: The viscosity and the average particle size change rate of the colorant are either 10% or more

(Low temperature aptitude)
The obtained ink was allowed to stand at −5 ° C. for 4 weeks, and then the ink viscosity at −5 ° C. was measured and evaluated according to the following criteria.
A: Less than 50 mPa · s B: 50 mPa · s or more and less than 100 mPa · s C: 100 mPa · s or more

(Discharge stability)
After each ink is loaded into an inkjet printer (Olfis X9050, manufactured by Riso Kagaku Kogyo Co., Ltd.) and printing is performed, the printing machine is stopped for 30 minutes and then discharged when the printing operation is resumed. Sex was evaluated according to the following criteria.
A: No ejection failure does not occur at all. B: Occasional ejection failure occurs but is recovered by suction cleaning operation. C: Non-ejection nozzles occur frequently.

(satellite)
Printing was performed on A4 paper with an inkjet printer (Olfis X9050 (manufactured by Riso Kagaku Co., Ltd.)) and evaluated according to the following criteria.
A: Almost no satellites can be confirmed and image quality is good. B: Satellites can be confirmed, but the image quality can withstand actual use. C: Satellites are remarkable and image quality cannot withstand actual use.

(Ink odor)
50 g of each ink was put in a 100 ml capacity container that was capable of being sealed, and was allowed to stand in an environment of 23 ° C. overnight. Then, the container was opened and smelled in the container, and evaluated according to the following criteria.
A: No amine odor B: Amine odor

(Ink repellency)
The ink was placed in a 30 ml container, one end of the nozzle plate was picked with tweezers, and the other end 2 cm was immersed in the ink. Thereafter, the nozzle plate was quickly pulled up, the time (seconds) until the ink film remaining on the nozzle plate became ink droplets was measured 10 times, and the average value was defined as the ink repellent time (seconds). Then, the ink repellent time after standing for 1 month at 60 ° C. with the nozzle plate immersed in ink was measured and evaluated according to the following criteria.
A: Less than 4 seconds B: 4 seconds or more and less than 8 seconds C: 8 seconds or more

From Tables 3 to 5, the following can be understood.
That is, the non-aqueous inks of Examples 1 to 11 are obtained by urethanating the amino group of polyethyleneimine, which is a water-soluble resin, with an isocyanate compound. Except for Examples 4 and 5, polyethyleneimine has an urethanated amino group. Functional group. In Examples 4 and 5, it is considered that the amino group of polyethyleneimine was uread, then became insoluble in a non-aqueous solvent, and was removed by filtration. In any of the examples, it can be seen that excellent evaluation results were obtained in printing density, storage stability, low temperature suitability, ejection stability, satellite suppression, ink odor reduction, and ink repellency (improvement in wettability).
On the other hand, Comparative Examples 1 and 2, which differ from Examples 1 and 2 only in that no isocyanate compound was added, respectively, were inferior only in ink repellency evaluation and improved in wettability to the nozzle plate. I understand that there is no. Moreover, in Comparative Examples 4-11, all did not use polyethyleneimine, and it was not able to make all the evaluations a favorable result simultaneously. In particular, in Comparative Examples 4, 5, 7 and 8, even dispersion could not be achieved.

Claims (1)

A non-aqueous ink containing a coloring material, a non-aqueous solvent, a non-aqueous resin, and a water-soluble resin,
The non-aqueous ink, wherein the water-soluble resin contains a functional group in which an amino group is uread.