JP2019086689A - Liquid developer - Google Patents

Abstract

To provide a liquid developer that is designed for acceleration of a liquid development system, has a small particle diameter and low viscosity, and has excellent electrification characteristics.SOLUTION: A liquid developer contains toner particles that contain a binder resin containing a resin having an acidic group and a colorant, a dispersant, and an insulating liquid, and the dispersant contains a copolymerization reactant (D) of an ethylenically unsaturated monomer (d-1) having an amino group, and a macromonomer (d-2) containing a (meth)acrylic polymer having a hydrocarbon group having 6 to 24 carbon atoms.SELECTED DRAWING: None

Description

  The present invention relates to a liquid developer used for developing a latent image formed in electrophotography, electrostatic recording, electrostatic printing and the like.

  The developer for electrophotography includes a dry developer using toner particles made of a material containing a colorant and a binder resin in a dry state, and a liquid developer in which toner particles are dispersed in an insulating carrier liquid.

  In the liquid developer, toner particles are dispersed in oil in the insulating liquid, and therefore, the particle diameter can be reduced as compared with the dry developer. Therefore, it is suitable for commercial printing applications because high quality printed matter over offset printing can be obtained. In addition, since the demand for speeding up has been increasing in recent years, it is required to lower the viscosity of the liquid developer.

  In a liquid development system, toner particles dispersed in an insulating carrier liquid are developed using an electric force on a latent image drawn on a photoreceptor, and further transferred to paper, and finally by heat or pressure. It is fixed. Conventional liquid developers have a low toner concentration, so the amount of toner supplied at one time is small, and speeding up is difficult. Therefore, to realize high speed, it is necessary to increase the toner concentration and to increase the toner supply amount, but when the toner concentration is high, the dispersibility is deteriorated. Although it is necessary to add a large amount of dispersant in order to improve the dispersibility, the amount of free dispersant increases and the chargeability is deteriorated.

  Patent Document 1 discloses a liquid developer containing resin particles insoluble in an insulating liquid and resin particles formed by suspension polymerization for the purpose of obtaining high image density with excellent dispersion stability. .

  In Patent Document 2, for the purpose of obtaining a resin particle dispersion having uniform particle diameter and shape and excellent low-temperature fixability, a dispersant has a single amount having an aliphatic cyclic hydrocarbon group having 5 to 30 carbon atoms. There is disclosed a resin particle dispersion containing a block copolymer having a body as a constituent unit or a graft copolymer having a monomer as a constituent unit in a main chain portion.

  In Patent Document 3, for the purpose of obtaining an output image excellent in fixability, offset resistance, color development and storage stability and stable over a long period of time, an ethylenically unsaturated monomer having an amino group, and having 4 to carbon atoms A liquid developer is disclosed which contains a polymeric dispersant copolymerized with an ethylenically unsaturated monomer containing 24 alkyl groups.

Japanese Patent Application Laid-Open No. 58-59458 JP 2012-140564 A JP, 2014-92579, A

  However, in the liquid developers described in Patent Documents 1 and 2, since the dispersant is difficult to be adsorbed to the binder resin, the dispersibility is poor, and it is difficult to reduce the particle diameter of the liquid developer. Further, in the liquid developer described in Patent Document 3, since the amount of the free dispersing agent in the insulating liquid is large, the chargeability is poor and an excellent image can not be obtained.

  The present invention relates to a liquid developer having a small particle size, a low viscosity, and an excellent chargeability, corresponding to the speeding up of a liquid development system.

  The present invention is a liquid developer containing a binder resin containing a resin having an acidic group and a toner particle containing a colorant, a dispersant, and an insulating liquid, and the dispersant contains ethylene having an amino group. Copolymer (D) of Polymerizable Unsaturated Monomer (d-1) and Macromonomer (d-2) Containing (Meth) acrylic Polymer Having a Hydrocarbon Group Having 6 to 24 Carbon Atoms A liquid developer containing

  The liquid developer according to the present invention has an effect that the particle diameter is small, the viscosity is low and the chargeability is excellent, corresponding to the speeding up of the liquid development system.

  The liquid developer of the present invention is a liquid developer containing a binder resin containing a resin having an acidic group and toner particles containing a colorant, a dispersant, and an insulating liquid, and the dispersant is amino Copolymerization reaction of an ethylenically unsaturated monomer (d-1) having a group and a macromonomer (d-2) containing a (meth) acrylic polymer having a hydrocarbon group having 6 to 24 carbon atoms It contains the substance (D), and has an effect of being small in particle diameter, low in viscosity and excellent in chargeability, corresponding to speeding up of the liquid development system.

  Although the reason which produces such an effect is not certain, it is considered as follows. In the copolymerization reaction product (D), the site derived from the ethylenically unsaturated monomer (d-1) having an amino group acts as an adsorptive group by acid-base interaction with the binder resin having an acidic group, Furthermore, a site derived from a macromonomer (d-2) containing a (meth) acrylic polymer having a hydrocarbon group having 6 to 24 carbon atoms functions as a dispersing group having high steric repulsion in the insulating liquid Therefore, it is considered that the particle diameter reduction and the viscosity reduction of the liquid developer are made possible. In addition, since the dispersing agent can be dispersed with a small amount of dispersing agent, it is considered that the amount of free dispersing agent can be reduced and the chargeability is improved.

  As resin which has an acidic group, composite resin etc. which have polyester resin, polyester resin, and other resin, such as a styrene resin, etc. are mentioned. In addition, the polyester resin may be a modified polyester resin which has been modified to an extent that the properties of the resin are not substantially impaired.

  In the present invention, the polyester resin is preferably a polycondensate of an alcohol component containing a dihydric or higher alcohol and a carboxylic acid component containing a dihydric or higher carboxylic acid compound.

  As the divalent alcohol, for example, an aliphatic diol having 2 to 20 carbon atoms, preferably 2 to 15 carbon atoms, and more preferably 2 to 10 carbon atoms, or a compound of formula (I):

(Wherein, OR and RO are oxyalkylene groups, R is ethylene and / or propylene groups, x and y indicate the average addition mole number of alkylene oxide, and each is a positive number, and x and y are The sum value is 1 or more, preferably 1.5 or more, and 16 or less, preferably 8 or less, more preferably 6 or less, further preferably 4 or less)
The alkylene oxide adduct of bisphenol A represented by these, bisphenol A, hydrogenated bisphenol A etc. are mentioned. Specific examples of the aliphatic diol having 2 to 20 carbon atoms include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol and the like. Be

  As the alcohol component, from the viewpoint of improving toner crushability to obtain toner particles having a small particle diameter, from the viewpoint of improving low-temperature fixability of liquid developer, and improving the dispersion stability of toner particles to improve storage stability. From the viewpoint of improving, an alkylene oxide adduct of bisphenol A represented by formula (I) or 1,2-propanediol is preferable, and from the viewpoint of grindability, an alkylene oxide of bisphenol A represented by formula (I) Adducts are more preferred. The content of the alkylene oxide adduct of bisphenol A represented by the formula (I) is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, still more preferably in the alcohol component. It is 95 mol% or more, more preferably 100 mol%.

  Examples of trihydric or higher alcohols include trihydric or higher alcohols having 3 to 20 carbon atoms, preferably 3 to 10 carbon atoms. Specifically, sorbitol, 1,4-sorbitan, pentaerythritol, glycerol, trimethylolpropane and the like can be mentioned.

  The divalent carboxylic acid compound is, for example, a dicarboxylic acid having 3 to 30 carbon atoms, preferably 3 to 20 carbon atoms, more preferably 3 to 10 carbon atoms, an anhydride thereof, or 1 or more carbon atoms. There may be mentioned derivatives such as alkyl esters having an alkyl group of 3 or less. Specifically, aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid, fumaric acid, maleic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, an alkyl group having 1 to 20 carbon atoms, or carbon Aliphatic dicarboxylic acids, such as a succinic acid substituted with several 2 or more and 20 or less alkenyl group, are mentioned.

  The carboxylic acid component is preferably terephthalic acid and / or fumaric acid from the viewpoint of improving the low temperature fixability of the toner and improving the dispersion stability of the toner particles to improve the storage stability, and terephthalic acid is more preferable. preferable. The content of terephthalic acid or fumaric acid or the total of both is preferably 40 mol% or more, more preferably 50 mol% or more, still more preferably 70 mol% or more, still more preferably 90 mol% in the carboxylic acid component. The above content is more preferably 95 mol% or more, and further preferably 100 mol%.

  The trivalent or higher carboxylic acid compound has, for example, 4 to 20 carbon atoms, preferably 6 to 20 carbon atoms, more preferably 7 to 15 carbon atoms, and still more preferably 8 to 12 carbon atoms, more preferably And C.sub.9 to C.sub.10 trivalent carboxylic acids, their anhydrides, or derivatives such as C.sub.1 to C.sub.3 alkyl esters and the like. Specifically, 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,4,5-benzenetetracarboxylic acid (pyromellitic acid), or their acid anhydrides and the like can be mentioned.

  The content of the trivalent or higher carboxylic acid compound is preferably 1% by mole or more, more preferably 2% by mole or more, in the carboxylic acid component from the viewpoint of improving the hot offset resistance of the toner and the pulverizing property of the toner particles. More preferably, it is 3 mol% or more, and preferably 30 mol% or less, more preferably 25 mol% or less, and still more preferably 20 mol% or less.

  The alcohol component may contain a monohydric alcohol, and the carboxylic acid component may contain a monovalent carboxylic acid compound from the viewpoint of adjusting the molecular weight and the softening point of the polyester resin.

  The equivalent ratio (COOH group / OH group) of the carboxylic acid component to the alcohol component in the polyester resin is preferably 0.6 or more, more preferably 0.7 or more, and still more preferably 0.75 or more from the viewpoint of adjusting the softening point of the polyester resin. And preferably 1.1 or less, more preferably 1.05 or less, more preferably 1 or less.

  The polyester resin is preferably, for example, an alcohol component and a carboxylic acid component in an inert gas atmosphere, preferably in the presence of an esterification catalyst, and, if necessary, in the presence of an esterification promoter, a polymerization inhibitor, etc. It can be produced by polycondensation at a temperature of 130 ° C. or more, more preferably 170 ° C. or more, and preferably 250 ° C. or less, more preferably 240 ° C. or less.

  Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin (II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropylate bis triethanol aminate, and the like, with preference given to tin compounds. The amount of the esterification catalyst used is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and preferably 1.5 parts by mass or less, based on 100 parts by mass of the total of the alcohol component and the carboxylic acid component. Preferably it is 1.0 mass part or less. Examples of the esterification promoter include gallic acid and the like. The amount of the esterification promoter is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 0.5 parts by mass or less, based on 100 parts by mass of the total of the alcohol component and the carboxylic acid component. More preferably, it is 0.1 parts by mass or less. Examples of the polymerization inhibitor include t-butyl catechol and the like. The amount of the polymerization inhibitor used is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 0.5 parts by mass or less, based on 100 parts by mass of the total of the alcohol component and the carboxylic acid component. Preferably it is 0.1 mass part or less.

  As the composite resin, a composite resin having the polyester resin and a styrene resin is preferable.

  The styrene-based resin is an addition polymer of a raw material monomer containing at least styrene or a styrene derivative such as α-methylstyrene or vinyltoluene (hereinafter, styrene and a styrene derivative are collectively referred to as “styrene compound”).

  The content of the styrene compound, preferably styrene, is preferably 50% by mass or more, more preferably 70% by mass, from the viewpoint of improving the storage stability by improving the dispersion stability of the toner particles in the raw material monomer of the styrene resin. Or more, more preferably 80% by mass or more, and from the viewpoint of improving the low-temperature fixability of the toner and the viewpoint of improving the wet pulverizability, it is preferably 95% by mass or less, more preferably 93% by mass or less, more preferably Is 90 mass% or less.

  In addition, the styrenic resin may contain, as a raw material monomer, a (meth) acrylic acid alkyl ester having 7 or more carbon atoms in the alkyl group. Examples of the (meth) acrylic acid alkyl ester include 2-ethylhexyl (meth) acrylate, (meth) acrylic acid (iso) octyl, (meth) acrylic acid (iso) decyl, (meth) acrylic acid (iso) stearyl and the like It can be mentioned. It is preferable to use one or more of these. In the present specification, "(iso)" is meant to include both cases where this group is present and cases where this group is not present, and when these groups are not present, they are normal. Indicates that. Moreover, "(meth) acrylic acid" shows acrylic acid, methacrylic acid, or both.

  The carbon number of the alkyl group in the (meth) acrylic acid alkyl ester as a raw material monomer of the styrenic resin is preferably 7 or more, more preferably 8 or more, from the viewpoint of improving the low temperature fixability of the toner. From the viewpoint of stability, it is preferably 12 or less, more preferably 10 or less. In addition, carbon number of this alkyl ester says carbon number derived from the alcohol component which comprises ester.

  Raw materials monomers of styrenic resins include raw material monomers other than styrene compounds and (meth) acrylic acid alkyl esters, for example, ethylenically unsaturated monoolefins such as ethylene and propylene; diolefins such as butadiene; vinyl chloride and the like Halovinyls; vinyl esters such as vinyl acetate and vinyl propionate; ethylenic monocarboxylic acid esters such as dimethylaminoethyl (meth) acrylate; vinyl ethers such as vinyl methyl ether; vinylidene halides such as vinylidene chloride; N- N-vinyl compounds such as vinyl pyrrolidone may be contained.

  The addition polymerization reaction of the raw material monomer of the styrene resin can be carried out in the presence of an organic solvent or in the absence of a solvent, for example, in the presence of a polymerization initiator such as dicumyl peroxide, a polymerization inhibitor, a crosslinking agent, etc. The temperature condition is preferably 110 ° C. or more, more preferably 140 ° C. or more, and preferably 200 ° C. or less, more preferably 170 ° C. or less.

  When an organic solvent is used in the addition polymerization reaction, xylene, toluene, methyl ethyl ketone, acetone or the like can be used. The amount of the organic solvent used is preferably 10 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the raw material monomer of the styrene resin.

  In the present invention, from the viewpoint of dispersion stability and grindability of the toner particles, the composite resin can be reacted with the polyester resin through the bireactive monomer which can react with either of the raw material monomer of the polyester resin and the raw material monomer of the styrenic resin. Resins in which a styrenic resin is chemically bonded are preferred.

  The dual reactive monomer has at least one functional group selected from the group consisting of a hydroxyl group, a carboxy group, an epoxy group, a primary amino group and a secondary amino group in the molecule, preferably a hydroxyl group and / or a carboxy group. Group, more preferably a compound having a carboxy group and an ethylenically unsaturated bond is preferable, and at least one selected from the group consisting of acrylic acid, methacrylic acid, fumaric acid, maleic acid and maleic anhydride is more preferable, From the viewpoint of the reactivity of the polycondensation reaction and the addition polymerization reaction, at least one selected from the group consisting of acrylic acid, methacrylic acid and fumaric acid is more preferable. Here, when used together with a polymerization inhibitor, a polyvalent carboxylic acid compound having an ethylenically unsaturated bond such as fumaric acid functions as a raw material monomer of the polyester resin. In this case, fumaric acid or the like is not a bireactive monomer but a raw material monomer of a polyester resin.

  In addition, the bireactive monomer may be one or two or more (meth) acrylic esters selected from acrylic esters and methacrylic esters each having 6 or less carbon atoms in the alkyl group.

  The (meth) acrylic acid ester is preferably a (meth) acrylic acid alkyl ester from the viewpoint of reactivity to transesterification, and the carbon number of the alkyl group is preferably 2 or more, more preferably 3 or more, and preferably Is 6 or less, more preferably 4 or less. The alkyl group may have a substituent such as a hydroxyl group.

  Specific examples of the (meth) acrylic acid alkyl ester include methyl (meth) acrylate, ethyl (meth) acrylate, (iso) propyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate ( And (meth) acrylic acid (iso or tertiary) butyl, hexyl (meth) acrylate and the like. In addition, "(iso or tertiary)" is meant to include both the case where these groups exist and the case where they do not exist, and they are normal when these groups do not exist. Indicates

  In the present invention, the acrylic acid ester is preferably an acrylic acid alkyl ester having 2 to 6 carbon atoms in the alkyl group, more preferably butyl acrylate, and the methacrylic acid ester preferably has a carbon number of the alkyl group It is a methacrylic acid alkyl ester which is 2 or more and 6 or less, more preferably butyl methacrylate.

  The amount of the dual reactive monomer used is preferably 1 mole or more from the viewpoint of enhancing the dispersibility of the styrene resin and the polyester resin and improving the durability of the toner with respect to 100 moles in total of the alcohol component of the polyester resin. It is more preferably 2 mol or more, and preferably 30 mol or less, more preferably 20 mol or less, still more preferably 10 mol or less from the viewpoint of low-temperature fixability. Further, the amount of the bireactive monomer used is preferably from the viewpoint of enhancing the dispersibility of the styrenic resin and the polyester resin with respect to the total of 100 parts by mass of the raw material monomer of the styrenic resin to improve the durability of the toner. Is 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 30 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 10 parts by mass or less from the viewpoint of low temperature fixability. Here, the polymerization initiator is included in the total of the raw material monomers of the styrenic resin.

  Specifically, it is preferable to produce the composite resin obtained by using the dual reactive monomer by the following method. The dual reactive monomer is preferably used for the addition polymerization reaction together with the raw material monomer of the styrenic resin from the viewpoint of improving the durability of the toner, and the viewpoint of improving the low temperature fixability and heat resistant storage stability of the toner.

(i) Method of carrying out the step (B) of addition polymerization reaction by the raw material monomer of styrenic resin and the bireactive monomer after the step (A) of the polycondensation reaction by the raw material monomer of the polyester resin Step (A) is carried out under a reaction temperature condition suitable for the reaction, the reaction temperature is lowered, and the step (B) is carried out under a temperature condition suitable for the addition polymerization reaction. It is preferable to add a raw material monomer of a styrenic resin and a bireactive monomer into the reaction system at a temperature suitable for the addition polymerization reaction. Both reactive monomers undergo addition polymerization and react with the polyester resin.
After the step (B), the reaction temperature is raised again, and if necessary, a raw material monomer or the like of a polyester resin having a valence of 3 or more serving as a crosslinking agent is added to the reaction system. The reaction with the organic monomer can be further advanced.

(ii) Method of carrying out step (A) of polycondensation reaction by raw material monomer of polyester resin after step (B) of addition polymerization reaction by raw material monomer of styrenic resin and both reactive monomers In this method, addition polymerization reaction is carried out Step (B) is carried out under a reaction temperature condition suitable for the reaction, the reaction temperature is raised, and the polycondensation reaction of step (A) is carried out under a temperature condition suitable for the polycondensation reaction. Both reactive monomers participate in the polycondensation reaction as well as the addition polymerization reaction.
The raw material monomers of the polyester resin may be present in the reaction system during the addition polymerization reaction, or may be added into the reaction system under temperature conditions suitable for the polycondensation reaction. In the former case, the progress of the polycondensation reaction can be controlled by adding an esterification catalyst at a temperature suitable for the polycondensation reaction.

(iii) Conducting the reaction under the condition that the step (A) of the polycondensation reaction with the raw material monomer of polyester resin and the step (B) of the addition polymerization reaction with the raw material monomer of styrenic resin and the bireactive monomer proceed in parallel Method In this method, step (A) and step (B) are performed in parallel under reaction temperature conditions suitable for addition polymerization reaction, the reaction temperature is raised, and temperature conditions suitable for polycondensation reaction are necessary. It is preferable to add to the polymerization system a raw material monomer of a polyester resin having a valence of 3 or more, which is to be a crosslinking agent according to the method, and to further carry out the polycondensation reaction of step (A). At that time, under the temperature condition suitable for the polycondensation reaction, a radical polymerization inhibitor may be added to proceed only with the polycondensation reaction. Both reactive monomers participate in the polycondensation reaction as well as the addition polymerization reaction.

  In the above method (i), a polycondensation resin polymerized in advance may be used instead of the step (A) in which the polycondensation reaction is performed. In the method (iii) above, when the step (A) and the step (B) proceed in parallel, the mixture containing the raw material monomer of the styrenic resin in the mixture containing the raw material monomer of the polyester resin is It is also possible to react dropwise.

  The methods (i) to (iii) are preferably carried out in the same container.

  The mass ratio of the styrene resin to the polyester resin (styrene resin / polyester resin) in the composite resin is preferably 3/97 or more, more preferably 7/93 or more, and still more preferably 10 from the viewpoint of the crushability of toner particles. / 90 or more, and preferably 45/55 or less, more preferably 40/60 or less, still more preferably 35/65 or less, still more preferably 30/70 or less, from the viewpoint of dispersion stability of toner particles Preferably it is 25/75 or less. In the above calculation, the mass of the polyester resin is an amount obtained by removing the amount (calculated value) of the reaction water to be dehydrated by the polycondensation reaction from the mass of the raw material monomer of the polyester resin to be used. Is included in the raw material monomer amount of the polyester resin. The mass of the styrene resin is the total amount of the raw material monomer of the styrene resin and the polymerization initiator.

  The softening point of the resin having an acidic group is preferably 70 ° C. or more, more preferably 75 ° C. or more, from the viewpoint of improving the dispersion stability of the toner particles to improve the storage stability, and the liquid developer From the viewpoint of improving low-temperature fixability, it is preferably 160 ° C. or less, more preferably 130 ° C. or less, still more preferably 120 ° C. or less, and still more preferably 110 ° C. or less.

  The glass transition temperature of the resin having an acidic group is preferably 40 ° C. or more, more preferably 45 ° C. or more, from the viewpoint of improving the dispersion stability of the toner particles to improve the storage stability, and low-temperature fixability Preferably, the temperature is 80 ° C. or less, more preferably 70 ° C. or less, and still more preferably 60 ° C. or less.

  The acid value of the resin having an acidic group is preferably 3 mgKOH / g or more, more preferably from the viewpoint of reducing the viscosity of the liquid developer and improving the storage stability by improving the dispersion stability of the toner particles. It is 5 mg KOH / g or more, more preferably 8 mg KOH / g or more, and preferably 60 mg KOH / g or less, more preferably 50 mg KOH / g or less, still more preferably 40 mg KOH / g or less, still more preferably 30 mg KOH / g or less. The acid value of the resin is adjusted by changing the equivalent ratio of the carboxylic acid component and the alcohol component, changing the reaction time during resin production, or changing the content of the trivalent or higher carboxylic acid compound. Can.

  90 mass% or more is preferable in binder resin, as for content of resin which has an acidic group, 95 mass% or more is more preferable, and it is still more preferable to use 100 mass%, ie, only resin which has an acidic group. However, in the range which does not impair the effect of the present invention, you may contain other resins other than resin which has an acidic group. As resins other than the resin having an acidic group, for example, polystyrene, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer Styrene resin, epoxy resin, rosin modified maleic acid which is a homopolymer or copolymer containing styrene or a styrene-substituted product such as a polymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, etc. One or more selected from resins such as resins, polyethylene resins, polypropylene resins, polyurethane resins, silicone resins, phenol resins, polyamide resins, aliphatic or alicyclic hydrocarbon resins and the like can be mentioned.

  As the colorant, any of the pigments used as colorants for toners can be used, and carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine-B base, solvent red 49 Solvent Red 146, Solvent Blue 35, quinacridone, carmine 6B, isoindoline, disazoeroe, etc. can be used. In the present invention, the toner particles may be either black toner or color toner.

  The colorant content is from the viewpoint of improving the grindability of toner particles and obtaining a liquid developer with a small particle diameter, the viewpoint of improving the low temperature fixability of liquid developer, and the storage stability of toner particles in liquid developer 100 parts by mass or less, more preferably 70 parts by mass or less, still more preferably 50 parts by mass or less, still more preferably 25 parts by mass or less, with respect to 100 parts by mass of the binder resin From the viewpoint of improving the image density of the developer, the amount is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and still more preferably 15 parts by mass or more with respect to 100 parts by mass of the binder resin.

  In the present invention, as a toner raw material, a releasing agent, a charge control agent, a magnetic powder, a fluidity improver, a conductivity regulator, a reinforcing filler such as a fibrous substance, an antioxidant, a cleaning improver, etc. Additives may be used as appropriate.

  The liquid developer of the present invention is obtained by dispersing toner particles containing a binder resin and a pigment in an insulating liquid in the presence of a dispersant.

  In the present invention, the dispersant is a macromonomer containing an ethylenic unsaturated monomer (d-1) having an amino group and a (meth) acrylic polymer having a hydrocarbon group having 6 to 24 carbon atoms It contains the copolymerization reaction product (D) with d-2).

As the ethylenically unsaturated monomer (d-1) having an amino group, a compound of the formula (II):
CH ₂ = C (R ³ ) COYR ⁴ NR ¹ R ² (II)
(Wherein, R ¹ and R ² each independently represent a hydrogen atom, or a linear or branched alkyl group having 1 to 4 carbon atoms, which are bonded to each other to form a ring structure R ³ represents a hydrogen atom or a methyl group, R ⁴ represents a linear or branched alkylene group having 2 to 4 carbon atoms, and Y represents —O— or —NH— Preferred is a monomer having an amino group, or an acid neutralized product (tertiary amine salt) or quaternary ammonium salt of this monomer. Preferred acids for obtaining the above-mentioned neutralized acid include hydrochloric acid, sulfuric acid, nitric acid, acetic acid, formic acid, maleic acid, fumaric acid, citric acid, tartaric acid, adipic acid, sulfamic acid, toluenesulfonic acid, lactic acid, pyrrolidone- 2-carboxylic acid, succinic acid and the like. Preferred examples of the quaternizing agent for obtaining the quaternary ammonium salt include alkyl halides such as methyl chloride, ethyl chloride, methyl bromide and methyl iodide, dimethyl sulfate, diethyl sulfate, di-n-propyl sulfate and the like. General alkylating agents of

In Formula (II), R ¹ and R ² are each independently preferably a linear or branched alkyl group having 1 to 4 carbon atoms, and NR ¹ R ² is preferably a tertiary amino group. Specific examples of R ¹ and R ² are a methyl group, an ethyl group, a propyl group, an isopropyl group and the like, preferably a methyl group.

Examples of R ⁴ include an ethylene group, a propylene group and a butylene group, with an ethylene group being preferred.

Specific examples of the monomer in which NR ¹ R ² is a tertiary amino group in the formula (II) (monomer having a tertiary amino group) include (meth) acrylic acid ester having a dialkylamino group, and dialkylamino group ( Meta) acrylamide etc. are mentioned. In addition, "(meth) acrylic acid ester" shows that acrylic acid ester and methacrylic acid ester and "(meth) acrylamide" includes the case of both acrylamide and methacrylamide.

  As the (meth) acrylic acid ester having a dialkylamino group, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dipropylaminoethyl (meth) acrylate, diisopropylaminoethyl (meth) acrylate, dibutylaminoethyl One or more selected from the group consisting of meta) acrylate, diisobutylaminoethyl (meth) acrylate, and di-t-butylaminoethyl (meth) acrylate, and the like can be mentioned.

  As (meth) acrylamide having a dialkylamino group, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide, dipropylaminopropyl (meth) acrylamide, diisopropylaminopropyl (meth) acrylamide, dibutylaminopropyl (meth) At least one selected from the group consisting of acrylamide, diisobutylaminopropyl (meth) acrylamide, and di-t-butylaminopropyl (meth) acrylamide, and the like can be mentioned.

  Among these, (meth) acrylic acid esters having a dialkylamino group are preferable from the viewpoint of small particle diameter, low viscosity, storage stability, and low-temperature fixability, and dimethylaminoethyl (meth) acrylate is more preferable.

  The carbon number of the hydrocarbon group having 6 to 24 carbon atoms of the (meth) acrylic polymer in the macromonomer (d-2) is 6 or more, preferably 8 or more, from the viewpoint of obtaining steric repulsion, and Or 24 or less, preferably 20 or less, more preferably 18 or less from the viewpoint of solubility in the insulating liquid.

  Examples of the hydrocarbon group having 6 to 24 carbon atoms include an alkyl group having 6 to 24 carbon atoms, a phenyl group, and an aralkyl group having 7 to 24 carbon atoms. Among these, an alkyl group having 6 to 24 carbon atoms is preferable from the viewpoint of affinity with the insulating liquid. Therefore, the (meth) acrylic polymer is preferably a polymer of a (meth) acrylic monomer having a hydrocarbon group having 6 to 24 carbon atoms, and as the (meth) acrylic monomer, 2-ethylhexyl acrylate (Meth) acrylic acid alkyl esters having 6 to 24 carbon atoms in the alkyl group such as 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, myristyl acrylate, myristyl methacrylate, cetyl acrylate, cetyl methacrylate, stearyl acrylate, stearyl methacrylate, etc. Preferably, the alkyl alkyl ester having a carbon number of 8 or more and 18 or less is more preferable.

  Although (meth) acrylic monomers other than the (meth) acrylic acid alkyl ester having an alkyl group having 6 to 24 carbon atoms may be used, it has an alkyl group having 6 to 24 carbon atoms (meta The acrylic acid alkyl ester is preferably 80 mol% or more, more preferably 90 mol% or more, still more preferably 95 mol% or more, based on the total amount of (meth) acrylic monomers.

  The acid value of the (meth) acrylic polymer is preferably 0.1 mg KOH / g or more, more preferably 0.5 mg KOH / g or more, still more preferably 1.0 mg KOH / g or more, from the viewpoint of introducing a reactive functional group. From the viewpoint of solubility in the insulating liquid, it is preferably 30 mg KOH / g or less, more preferably 25 mg KOH / g or less, and still more preferably 20 mg KOH / g or less.

  As a macromonomer (d-2) containing the (meth) acrylic-type polymer which has a C6 or more and 24 or less hydrocarbon group, Formula (III):

[Wherein, R ¹ , R ² , R ³ , and R ⁴ may be the same as or different from each other, and each independently represent a hydrogen atom, a halogen atom, a cyano group, or a hydrocarbon group having 1 to 4 carbon atoms. R ⁵ represents -COO-Z ¹ ; Here, Z ¹ represents a hydrocarbon group having 6 to 24 carbon atoms. Z ¹ represents an alkyl group having 6 to 24 carbon atoms, a phenyl group, or an aralkyl group having 7 to 24 carbon atoms.
V is, -COO -, - COO (CH 2) m -, - OCO -, - OCO (CH 2) m -, - (CH 2) k -OCO -, - (CH 2) k -COO -, - O -, - CONHCOO -, - CONHCO -, - CONH (CH 2) m -, - COO (CH 2) m (OH) -, - COO (CH 2) m (OH) (CH 2) l -, - _{SO 2 -, - CO -,} - CONZ 2 -, - SO 2 NZ 2 -, or an phenylene group. Here, Z ² is a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, m is an integer of 1 to 10, l is an integer of 0 to 10, and k is an integer of 1 to 3. V preferably represents —COO— or —COO (CH ₂ ) _m (OH) (CH ₂ ) ₁ —.
W represents a single bond, or ^{-C (Z 3) (Z 4} ) -, - (CH = CH) -, a cyclohexylene group, a phenylene group, -O -, - S -, - C (= O) -, ^{-N (Z 5) -, -} COO -, - OCO -, - SO 2 -, - CON (Z 5) -, - SO 2 N (Z 5) -, - NHCOO -, - NHCONH -, - CH = This represents a single linking group selected from the group of N- and -COOH, or a linking group composed of any combination of these. Here, Z ³ and Z ⁴ are each a hydrogen atom, a halogen atom (e.g. fluorine atom, a chlorine atom, a bromine atom), a cyano group, or a hydroxy group, Z ⁵ are the same as the Z ^2. The W, -OCO -, - C ( Z 3) (Z 4) -, or -S- are preferred.
n is an integer of 3 or more, preferably 5 or more, and 110 or less, preferably 80 or less. ]
Macromonomers represented by are preferred.

  The macromonomer (d-2) is, for example, a methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, butyl methacrylate, acrylic acid, acrylic acid, and the like to a (meth) acrylic polymer introduced with a reactive functional group It can be obtained by a method of reacting (meth) acrylic acid such as methyl, propyl acrylate, butyl acrylate, glycidyl methacrylate or the like or an ester thereof. Among them, (meth) acrylic acid or ester thereof is preferably (meth) acrylic acid when the terminal of the (meth) acrylic polymer is a hydroxyl group, and methacrylic acid when the terminal is a carboxy group. It is preferable that it is glycidyl.

  As a method for introducing a reactive functional group into the (meth) acrylic polymer, for example, (a) a (meth) acrylic monomer having a hydrocarbon group having 6 to 24 carbon atoms and (a) a polymerization having a reactive functional group Initiator, (b) a polymerization initiator having a reactive functional group and a chain transfer agent having no reactive functional group, or (c) a polymerization initiator having no reactive functional group and a reactive functional group Examples thereof include a method of polymerizing a chain transfer agent. By using a polymerization initiator having a reactive functional group or a chain transfer agent having a reactive functional group, a reactive functional group can be introduced to one end of the (meth) acrylic polymer, and the crosslinking reaction can be suppressed. Therefore, when copolymerizing the macromonomer (d-2) with the ethylenically unsaturated monomer (d-1) having an amino group, to obtain a copolymer having a more ideal comb-shaped polymer structure Can.

  As a polymerization initiator having a reactive functional group, an azo compound having a carboxy group or a hydroxy group is preferable. Among them, as a polymerization initiator having a carboxy group or a hydroxy group, 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] tetrahydrate, 4,4′-azobis ( 4-cyanovaleric acid), 2,2'-azobis [2-methyl-N- (2-hydroxyethyl) propanamide] and the like. Examples of commercially available products include VA-057, V-501, and VA-086 (manufactured by Wako Pure Chemical Industries, Ltd.). Among these, 4,4′-azobis (4-cyanovaleric acid) is preferable from the viewpoint of the reactivity with the (meth) acrylic polymer.

  The amount of the polymerization initiator having a reactive functional group is such that it suppresses the formation of a high molecular weight component of the (meth) acrylic polymer to be produced per 100 moles of the (meth) acrylic monomer constituting the (meth) acrylic polymer It is preferably at least 0.1 mol, more preferably at least 0.3 mol, further preferably at least 0.5 mol, and from the viewpoint of solubility in the insulating liquid, preferably at most 10 mol, more preferably at most 8 mol, More preferably, it is 6 moles or less.

  Examples of the polymerization initiator having no reactive functional group include 1,1′-azobis- (cyclohexane-1-carbonitrile), 2,2′-azobis (2-methylbutyronitrile), and 2,2′-azobis (Isobutyronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) and the like. Examples of commercially available products include V-40, V-59, AIBN, V-65, and V-70 (manufactured by Wako Pure Chemical Industries, Ltd.). Among these, 2,2′-azobis (2,4-dimethylvaleronitrile) is preferable from the viewpoint of the reactivity with the (meth) acrylic polymer.

  As a chain transfer agent having a reactive functional group, a mercapto compound having a carboxy group or a hydroxy group is preferable. Among them, as a chain transfer agent having a carboxy group or a hydroxy group, thioglycolic acid, 2-mercaptopropionic acid, thiomalic acid, 2-mercaptoethanol, 3-mercapto-1,2-propanediol and the like can be mentioned. Among these, 2-mercaptopropionic acid is preferable from the viewpoint of the reactivity with the (meth) acrylic polymer.

  The amount of the chain transfer agent having a reactive functional group used is that of the macromer formed relative to 100 moles of (meth) acrylic monomer comprising a (meth) acrylic monomer having a hydrocarbon group having 6 to 24 carbon atoms. From the viewpoint of suppressing high molecular weight formation, it is preferably 0.1 mol or more, more preferably 0.3 mol or more, and from the viewpoint of increasing the hydrophobicity of the formed macromer, preferably 10 mol or less, more preferably 8 mol or less It is.

  As a chain transfer agent having no reactive functional group, 1-butanethiol, 1-decanethiol, 1-dodecanethiol, 1-hexadecanethiol, thiophenol, 2,4-diphenyl-4-methyl-1-pentene And cyclohexanethiol. Among these, 1-butanethiol is preferable from the viewpoint of solubility in the insulating liquid.

  In (b), the molar ratio of a chain transfer agent having no reactive functional group to a polymerization initiator having a reactive functional group (chain transfer agent / polymerization initiator) is preferably 0.5 or more, more preferably 2.0 or more And preferably 10 or less, more preferably 8 or less.

  In (c), the molar ratio of a chain transfer agent having a reactive functional group to a polymerization initiator having no reactive functional group (chain transfer agent / polymerization initiator) is preferably 1 or more, more preferably 3 or more. And preferably 10 or less, more preferably 8 or less.

  The reaction temperature when introducing the reactive functional group to the (meth) acrylic polymer is the temperature when the half life of the polymerization initiator is 3 hours, and the solubility of the polymerization initiator and the (meth) acrylic polymer is From the viewpoint, it is preferably 60 ° C. or more, more preferably 70 ° C. or more.

  The number average molecular weight of the macromonomer (d-2) is preferably 2,000 or more, more preferably 4,000 or more, still more preferably 6,000 or more, from the viewpoint of imparting steric repulsion to the toner particles, and dissolving in the insulating liquid From the viewpoint of the properties, it is preferably 20,000 or less, more preferably 18,000 or less, and still more preferably 16,000 or less.

  The acid value of the macromonomer (d-2) is preferably 0.01 mg KOH / g or more, more preferably 0.05 mg KOH / g or more, further preferably from the viewpoint of reactivity with the ethylenically unsaturated monomer having an amino group. Is preferably 0.1 mg KOH / g or more, and preferably 5 mg KOH / g or less, more preferably 3 mg KOH / g or less, and still more preferably 1 mg KOH / g or less from the viewpoint of solubility in the insulating liquid.

  In the present invention, the macromonomer (d-2) may contain a small amount of an oligomer or an unreacted material.

  The copolymerization reaction of the ethylenically unsaturated monomer (d-1) having an amino group and the macromonomer (d-2) containing a (meth) acrylic polymer is carried out in a conventional manner using a polymerization initiator etc. as appropriate. Can be done by

  Mass ratio of the ethylenically unsaturated monomer (d-1) having an amino group to the macromonomer (d-2) containing a (meth) acrylic polymer in the copolymerization reaction product (D) ((d-1) / (D-2) is preferably 5/95 or more, more preferably 7/93 or more, still more preferably 10/90 or more, from the viewpoint of the small particle diameter and low viscosity of the liquid developer. From the viewpoint of solubility in the insulating liquid, it is preferably 35/65 or less, more preferably 33/67 or less, and still more preferably 30/70 or less.

  The number average molecular weight of the copolymerization reaction product (D) is preferably 5,000 or more, more preferably 7,000 or more, still more preferably 9,000 or more, from the viewpoint of imparting steric repulsion to the toner particles, and the insulating liquid From the viewpoint of solubility, it is preferably 100,000 or less, more preferably 80,000 or less, and still more preferably 60,000 or less.

  The amine value of the copolymerization reaction product (D) is preferably 15 mg KOH / g or more, more preferably 25 mg KOH / g or more, and further preferably from the viewpoint of the affinity between the copolymerization reaction product (D) and the resin having the acidic group. The amount is preferably 35 mg KOH / g or more, and preferably 150 mg KOH / g or less, more preferably 135 mg KOH / g or less, and still more preferably 120 mg KOH / g or less from the viewpoint of solubility in the insulating liquid.

  The liquid developer of the present invention may contain known dispersants other than the copolymerization reaction product (D), but the content of the copolymerization reaction product (D) is preferably 50 in the dispersion agent. The content is preferably at least 70% by mass, more preferably at least 90% by mass, still more preferably at least 95% by mass, and still more preferably 100% by mass.

The insulating liquid in the present invention means a liquid in which electricity does not easily flow, but in the present invention, the conductivity of the insulating liquid is preferably 1.0 × 10 ⁻¹¹ S / m or less, more preferably 5.0. It is not more than 10 ^-12 S / m, and preferably not less than 1.0 10 ^-13 S / m.

  Specific examples of the insulating liquid include, for example, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, hydrocarbon solvents such as halogenated hydrocarbons, polysiloxanes, vegetable oils, etc. At least one member selected from the group consisting of solvents and polysiloxanes is preferable. Among them, hydrocarbon solvents are more preferable from the viewpoint of low-temperature fixability, low viscosity, grindability, low-temperature fixability, and resistance Aliphatic hydrocarbons are more preferred because of their excellent balance of abrasiveness. Examples of aliphatic hydrocarbons include paraffinic hydrocarbons and olefins having 12 to 18 carbon atoms. One or two or more of these can be used in combination.

  Commercial products of aliphatic hydrocarbons include Isopar G, Isopar H, Isopar L, Isopar K, Isopar M, Exol D110 (all from ExxonMobil), Shellsol 71, Shellsol TM (all, all Shell Chemicals Japan Inc.), IP Solvent 1620, IP Solvent 2028, IP Solvent 2835 (all are manufactured by Idemitsu Kosan Co., Ltd.), Moresco White P-55, Moresco White P-70, Moresco White P-100, Moresco White P-150, Moresco White P-260 (all manufactured by MORESCO), Cosmo White P-60, Cosmo White P-70 (all manufactured by Cosmo Petroleum Lubricants), Lightol (Sonneborn) ), Isosol 400 (JX Nippon Oil & Energy Corporation), Linearen 14, Linearen 16, Linearen 18, Linearen 124, Linearle 148, Linearen 168 (all manufactured by Idemitsu Kosan Co., Ltd.), NAS-3, NAS-4, NAS-5H (above all are manufactured by NOF CORPORATION), and the like. One or two or more of these can be combined.

  The content of the hydrocarbon solvent in the insulating liquid is preferably 60% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, further preferably 100% by mass %.

  The viscosity of the insulating liquid at 25 ° C. is preferably 100 mPa · s or less, more preferably 50 mPa · s or less, still more preferably 20 mPa · s or less, still more preferably 10 mPa · s, from the viewpoint of improving the developability of the liquid developer. or less, more preferably 5 mPa · s or less, and preferably 1 mPa · s or more, more preferably 1.5 mPa · s or more from the viewpoint of improving the storage stability of the toner particles in the liquid developer.

In the present invention, as a method of obtaining toner particles, a method of melt-kneading a toner raw material containing a binder resin and a colorant, and pulverizing the obtained melt-kneaded product, an aqueous resin dispersion and an aqueous pigment dispersion And a method of mixing resin particles and colorant particles, a method of stirring the aqueous resin dispersion liquid and the colorant at high speed, and the like. From the viewpoint of improving the developability and fixability of the liquid developer, it is preferable to melt and knead the toner raw material and then grind it. From such a viewpoint, the liquid developer of the present invention is
Step 1: At least a binder resin-containing binder resin and a colorant are melt-kneaded, and the obtained kneaded product is pulverized to obtain toner particles, and Step 2: Toner obtained in Step 1 The particles are preferably produced by a process comprising the steps of dispersing in an insulating liquid in the presence of a dispersant.

  In step 1, at least a binder resin containing a binder resin and a colorant are melt-kneaded, and the obtained kneaded product is pulverized to obtain toner particles.

  The melt-kneading in step 1 can be carried out using a known kneader such as a closed kneader, a single-screw or twin-screw extruder, an open roll kneader or the like. It is preferable to use an open-roll type kneader from the viewpoint of being able to efficiently disperse the colorant in the resin efficiently without repeating the kneading and using the dispersing aid.

  The binder resin and the colorant are preferably mixed in advance with a mixer such as a Henschel mixer or a ball mill and then supplied to the kneader. If necessary, additives such as a mold release agent and a charge control agent may be used together with the resin and the like for melt kneading.

  An open roll type kneader is a machine in which the kneading section is not sealed but is open, and the heat of kneading generated at the time of kneading can be easily dissipated. The continuous open-roll type kneader is preferably a kneader equipped with at least two rolls, and the continuous open-roll type kneader used in the present invention is two rolls having different circumferential speeds, That is, it is a kneader equipped with two rolls of a high rotation side roll having a high peripheral speed and a low rotation side roll having a low peripheral speed. In the present invention, from the viewpoint of improving the dispersibility of the colorant in the resin, the high rotation side roll is preferably a heating roll, and the low rotation side roll is preferably a cooling roll.

  The temperature of the roll can be adjusted, for example, by the temperature of the heat medium passed through the inside of the roll, and in each roll, the inside of the roll may be divided into two or more places and heat medium having different temperatures may be passed.

  The raw material input side end temperature of the high rotation side roll is 80 ° C. or higher, from the viewpoint of reducing the mechanical force at the time of melt-kneading to suppress heat generation and improving the dispersibility of the colorant in the binder resin. 160 degreeC or less is preferable, From the same viewpoint, the raw material injection | pouring end part temperature of the low rotation side roll has preferable 30 degreeC or more and 100 degrees C or less.

  The high-rotation-side roll has a difference in the set temperature between the end on which the raw material is input and the end on which the kneaded material is discharged to prevent detachment of the kneaded material from the roll. Preferably, it is 2 ° C. or more, and preferably 60 ° C. or less, more preferably 50 ° C. or less, still more preferably 30 ° C. or less, from the viewpoint of suppressing and improving the dispersibility of the colorant in the binder resin. It is. On the low rotation side roll, the difference in the set temperature between the raw material input side and the kneaded material discharge end reduces the mechanical force at the time of melt-kneading and suppresses heat generation, and the dispersibility of the coloring agent in the resin From the viewpoint of improving, it is preferably 50 ° C. or less, more preferably 30 ° C. or less, and may be 0 ° C.

  The peripheral speed of the high rotation side roll is preferably 2 m / min or more, from the viewpoint of reducing the mechanical force at the time of melt-kneading to suppress heat generation and improving the dispersibility of the colorant in the binder resin. It is preferably 10 m / min or more, more preferably 25 m / min or more, and preferably 100 m / min or less, more preferably 75 m / min or less, and still more preferably 50 m / min or less. From the same viewpoint, the peripheral speed of the low rotation side roll is preferably 1 m / min or more, more preferably 5 m / min or more, still more preferably 10 m / min or more, and preferably 90 m / min or less, more preferably Is 60 m / min or less, more preferably 30 m / min or less, and further preferably 20 m / min or less, and the ratio of peripheral speeds of the two rolls (low rotation side roll / high rotation side roll) is preferably 1/00. 10 or more, more preferably 3/10 or more, and preferably 9/10 or less, more preferably 8/10 or less.

  The structure, size, material, and the like of the roll are not particularly limited, and the roll surface may be smooth, corrugated, uneven or the like, but the mechanical force during melt kneading is reduced to suppress heat generation. From the viewpoint and the viewpoint of improving the dispersibility of the colorant in the resin, it is preferable that a plurality of spiral grooves be cut on the surface of each roll.

  The kneaded material obtained by the melt-kneading is appropriately cooled and pulverized until the hardness which can be pulverized is reached.

  The grinding may be performed in multiple stages. For example, after the resin kneaded material is roughly pulverized to about 1 to 5 mm, it may be further pulverized to a desired particle size.

  Although the grinder used for grinding is not particularly limited, for example, as a grinder suitably used for coarse grinding, a hammer mill, an atomizer, Rotoplex, etc. may be mentioned. Moreover, as a pulverizer suitably used for pulverization, an air jet type jet mill, a fluidized bed type counter jet mill, a collision plate type jet mill, a rotary mechanical mill and the like can be mentioned.

  In Step 1, after the pulverization, the obtained toner particles are preferably classified, if necessary.

  Examples of classifiers used for classification include pneumatic classifiers, inertial classifiers, and sieve classifiers. In the classification step, the pulverized material which has been insufficiently ground and removed may be subjected to the grinding step again, and the grinding step and the classification step may be repeated as necessary.

The volume median particle diameter (D ₅₀ ) of the toner particles obtained by Step 1 is preferably 3 μm or more, more preferably 4 μm or more, and preferably 15 μm or less, from the viewpoint of improving the productivity of the wet pulverizing step described later. And more preferably 12 μm or less. In the present specification, the volume median particle size (D ₅₀ ) means a particle size at which the cumulative volume frequency calculated by volume fraction is 50% as calculated from the smaller particle size.

  Step 2 is a step of dispersing the toner particles obtained in Step 1 in an insulating liquid in the presence of a dispersant.

  In the present invention, from the viewpoint of reducing the particle diameter of the toner particles in the liquid developer and the viewpoint of reducing the viscosity of the liquid developer, the step 2 is carried out by a method including the following steps 2-1 and 2-2. It is preferred to do.

Step 2-1: A step of adding a dispersant to the toner particles obtained in Step 1 and dispersing it in an insulating liquid to obtain a toner particle dispersion.
Step 2-2: A step of wet-pulverizing the toner particle dispersion obtained in Step 2-1 to obtain a liquid developer

  In Step 2-1, as a method of mixing the toner particles, the insulating liquid, and the dispersing agent, a method of stirring with a stirring and mixing device is preferable.

  The stirring and mixing device is not particularly limited, but a high-speed stirring and mixing device is preferable from the viewpoint of improving the productivity and storage stability of the toner particle dispersion, and specifically, Despa (manufactured by Asada Iron Works Co., Ltd.), T.I. K. homomixer, T. K. homodisperser, T. K. Robomix (all of which are manufactured by Primix, Inc.), Creamix (manufactured by Em Technics, Inc.), Kedy Mill (manufactured by Caddy International Inc.) and the like are preferable.

  By mixing the toner particles with the insulating liquid and the dispersing agent using a high-speed stirring and mixing device, the toner particles can be predispersed to obtain a toner particle dispersion, and the productivity of the liquid developer is improved by the following wet grinding Do.

  The subsequent step 2-2 is a step of wet-pulverizing the toner particle dispersion obtained in the step 2-1 to obtain a liquid developer. Wet grinding is a method of mechanically grinding toner particles dispersed in an insulating liquid in a state of being dispersed in the insulating liquid.

  The solid content concentration of the toner particle dispersion to be subjected to wet pulverization is preferably 20% by mass or more, more preferably 30% by mass or more, still more preferably 33% by mass or more, from the viewpoint of improving the image density of the liquid developer. From the viewpoint of improving the storage stability of the toner particles in the liquid developer, it is preferably 50% by mass or less, more preferably 45% by mass or less, and still more preferably 40% by mass or less.

  As an apparatus used for wet pulverization, for example, a generally used stirring and mixing apparatus such as an anchor wing can be used. Among the stirring and mixing devices, high-speed stirring and mixing devices such as Despa (manufactured by Asada Iron Works, Ltd.) and TK Homomixer (manufactured by Primix), mills such as roll mills, beads mills, kneaders, and extruders, kneaders, etc. may be mentioned. . These devices can also be combined.

  Among these, from the viewpoint of reducing the particle size of toner particles in the liquid developer, and from the viewpoint of improving the storage stability of the toner particles in the liquid developer, and from the viewpoint of reducing the viscosity of the toner particle dispersion The use of a bead mill is preferred.

  In the bead mill, toner particles having a desired particle size and particle size distribution can be obtained by controlling the particle size and filling ratio of the medium used, the circumferential velocity of the rotor, the residence time and the like.

  The solid content concentration of the liquid developer is preferably 10% by mass or more, more preferably 15% by mass or more, and still more preferably 20% by mass or more from the viewpoint of improving the image density of the liquid developer, and in the liquid developer From the viewpoint of improving the storage stability of the toner particles, it is preferably 50% by mass or less, more preferably 45% by mass or less, still more preferably 40% by mass or less, and still more preferably 30% by mass or less. After preparation of the toner particle dispersion, if there is no operation such as dilution and concentration, the solid content concentration of the toner particle dispersion becomes the solid content concentration of the liquid developer, but after wet grinding, it is diluted with an insulating liquid and solid content concentration You may adjust the

  The content of the binder resin in the liquid developer of the present invention is preferably 3% by mass or more, more preferably 5% by mass from the viewpoint of improving the storage stability of the toner particles in the liquid developer and reducing the viscosity. % Or more, more preferably 10% by mass or more, and further preferably 15% by mass or more, and from the viewpoint of improving the grindability of the liquid developer, preferably 40% by mass or less, more preferably 30% by mass or less More preferably, it is 25 mass% or less. Here, the content of the binder resin in the liquid developer means that when the liquid developer is obtained, the liquid developer obtained by dispersing the toner particles in the insulating liquid is obtained and then diluted. , And the content in the liquid developer after dilution. Hereinafter, the same applies to the colorant and the dispersant.

  In the liquid developer of the present invention, the content of the dispersant improves the storage stability of the toner particles in the liquid developer, and from the viewpoint of lowering the viscosity, preferably 0.05% by mass or more, more preferably 0.1% by mass. Or more, more preferably 0.5% by mass or more, further preferably 1% by mass or more, and from the viewpoint of improving the low-temperature fixability of the liquid developer, preferably 8% by mass or less, more preferably 6% by mass or less More preferably, it is 4% by mass or less.

  In the liquid developer according to the present invention, the content of the copolymerization reaction product (D) is preferably 0.05% by mass or more from the viewpoint of improving the storage stability of the toner particles in the liquid developer and reducing the viscosity. It is more preferably 0.1% by mass or more, still more preferably 0.2% by mass or more, and further preferably 0.3% by mass or more, and from the viewpoint of improving the low temperature fixability of the liquid developer, preferably 8% by mass or less Preferably it is 6 mass% or less, More preferably, it is 4 mass% or less.

The volume median particle diameter (D ₅₀ ) of the toner particles in the liquid developer is preferably 5 μm or less from the viewpoint of reducing the particle diameter of the toner particles in the liquid developer and improving the image quality of the liquid developer. The thickness is preferably 3 μm or less, more preferably 2.5 μm or less, and from the viewpoint of reducing the viscosity of the liquid developer, preferably 0.5 μm or more, more preferably 1.0 μm or more, and still more preferably 1.5 μm or more.

  The viscosity of the liquid developer having a solid content of 25% by mass at 25 ° C. is preferably 30 mPa · s or less, more preferably 20 mPa · s or less, still more preferably 15 mPa · s or less, from the viewpoint of improving the fixability of the liquid developer. And more preferably 10 mPa · s or less, and from the viewpoint of improving the storage stability of the toner particles in the liquid developer, preferably 1 mPa · s or more, more preferably 2 mPa · s or more, still more preferably 3 mPas. · S or more, more preferably 4 mPa · s or more.

The conductivity of the liquid developer is preferably 1.00 × 10 ⁻¹¹ S / m or more, more preferably 5.00 × 10 ⁻¹¹ S / m or more, from the viewpoint of the developability of the liquid toner and the image quality, and preferably It is 1.00 × 10 ⁻¹⁰ S / m or less, more preferably 7.00 × 10 ⁻¹¹ S / m or less.

  EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited by these examples. Physical properties of the resin and the like were measured by the following methods.

[Softening point of resin]
Using a flow tester "CFT-500D" (manufactured by Shimadzu Corporation), while heating a 1 g sample at a heating rate of 6 ° C./min, a load of 1.96 MPa is applied by a plunger, diameter 1 mm, length 1 mm Push out of the nozzle. The plunger drop amount of the flow tester is plotted against the temperature, and the temperature at which half of the sample flowed out is taken as the softening point.

[Glass transition temperature of resin]
Using a differential scanning calorimeter "Q20" (manufactured by TA instruments), measure 0.01 to 0.02 g of a sample in an aluminum pan, raise the temperature to 200 ° C, and cool it to 0 ° C at a temperature decrease rate of 10 ° C / min. Do. Next, the sample is heated at a temperature rising rate of 10 ° C./min to measure an endothermic peak. The temperature at the intersection of the extension of the baseline below the highest endothermic peak temperature and the tangent showing the maximum slope from the rising portion of the peak to the peak of the peak is taken as the glass transition temperature.

[Acid value of resin, (meth) acrylic polymer, and macromonomer]
It measures based on the method of JISK0070. However, only the measurement solvent is changed to a mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)) from a mixed solvent of ethanol and ether defined in JIS K0070.

[Number average molecular weight (Mn) of macromonomer and dispersant]
The molecular weight distribution is measured by gel permeation chromatography (GPC) according to the following method to determine the number average molecular weight (Mn).
(1) Preparation of Sample Solution A dispersant (distillation of insulating liquid from the dispersant solution) was dissolved in tetrahydrofuran so that the concentration was 0.5 g / 100 mL. Then, this solution was filtered using a fluororesin filter “FP-200” (manufactured by Sumitomo Electric Industries, Ltd.) with a pore size of 2 μm to remove insoluble components, and used as a sample solution.
(2) Molecular weight distribution measurement Using the following measuring device and analysis column, flow tetrahydrofuran as an eluent at a flow rate of 1 mL per minute, and stabilize the column in a 40 ° C. thermostat. Then, 100 μL of the sample solution is injected to perform measurement. The molecular weight of the sample is calculated based on a calibration curve prepared in advance. The calibration curve at this time includes several types of monodispersed polystyrene (A-500 (5.0 × 10 ² ), A-1000 (1.01 × 10 ³ ), A-2500 (2.63 × 10 ³ ), manufactured by Tosoh Corporation), A-5000 (5.97 × 10 ³ ), F-1 (1.02 × 10 ⁴ ), F-2 (1.81 × 10 ⁴ ), F-4 (3.97 × 10 ⁴ ), F-10 (9.64 × 10 ⁴ ), Those prepared using F-20 (1.90 × 10 ⁵ ), F-40 (4.27 × 10 ⁵ ), F-80 (7.06 × 10 ⁵ ), and F-128 (1.09 × 10 ⁶ ) as standard samples are used. The parentheses indicate the molecular weight.
Measuring device: HLC-8220GPC (made by Tosoh Corporation)
Analysis column: TSKgel GMH _XL + TSKgel G3000H _XL (manufactured by Tosoh Corporation)

[Amine value of dispersant]
Measure according to the method of JIS K2501. However, only the measurement solvent is changed from chlorobenzene to chloroform as prescribed in JIS K2501.

[Volume median particle size of toner particles before mixing with insulating liquid]
Measuring machine: Coulter Multisizer II (manufactured by Beckman Coulter Co., Ltd.)
Aperture diameter: 100 μm
Analysis software: Coulter multisizer Accucomp version 1.19 (manufactured by Beckman Coulter Co., Ltd.)
Electrolyte: Isoton II (manufactured by Beckman Coulter Co., Ltd.)
Dispersion solution: Emulgen 109P (manufactured by Kao Corporation, polyoxyethylene lauryl ether, HLB (glyphin): 13.6) dissolved in electrolyte to adjust to 5% by mass Dispersion conditions: 10 mg of measurement sample in 5 mL of the dispersion Is added and dispersed for 1 minute with an ultrasonic dispersion machine (machine name: US-1, manufactured by SND Co., Ltd., output: 80 W), and then 25 mL of the electrolytic solution is added, and further an ultrasonic dispersion machine The mixture is dispersed for 1 minute to prepare a sample dispersion.
Measurement conditions: The sample dispersion is added to 100 mL of the electrolyte so that the particle size of 30,000 particles can be measured in 20 seconds, 30,000 particles are measured, and the volume is determined from the particle size distribution. Determine the median particle size (D ₅₀ ).

[Conductivity of Insulating Liquid and Liquid Developer]
Put 25 g of insulating liquid into a 40 mL glass sample tube “screw No. 7” (manufactured by Marem Co.) and use the non-aqueous conductivity meter “DT-700” (manufactured by Dispersion Technology) to develop the electrode as a liquid Immerse in an agent, measure 20 times, calculate the average value, and measure the conductivity. The smaller the value, the higher the resistance.

[Viscosity of Insulating Liquid and Liquid Developer at 25 ° C.]
Put 4 to 5 mL of the measurement solution into a 6 mL glass sample tube “screw No. 2” (manufactured by Marem Co., Ltd.), and use a rotational vibration viscometer “Biscomate VM-10A-L” (manufactured by Seconik Co., Ltd.) Measure the viscosity at 25 ° C.

[Solid Content Concentration of Toner Particle Dispersion and Liquid Developer]
Ten parts by mass of the sample is diluted with 90 parts by mass of hexane and rotated for 20 minutes at a rotational speed of 25000 r / min using a centrifugal separator “H-201F” (manufactured by Koksan Co., Ltd.). After standing, the supernatant is removed by decantation, diluted with 90 parts by mass of hexane, and centrifuged again under the same conditions. After removing the supernatant liquid by decantation, the lower layer is dried with a vacuum dryer at 0.5 kPa and 40 ° C. for 8 hours, and the solid content concentration is calculated from the following equation.

[Volume median particle diameter (D ₅₀ ) of toner particles in liquid developer]
Isopar L (Exxon Mobil, isoparaffin, viscosity 1 mPa · s at 25 ° C) is added to the cell for measurement using a laser diffraction / scattering type particle sizer “Mastersizer 2000” (manufactured by Malvern), and the scattering intensity is measured. The volume median particle size (D ₅₀ ) is measured under the conditions of a particle refractive index of 1.58 (imaginary part 0.1) and a dispersion medium refractive index of 1.42 at a concentration of 5 to 15%.

Resin production example 1
10 L four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer and a thermocouple, as raw materials monomers for the polyester resin other than fumaric acid and trimellitic anhydride shown in Table 1, esterification catalyst and esterification co-catalyst Put in. The temperature was raised to 235 ° C. using a mantle heater, and then reacted for 8 hours at 235 ° C., and then reduced for pressure to 8.3 kPa for 1 hour. The temperature was lowered to 170 ° C., and the raw material monomers of the styrene resin shown in Table 1, the bireactive monomer and the polymerization initiator were dropped over 1 hour by the dropping funnel. The addition polymerization reaction was aged for 1 hour while being maintained at 170 ° C. Thereafter, the temperature was raised to 210 ° C., and the raw material monomer of the styrene resin was removed at 8.3 kPa for 1 hour, and the reaction between the bireactive monomer and the polyester resin portion was performed. Furthermore, trimellitic anhydride, fumaric acid and a polymerization inhibitor are added at 210 ° C., and the reaction is performed until the softening point shown in Table 1 is reached, and a composite resin (Resin A) having physical properties shown in Table 1 is obtained. Obtained.

Resin production example 2
The raw material monomers of polyester resin shown in Table 1, esterification catalyst and esterification co-catalyst are put into a 10 L four-necked flask equipped with a nitrogen introducing pipe, a dewatering pipe, a stirrer and a thermocouple, and heated to 235 ° C. The reaction was carried out until the reaction rate reached 90%, and the reaction was terminated when the softening point reached 93 ° C. at 8.3 kPa, and a polyester resin (Resin B) having physical properties shown in Table 1 was obtained. The reaction rate refers to the value of the amount of reaction water produced (mol) / the amount of water theoretically produced (mol) × 100.

Production Example 1 of Macromonomer
500 g of methyl ethyl ketone as a solvent was placed in a 2 L four-necked flask equipped with a cooling pipe, a nitrogen introducing pipe, a stirrer and a thermocouple, and the inside of the reaction vessel was replaced with nitrogen gas. The inside of the reaction vessel was heated to 80 ° C., and a mixture of a (meth) acrylic monomer, a chain transfer agent, and a polymerization initiator shown in Table 2 was added dropwise over 3 hours to carry out a polymerization reaction. After completion of the dropwise addition, the reaction was further allowed to proceed at 80 ° C for 3 hours. The solvent was distilled off at 80 ° C. to obtain (meth) acrylic polymers (F-1 to F-3) having physical properties shown in Table 2.

  A 2-L four-necked flask equipped with a (meth) acrylic polymer, glycidyl methacrylate, a catalyst, and a polymerization inhibitor shown in Table 3, 250 g of methyl ethyl ketone as a solvent, a cooling pipe, a nitrogen introducing pipe, a stirrer and a thermocouple Put in. Then, the reaction vessel is heated to 80 ° C. and reacted while air bubbling, and while measuring the acid value, the reaction is performed until the reaction rate reaches 95% or more, and the macromonomer (M-1 having physical properties shown in Table 3) To M-3).

Production Example of Dispersant 100 g of methyl ethyl ketone as a solvent was placed in a 2 L four-necked flask equipped with a condenser, a nitrogen introduction pipe, a stirrer and a thermocouple, and the inside of the reaction vessel was replaced with nitrogen gas. The inside of the reaction vessel was heated to 80 ° C., and a mixture of an adsorptive group raw material, a dispersible base material and a polymerization initiator shown in Table 4 was dropped over 3 hours to carry out a polymerization reaction. After completion of the dropwise addition, the reaction was further allowed to proceed at 80 ° C for 3 hours. The solvent was distilled off at 80 ° C. to obtain dispersants (D-1 to D-5, D-7 to D-9) having physical properties shown in Table 4.

Examples 1 to 6 and Comparative Examples 1 to 4
80 parts by mass of a binder resin shown in Table 5 and 20 parts by mass of a coloring agent “ECB-301” (manufactured by Dainichi Seika Kogyo Co., Ltd., phthalocyanine blue 15: 3) are preliminarily rotated using a 20 L volume Henschel mixer After stirring and mixing for 3 minutes at several 1500 r / min (circumferential velocity 21.6 m / sec), melt kneading was performed under the conditions shown below.

Melting and kneading conditions
A continuous double-open-roll type kneader "Kinedex" (manufactured by Nippon Coke Industry Co., Ltd., roll outer diameter: 14 cm, effective roll length: 55 cm) was used. The operating conditions of the continuous two-open-roll type kneader are: high speed roll (front roll) rotation speed 75 r / min (circumferential velocity 32.4 m / min), low speed roll (back roll) rotation speed 35 r / min ( The circumferential speed was 15.0 m / min) and the roll gap at the end of the kneaded material supply port was 0.1 mm. The temperature of the heating medium and the temperature of the cooling medium in the roll are 90 ° C for the raw material input side of the high rotation side roll and 85 ° C for the kneaded material discharge side, 35 ° C for the raw material input side of the low rotation side roll and 35 ° C for the kneaded material discharge side there were. The feed rate of the raw material mixture to the kneader was 10 kg / h, and the average residence time in the kneader was about 3 minutes.

The obtained kneaded product was rolled and cooled with a cooling roll, and then roughly crushed to about 1 mm using a hammer mill. The obtained coarsely pulverized product was finely pulverized and classified by a pneumatic jet mill "IDS" (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) to obtain toner particles having a volume median particle size (D ₅₀ ) of 10 μm.

35 parts by mass of the obtained toner particles and insulating liquid “NAS-4” (manufactured by NOF Corporation, polyisobutene, conductivity: 1.52 × 10 ⁻¹² S / m, viscosity at 25 ° C .: 2 mPa · s) 63.95 mass Parts and 1.05 parts by mass of the dispersant shown in Table 5 (2.1 parts by mass of Comparative Example 1 only) are placed in a 1 L polyethylene container, and ice-cooled using "TK Robomix" (manufactured by Primix Co., Ltd.) The mixture was stirred for 30 minutes at a rotational speed of 7000 r / min to obtain a toner particle dispersion having a solid content concentration of 36% by mass.

  Next, the obtained toner particle dispersion is rotated at a volume packing ratio of 60% by volume using zirconia beads of diameter 0.8 mm with a six-cylinder sand mill “TSG-6” (manufactured by Imex Co., Ltd.) It wet-grounded at 1300 r / min (circumferential velocity 4.8 m / sec). After removing the beads by filtration, 44 parts by mass of an insulating liquid "NAS-4" (manufactured by NOF Corporation) was added to 100 parts by mass of the filtrate to dilute and adjust the solid concentration to 25% by mass. A liquid developer having physical properties shown in Table 5 was obtained.

The liquid developers of Examples 1 to 6 have small particle diameter and low viscosity, and are found to have good chargeability because of their low conductivity.
On the other hand, Comparative Example 1 using a dispersant which is not the copolymerization reaction product (D) in the present invention is difficult in small particle size and low viscosity, and has poor chargeability. Further, in Comparative Examples 2 and 3, since methacrylic acid or cyclohexyl methacrylate is used as the adsorptive group, acid-base interaction with the binder resin having an acidic group does not work, and the dispersibility is deteriorated. The viscosity increases and the chargeability is also poor. In Comparative Example 4, since the dispersing group is lauryl methacrylate having 12 carbon atoms, the dispersibility is poor, and it is difficult to reduce the particle size and reduce the viscosity.

  The liquid developer of the present invention is suitably used, for example, for the development of a latent image formed by an electrophotographic method, an electrostatic recording method, an electrostatic printing method or the like.

Claims (6)

  A liquid developer comprising a binder resin comprising a resin having an acidic group, a toner particle comprising a colorant, a dispersant, and an insulating liquid, wherein the dispersant comprises an ethylenically unsaturated single monomer having an amino group. A liquid comprising a copolymerization reaction product (D) of a monomer (d-1) and a macromonomer (d-2) containing a (meth) acrylic polymer having a hydrocarbon group having 6 to 24 carbon atoms Developer.   The liquid developer according to claim 1, wherein the number average molecular weight of the macromonomer (d-2) is 2,000 or more and 20,000 or less.   The liquid developer according to claim 1 or 2, wherein the (meth) acrylic polymer in the macromonomer (d-2) is a polymer of methacrylic acid alkyl ester in which the carbon number of the alkyl group is 8 or more and 18 or less.   The liquid developer according to any one of claims 1 to 3, wherein the number average molecular weight of the copolymerization reaction product (D) is 5,000 or more and 100,000 or less.   The mass ratio ((d-1) / (d-2)) of the ethylenically unsaturated monomer (d-1) to the macromonomer (d-2) is 5/95 or more and 35/65 or less. The liquid developer according to any one of Items 1 to 4.   The liquid developer according to any one of claims 1 to 5, wherein the amine value of the copolymerization reaction product (D) is 15 mgKOH / g or more and 150 mgKOH / g or less.