JP2017067861A - Liquid developer, liquid developer cartridge, image forming apparatus, and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid developer that has low-temperature fixability and can provide toner images with high fixing strength.SOLUTION: There is provided a liquid developer comprising: toner particles containing a polymer including an active hydrogen group and a polymer including a block isocyanate group, and having a volume average particle diameter of 0.5 μm or more and 3 μm or less; and a carrier liquid having the toner particles dispersed therein.SELECTED DRAWING: None

Description

  The present invention relates to a liquid developer, a liquid developer cartridge, an image forming apparatus, and an image forming method.

  For example, Patent Document 1 discloses a colored particle dispersion obtained by dispersing colored particles containing a colorant, a fixing agent and a dispersant in an electrically insulating carrier liquid, and a crosslinking agent particle containing a crosslinking agent and a dispersant. In a thermosetting liquid developer comprising a dispersion of a crosslinking agent particle dispersed in an electrically insulating carrier liquid, (1) the fixing agent is a resin containing an active hydrogen group, and (2) the dispersant is electrically insulating. Disclosed is a thermosetting liquid developer which is a colored particle dispersion which is a non-aqueous dispersible resin insoluble in a carrier liquid, and (3) the crosslinking agent is a polyisocyanate and / or a block polyisocyanate. Yes.

Japanese Patent Laid-Open No. 06-032861

  The present invention relates to a liquid developer in which the toner particles dispersed in a carrier liquid include a polymer having an active hydrogen group and a polymer having a blocked isocyanate group, and the volume average particle size is less than 0.5 μm or more than 3 μm. Another object of the present invention is to provide a liquid developer capable of obtaining a toner image having low temperature fixability and high fixing strength.

In order to achieve the above object, the following invention is provided.
The invention according to claim 1 includes a toner particle containing a polymer having an active hydrogen group and a polymer having a blocked isocyanate group, and having a volume average particle size of 0.5 μm or more and 3 μm or less, and a carrier liquid in which the toner particles are dispersed. And a liquid developer.

  The invention according to claim 2 is the liquid developer according to claim 1, wherein the polymer having an active hydrogen group has a number average molecular weight (Mn) of 2,000 or more and 10,000 or less.

  According to a third aspect of the present invention, the toner particles include the polymer having the blocked isocyanate group and the active hydrogen group as at least a part of the polymer having the active hydrogen group and the polymer having the blocked isocyanate group. The liquid developer according to claim 1.

  The invention according to claim 4 is the liquid developer according to any one of claims 1 to 3, wherein the polymer having active hydrogen groups is a polyester resin.

  The invention according to claim 5 is the liquid developer according to any one of claims 1 to 4, wherein the polymer having a blocked isocyanate group is a vinyl resin.

  The invention according to claim 6 comprises a polyhydric alcohol ester compound comprising a reaction product of a linear or branched saturated aliphatic polyhydric alcohol and a linear or branched saturated aliphatic monovalent carboxylic acid. The liquid developer according to any one of claims 1 to 5.

The invention according to claim 7 is the liquid developer according to claim 6, wherein the polyhydric alcohol ester compound has an electrical conductivity of 10 ⁻¹¹ S / m or less.

  The invention according to claim 8 is the liquid developer according to claim 6 or 7, wherein the saturated aliphatic polyhydric alcohol has a valence of 3 to 6.

  The invention according to claim 9 is the invention according to any one of claims 1 to 8, wherein the toner particles contain a colorant in a proportion of 15% by mass or more and 50% by mass or less with respect to the total mass of the toner particles. The liquid developer described in 1.

  According to a tenth aspect of the present invention, there is provided a liquid developer cartridge that houses the liquid developer according to any one of the first to ninth aspects and is detachable from the image forming apparatus.

  According to an eleventh aspect of the present invention, there is provided an electrostatic latent image holding body, a charging device for charging the surface of the electrostatic latent image holding body, and a latent image for forming an electrostatic latent image on the surface of the electrostatic latent image holding body. An image forming apparatus and the liquid developer according to claim 1 are stored, and an electrostatic latent image formed on a surface of the electrostatic latent image holding member is stored in the liquid developing device. Image forming apparatus comprising: a developing device that develops a toner image by developing with an agent; a transfer device that transfers the toner image to a recording medium; and a fixing device that fixes the toner image on the recording medium to the recording medium. apparatus.

  According to a twelfth aspect of the present invention, there is provided a charging step for charging the surface of the electrostatic latent image holding member, a latent image forming step for forming an electrostatic latent image on the surface of the electrostatic latent image holding member, and the electrostatic latent image holding member. A developing step for developing a toner image by developing the electrostatic latent image formed on the surface of the image carrier with the liquid developer according to any one of claims 1 to 9, and recording the toner image An image forming method comprising: a transfer step of transferring to a medium; and a fixing step of fixing the toner image on the recording medium to the recording medium.

  According to the invention of claim 1, the toner particles dispersed in the carrier liquid include a polymer having an active hydrogen group and a polymer having a blocked isocyanate group, and the volume average particle diameter is less than 0.5 μm or 3 μm. Provided is a liquid developer capable of obtaining a toner image having low-temperature fixability and high fixing strength as compared with an excess liquid developer.

  According to the second aspect of the present invention, a toner image having a high fixing strength is obtained as compared with the case where the number average molecular weight (Mn) of the polymer having an active hydrogen group is less than 2000, and the polymer having the active hydrogen group. Compared with the case where the number average molecular weight (Mn) of the polymer exceeds 10,000, a liquid developer excellent in low-temperature fixability is provided.

  According to the invention of claim 3, a toner image having a high fixing strength can be obtained as compared with the case where the toner particles include the polymer having the blocked isocyanate group and the polymer having the active hydrogen group as separate polymers. A liquid developer is provided.

  According to the fourth aspect of the invention, there is provided a liquid developer capable of obtaining a toner image having low temperature fixability and high fixing strength as compared with the case where the polymer having active hydrogen groups is a styrene acrylic resin. Provided.

  According to the fifth aspect of the present invention, there is provided a liquid developer capable of obtaining a toner image having a high fixing strength as compared with the case where the polymer having the blocked isocyanate group is a polyester resin.

  The invention according to claim 6 includes a polyhydric alcohol ester compound comprising a reaction product of a linear or branched saturated aliphatic polyhydric alcohol and a linear or branched saturated aliphatic monovalent carboxylic acid. A liquid developer is provided that has a low-temperature fixability and a high fixing strength as compared with the case where no toner image is obtained.

According to the seventh aspect of the present invention, there is provided a liquid developer having a low temperature fixability as compared with the case where the polyhydric alcohol ester compound has a conductivity exceeding 10 ⁻¹¹ S / m.

  According to the invention of claim 8, a toner image having low temperature fixability and high fixing strength can be obtained as compared with the case where the saturated aliphatic polyhydric alcohol is less than trivalent or more than hexavalent. A liquid developer is provided.

  According to the invention of claim 9, the amount of toner to be transferred to the recording medium as compared with the case where the content of the colorant contained in the toner particles is less than 15 mass% with respect to the total mass of the toner particles. Is provided, and a liquid developer capable of obtaining a toner image having a high fixing strength as compared with the case where it exceeds 50% by mass is provided.

  According to the invention of claim 10, 11 or 12, the toner particles dispersed in the carrier liquid contain a polymer having an active hydrogen group and a polymer having a blocked isocyanate group, and the volume average particle diameter is less than 0.5 μm. Or a liquid developer cartridge, an image forming apparatus, or an image forming method capable of obtaining a toner image having a low-temperature fixability and a high fixing strength as compared with a case where a liquid developer exceeding 3 μm is applied. The

1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an exemplary embodiment. It is a schematic block diagram which shows another example of the image forming apparatus of this embodiment.

  Embodiments that are examples of the present invention will be described below.

[Liquid developer]
The liquid developer according to the exemplary embodiment includes a toner particle including a polymer having an active hydrogen group and a polymer having a blocked isocyanate group, and having a volume average particle diameter of 0.5 μm to 3 μm, and the toner particles are dispersed. A carrier liquid.
By using the liquid developer according to the exemplary embodiment, it is possible to fix a recording medium at a low temperature, while obtaining a toner image having a high fixing strength. The reason is guessed as shown below.

  In addition to paper, a thermoplastic resin film (for example, a polypropylene film or a polyethylene terephthalate film) may be used as a recording medium for forming an image using a liquid developer. Examples of applications in this case include labels, posters, various packaging materials (for example, flexible packaging materials) and the like.

In the case of forming an image on a thermoplastic resin film, if a fixing temperature for fixing the image, for example, a temperature equivalent to that for fixing an image on paper is adopted, the thermoplastic resin film may be deformed by heat. There is. Furthermore, for example, when applied to a soft packaging material as a thermoplastic resin film, the suitability as a soft packaging material may be reduced due to deformation of the film.
On the other hand, when the fixing temperature is lowered for the purpose of suppressing the deformation of the thermoplastic resin film, the toner particles are insufficiently melted because the temperature is low, and the fixing strength of the image to the thermoplastic resin film is lowered.
Also, when using paper as a recording medium, improvement in low-temperature fixability and fixing strength is required.

  In order to improve the fixing strength of the toner image, for example, there are a method of performing a surface treatment on the surface of the recording medium in advance by corona discharge or a method of using a recording medium in which a primer layer is provided in advance. However, the cost of the recording medium will increase.

On the other hand, since the toner particles contained in the liquid developer according to the present embodiment are small-sized toner particles having a volume average particle diameter of 0.5 μm or more and 3 μm or less, the toner particles are relatively low in temperature (for example, Fixing at 100 ° C. or lower).
Further, the toner particles contained in the liquid developer according to the exemplary embodiment include a polymer having a blocked isocyanate group as a binder resin (hereinafter sometimes referred to as “block isocyanate group-containing polymer”) and a polymer having an active hydrogen group. (Hereinafter sometimes referred to as “active hydrogen group-containing polymer”), the blocked isocyanate group-containing polymer is unblocked by heating at the time of fixing, reacts with the active hydrogen group-containing polymer, and has a molecular weight due to bonding between the polymers. Greatly increases. Therefore, the toner image after fixing has a high fixing strength by including a binder resin having an increased molecular weight.
In addition, when a functional group such as an OH group is present on the surface of the recording medium, a part of the isocyanate group from which the block of the blocked isocyanate group-containing polymer contained in the toner particles is removed during fixing is the OH group on the surface of the recording medium. It is considered that the fixing strength further increases by reacting with both.
Therefore, when the liquid developer according to this embodiment is used, for example, even for a thermoplastic resin film used as a soft packaging material, deformation of the film such as generation of wrinkles can be achieved by fixing the toner image at a low temperature. In addition, it is possible to form a toner image that is suppressed and has a high fixing strength.

  In addition, since the liquid developer according to this embodiment uses small-diameter toner particles having a volume average particle diameter of 0.5 μm or more and 3 μm or less, a high-definition fixed image can be obtained with a small amount of toner. When toner particles having a volume average particle size of 3 μm or less are used as a dry developer, the toner particles easily diffuse into the atmosphere. However, in the present embodiment, a liquid developer in which toner particles are diffused in a carrier liquid is used. Therefore, the diffusion of toner particles into the atmosphere can be suppressed.

  Hereinafter, the configuration of the liquid developer according to this embodiment will be described in detail.

<Toner particles>
First, the toner particles in this embodiment will be described in detail.
The toner particles in the present embodiment include an active hydrogen group-containing polymer and a blocked isocyanate group-containing polymer, and have an average particle size of 0.5 μm to 3 μm. The toner particles in the present embodiment are configured to include a colorant, a release agent, and other additives as necessary.

(Active hydrogen group-containing polymer and blocked isocyanate group-containing polymer)
The toner particles in the present embodiment contain an active hydrogen group-containing polymer and a blocked isocyanate group-containing polymer as a binder resin. The toner particles in the present embodiment may include an active hydrogen group-containing polymer and a blocked isocyanate group-containing polymer as separate polymers, or as at least a part of the active hydrogen group-containing polymer and the blocked isocyanate group-containing polymer, A polymer having an active hydrogen group and a blocked isocyanate group may be included. That is, the toner particles in the present embodiment may include only a polymer having an active hydrogen group and a blocked isocyanate group as an active hydrogen group-containing polymer and a blocked isocyanate group-containing polymer, or a polymer having an active hydrogen group and a blocked isocyanate group. And one or both of a polymer having an active hydrogen group and not having a blocked isocyanate group, and a polymer having no active hydrogen group and having a blocked isocyanate group.

  Further, the toner particles in the present exemplary embodiment may contain a resin other than the active hydrogen group-containing polymer and the blocked isocyanate group-containing polymer as the binder resin as long as the low temperature fixability and the fixing strength are not impaired.

-Active hydrogen group-containing polymer-
The toner particles in the present embodiment contain an active hydrogen group-containing polymer as a binder resin. The active hydrogen group in the present embodiment is a group having active hydrogen, and examples thereof include a hydroxyl group, an amino group, an imino group, a carboxyl group, a urethane group, and a urea group. In the blocked isocyanate group-containing polymer, the polymer having an active hydrogen group reacts with an isocyanate group that is unblocked, and the polymers are linked to each other by generating a bond such as a urethane bond or a urea bond in accordance with the active hydrogen group. The molecular weight of the binder resin will be greatly increased.

  Examples of the active hydrogen group-containing polymer in the present embodiment include an epoxy resin having an active hydrogen group, an acrylic resin, a polyester resin, a polyol resin, a polyurethane resin, and the like. Compatibility with the blocked isocyanate group-containing polymer, release From the viewpoint of inclusion of the agent, an acrylic resin and a polyester resin are preferable, and a polyester resin is particularly preferable.

  The polyester resin that can be used as the active hydrogen group-containing polymer in the present embodiment is not particularly limited. From the viewpoint of reducing the diameter, for example, (1) ethoxylated bisphenol type diol, (2) propoxylated bisphenol type diol, (3) Aromatic dicarboxylic acid or acid anhydride or ester thereof, and (4) at least one selected from alkyl succinic acid, alkenyl succinic acid, acid anhydride, and ester thereof in the total monomer amount. 5 mol% or more and 25 mol% or less, and (5) at least one selected from trivalent or higher polyvalent carboxylic acid, its acid anhydride, its ester, and trivalent or higher polyvalent alcohol. The polyester resin which co-condensed 1 mol% or more and 10 mol% or less of these is mentioned.

(1) ethoxylated bisphenol type diol, and (2) propoxylated bisphenol type diol (hereinafter, both compounds may be collectively referred to as “etherified bisphenol type diol”).
An ethoxylated bisphenol type diol means a compound obtained by ethoxylation of a bisphenol compound, and a propoxylated bisphenol type diol means a compound obtained by propoxylation of a bisphenol compound. Although the ratio of ethoxylation and propoxylation is not particularly limited, a compound having 2 mol or more and 3 mol or less of oxyethylene or oxypropylene is preferably used per 1 mol of the bisphenol compound. For example, the compound represented with the following general formula (I) is mentioned.

  When the general formula (I) is an ethoxylated bisphenol type diol, R represents an ethylene group, and when it is a propoxylated bisphenol type diol, R represents a propylene group. x and y are integers of 1 or more, and the average value of x + y is preferably 2 or more and 7 or less. Specific examples of the ethoxylated bisphenol type diol include polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (1.5) -2,2-bis (4- Hydroxyphenyl) propane and the like. Specific examples of the propoxylated bisphenol type diol include polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (6) -2,2-bis (4- Hydroxyphenyl) propane, polyoxypropylene (2.2) -2,2-bis (4-hydroxy-2,6-dichlorophenyl) propane and the like.

  These etherified bisphenol type diols can be produced by directly adding ethylene oxide or propylene oxide to diphenol, or by reacting an olefin halohydrin with diphenol. The molar ratio of the ethoxylated bisphenol type diol and the propoxylated bisphenol type diol in the polyester resin is preferably in the range of 1:10 to 10: 1, and in the range of 1: 4 to 4: 1. More preferably.

In the present embodiment, the polyester resin used as the binder resin is a divalent alcohol component other than the etherified bisphenol type diol, as long as it does not interfere with the effects of the present embodiment, ethylene glycol, propylene glycol. Aliphatic polyols such as 1, 4-butanediol, 1,5-pentanediol, 1,6-hexanediol, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, 1,4-butanediol,
Alicyclic alcohols such as cyclohexanediol and 1,4-cyclohexanedimethanol may be used in combination as monomers.

(3) Aromatic dicarboxylic acid or acid anhydride or ester thereof Examples of the aromatic dicarboxylic acid include aromatic carboxylic acids such as terephthalic acid, isophthalic acid, and phthalic acid. Examples of the esters include the above dicarboxylic acids and lower alkyl esters such as dimethyl terephthalate, diethyl terephthalate, and dimethyl isophthalate.

(4) At least one selected from alkyl succinic acid, alkenyl succinic acid, acid anhydrides thereof, and esters thereof (hereinafter may be collectively referred to as “succinic acid compounds”).
Examples of the succinic acid compound include n-butyl succinic acid, n-butenyl succinic acid, isobutyl succinic acid, isobutenyl succinic acid, n-octyl succinic acid, n-octenyl succinic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid, Examples thereof include isododecyl succinic acid, isododecenyl succinic acid, anhydrides thereof, and lower alkyl esters. These components are considered to contribute to suppression of aggregation of toner particles and to prevent permeation of a fixed image onto a sheet at the time of fixing. The succinic acid compound is contained in the polyester resin at a ratio of 5 mol% or more and 25 mol% or less of the total monomer amount. Preferably, they are 6 mol% or more and 20 mol% or less, More preferably, they are 7 mol% or more and 15 mol% or less.

(5) At least one selected from trivalent or higher polyvalent carboxylic acids, acid anhydrides, esters thereof, and trivalent or higher polyvalent alcohols. Examples of the carboxylic acid or acid anhydride or ester thereof (hereinafter sometimes collectively referred to as “polyvalent carboxylic acids”) include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5. -Benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, tetra (methylenecarboxyl) methane, 2,7,8-octanetetracarboxylic acid, trimesic acid, pyromellitic acid, and acid anhydrides or ester compounds thereof. As the ester compound, a lower alkyl ester is preferable. In particular, trimellitic acid, trimesic acid, pyromellitic acid, or their acid anhydrides, methyl ester compounds, and ethyl ester compounds are preferable. On the other hand, as trihydric or higher polyhydric alcohol (hereinafter sometimes referred to as “polyhydric alcohol”), sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, Pentaerythrole, dipentaerythrole, tripentaerythrole, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2 -Methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene and the like are used. In addition, the said polyhydric carboxylic acid and polyhydric alcohol function as a crosslinking agent of a polyester resin.

  The polyvalent carboxylic acids and at least one selected from trivalent or higher polyhydric alcohols are contained in the polyester resin in a proportion of 1 mol% to 10 mol% of the total monomer amount. Preferably, they are 2 mol% or more and 8 mol% or less, More preferably, they are 2 mol% or more and 6 mol% or less.

  In this embodiment, the polyester resin used as the active hydrogen group-containing polymer can be produced by co-condensing the monomers (1) to (5).

  In addition, a known catalyst is used as a polycondensation catalyst in the synthesis of the polyester resin. Specific examples thereof include titanium tetrabutoxide, dibutyltin oxide, germanium dioxide, antimony trioxide, tin acetate, zinc acetate, and disulfide. Tin etc. are mentioned.

When the molecular weight of the polyester resin is too large, the low-temperature fixability tends to decrease, and when it is too small, the fixing strength tends to decrease. From this viewpoint, in this embodiment, the polyester resin used as the active hydrogen group-containing polymer has a number average molecular weight (Mn) of preferably 1000 or more and 30000 or less, more preferably 2000 or more and 10,000 or less, and further preferably 3000 or more and 6000 or less. preferable.
In addition, also when using resin other than a polyester resin as an active hydrogen group containing polymer, it is preferable that a number average molecular weight (Mn) is the said range.

  In addition, the weight average molecular weight and number average molecular weight (Mn) of the polymer in this embodiment are values measured by GPC (gel permeation chromatography). “HLC-8120GPC, SC-8020 (manufactured by Tosoh Corporation)” is used as the GPC apparatus, two columns “TSKgel, SuperHM-H (6.0 mm ID × 15 cm, manufactured by Tosoh Corporation)” are used, and THF (tetrahydrofuran) is used as the eluent. ) Is used. As experimental conditions, an experiment is performed using a sample concentration of 0.5%, a flow rate of 0.6 ml / min, a sample injection amount of 10 μl, a measurement temperature of 40 ° C., and a RI (Refractive Index) detector. The calibration curve is “polystylen standard sample TSK standard” manufactured by Tosoh Corporation: “A-500”, “F-1”, “F-10”, “F-80”, “F-380”, “A-2500”. ”,“ F-4 ”,“ F-40 ”,“ F-128 ”, and“ F-700 ”.

  The glass transition point Tg of the polyester resin is preferably 60 ° C. or higher, and more preferably 60 ° C. or higher and 90 ° C. or lower. When Tg is less than 60 ° C., it is not preferable in terms of storage stability. On the other hand, if the Tg is too high, it is not preferable from the viewpoints of pulverization properties and fixed image strength during toner production. In addition, the glass transition point of a polyester resin means the peak value measured according to DSC method (heating rate 10 degreeC / min) of JISK7122.

  The polyester resin preferably has an acid value of 20 mgKOH / g or less and a hydroxyl value of 30 mgKOH / g or less. When the hydroxyl value of the polyester resin is 30 mgKOH or less, the charging environmental characteristics of the toner are hardly deteriorated. In particular, an increase in charge amount difference under high temperature and high humidity and low temperature and low humidity is suppressed, and it may be easy to ensure environmental stability. On the other hand, if the acid value is 20 mgKOH or less, it may be easy to adjust the charge amount to an appropriate value.

The active hydrogen group-containing polymer has been described mainly with a polyester resin, but a resin other than the polyester resin may be used.
Examples of the active hydrogen group-containing polymer include a homopolymer of a monomer having an active hydrogen group and a polymerizable group, or a copolymer with another monomer.

  Examples of the monomer having an active hydrogen group and a polymerizable group include (meth) acrylic acid hydroxy monomers such as acrylic acid, methacrylic acid, and 2-hydroxyethyl methacrylate (HEMA), and (meth) acrylic acid 2-aminoethyl. And the primary amino group-containing vinyl monomer.

In the present specification, “(meth) acryl” means that both “acryl” and “methacryl” are included.
In addition, “(meth) acrylate” means that both “acrylate” and “methacrylate” are included.

  Moreover, as an active hydrogen group containing polymer in this embodiment, as a monomer (monomer) which can form a copolymer with a monomer having an active hydrogen group and a polymerizable group, for example, styrene, parachlorostyrene, α -Styrenes such as methyl styrene; acrylic monomers such as methyl acrylate, ethyl acrylate, n-propyl acrylate, butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate; methyl methacrylate, ethyl methacrylate , Methacrylic monomers such as n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate; ethylenically unsaturated acid monomers such as sodium styrenesulfonate; vinyl nitriles such as acrylonitrile and methacrylonitrile; Vinyl methyl ether, vinyl isobutyl ether Vinyl ethers and the like; vinyl methyl ketone, vinyl ethyl ketone, vinyl ketones such as vinyl isopropenyl ketone, ethylene, propylene, olefins monomers such as butadiene and the like.

  The monomers that can constitute the active hydrogen group-containing polymer may be used alone or in combination of two or more. For example, a styrene acrylic resin synthesized by terpolymerization of styrene, methyl methacrylate, and methacrylic acid can be used as the active hydrogen group-containing polymer.

  When the active hydrogen group-containing polymer is a vinyl resin such as a styrene acrylic resin, it can be obtained by radical polymerization of a polymerizable monomer.

  The initiator for radical polymerization is not particularly limited as long as it can undergo emulsion polymerization. Specifically, hydrogen peroxide, acetyl peroxide, cumyl peroxide, tert-butyl peroxide, propionyl peroxide, benzoyl peroxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, lauroyl peroxide , Ammonium persulfate, sodium persulfate, potassium persulfate, diisopropyltetralin hydroperoxide, 1-phenyl-2-methylpropyl-1-hydroperoxide, pertriphenylacetic acid-tert-butyl hydroperoxide, tert-butyl formate, Peroxides such as tert-butyl peracetate, tert-butyl perbenzoate, tert-butyl perphenylacetate, tert-butyl permethoxyacetate, tert-butyl perN- (3-toluyl) carbamate, 2,2 '-Azobisp Bread, 2,2′-dichloro-2,2′-azobispropane, 1,1′-azo (methylethyl) diacetate, 2,2′-azobis (2-amidinopropane) hydrochloride, 2,2 ′ -Azobis (2-amidinopropane) nitrate, 2,2'-azobisisobutane, 2,2'-azobisisobutyramide, 2,2'-azobisisobutyronitrile, 2,2'-azobis-2- Methyl methylpropionate, 2,2′-dichloro-2,2′-azobisbutane, 2,2′-azobis-2-methylbutyronitrile, dimethyl 2,2′-azobisisobutyrate, 1,1′-azobis (1 -Sodium methylbutyronitrile-3-sulfonate), 2- (4-methylphenylazo) -2-methylmalonodinitrile, 4,4'-azobis-4-cyanovaleric acid, 3,5-dihy Roxymethylphenylazo-2-methylmalonodinitrile, 2- (4-bromophenylazo) -2-allylmalonodinitrile, 2,2′-azobis-2-methylvaleronitrile, 4,4′-azobis-4 -Dimethyl cyanovalerate, 2,2'-azobis-2,4-dimethylvaleronitrile, 1,1'-azobiscyclohexanenitrile, 2,2'-azobis-2-propylbutyronitrile, 1,1'- Azobis-1-chlorophenylethane, 1,1′-azobis-1-cyclohexanecarbonitrile, 1,1′-azobis-1-cycloheptanenitrile, 1,1′-azobis-1-phenylethane, 1,1 ′ -Azobiscumene, 4-nitrophenylazobenzyl cyanoacetate ethyl, phenylazodiphenylmethane, phenylazotriphenylmeth Tan, 4-nitrophenylazotriphenylmethane, 1,1′-azobis-1,2-diphenylethane, poly (bisphenol A-4,4′-azobis-4-cyanopentanoate), poly (tetraethylene glycol) -2,2'-azobisisobutyrate) and the like, 1,4-bis (pentaethylene) -2-tetrazene, 1,4-dimethoxycarbonyl-1,4-diphenyl-2-tetrazene and the like Can be mentioned. These polymerization initiators are also used as initiators in the crosslinking reaction.

  The content of the active hydrogen group-containing polymer contained in the toner particles in this embodiment depends on the required fixing temperature, fixing strength, the type of block isocyanate group-containing polymer used together, etc., but low temperature fixability and fixing strength. From the viewpoint, it is preferably 1% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 20% by mass or less, and still more preferably 5% by mass or more and 15% by mass or less with respect to the total amount of toner particles.

-Block isocyanate group-containing polymer-
The toner particles in this embodiment contain a blocked isocyanate group-containing polymer as a binder resin. In the blocked isocyanate group-containing polymer in the present embodiment, the isocyanate group is masked with a blocking agent, which remains stable near room temperature (for example, 10 ° C. or more and 30 ° C. or less), and the blocking agent is separated by heat treatment. , The active isocyanate group (—N═C═O) is regenerated. The isocyanate group regenerated by removing the blocking agent mainly reacts with the active hydrogen groups of the active hydrogen group-containing polymer contained in the same toner particles, and the polymers are bonded to each other to greatly increase the molecular weight.

  The number average molecular weight (Mn) of the blocked isocyanate group-containing polymer is preferably 1000 or more from the viewpoint of improving the fixing strength by greatly increasing the molecular weight of the binder resin by bonding with the active hydrogen group-containing polymer during fixing. The above is more preferable, and 3000 or more is more preferable. On the other hand, if the molecular weight of the blocked isocyanate group-containing polymer is too large, it is difficult to reduce the particle size to 3 μm or less when producing toner particles. Therefore, the number average molecular weight (Mn) of the blocked isocyanate group-containing polymer is 15000. The following is preferable, 10000 or less is more preferable, and 6000 or less is more preferable.

The production method of the blocked isocyanate group-containing polymer in the present embodiment is not limited, and for example, it can be obtained by homopolymerizing or copolymerizing a blocked isocyanate compound having a polymerizable group as a monomer with another monomer.
The blocked isocyanate compound used as a monomer can be obtained by reacting an isocyanate compound having a polymerizable group with a blocking agent.

  The blocked isocyanate compound having a polymerizable group is not particularly limited as long as the blocked isocyanate group-containing polymer can be obtained by polymerization of a reactive group or the like without at least a part of the blocking agent separating. For example, an acrylic resin obtained by homopolymerization or copolymerization using a blocked isocyanate compound having an acryl group or a methacryl group has a large number of blocked isocyanate groups and is advantageous for increasing the molecular weight during fixing. In particular, a blocked isocyanate group-containing polymer having an acryl group or a methacryl group at the terminal in addition to the blocked isocyanate group is preferred because it tends to have a higher molecular weight at the time of fixing.

  Examples of the blocked isocyanate compound used for producing the blocked isocyanate group-containing polymer in the present embodiment include a blocked isocyanate compound having a (meth) acryl group having a structure represented by the following general formula (II). .

In Formula (II), R ⁰ is a methyl group or a hydrogen atom, and R ¹ is —CO— or —COOR ⁴ —. R ⁴ is an alkylene group having 1 to 10 carbon atoms which may contain an ether bond and / or a phenylene group. Bk is a block site.

  Examples of the blocking agent that can constitute the block site (Bk) in the formula (II) include alcohols, phenols, lactams, oximes, acetoacetic acid alkyl esters, malonic acid alkyl esters, phthalimides, imidazoles, Examples include pyrazoles, hydrogen chloride, hydrogen cyanide, sodium hydrogen sulfite and the like.

  For example, a blocked isocyanate obtained by homopolymerizing or copolymerizing a blocked isocyanate compound having a (meth) acryl group having a structure represented by the following general formula (III) using oximes (oxime compounds) as a blocking agent Examples thereof include group-containing polymers.

In the formula, R ⁰ is a methyl group or a hydrogen atom, and R ¹ is —CO— or —COOR ⁴ —. R ⁴ is an alkylene group having 1 to 10 carbon atoms which may contain an ether bond and / or a phenylene group. R ² and R ³ are each independently any one group selected from the group consisting of a methyl group, an ethyl group, an n-propyl group, an n-butyl group, and an n-pentyl group.
The blocked isocyanate compound having a structure represented by the general formula (III) has, for example, an acrylic group when R ⁰ is hydrogen, and obtains a blocked isocyanate group-containing polymer as a vinyl resin by radical polymerization. Can do. Further, in the general formula (III), even when R ⁰ is a methyl group, a blocked isocyanate group-containing polymer as a vinyl resin can be obtained by copolymerization with another monomer having a vinyl group such as styrene. In the present specification, the “vinyl resin” means a homopolymer or copolymer using a monomer having a vinyl group, for example, a copolymer of a monomer having a vinyl group and a monomer having no vinyl group. A polymer also corresponds to a vinyl resin.
In addition, the blocked isocyanate compound represented by general formula (III) can be manufactured by the manufacturing method of the blocked isocyanate compound described in international publication WO2014 / 021166, for example.

  When obtaining a polymer having both an active hydrogen group and a blocked isocyanate group, for example, a monomer having a polymerizable group and a blocked isocyanate group, a monomer having a polymerizable group and an active hydrogen group (for example, HEMA), If necessary, it can be obtained by copolymerizing with other polymerizable monomers.

  Commercially available products can be used as the blocked isocyanate group-containing polymer or the blocked isocyanate for obtaining the blocked isocyanate group-containing polymer. For example, Karenz MOI-BM, MOI-BP (manufactured by Showa Denko), Duranate MF-K60B, SBN-70D, MF-B60B, MF-B90B, 17B-60P, TPA-B80B, TPA-B80E, E402-B80B ( Asahi Kasei Chemicals Co., Ltd.), BI-7950, BI-7951, BI-7960, BI-7961, BI-7963, BI-7982, BI-7991, BI-7992 (manufactured by Baxenden).

  The block separation start temperature of the blocked isocyanate group-containing polymer used in the exemplary embodiment is preferably 75 ° C. or higher and 200 ° C. or lower, and preferably 80 ° C. or higher and 120 ° C. or lower, from the viewpoint of stability when the liquid developer is not used and low-temperature fixability. It is more preferable that

  The content of the blocked isocyanate group-containing polymer contained in the toner particles in the present embodiment depends on the required fixing temperature, fixing strength, the type of active hydrogen group-containing polymer used together, but the low-temperature fixing property and the fixing strength. From the viewpoint, it is preferably 3% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 30% by mass or less, and still more preferably 10% by mass or more and 20% by mass or less with respect to the total amount of toner particles.

-Colorant-
The toner particles in the present embodiment contain a colorant as necessary.
As the colorant, a known pigment can be used. For example, carbon black, oil black, nigrosine dye, aniline blue, chrome yellow, ultramarine blue, Dupont oil red, quinoline yellow, tylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, C.I. I. Pigment Red 57: 1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 149, C.I. I. Pigment Red 81: 1, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 180, C.I. I. Pigment Yellow 17, C.I. I. Pigment Blue 15: 1, C.I. I. Pigment Blue 15: 3 and the like.

In particular, as a colorant for magenta toner, C.I. I. Pigment Red 57: 1, C.I. I. Pigment Red 122, or C.I. I. Pigment Red 238; as a colorant for yellow toner, C.I. I. Pigment Yellow 180, C.I. I. Pigment Yellow 185, C.I. I. Pigment Yellow 17, or C.I. I. Pigment Yellow 74; C.I. I. Pigment Blue 15: 3; and carbon black as the colorant of the black toner are preferable because the hue of the toner particles to be formed is improved and the color reproducibility and stability are improved. Furthermore, after the pigment other than carbon black is made into a flushing pigment or high-concentration pigment pellets by the treatment described below, it is preferably used as a colorant.
The flushing pigment and the high-concentration pigment pellets contain the pigment uniformly in a high concentration in the same type of resin as the binder resin that constitutes the toner particles. Compared with the case where the toner is blended as a colorant as it is, a toner in which the pigment is more uniformly dispersed can be produced. As a result, the color reproducibility of the generated image is further improved, which is preferable. From the viewpoint of ease of production and pigment uniformity, it is more preferable to use a flushing pigment.

  The flushing pigment refers to a pigment that has been subjected to a melt flushing treatment described in JP-A-7-319209. The melt flushing treatment is one of the methods for dispersing pigment particles in a binder resin, and replaces the water in the water-containing cake of the pigment generated in the pigment production process with the molten binder resin. By performing this treatment, the pigment is uniformly dispersed in the binder resin. The content of the pigment in the flushing pigment is not particularly limited, but is preferably 20% by mass or more and 60% by mass or less.

  The high-concentration pigment pellets are produced by adding each pigment in a dry state to a binder resin in advance, and heating and melting and mixing the mixture using a kneader such as a kneader. At the time of melting and mixing, a high shear force is applied to the mixture using a heating type two-roll or three-roll, or the mixture is passed through the nip portion of a plurality of rolls, and further the pigment is put into the resin. It can also be dispersed with high uniformity. The pigment content in the high-concentration pigment pellets is not particularly limited, but is preferably 20% by mass or more and 60% by mass or less.

  When the toner particles in this embodiment contain a colorant, the content of the colorant depends on the required color and the colorant used, but if the content of the colorant such as a pigment is too small, the color In order to obtain a dark toner image, it is necessary to increase the amount of toner on the recording medium (the thickness of the toner image). If the content of the colorant is too high, the content of the binder resin is relatively reduced, and the fixing strength is increased. Tends to decrease. From the viewpoint of the amount of toner formed on the recording medium, low-temperature fixability, fixing strength, etc., the content of the colorant is preferably 10% by mass or more and 50% by mass or less, and preferably 15% by mass with respect to the total mass of the toner particles. More preferred is 25% by mass or less.

-Release agent-
The toner particles in the present embodiment may contain a release agent as necessary.
As release agents, low molecular weight polyolefins such as polyethylene, polypropylene and polybutene; fatty acid amides such as silicones, oleic acid amide, erucic acid amide, ricinoleic acid amide, stearic acid amide; carnauba wax, rice wax, candelilla Plant waxes such as wax, tree wax, and Liliba oil; animal waxes such as beeswax; minerals such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, petroleum wax, and their Examples include modified products.

-Other additive components-
When the toner particles of this embodiment are used as magnetic toner particles, magnetic powder is included. Examples of the magnetic powder include magnetic oxides such as ferrite and magnetite; magnetic metals such as reduced iron, cobalt, nickel, and manganese; alloys or compounds containing these magnetic metals. Furthermore, various commonly used charge control agents such as quaternary ammonium salts, nigrosine compounds and triphenylmethane pigments may be added.

  The toner particles of the present embodiment may contain inorganic particles. Inorganic particles having a central particle size of 5 nm to 30 nm and inorganic particles having a central particle size of 30 nm to 100 nm may be contained in a range of 0.5% by mass to 10% by mass with respect to the toner. More desirable in terms of durability.

  As the inorganic particles, silica, hydrophobized silica, titanium oxide, alumina, calcium carbonate, magnesium carbonate, tricalcium phosphate, colloidal silica, cationic surface-treated colloidal silica, anion surface-treated colloidal silica, or the like is used. These inorganic particles are dispersed in advance in the presence of an ionic surfactant using an ultrasonic disperser or the like, and it is more desirable to use colloidal silica that does not require this dispersion treatment.

  In addition, a known external additive may be externally added to the toner particles of this embodiment. As the external additive, inorganic particles such as silica, alumina, titania, calcium carbonate, magnesium carbonate, and tricalcium phosphate are used. For example, as fluidity aids and cleaning aids, inorganic particles such as silica, alumina, titania and calcium carbonate, and resin particles such as vinyl resin, polyester resin and silicone resin are used. The method for adding the external additive is not particularly limited, but may be added to the toner particle surface by applying a shearing force in a dry state.

(Toner particle size)
The toner particles used in this embodiment have a volume average particle diameter D50v of 0.5 μm or more and 3.0 μm or less. When the volume average particle diameter D50v of the toner particles is within the above range, low-temperature fixing (for example, 100 ° C. or less) is possible, the adhesion is high, and the developability is improved. In addition, the resolution of the image can be improved. The volume average particle diameter D50v of the toner particles is more preferably 0.8 μm or more and 2.5 μm or less, and further preferably 1.0 μm or more and 2.0 μm or less.

  The volume average particle diameter D50v of the toner particles is measured using a laser diffraction / scattering particle size distribution measuring apparatus, for example, LA920 (manufactured by Horiba, Ltd.). A cumulative distribution is drawn from the smaller diameter side with respect to the particle size range (channel) divided on the basis of the particle size distribution, and the particle diameter at which accumulation is 50% is defined as volume D50v.

(Method for producing toner particles)
The method for producing toner particles used in the present embodiment is not particularly limited as long as toner particles containing a blocked isocyanate group-containing polymer and a polymer having an active hydrogen group and having a volume average particle size of 0.5 μm to 3 μm can be obtained. The toner particles used in the present embodiment can be produced by using, for example, a melt kneading method, a suspension polymerization method, an emulsion polymerization method, etc. Among them, the toner particles are preferably produced by a melt kneading method.

  The blending ratio of each material (block isocyanate group-containing polymer, active hydrogen group-containing polymer, colorant, and other additives) in obtaining the toner particles used in this embodiment depends on the required low-temperature fixability and fixing strength (resistance to resistance). (Bending characteristics, anti-scratch characteristics, etc.), color, etc. may be set.

  The toner particles obtained by the melt kneading method are pulverized in a carrier liquid using a known pulverization apparatus such as a ball mill, a bead mill, a high-pressure wet atomization apparatus, and the like. Is obtained. The volume average particle diameter D50v of the toner particles can be adjusted by the medium used for pulverization, the pulverization time, and the like. For example, as the pulverization time is increased, toner particles having a smaller particle diameter can be obtained.

[Carrier liquid]
Next, the carrier liquid in the present embodiment will be described in detail.

In the liquid developer according to this embodiment, the carrier liquid may be either nonvolatile or volatile.
In the liquid developer of this embodiment, non-volatile means that the flash point is 130 ° C. or higher, or the volatile content after 24 hours at 150 ° C. is 8% by mass or less. The flash point is measured according to JIS K2265-4 (2007).

  Examples of the component constituting the carrier liquid include silicone oil such as dimethyl silicone oil, paraffin oil, vegetable oil and the like, and these may be used alone or in combination of two or more.

Examples of the silicone oil include dimethyl silicone oil (commercially available from Shin-Etsu Chemical Co., KF-96, KF-965, KF-968; Toray Dow Corning, SH200; Momentive Performance Materials, TSF451). Etc.), methyl hydrogen silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-99, etc.), methyl phenyl silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-50, KF-54, etc.) and the like.
These silicone oils may be used alone or in combination of two or more.

An example of the non-volatile silicone oil as the silicone oil is, for example, KF-96 (kinematic viscosity of 10 mm ² / s or more) manufactured by Shin-Etsu Chemical Co., Ltd., SH200 (dynamic viscosity of 10 mm) manufactured by Toray Dow Corning. ² / s or higher), Momentive Performance Materials, TSF451 (kinematic viscosity of 10 mm ² / s or higher), and the like.

Examples of carrier liquids other than silicone oil include polyol compounds such as ethylene glycol, diethylene glycol, and propylene glycol; aliphatic hydrocarbon solvents such as paraffin oil (commercially available, MORESCO, Moresco White P-40, Molecule Sco White P-55, Moresco White P-70, Moresco White P-100, Moresco White P-200, Moresco White P-350P, Exxon Chemical Corporation Isopar L, Isopar M, etc.); naphthenic oils, etc. Hydrocarbon solvents (exon chemical, Exol D80, Exol D110, Exol D130, Nippon Petrochemical, Naphthezol L, Naphthezol M, Naphthezol H, New Naphthezol 160, New Naphthezol 200, Ne Naphtesol 220, New NAPHTESOL MS-20P, etc.); an aromatic compound such as toluene.
Besides these, cyclohexane, tetrahydrofuran, acetone, 2-butanol and the like can be mentioned. When these components are contained, they may be contained in an amount of less than 50% by mass with respect to the entire carrier liquid as long as the effect on properties such as low-temperature fixability and toner image fixability is not impaired. The content is preferably less than 3%, more preferably less than 3% by mass.

[Specific polyhydric alcohol ester compound]
The liquid developer according to the exemplary embodiment further includes a polyhydric alcohol ester compound comprising a reaction product of a linear or branched saturated aliphatic polyhydric alcohol and a linear or branched saturated aliphatic monovalent carboxylic acid. (Hereinafter also referred to as “specific polyhydric alcohol ester compound”).
The specific polyhydric alcohol ester compound is a reaction product of a linear or branched saturated aliphatic polyhydric alcohol and a linear or branched saturated aliphatic monovalent carboxylic acid.
In the present embodiment, the saturated aliphatic monovalent carboxylic acid includes a form of a lower alkyl ester of a saturated aliphatic monovalent carboxylic acid.

  The specific polyhydric alcohol ester compound can be produced by a known general method. For example, a method in which the polyhydric alcohol and the monovalent carboxylic acid are subjected to a dehydration condensation reaction can be given. Moreover, for example, a method of reacting the above polyhydric alcohol and the above monovalent carboxylic acid alkyl ester having 1 to 5 carbon atoms by a transesterification method may be mentioned.

  The polyhydric alcohol is represented by the following general formula (1). The monovalent carboxylic acid is represented by the following general formula (2). And the specific polyhydric alcohol ester compound which is these reaction products is represented by following General formula (3).

In the general formula (1), R ¹ represents a residue obtained by removing a hydroxyl group from a linear or branched saturated aliphatic polyhydric alcohol. n represents an integer of 2 or more (preferably an integer of 2 or more and 8 or less, more preferably an integer of 3 or more and 6 or less).

In general formula (2), R ² represents a residue obtained by removing a carboxy group from a linear or branched saturated aliphatic carboxylic acid (or a residue obtained by removing an ester group from a saturated aliphatic carboxylic acid ester). . R ³ represents a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms.

In the general formula (3), ^{R 1} and ^{R 2} represents the general formula (1) ^{R 1,} and the formula in the (2) the same group as ^{R 2} in. N represents the same numerical value as n in the general formula (1).
That is, in the general formula (3), R ¹ represents a residue obtained by removing a hydroxyl group from a linear or branched saturated aliphatic polyhydric alcohol. R ² represents a residue obtained by removing a carboxy group from a linear or branched saturated aliphatic carboxylic acid (or a residue obtained by removing an ester group from a saturated aliphatic carboxylic acid ester). N represents an integer of 2 or more (preferably an integer of 2 or more and 8 or less, more preferably an integer of 3 or more and 6 or less).

  Specific examples of the linear or branched saturated aliphatic polyhydric alcohol of the present embodiment include, for example, ethylene glycol, propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, and 1,4-butylene. Dihydric alcohols such as glycol, 2,3-butylene glycol, 1,5-pentamethylene glycol, hexylene glycol, octylene glycol, neopentyl glycol; glycerin, trimethylolethane, trimethylolpropane, 1,2,6- Examples include trivalent alcohols such as hexanetriol; tetravalent alcohols such as pentaerythritol; pentavalent alcohols such as xylitol; hexavalent alcohols such as sorbitol, mannitol, and dipentaerythritol; octavalent alcohols such as tripentaerythritol. These may be used alone or in combination of two or more. These polyhydric alcohols preferably have 1 to 20 carbon atoms, more preferably 2 to 15 carbon atoms, and even more preferably 3 to 12 carbon atoms in that they have low temperature fixability and improve fixing strength.

  The saturated aliphatic polyhydric alcohol is preferably divalent or higher and octavalent or lower, more preferably divalent or higher and hexavalent or lower, more preferably trivalent or higher and 6 or lower, from the viewpoints of low-temperature fixability and fixing strength. It is more preferable that it is not more than the valence, and it is particularly preferable that the valence is not less than 3 and not more than 4.

  Among these, the linear or branched saturated aliphatic polyhydric alcohol of the present embodiment is preferably at least one selected from the group consisting of neopentyl glycol, glycerin, and pentaerythritol.

  Among the linear or branched saturated aliphatic monovalent carboxylic acids of the present embodiment, specific examples of the linear saturated aliphatic monovalent carboxylic acid include acetic acid, propanoic acid, butanoic acid, and pentanoic acid. , Hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, eicosanoic acid and the like.

  Among the straight chain or branched chain saturated aliphatic monovalent carboxylic acids of the present embodiment, specific examples of the branched chain saturated aliphatic monovalent carboxylic acid include ethylmethylacetic acid, 2-methylbutanoic acid, 3 -Methylbutanoic acid, 2-ethylbutanoic acid, neopentanoic acid, isoheptanoic acid, 2-methylhexanoic acid, 5-methylhexanoic acid, 2-ethylhexanoic acid, isoheptanoic acid, 2-butyloctanoic acid, isooctanoic acid, 2-methylnonane Examples include acid, isononanoic acid, isodecanoic acid, dimethyloctanoic acid, isotridecanoic acid, 12-methyltridecanoic acid, 2-hexyldecanoic acid, 16-methylheptadecanoic acid, 2-heptylundecanoic acid and the like.

  When the saturated aliphatic monovalent carboxylic acid is in the form of an alkyl ester having 1 to 5 carbon atoms of the monovalent carboxylic acid, for example, methyl ester, ethyl ester, propyl ester of saturated aliphatic monovalent carboxylic acid, Examples thereof include butyl ester and pentyl ester.

  The saturated aliphatic monovalent carboxylic acid (including the lower alkyl ester of carboxylic acid) has low-temperature fixability and improves the fixing strength, so that its carbon number (however, the carbon of the carboxy group (or ester group)) 1 to 20 is preferable, 2 to 15 is more preferable, and 3 to 12 is more preferable.

  In addition, even when the specific polyhydric alcohol ester compound is included in the image formed using the liquid developer according to the present embodiment, a phenomenon (bleed) that precipitates on the surface of the image occurs due to environmental conditions or the like. It becomes easy to be suppressed.

  The specific polyhydric alcohol ester compound is considered to enter a binder resin (for example, a polyester resin) and exhibit a plasticizing effect. As the number of ester skeletons in the specific polyhydric alcohol ester compound increases, even if external stimuli due to environmental conditions etc. are given to the image, the specific polyhydric alcohol ester compound has a specific chemical structure. It is considered that precipitation from the resin hardly occurs. When the carboxylic acid portion of the specific polyhydric alcohol ester compound has a branched chain (that is, when the saturated aliphatic monovalent carboxylic acid is a branched saturated aliphatic monovalent carboxylic acid), it has a branched chain that is a polar group. Therefore, it is considered that it is difficult to precipitate from the binder resin.

  From the above, since the specific polyhydric alcohol ester compound of this embodiment has a unique structure, even when an image is formed using the liquid developer according to this embodiment, the occurrence of bleeding is easily suppressed. Presumed to be.

  An example of the specific polyhydric alcohol ester compound of the present embodiment is, for example, a linear or branched saturated aliphatic polyhydric alcohol having 1 to 20 carbon atoms, and 1 to 20 carbon atoms. (However, carbon of a carboxy group is not included.) A reaction product of a linear or branched saturated aliphatic monovalent carboxylic acid (including an alkyl ester having 1 to 5 carbon atoms of a carboxylic acid) is included. In addition, the polyhydric alcohol of the specific polyhydric alcohol ester compound may be divalent or higher (preferably divalent to octavalent or lower, more preferably trivalent or higher to hexavalent or lower).

  Specific examples of the specific polyhydric alcohol ester compound of the present embodiment represented by the general formula (3) are shown below, but are not limited thereto. In addition, the following exemplary compound numbers are described as an exemplary compound (3-number) below. Specifically, for example, “Exemplary Compound (3-15)” is represented below.

  These specific polyhydric alcohol ester compounds may be used alone or in combination of two or more. Among these specific polyhydric alcohol ester compounds, exemplary compound (3-17) (neopentyl glycol diethylhexanoate) and exemplary compound (3-) have low-temperature fixability and plasticize toner particles. 14) At least one selected from the group consisting of (nepentyl glycol dicaprate), exemplary compound (3-23) (triethylhexanoin), and exemplary compound (3-34) (pentaerythrityl tetraethylhexanoate). It is preferable. In particular, at least one of exemplary compound (3-17), exemplary compound (3-23), and exemplary compound (3-34) is more preferable.

The specific polyhydric alcohol ester compound preferably has a conductivity of 10 ⁻¹¹ S / m or less, and more preferably 10 ⁻¹² S / m or less, from the viewpoint of plasticizing the toner particles. Although it does not specifically limit as a minimum, It is preferable that it is 10 ^<-15 > S / m or more, and it is preferable that it is 10 ^<-14 > S / m or more. When the electrical conductivity of the specific polyhydric alcohol ester compound is in the above range, a decrease in transferability is suppressed, and the fixing strength is more likely to be improved.

  In this embodiment, the electrical conductivity of the specific polyhydric alcohol ester compound is measured by MPC227 (pH / Conductivity Meter, manufactured by METTLER TOLEDO).

  The content of the specific polyhydric alcohol ester compound is preferably 0.5% by mass or more and 50% by mass or less based on the toner particles in terms of having low-temperature fixability and plasticizing the toner particles. It is more preferably 5% by mass or more and 20% by mass or less, and further preferably 1% by mass or more and 10% by mass or less. Moreover, generation | occurrence | production of a bleed can also be suppressed by containing in this range. Furthermore, image durability when an image is formed on a thermoplastic resin film is improved, and deformation of the film can be suppressed.

(Other additives)
For the carrier liquid, for example, a dispersant, an emulsifier, a surfactant, a stabilizer, a wetting agent, a thickening agent, a foaming agent, an antifoaming agent, a coagulant, a gelling agent, an anti-settling agent. In addition, various auxiliary materials such as a charge control agent, an antistatic agent, an anti-aging agent, a softening agent, a filler, a flavoring agent, an anti-tacking agent, and a release agent may be contained.

[Method for producing liquid developer]
The liquid developer according to the exemplary embodiment includes the above-described toner particles, carrier liquid, and, if necessary, a specific polyhydric alcohol ester compound and other additives, for example, a ball mill, a sand mill, an attritor, a bead mill, etc. It is obtained by mixing using a machine, pulverizing, and dispersing toner particles and the like in the carrier liquid.
The dispersion of the toner particles and the like in the carrier liquid is not limited to the disperser, and may be dispersed by rotating a special stirring blade at a high speed like a mixer, or by the shearing force of a rotor / stator known as a homogenizer. You may disperse | distribute and may disperse | distribute with an ultrasonic wave.

  The concentration of the toner particles in the carrier liquid may be in the range of 0.5% by mass or more and 40% by mass or less from the viewpoint of controlling the viscosity of the developer appropriately and facilitating the circulation of the developer in the developing machine. Desirably, it is more desirable to set it as the range of 1 to 30 mass%.

  Thereafter, the obtained dispersion liquid may be filtered using, for example, a membrane filter having a pore diameter of 100 μm to remove dust and coarse particles.

[Liquid developer cartridge]
The liquid developer cartridge according to the present embodiment is a liquid developer cartridge in which the liquid developer of the present embodiment is accommodated. For example, the liquid developer accommodated in the liquid developer cartridge is a supply pipe or the like. To the developing device of the image forming apparatus. The liquid developer cartridge may be attached to and detached from the image forming apparatus in order to replace the liquid developer cartridge when the remaining amount of the liquid developer in the liquid developer cartridge runs out. The form of the liquid developer cartridge of the present embodiment is not particularly limited, but may be a tank form or a bottle form. The form of the liquid developer cartridge may be selected according to the capacity for storing the liquid developer.

[Image Forming Apparatus and Image Forming Method]
The image forming apparatus according to the present embodiment is not particularly limited as long as at least the liquid developer according to the present embodiment is used. For example, the electrostatic latent image holding body and the electrostatic latent image holding A charging device that charges the surface of the body, a latent image forming device that forms an electrostatic latent image on the surface of the electrostatic latent image holding member, the liquid developer according to the present embodiment, and the electrostatic device A developing device that develops an electrostatic latent image formed on the surface of the latent image holding member with the liquid developer to form a toner image, a transfer device that transfers the toner image to a recording medium, and a recording medium on the recording medium. And an image forming apparatus having a fixing device for fixing the toner image to a recording medium. Examples of the fixing device include a fixing device that heats and pressurizes the toner image on the recording medium and fixes the toner image on the recording medium.

  The image forming method according to the present embodiment is not particularly limited as long as at least the liquid developer according to the present embodiment is used. For example, a charging step for charging the surface of the electrostatic latent image holding member. A latent image forming step of forming an electrostatic latent image on the surface of the electrostatic latent image holding member, and a liquid developing method according to the present embodiment using the electrostatic latent image formed on the surface of the electrostatic latent image holding member. An image forming method comprising: a developing step for forming a toner image by developing with an agent; a transfer step for transferring the toner image to a recording medium; and a fixing step for fixing the toner image on the recording medium to the recording medium. Is mentioned. Examples of the fixing step include a fixing step in which the toner image on the recording medium is heated and pressed to be fixed on the recording medium.

In the image forming apparatus (image forming method), it is preferable that the fixing device (fixing step) performs fixing in two stages. Specifically, the first heating device (first heating device) heats the toner image in a non-contact manner to a temperature equal to or higher than the temperature (A) at which the storage elastic modulus of the toner particles in the toner image is 1 × 10 ⁶ Pa. 1 heating step) and a second heating and pressurizing device (second heating heating device) for applying pressure while heating at a temperature equal to or higher than the temperature (A) after heating in the first heating device (after the first heating step). Pressure step).
In the first heating device (first heating step), from the viewpoint of ensuring the fluidity of the toner particles, the toner image on the recording medium is formed by a heating device that performs heating without contact, that is, heating without contact. It is desirable that the heating is performed from the side where the recording is performed, the rear side (the side where the toner image is not formed) of the recording medium, or a combination of both.

In the image forming apparatus (image forming method) according to the present embodiment, the recording medium is not particularly limited, and a known recording medium is applied. For example, a thermoplastic resin film may be applied.
Examples of the thermoplastic resin film include polyolefin films such as polyethylene and polypropylene; polyester films such as polyethylene terephthalate and polybutylene terephthalate; polyamide films such as nylon. Other examples include films of polycarbonate, polystyrene, modified polystyrene, polyvinyl chloride, polyvinyl alcohol, polylactic acid, and the like. These films may be any of an unstretched film, a stretched film stretched in a uniaxial direction or a biaxial direction. Furthermore, the thermoplastic resin film may be in the form of a single layer or multiple layers. If necessary, a surface coat layer that assists toner fixing, a plasma treatment, or a corona treatment may be used.

  When a thermoplastic resin film is applied as a recording medium, the thermoplastic resin film is uniaxial or biaxial in terms of deformation of the thermoplastic resin film when an image is formed using the liquid developer of this embodiment. The film is preferably stretched in the direction. Further, when the recording medium is a thermoplastic resin film for use in a soft packaging material, for example, the recording medium is preferably stretched in a uniaxial direction or a biaxial direction from the characteristics required for the flexible packaging material. Moreover, as a thickness of the thermoplastic resin film for using for a flexible packaging material, 5 micrometers or more and 250 micrometers or less are mentioned, for example, Preferably 10 micrometers or more and 100 micrometers or less are mentioned. Furthermore, the thermoplastic resin film may be untreated. From the standpoint of enhancing image fixability, the thermoplastic resin film is subjected to various treatments (for example, resin coating) for improving adhesion, such as corona treatment, ozone treatment, low-temperature plasma treatment, flame treatment, glow discharge treatment, and the like. May be.

Among the thermoplastic resin films listed above, the thermoplastic resin film on which an image is formed is more preferably at least one of a polyolefin film, a polyester film, and a polyamide film, a polyethylene terephthalate film, a polypropylene, And at least one selected from the group consisting of nylon films. In the case of a multilayer film, the surface on which an image is formed is more preferably at least one thermoplastic resin film selected from the group consisting of a polyolefin film, a polyester film, and a polyamide film, and a polyethylene terephthalate film It is further desirable that it is at least one selected from the group consisting of polypropylene, and nylon film. At least one of polyethylene terephthalate film and polypropylene is particularly desirable.
The polyethylene terephthalate film, polypropylene, and nylon film are more preferably stretched in a uniaxial direction or a biaxial direction.

  Hereinafter, the configuration of the image forming method and the image forming apparatus according to the present embodiment will be described in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to the present embodiment.
The image forming apparatus 100 includes a photosensitive member (electrostatic latent image holding member) 10, a charging device 20, an exposure device (latent image forming device) 12, a developing device 14, an intermediate transfer member 16, a cleaner 18, and a transfer roll (transfer device). 28, a non-contact heating device (first heating device) 32, and heating and pressing rolls (second heating and pressing device) 34A and 34B.
The photosensitive member 10 has a cylindrical shape, and a charging device 20, an exposure device 12, a developing device 14, an intermediate transfer member 16, and a cleaner 18 are sequentially provided on the outer periphery of the photosensitive member 10. Further, a transfer roll 28 is provided at a position where the toner image 26 transferred to the intermediate transfer body 16 is transferred to the recording medium 30. Further, a non-contact heating device (first heating device) 32 is provided on the downstream side of the transfer roll 28 in the traveling direction of the recording medium 30, and heating is performed on the downstream side of the non-contact heating device 32 in the traveling direction of the recording medium 30. Pressure rolls (second heating and pressure devices) 34A and 34B are provided in pairs.

  The operation of the image forming apparatus 100 will be briefly described below.

The charging device 20 charges the surface of the photoconductor 10 to a predetermined potential, and based on the image signal, the exposure device 12 exposes the charged surface with, for example, a laser beam to form an electrostatic latent image.
The developing device 14 includes a developing roll 14a and a developer storage container 14b. The developing roll 14a is provided so that a part thereof is immersed in the liquid developer 24 stored in the developer storage container 14b. In the liquid developer 24, the toner particles are dispersed. However, for example, the liquid developer 24 may be further stirred by a stirring member provided in the developer storage container 14b.

  The liquid developer 24 supplied to the developing roll 14a is transported to the photoconductor 10 in a state limited to the supply amount determined by the regulating member, and the position where the developing roll 14a and the photoconductor 10 face (or contact). Is supplied to the electrostatic latent image. As a result, the electrostatic latent image is visualized and becomes a toner image 26.

  The developed toner image 26 is conveyed to the photoreceptor 10 rotating in the direction of arrow B in the figure and transferred to the recording medium 30. In this embodiment, before transferring to the recording medium 30, the intermediate transfer is temporarily performed. The toner image is transferred to the body 16. At this time, a peripheral speed difference may be provided between the photosensitive member 10 and the intermediate transfer member 16.

  Next, the toner image conveyed in the direction of arrow C by the intermediate transfer member 16 is transferred to the recording medium 30 at a position where the toner image is in contact with the transfer roll 28.

A non-contact heating device (first heating device) 32 is provided downstream of the transfer roll 28 in the traveling direction of the recording medium 30. The non-contact heating device 32 is a plate-like heating device, and a heater is provided inside a plate-like body whose surface is made of metal. At the position of the non-contact heating device 32, the toner image is heated to a temperature equal to or higher than the temperature (A) at which the storage elastic modulus of the toner particles becomes 1 × 10 ⁶ Pa.

As the heater used in the non-contact heating device 32, for example, when the toner image is heated in a non-contact manner from the toner image side to be heated, a halogen heater, a hot air dryer or the like is used as the toner image to be heated. When heating from the back surface (that is, the recording medium side), a heating plate, a heating roll, or the like that contacts the back surface is used.
The heating temperature in the non-contact heating device 32 is desirably 70 ° C. or higher. However, when a thermoplastic resin film is used as the recording medium, it is preferably 70 ° C. or higher and lower than 110 ° C., more preferably 80 ° C. or higher and 100 ° C. or lower, and 80 ° C. or higher and 90 ° C. or lower. Is more desirable. The heating time is determined by the length of the non-contact heating device 32 in the traveling direction of the recording medium 30 and the process speed.

Heating and pressing rolls (second heating and pressing devices) 34A and 34B are provided downstream of the non-contact heating device (first heating device) 32 in the traveling direction of the recording medium 30. The toner image heated by the non-contact heating device 32 is further pressed while being heated by the heating and pressing rolls 34A and 34B at a temperature equal to or higher than the temperature (A), so that the recording medium 30 is heated. It is fixed.
The heat and pressure rolls 34A and 34B are arranged to face each other so as to form a nip with the recording medium 30 interposed therebetween. The heat and pressure rolls 34A and 34B form an elastic rubber layer and a release layer for releasing the toner on a metal roll, and a recording medium 30 is formed by a pressure mechanism (not shown) so as to obtain a predetermined pressure and nip width. Is sandwiched. In addition, at least one of the heat and pressure rolls 34A and 34B includes a heater, but the heater may include both the heat and pressure rolls 34A and 34B.

The heating temperature of the heating and pressing rolls (second heating and pressing apparatus) 34A and 34B may be a temperature equal to or higher than the temperature (A). When a thermoplastic resin film is used, it is preferably 70 ° C. or higher and lower than 110 ° C., more preferably 80 ° C. or higher and 100 ° C. or lower, and further preferably 80 ° C. or higher and 90 ° C. or lower. The applied pressure is desirably 1.5 kg / cm ² or more and 5 kg / cm ² or less, and more desirably 2 kg / cm ² or more and 3.5 kg / cm ² or less.

  The toner image is fixed on the recording medium 30 at the positions of the heat and pressure rolls 34A and 34B, and a fixed image 29 is formed. Thereafter, the recording medium 30 is conveyed to a discharge unit (not shown).

  On the other hand, in the photoconductor 10 that has transferred the toner image 26 to the intermediate transfer body 16, the toner particles that are not transferred and remain on the photoconductor 10 are conveyed to a contact position with the cleaner 18 and collected by the cleaner 18. If the transfer efficiency is close to 100% and the generation of residual toner particles is reduced, the cleaner 18 need not be provided.

The image forming apparatus 100 may further include a neutralization device (not shown) that neutralizes the surface of the photoconductor 10 after the transfer and before the next charging.
The charging device 20, the exposure device 12, the developing device 14, the intermediate transfer body 16, the transfer roll 28, the cleaner 18, the non-contact heating device (first heating device) 32, and the heating and pressing roll (provided in the image forming apparatus 100 The second heating / pressurizing devices 34A and 34B are all operated in synchronism with the rotational speed of the photoconductor 10.

  Next, another aspect of the image forming apparatus according to this embodiment will be described in detail with reference to the drawings.

FIG. 2 is a schematic configuration diagram illustrating an example of another aspect of the image forming apparatus according to the present embodiment, and is a diagram illustrating a tandem image forming apparatus.
The image forming apparatus illustrated in FIG. 2 includes a cyan developing unit 101-C, a magenta developing unit 101-M, a yellow developing unit 101-Y, and a black developing unit 101-K. Each developing unit includes a developer tank 102, a developer supply roll 103, a supply amount regulating means 104, a developing roll (developing device) 105, a developing roll cleaner 106, a photosensitive member (electrostatic latent image holding member) 107, and a charging device 108. , An exposure device (latent image forming device) 109, a primary transfer device 110, and a photoreceptor cleaner 111. Further, an intermediate transfer body 125 is provided so as to be in contact with each of the photosensitive members 107 of the four developing units, and further, secondary transfer devices 124 and 126 that transfer the toner image transferred to the intermediate transfer body 125 to the recording medium 127 are provided. Provided. A fixing unit (fixing device) 131 is provided on the downstream side of the secondary transfer devices 124 and 126 in the traveling direction of the recording medium 127, and a discharge roller 135 is provided on the downstream side of the fixing unit 131.
The fixing unit 131 includes a non-contact heating device (first heating device) 136 and 138, a heat roll 132 and a pressure roll 133 (second heating and pressing device) in order from the upstream side in the traveling direction of the recording medium 127. It is done.

  The liquid developer 112 is maintained in a predetermined amount in the developer tank 102 by a developer circulation means (not shown), and is conveyed from the developer tank 102 to the developing roll 105 by the developer supply roll 103. The developer supply roll 103 includes a system in which the surface is charged and the developer is attached by an electrostatic force, and a system in which a groove or a recess is provided in the roll to convey the liquid so as to supply liquid. The transport amount is restricted to a predetermined value. The photosensitive member 107 is charged by a charging device 108 so that the surface has a predetermined charging bias amount, and an electrostatic latent image is formed on the surface by a light beam from the exposure device 109 in accordance with an image signal sent from a host computer (not shown). It is formed. The liquid developer on the developing roll 105 is transferred to the photoreceptor 107 in accordance with the electrostatic latent image to form a toner image. Unnecessary developer is removed from the developer tank 102 by the developing roll cleaner 106 and a developer circulating means (not shown). Returned to

  The toner image formed on the photosensitive member 107 is transferred to the intermediate transfer member 125 by the primary transfer device 110. The intermediate transfer body 125 is supported by a drive roll 121, support rolls 122 and 123, and a secondary transfer device 124. The drive roll 121 drives the intermediate transfer body 125 in the direction of the arrow by a drive motor and a power transmission mechanism (not shown). Further, a tension determined by a spring mechanism (not shown) is applied to the intermediate transfer body 125. The primary transfer device 110 sequentially transfers cyan, magenta, yellow, and black toner images to the intermediate transfer member 125 by electrostatic force and pressure. The primary transfer device 110 for each color may make a difference in the set potential. The liquid developer remaining on the photoconductor 107 is removed by the photoconductor cleaner 111.

The toner image transferred to the intermediate transfer member 125 is transferred to the recording medium 127 by the secondary transfer devices 124 and 126 and further fixed by the fixing unit 131.
The fixing unit 131 includes a first heating device and a second heating and pressing device in order from the upstream side in the traveling direction of the recording medium 127, and includes non-contact heating devices 136 and 138 as the first heating device. The non-contact heating devices 136 and 138 are plate-like heating devices, and a heater is provided inside a plate-like body whose surface is made of metal. At the positions of the non-contact heating devices 136 and 138, the toner image is heated to a temperature equal to or higher than the temperature (A) at which the storage elastic modulus of the toner particles becomes 1 × 10 ⁶ Pa.

  The heating temperature in the non-contact heating devices 136 and 138 is desirably 70 ° C. or higher. However, when a thermoplastic resin film is used as the recording medium, it is preferably 70 ° C. or higher and lower than 110 ° C., more preferably 80 ° C. or higher and 100 ° C. or lower, and 80 ° C. or higher and 90 ° C. or lower. Is more desirable. The heating time is determined by the length of the recording medium 127 in the traveling direction of the non-contact heating devices 136 and 138 and the process speed.

Further, the fixing unit 131 includes a roll pair of a heat roll 132 and a pressure roll 133 and a heater 134 provided inside each roll as a second heating and pressing apparatus. The toner images heated by the non-contact heating devices 136 and 138 are further pressed while being heated at a temperature equal to or higher than the temperature (A) by the roll pair of the heat roll 132 and the pressure roll 133. Then, it is fixed on the recording medium 127.
The heat roll 132 and the pressure roll 133 are arranged to face each other so as to form a nip across the recording medium 127. Each of the heat roll 132 and the pressure roll 133 is formed with an elastic rubber layer and a release layer for releasing the toner particles on the metal roll, and a pressure mechanism (not shown) so as to obtain a predetermined pressure and nip width. Thus, the recording medium 127 is sandwiched. Moreover, although the heater is provided in both the heat roll 132 and the pressure roll 133, this heater may be provided only in one of the heat roll 132 and the pressure roll 133.

The heating temperature of the heat roll 132 and the pressure roll 133 is preferably equal to or higher than the temperature (A). When a thermoplastic resin film is used, it is preferably 70 ° C. or higher and lower than 110 ° C., more preferably 80 ° C. or higher and 100 ° C. or lower, and further preferably 80 ° C. or higher and 90 ° C. or lower. The applied pressure is desirably 1.5 kg / cm ² or more and 5 kg / cm ² or less, and more desirably 2 kg / cm ² or more and 3.5 kg / cm ² or less.

  Further, a discharge roll 135 is provided on the downstream side of the fixing unit 131, and the recording medium 127 on which the toner image is fixed is conveyed by the discharge roll 135 to a discharge unit (not shown).

  As the first heating device, FIG. 1 shows a plate-like heating device that is heated from the back side (opposite side of the toner image) of the recording medium and has a heater inside, and FIG. 2 has a heater inside. The method of heating in a non-contact manner from the front and back sides of the recording medium with a certain plate-shaped heating device has been described. However, the method of the first heating device is not limited to this, and the front side (toner image side) of the recording medium is not contacted. Any material can be used as long as it can be heated. For example, heating may be performed only from the front side (toner image side) of the recording medium by a plate-shaped heating device provided with a heater inside. Moreover, you may apply the air blower which blows a hot air, the irradiation apparatus which irradiates infrared light, etc.

  Further, as the second heating and pressing apparatus, FIG. 1 shows a pair of heating and pressing rolls 34A and 34B, and FIG. 2 shows a pair of heating roll 132 and a pressure roll 133. However, the present invention is not limited to this. Absent. For example, an apparatus that combines a heating and pressing roll and a pressing belt, an apparatus that combines a pressing roll and a heating and pressing belt, and the like may be used.

  In the image forming apparatus shown in FIGS. 1 and 2, a liquid developer is supplied from a liquid developer cartridge (not shown) attached to the image forming apparatus to the developer storage container 14b or the developer tank 102. It is good. Further, the liquid developer cartridge may be configured to be attached to and detached from the image forming apparatus so that the liquid developer cartridge can be replaced when the remaining amount of the liquid developer is exhausted.

  Hereinafter, although an embodiment explains this embodiment in detail, this embodiment is not limited to these examples at all. In the following description, “part” and “%” are all based on mass unless otherwise specified. Further, the glass transition point (Tg), volume average particle diameter (D50v), number average molecular weight (Mn), and electrical conductivity of the polyhydric alcohol ester compound are values measured by the method (apparatus) described above.

<Manufacture of toner particles>
[Example of binder resin production]
(Polyester resin production example 1)
Polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane: 0.7 mol Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane: 1.6 mol terephthalic acid: 1.4 mol n-dodecenyl succinic acid: 0.9 mol

The raw material compound was put into a glass 2-liter four-necked flask, and a stirring rod, a condenser, a nitrogen gas inlet tube, and a thermometer were set, and set in a mantle heater. After replacing the inside of the reaction vessel with nitrogen gas, 1 g of dibutyltin oxide was added, the reaction was performed at about 180 ° C. in the first half under a nitrogen stream while heating with a mantle heater, and the reaction was performed at 220 ° C. under reduced pressure in the second half. . The degree of polymerization was monitored by a ring and ball softening point measurement method (JIS-K2531), and the reaction was terminated when the softening point reached 140 ° C. After completion of the reaction, the reaction solution was cooled to room temperature.
The glass transition point Tg of the resin thus obtained (hereinafter referred to as “polyester resin-1”) was 67 ° C., and the number average molecular weight (Mn) was 5000.

(Polyester resin production example 2)
Polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane: 0.7 mol Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane: 1.6 mol terephthalic acid: 1.4 mol n-dodecenyl succinic acid: 0.9 mol

The raw material compound was put into a glass 2-liter four-necked flask, and a stirring rod, a condenser, a nitrogen gas inlet tube, and a thermometer were set, and set in a mantle heater. After replacing the inside of the reaction vessel with nitrogen gas, 1 g of dibutyltin oxide was added, the reaction was performed at about 180 ° C. in the first half under a nitrogen stream while heating with a mantle heater, and the reaction was performed at 220 ° C. under reduced pressure in the second half. . The degree of polymerization was monitored by a ring and ball softening point measurement method (JIS-K2531), and the reaction was terminated when the softening point reached 100 ° C. After completion of the reaction, the reaction solution was cooled to room temperature.
The glass transition point Tg of the resin thus obtained (hereinafter referred to as “polyester resin-2”) was 58 ° C., and the number average molecular weight (Mn) was 2500.

(Polyester resin production example 3)
Polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane: 0.7 mol Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane: 1.6 mol terephthalic acid: 1.4 mol n-dodecenyl succinic acid: 0.9 mol

The raw material compound was put into a glass 2-liter four-necked flask, and a stirring rod, a condenser, a nitrogen gas inlet tube, and a thermometer were set, and set in a mantle heater. After replacing the inside of the reaction vessel with nitrogen gas, 1 g of dibutyltin oxide was added, the reaction was performed at about 180 ° C. in the first half under a nitrogen stream while heating with a mantle heater, and the reaction was performed at 220 ° C. under reduced pressure in the second half. . The degree of polymerization was monitored by a ring and ball softening point measurement method (JIS-K2531), and the reaction was terminated when the softening point reached 90 ° C. After completion of the reaction, the reaction solution was cooled to room temperature.
The glass transition point Tg of the resin thus obtained (hereinafter referred to as “polyester resin-3”) was 55 ° C., and the number average molecular weight (Mn) was 1900.

(Polyester resin production example 4)
Polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane: 0.7 mol Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane: 1.6 mol terephthalic acid: 1.4 mol n-dodecenyl succinic acid: 0.9 mol

The raw material compound was put into a glass 2-liter four-necked flask, and a stirring rod, a condenser, a nitrogen gas inlet tube, and a thermometer were set, and set in a mantle heater. After replacing the inside of the reaction vessel with nitrogen gas, 1 g of dibutyltin oxide was added, the reaction was performed at about 180 ° C. in the first half under a nitrogen stream while heating with a mantle heater, and the reaction was performed at 220 ° C. under reduced pressure in the second half. . The degree of polymerization was monitored by a ring and ball softening point measurement method (JIS-K2531), and the reaction was terminated when the softening point reached 158 ° C. After completion of the reaction, the reaction solution was cooled to room temperature.
The glass transition point Tg of the resin thus obtained (hereinafter referred to as “polyester resin-4”) was 70 ° C., and the number average molecular weight (Mn) was 7800.

(Polyester resin production example 5)
Polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane: 0.7 mol Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane: 1.6 mol terephthalic acid: 1.4 mol n-dodecenyl succinic acid: 0.9 mol

The raw material compound was put into a glass 2-liter four-necked flask, and a stirring rod, a condenser, a nitrogen gas inlet tube, and a thermometer were set, and set in a mantle heater. After replacing the inside of the reaction vessel with nitrogen gas, 1 g of dibutyltin oxide was added, the reaction was performed at about 180 ° C. in the first half under a nitrogen stream while heating with a mantle heater, and the reaction was performed at 220 ° C. under reduced pressure in the second half. . The degree of polymerization was monitored by a ring and ball softening point measurement method (JIS-K2531), and the reaction was terminated when the softening point reached 165 ° C. After completion of the reaction, the reaction solution was cooled to room temperature.
The glass transition point Tg of the resin thus obtained (hereinafter referred to as “polyester resin-5”) was 74 ° C., and the number average molecular weight (Mn) was 8100.

(Styrene acrylic resin production example 1)
-Styrene: 100 parts by mass-Methyl methacrylate: 20 parts by mass-Methacrylic acid: 10 parts by mass-Toluene: 200 parts by mass The above raw material compound is placed in a glass 2-liter four-necked flask, a stirring rod, a condenser, nitrogen gas An introduction tube and a thermometer were set, and a mantle heater was set. After replacing the inside of the reaction vessel with nitrogen gas, 2 parts by mass of AIBN (2,2′-azobisisobutyronitrile) was added as an initiator, and the mixture was heated with a mantle heater under a nitrogen stream at 70 ° C. for 7 hours. Polymerization was performed. Thereby, styrene acrylic resin-1 was obtained.
The styrene acrylic resin-1 thus obtained had a glass transition point Tg of 75 ° C. and a number average molecular weight (Mn) of 7500.

(Blocked isocyanate polymer production example 1)
-Styrene: 100 parts by mass-Methyl methacrylate: 30 parts by mass-Toluene: 200 parts by mass-Block isocyanate (Karenz MOI-BP (registered trademark), manufactured by Showa Denko KK): 10 parts by mass 2 liters of the above raw material compound made of glass Were placed in a four-necked flask, and a stir bar, condenser, nitrogen gas inlet tube and thermometer were set, and set in a mantle heater. After replacing the inside of the reaction vessel with nitrogen gas, 2 parts by mass of AIBN (2,2′-azobisisobutyronitrile) was added as an initiator, and the mixture was heated with a mantle heater under a nitrogen stream at 70 ° C. for 5 hours. Polymerization was performed.
Thereafter, reprecipitation purification was performed with methanol, and vacuum drying was performed at 30 ° C. for 8 hours to obtain a blocked isocyanate polymer (hereinafter referred to as “block isocyanate polymer A”). The blocked isocyanate polymer A thus obtained had a glass transition point Tg of 65 ° C. and a number average molecular weight (Mn) of 5000.

Example 1
<Preparation of liquid developer E1>
Polyester resin-1: 60 parts by mass, blocked isocyanate polymer A: 10 parts by mass, and cyan pigment C.I. I. 30 parts by weight of Pigment Blue 15: 3 (manufactured by Clariant Co., Ltd.) was blended and kneaded with a pressure kneader. The kneaded product was pulverized with a jet mill to obtain cyan particles having an average particle size of 10 μm.
Liquid development including toner particles e1 having a volume average particle diameter D50v of 1.1 μm by mixing 35 parts by mass of cyan particles with 103 parts by mass of volatile paraffin oil Isopar (Isopar) L and pulverizing the mixture with a ball mill. Agent E1 was obtained.

(Example 2)
<Preparation of liquid developer E2>
In the production of the liquid developer E1, a liquid developer E2 containing toner particles e2 having a volume average particle diameter D50v of 0.5 μm was obtained in the same manner as in the production of the liquid developer E1 except that the pulverization time was changed.

(Example 3)
<Preparation of liquid developer E3>
In the production of the liquid developer E1, a liquid developer E3 containing toner particles e3 having a volume average particle diameter D50v of 3.0 μm was obtained in the same manner as in the production of the liquid developer E1 except that the pulverization time was changed.

(Comparative Example 1)
<Preparation of liquid developer C1>
In the production of the liquid developer E1, a liquid developer C1 containing toner particles c1 having a volume average particle diameter D50v of 0.4 μm was obtained in the same manner as in the production of the liquid developer E1 except that the pulverization time was changed.

(Comparative Example 2)
<Preparation of liquid developer C2>
In the production of the liquid developer E1, a liquid developer C2 containing toner particles c2 having a volume average particle diameter D50v of 3.2 μm was obtained in the same manner as in the production of the liquid developer E1 except that the pulverization time was changed.

Example 4
<Preparation of liquid developer E4>
A toner having a volume average particle diameter D50v of 2.1 μm is the same as the preparation of the liquid developer E1 except that the polyester resin-1 is changed to the polyester resin-2 (Mn: 2500) in the preparation of the liquid developer E1. A liquid developer E4 containing the particles e4 was obtained.

(Example 5)
<Preparation of liquid developer E5>
In the production of the liquid developer E1, a toner having a volume average particle diameter D50v of 1.4 μm is the same as the production of the liquid developer E1, except that the polyester resin-1 is changed to the polyester resin-3 (Mn: 1900). A liquid developer E5 containing the particles e5 was obtained.

(Example 6)
<Preparation of liquid developer E6>
A toner having a volume average particle diameter D50v of 2.8 μm is the same as the preparation of the liquid developer E1 except that the polyester resin-1 is changed to the polyester resin-4 (Mn: 7800) in the preparation of the liquid developer E1. A liquid developer E6 containing the particles e6 was obtained.

(Example 7)
<Preparation of liquid developer E7>
In the production of the liquid developer E1, a toner having a volume average particle diameter D50v of 3.0 μm is the same as the production of the liquid developer E1 except that the polyester resin-1 is changed to the polyester resin-5 (Mn: 8100). A liquid developer E7 containing particles e7 was obtained.

(Example 8)
<Preparation of liquid developer E8>
Toner particles e1: 40 parts obtained above, 50 parts of dimethyl silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-96L-2cs), and a polyhydric alcohol ester compound of a plasticizer are exemplified compounds (3-17) ( Diethylhexanoic acid neopentyl glycol: Nisshin Oillio Group Co., Ltd., Cosmol 525 (5 parts) (12.5% by mass with respect to toner particles) was weighed.
Next, dimethyl silicone oil and neopentyl glycol diethylhexanoate were mixed in advance in a glass container to prepare a mixture, and toner particles e1 were charged into this mixture. The container was sealed with a lid, premixed with a spatula, and then mixed at a rotation speed of 10,000 rpm for 20 seconds using a blender (manufactured by IKA, Ultra Turrax Homogenizer Digital T-25). As a result, a liquid developer E8 containing toner particles e8 having a volume average particle diameter D50v of 1.0 μm was obtained.

Example 9
<Preparation of liquid developer E9>
In the production of the liquid developer E1 (toner e1), the liquid developer E1 (toner) was used except that the blending amount of the polyester resin-1 before kneading was 90 parts by mass and the blending amount of the block isocyanate polymer A was 1 part by mass. Kneading and pulverization was performed in the same manner as in the preparation of e1), and thus toner particles e9 having a volume average particle diameter D50v of 1.2 μm were obtained.
Next, in the production of the liquid developer E8, a liquid developer E9 was obtained in the same manner as in the production of the liquid developer E8 except that the toner e9 was used instead of the toner particles e1.

(Example 10)
<Preparation of liquid developer E10>
In the production of the liquid developer E1 (toner e1), the polyester resin before kneading-1: 40 parts by mass is changed to styrene acrylic resin-1: 90 parts by mass, and the blending amount of the block isocyanate polymer A is changed to 1 part by mass. Except for the above, kneading and pulverization were carried out in the same manner as in the preparation of the liquid developer E1 (toner e1) to obtain toner particles e10 having a volume average particle diameter D50v of 1.2 μm.
Next, in the production of the liquid developer E8, a liquid developer E10 was obtained in the same manner as in the production of the liquid developer E8 except that the toner e10 was used instead of the toner particles e1.

(Example 11)
<Production of polymer 1 having active hydrogen group and blocked isocyanate group>
Block isocyanate (Karenz MOI-BP (registered trademark), manufactured by Showa Denko KK): 2 mol%
MMA (methyl methacrylate): 95 mol%
-HEMA (2-hydroxyethyl methacrylate): 2 mol%
Initiator V-65 (compound name 2,4-dimethylvaleronitrile, manufactured by Wako Pure Chemical Industries, Ltd.): 1 mol%
The raw material compounds were weighed and polymerized in THF (tetrahydrofuran) at 65 ° C. for 8 hours under nitrogen flow. Then, it refine | purified with hexane and dried under reduced pressure, and the polymer 1 (henceforth "acrylic resin-1" may be described) which has a hydroxyl group and a block isocyanate group was obtained.
The glass transition point Tg of the acrylic resin-1 thus obtained was 76 ° C., and the number average molecular weight (Mn) was 4500.

<Manufacture of liquid developer E11>
Cyan pigment (PB15: 3): 10 parts by mass Acrylic resin-1: 90 parts by mass Organic solvent: Toluene 100 parts by mass The above raw material compounds were mixed with a ball mill for 10 hours, and then the mixture was taken out and dried under reduced pressure. After that, the solvent was dried. Then, it crushed with the hammer and the crushed material 1 was obtained.

Crushed material: 20 parts by mass Moresco White P70 (hydrocarbon solvent, manufactured by Matsumura Oil Co., Ltd.): 80 parts by mass The above raw material compound was pulverized with a ball mill until the particle diameter became 2 μm, the media was removed, and toner particles Dispersion 1 was obtained.
Dispersion 1 was heated at about 80 ° C. for 3 hours, allowed to react, cooled, and after removing Moresco White P70 with a centrifuge, diluted with Isopar L (manufactured by Exxon Chemical) to obtain a solid content 20 mass% liquid developer E11 was obtained.

(Example 12)
<Production of polymer 2 having active hydrogen group and blocked isocyanate group>
Block isocyanate (Karenz MOI-BP (registered trademark), manufactured by Showa Denko KK): 2 mol%
MMA (methyl methacrylate): 95 mol%
-Methacrylic acid: 2 mol%
Initiator V-65 (compound name 2,4-dimethylvaleronitrile, manufactured by Wako Pure Chemical Industries, Ltd.): 1 mol%
The raw material compounds were weighed and polymerized in THF (tetrahydrofuran) at 65 ° C. for 8 hours under nitrogen flow. Then, it refine | purified with hexane and dried under reduced pressure, and the polymer 2 (henceforth "acrylic resin-2" may be described) which has a hydroxyl group and a block isocyanate group was obtained.
The thus obtained acrylic resin-2 had a glass transition point Tg of 80 ° C. and a number average molecular weight (Mn) of 6500.

<Manufacture of liquid developer E12>
Cyan pigment (PB15: 3): 10 parts by mass Acrylic resin-2: 90 parts by mass Organic solvent: Toluene 100 parts by mass The above raw material compounds were mixed with a ball mill for 10 hours, and then the mixture was taken out and dried under reduced pressure. After that, the solvent was dried. Then, it crushed with the hammer and the crushed material 2 was obtained.

Crushed material 2: 20 parts by weight Moresco White P70 (hydrocarbon solvent, manufactured by Matsumura Oil Co., Ltd.): 80 parts by weight The above raw material compound is pulverized with a ball mill until the particle diameter becomes 2 μm, the media is removed, and toner particles Dispersion 2 was obtained.
Dispersion 2 was heated at about 80 ° C. for 3 hours, allowed to react, cooled, and after removing Moresco White P70 with a centrifuge, diluted with Isopar L (manufactured by Exxon Chemical) to obtain a solid content. 20% by mass of liquid developer E12 was obtained.

(Comparative Example 3)
<Preparation of liquid developer C3>
Polyester resin-1: 70 parts by mass and cyan pigment C.I. I. 30 parts by weight of Pigment Blue 15: 3 (manufactured by Clariant Co., Ltd.) was blended and kneaded with a pressure kneader. The kneaded product was pulverized with a jet mill to obtain cyan particles having an average particle size of 10 μm.
Liquid development including toner particles c3 having a volume average particle diameter D50v of 1.1 μm by mixing 35 parts by mass of the cyan particles with 103 parts by mass of volatile paraffin oil Isopar (Isopar) L and pulverizing the mixture with a ball mill. Agent C3 was obtained.

<Evaluation sample preparation>
As a recording medium (base film), a biaxially stretched polypropylene film (FOR (manufactured by count 15) manufactured by Futamura Chemical Co., Ltd.) and a polyethylene terephthalate film (Espet film T4102 manufactured by Toyobo Co., Ltd.) were prepared.
Next, using a bar coater, on each recording medium, the toner particle mass (TMA) in each liquid developer is 3.5 g / m ² , the carrier liquid mass (CMA) is 4.8 g / m ² , The coating area was adjusted to 8 cm × 5 cm (the excess was removed with a waste cloth) to form a coating film with each liquid developer.
After that, the fixing conditions are pre-heated at 60 ° C. in the first stage in a non-contacting manner, and then the same film as the base film is combined and fixed at a speed of 60 m / min at 120 ° C., 2.7 kg / cm ² in the second stage. A fixed image was formed on each recording medium under the condition of applying heat and pressure with a roll pair, and used as an evaluation sample.
Similarly, only for the evaluation sample of the biaxially stretched polypropylene film, the temperature condition of the fixing roller in the second stage was set to 95 ° C., and a fixed image was formed as an evaluation sample.
That is, the base film (recording medium) of the evaluation sample prepared using each liquid developer, and the second stage fixing temperature are as follows.
Evaluation sample 1: biaxially stretched polypropylene film, second stage fixing temperature: 120 ° C.
Evaluation sample 2: polyethylene terephthalate film, second stage fixing temperature: 120 ° C.
Evaluation sample 3: biaxially oriented polypropylene film, second stage fixing temperature: 95 ° C.

[Evaluation]
The following evaluation was performed on the liquid developer and the evaluation sample prepared in each example.

(Low-temperature fixability, fixing strength)
For the evaluation samples 1 and 3, the fixing strength was evaluated using a 90 ° peel tester P90-200N (manufactured by Imada Co., Ltd.) at a pulling speed of 300 mm / min. The peel strength (fixing strength) was measured at a sample width of 15 mm, an image area of 15 mm × 80 mm, and room temperature (25 ° C.), and evaluated according to the following criteria.

A: 2.0N or more B: 1.0N or more and less than 2.0N C: 0.7N or more and less than 1.0N D: Less than 0.7N

(Wrinkle generation)
For evaluation sample 2, the appearance of wrinkles at the interface between the non-image area where the fixed image is not formed and the toner fixed image was visually evaluated.
A: No wrinkles B: Wrinkles

(Appropriate viscosity)
The viscosity of the liquid developer produced in each example was measured to evaluate its suitability as a liquid developer. Viscosity was measured at 25 ° C. using an RST-CPS cone plate type (Eihiro Seiki Co., Ltd.), a plate spindle φ25 mm, a rotation speed of 2 rpm, and evaluated according to the following criteria.
A: 1000 poise or more and less than 5000 poise B: 5000 poise or more and less than 10,000 poise C: 10,000 poise or more

  Table 1 shows the liquid developer (toner particles) produced in each example and the evaluation results.

From the above results, it can be seen that in the examples, evaluation of “fixability”, “fixing strength”, and “viscosity” is particularly excellent as compared with the comparative example.

10 Photoconductor (electrostatic latent image holder)
12 Exposure device (latent image forming device)
14 Developing device 16 Intermediate transfer body 18 Cleaner 20 Charging device 24 Liquid developer 26 Toner image 28 Transfer roll 29 Fixed image 30 Recording medium 32 Non-contact heating device (first heating device)
34A, 34B Heating and pressing roll (second heating and pressing device)
100 Image forming apparatus 101-C Cyan developing unit 101-M Magenta developing unit 101-Y Yellow developing unit 101-K Black developing unit 102 Developer tank 103 Developer supplying roll 104 Supply amount regulating means 105 Developing roll 106 Developing roll cleaner 107 Photoconductor (electrostatic latent image holder)
108 Charging Device 109 Exposure Device (Latent Image Forming Device)
110 Primary transfer device 111 Photoconductor cleaner 112 Liquid developer 121 Drive roll 122 Support rolls 124 and 126 Secondary transfer device 125 Intermediate transfer body 127 Recording medium 131 Fixing unit (fixing device)
132 Heat roll (second heating and pressurizing device)
133 Pressure roll (second heating and pressurizing device)
134 heater 135 discharge roll 136,138 non-contact heating device (first heating device)

Claims (12)

Toner particles including a polymer having an active hydrogen group and a polymer having a blocked isocyanate group, and having a volume average particle size of 0.5 μm or more and 3 μm or less;
A carrier liquid in which the toner particles are dispersed;
A liquid developer.   The liquid developer according to claim 1, wherein the polymer having an active hydrogen group has a number average molecular weight (Mn) of 2,000 or more and 10,000 or less.   3. The toner particle according to claim 1, wherein the toner particles include a polymer having the blocked isocyanate group and the active hydrogen group as at least a part of the polymer having the active hydrogen group and the polymer having the blocked isocyanate group. The liquid developer as described.   The liquid developer according to any one of claims 1 to 3, wherein the polymer having an active hydrogen group is a polyester resin.   The liquid developer according to any one of claims 1 to 4, wherein the polymer having a blocked isocyanate group is a vinyl resin.   Any one of Claims 1-5 which further contains the polyhydric alcohol ester compound which consists of a reaction product of a linear or branched saturated aliphatic polyhydric alcohol and a linear or branched saturated aliphatic monovalent carboxylic acid. 2. A liquid developer according to item 1. The liquid developer according to claim 6, wherein the polyhydric alcohol ester compound has a conductivity of 10 ⁻¹¹ S / m or less.   The liquid developer according to claim 6 or 7, wherein the saturated aliphatic polyhydric alcohol has a valence of 3 to 6.   The liquid developer according to any one of claims 1 to 8, wherein the toner particles contain a colorant in a proportion of 15% by mass or more and 50% by mass or less with respect to the total mass of the toner particles.   A liquid developer cartridge that houses the liquid developer according to claim 1 and is detachable from an image forming apparatus. An electrostatic latent image carrier;
A charging device for charging the surface of the electrostatic latent image holding member;
A latent image forming apparatus that forms an electrostatic latent image on the surface of the electrostatic latent image holding member;
The liquid developer according to claim 1 is stored, and the electrostatic latent image formed on the surface of the electrostatic latent image holding member is developed with the liquid developer. A developing device for forming a toner image;
A transfer device for transferring the toner image to a recording medium;
A fixing device for fixing the toner image on the recording medium to the recording medium;
An image forming apparatus. A charging step for charging the surface of the electrostatic latent image holding member;
A latent image forming step of forming an electrostatic latent image on the surface of the electrostatic latent image holder;
A developing step of developing a toner image by developing the electrostatic latent image formed on the surface of the electrostatic latent image holding member with the liquid developer according to any one of claims 1 to 9,
A transfer step of transferring the toner image to a recording medium;
A fixing step of fixing the toner image on the recording medium to the recording medium;
An image forming method comprising: