JP2021056477A - Liquid developer - Google Patents

Abstract

To provide a liquid developer excellent in fixability to a plastic film, and usage thereof.SOLUTION: There are provided a liquid developer that contains toner particles containing a binder resin and a coloring agent, a dispersant and an insulative liquid, in which the binder resin is a polyester resin that is a polycondensation product of a raw material containing an alcohol component, a carboxylic component and polyethylene terephthalate, an acid value of the polyester resin is 15 mgKOH/g or more and 70 mgKOH/g or less, and an amine value of the dispersant is 50 mgKOH/g or more and 300 mgKOH/g or less; and usage of the liquid developer in printing on a plastic film.SELECTED DRAWING: None

Description

The present invention relates to, for example, a liquid developer used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, or the like, and its use.

In recent years, plastics have been used in an extremely wide variety of applications such as containers and packaging bags, and many of them are composed of completely different types of films, inorganic substances such as aluminum, inks, etc. for functional reasons. In particular, printed matter made of ink or the like is indispensable for containers and packaging bags in information transmission to general consumers and distribution management of products.

Since the surface of a plastic film such as polyethylene terephthalate (PET) film is smooth and non-absorbent, adhesion due to the anchor effect cannot be expected. Therefore, an anchor agent is required for printing with a liquid developer, but the use of the anchor agent causes poor image quality, an increase in size of the machine, an increase in cost, and the like.

Patent Document 1 discloses a liquid developer having high adhesiveness of a fixed image to a resin recording medium.

Japanese Unexamined Patent Publication No. 2017-173731

However, since the liquid developer described in Patent Document 1 does not contain a skeleton that is compatible with PET in the resin skeleton, the fixability to the plastic film may vary depending on the amount of the dispersant added. Regardless, there is a demand for a liquid developer that can be stably fixed to a plastic film.

The present invention relates to a liquid developer having excellent fixability to a plastic film and its use.

The present invention
[1] A liquid developer containing toner particles containing a binder resin and a colorant, a dispersant, and an insulating liquid, wherein the binder resin contains an alcohol component, a carboxylic acid component, and polyethylene terephthalate. Liquid development which is a polyester resin which is a polycondensate of a raw material, the acid value of the polyester resin is 15 mgKOH / g or more and 70 mgKOH / g or less, and the amine value of the dispersant is 50 mgKOH / g or more and 300 mgKOH / g or less. The present invention relates to an agent, and [2] the use of the liquid developer according to the above [1] in printing on a plastic film.

The liquid developer of the present invention exerts an excellent effect on the fixability to a plastic film.

The liquid developer of the present invention is characterized in that it contains a polyester resin having a high acid value and a dispersant having a specific amine value using polyethylene terephthalate (PET), and is characterized in that it contains a dispersant having a specific amine value, such as a PET film. It has excellent fixability to a plastic film.

The reason for this effect is not clear, but it is presumed as follows.
Since the surface of the untreated plastic film that has not been subjected to surface treatment such as corona treatment is smooth and non-liquid absorbing, adhesion due to the anchor effect cannot be expected, and such adhesion to the base material is performed on the surface of the base material. It is effective to use polarity to enhance physical or chemical interactions.
In the present invention, it is considered that the polar groups derived from these are effective in expressing the interaction with the film by using the polyester resin having a high acid value and the dispersant having a high amine value in combination. In addition, the acid value of the polyester resin is due to the acid-base interaction between the carboxylic acid, which is the adsorption site on the surface of the toner particles, and the group derived from the amino group of the adsorbing group of the dispersant. And increasing the amine value of the dispersant can also be expected to have the effect of enhancing the interaction between the binder resin and the dispersant.
Further, the polyester resin in the liquid developer of the present invention has a PET skeleton in its molecular structure. As a result, PET affinity is imparted to the resin itself, and it is considered that the structure is such that it easily interacts with the plastic film.
From the above, the liquid developer in the present invention maximizes the interaction between the binder resin and the film, the dispersant and the film, and the binder resin and the dispersant, so that an adhesive (fixing) effect can be obtained. Is considered to be.

The liquid developer of the present invention contains toner particles containing a binder resin and a colorant, a dispersant, and an insulating liquid.

The binder resin contains a polyester resin which is a polycondensate of a raw material containing an alcohol component, a carboxylic acid component, and polyethylene terephthalate.

Alcohol components include divalent or higher alcohols.

Examples of the divalent alcohol include an aliphatic diol having 2 or more and 20 or less carbon atoms, preferably 2 or more and 15 or less carbon atoms, and the formula (I):

(In the formula, OR and RO are oxyalkylene groups, R is an ethylene group and / or a propylene group, x and y indicate the average number of moles of alkylene oxide added, which are positive numbers, respectively, and x and y. The value of the sum of is 1 or more, preferably 1.5 or more, and 16 or less, preferably 8 or less, more preferably 6 or less, still more preferably 4 or less).
Examples thereof include an alkylene oxide adduct of bisphenol A represented by, bisphenol A, hydrogenated bisphenol A and the like. Examples of the aliphatic diol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol and the like. An aliphatic diol having a hydroxyl group bonded to a secondary carbon atom having 3 or more and 5 or less carbon atoms is preferable.

The alcohol component preferably contains an aliphatic diol from the viewpoint of fixability to a plastic film. The content of the aliphatic diol is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, still more preferably 95 mol% or more, still more preferably 100 mol% in the alcohol component. is there.

Examples of the trihydric or higher alcohol include trihydric or higher alcohols having 3 or more and 20 or less carbon atoms, preferably 3 or more and 10 or less carbon atoms. Specific examples thereof include sorbitol, 1,4-sorbitan, pentaerythritol, glycerol, trimethylolpropane and the like.

The carboxylic acid component includes a carboxylic acid compound having a divalent value or higher.

Examples of the divalent carboxylic acid compound include dicarboxylic acids having 3 to 30 carbon atoms, preferably 3 to 20 carbon atoms, and more preferably 3 to 10 carbon atoms, anhydrides thereof, or alkyl groups. Examples thereof include derivatives such as alkyl esters having 1 or more and 3 or less carbon atoms. Specific examples of the dicarboxylic acid include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid, fumaric acid, maleic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, and alkyl having 1 to 20 carbon atoms. Examples thereof include aliphatic dicarboxylic acids such as succinic acid substituted with a group or an alkenyl group having 2 or more and 20 or less carbon atoms.

The carboxylic acid component preferably contains an aromatic dicarboxylic acid compound from the viewpoint of improving the low temperature fixability of the toner and improving the dispersion stability of the toner particles to improve the storage stability. The content of the aromatic dicarboxylic acid compound is preferably 40 mol% or more, more preferably 50 mol% or more, still more preferably 70 mol% or more, and preferably 98 mol% or less in the carboxylic acid component. , More preferably 95 mol% or less, still more preferably 93 mol% or less.

Examples of the trivalent or higher carboxylic acid compound include 4 or more and 20 or less carbon atoms, preferably 6 or more and 20 or less carbon atoms, more preferably 7 or more and 15 or less carbon atoms, still more preferably 8 or more and 12 or less carbon atoms, and further. Preferred examples thereof include trivalent or higher carboxylic acids having 9 or more and 10 or less carbon atoms, anhydrides thereof, or derivatives such as alkyl esters having 1 or more and 3 or less carbon atoms in the alkyl group. Specific examples thereof include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,4,5-benzenetetracarboxylic acid (pyromellitic acid), and acid anhydrides thereof.

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

As the polyethylene terephthalate (PET), those produced according to a conventional method by polycondensation of ethylene glycol with terephthalic acid, dimethyl terephthalate and the like can be used.

In the polycondensation reaction, PET reacts with an alcohol component and a carboxylic acid component and is incorporated into the structure of the resin. At this time, PET may be depolymerized.
Therefore, in the present invention, the PET preferably has a relatively low IV value, that is, a PET having a low molecular weight as compared with the PET conventionally used. In the present invention, by introducing PET having a low IV value (low molecular weight) into the polyester resin, depolymerization of PET proceeds more uniformly. As a result, it can be uniformly dispersed while leaving a highly polar PET skeleton in the polymer, and it is presumed that the fixability to the plastic film is further improved as compared with the conventional PET-introduced resin.

From the above viewpoint, the IV value of PET is preferably 0.40 or more, more preferably 0.45 or more, further preferably 0.50 or more, still more preferably 0.55 or more, and from the viewpoint of low temperature fixability and homogenization of depolymerization. It is preferably 0.85 or less, more preferably 0.80 or less, still more preferably 0.75 or less, still more preferably 0.70 or less, still more preferably 0.65 or less, still more preferably 0.62 or less, still more preferably 0.60 or less. The IV value is an intrinsic viscosity and is an index of molecular weight. The IV value of PET can be adjusted by the polycondensation time and the like.

Commercially available PET products with an IV value of 0.40 or more and 0.80 or less include RAMAPET L1 (manufactured by Indorama Ventures, IV value: 0.60), RAMAPET N2G (manufactured by Indorama Ventures, IV value: 0.75), TRN-NTJ (Teijin Corporation). ), IV value: 0.53), TRN-RTJC (Teijin Co., Ltd., IV value: 0.64), RAMAPET S1 (Indorama Ventures, IV value: 0.84), etc.

The PET in the raw material is preferably 5 mol or more, more preferably 15 mol or more, still more preferably 20 mol, with respect to a total of 100 mol of the alcohol component and the ethylene glycol unit in the PET from the viewpoint of fixability to the plastic film. It is preferable to polycondensate with the carboxylic acid component and the alcohol component in an amount of mol or more, more preferably 30 mol or more, and preferably less than 60 mol, more preferably 55 mol or less. For PET, the unit of terephthalic acid-ethylene glycol (Mw: 192) is converted as 1 mol. Therefore, the number of moles of PET = the number of moles of ethylene glycol units.

The polycondensation reaction between the alcohol component, the carboxylic acid component, and PET is carried out, for example, in an inert gas atmosphere, preferably in the presence of an esterification catalyst, and if necessary, an esterification co-catalyst, a polymerization inhibitor, or the like. In the presence, it can be carried out preferably at a temperature of about 180 ° C. or higher and 250 ° C. or lower. Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin (II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropyrate bistriethanolamite. Of these, tin compounds such as tin (II) 2-ethylhexanoate are preferred. The amount of the esterification catalyst used is preferably 0.01 part by mass or more, more preferably 0.1 part by mass or more, and preferably 1.5 part by mass with respect to 100 parts by mass of the total amount of the alcohol component, the carboxylic acid component, and PET. It is less than a part, more preferably 1.0 part by mass or less. Examples of the esterification co-catalyst include gallic acid and the like. The amount of the esterification co-catalyst used is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and preferably 0.5 part by mass with respect to 100 parts by mass of the total amount of the alcohol component, the carboxylic acid component, and PET. It is less than a part by mass, more preferably 0.1 part by mass or less. Examples of the polymerization inhibitor include tert-butylcatechol and the like. The amount of the polymerization inhibitor used is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and preferably 0.5 part by mass with respect to 100 parts by mass of the total amount of the alcohol component, the carboxylic acid component, and PET. Parts or less, more preferably 0.1 parts by mass or less.

In the present invention, the polyester resin may be a polyester resin modified to such an extent that its characteristics are not substantially impaired. Examples of the modified polyester resin include grafting and blocking with phenol, urethane, epoxy and the like by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636 and the like. Examples of the modified polyester resin include a modified polyester resin, and among the modified polyester resins, a urethane-modified polyester resin obtained by urethane-extending the polyester resin with a polyisocyanate compound is preferable.

The softening point of the polyester resin is preferably 70 ° C. or higher, more preferably 75 ° C. or higher, still more preferably 80 ° C. or higher, still more preferably 85 ° C., from the viewpoint of improving the dispersion stability of the toner particles and improving the storage stability. The above is more preferably 90 ° C. or higher, and from the viewpoint of improving the low temperature fixability of the toner, it is preferably 120 ° C. or lower, more preferably 110 ° C. or lower, still more preferably 105 ° C. or lower, still more preferably 100 ° C. or lower. Is.

The glass transition temperature of the polyester resin is preferably 40 ° C. or higher, more preferably 45 ° C. or higher, still more preferably 50 ° C. or higher, and from the viewpoint of improving the dispersion stability of the toner particles and improving the storage stability. From the viewpoint of improving low-temperature fixability, the temperature is preferably 65 ° C. or lower, more preferably 60 ° C. or lower, and further preferably 57 ° C. or lower.

The acid value of the polyester resin is 15 mgKOH / g or more, preferably 20 mgKOH / g or more, more preferably 25 mgKOH / g or more, still more preferably 30 mgKOH / g or more, and more preferably 30 mgKOH / g or more, from the viewpoint of fixability to the plastic film. , 70 mgKOH / g or less, preferably 60 mgKOH / g or less, and more preferably 40 mgKOH / g or less. The acid value of the polyester resin is adjusted by changing the equivalent ratio of the carboxylic acid component and the alcohol component, changing the reaction time during resin production, or changing the content of a carboxylic acid compound having a valence of 3 or more. can do.

The number average molecular weight of the polyester resin is preferably 1,500 or more, more preferably 2,000 or more from the viewpoint of improving the dispersion stability of the toner particles and improving the storage stability, and from the viewpoint of the grindability of the toner particles. It is preferably 4,000 or less, more preferably 3,500 or less, still more preferably 3,000 or less, still more preferably 2,500 or less.

The weight average molecular weight of the polyester resin is preferably 3,500 or more, more preferably 4,000 or more, from the viewpoint of improving the dispersion stability of the toner particles and improving the storage stability, and from the viewpoint of the grindability of the toner particles. It is preferably 10,000 or less, more preferably 8,000 or less, still more preferably 6,000 or less, still more preferably 5,500 or less, still more preferably 5,000 or less.

The polyester resin is preferably amorphous in order to enhance the adsorption with the dispersant and the surface modification effect associated therewith.
The crystallinity of the resin is represented by the crystallinity index defined by the ratio of the softening point to the maximum endothermic temperature by the differential scanning calorimeter, that is, the value of [softening point / maximum endothermic temperature]. The crystalline resin is an amorphous resin having a crystallinity index of 0.6 or more, preferably 0.7 or more, more preferably 0.9 or more, and 1.4 or less, preferably 1.2 or less, more preferably 1.1 or less. Is a resin having a crystallinity index of more than 1.4, preferably more than 1.5, more preferably 1.6 or more, or less than 0.6, preferably 0.5 or less. The crystallinity of the resin can be adjusted by the type and ratio of the raw material monomers, the production conditions (for example, reaction temperature, reaction time, cooling rate) and the like. The maximum endothermic temperature refers to the temperature of the peak with the largest endothermic area among the observed endothermic peaks.

The content of the polyester resin is preferably 90% by mass or more, more preferably 95% by mass or more, and further preferably 100% by mass, that is, only the polyester resin is used in the binder resin. However, a resin other than the polyester resin may be contained as long as the effect of the present invention is not impaired. Examples of resins other than the polyester resin include polystyrene, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, and the like. Styrene-based resin, epoxy-based resin, rosin-modified maleic acid resin, polyethylene, which are homopolymers or copolymers containing styrene or styrene-substituted products such as styrene-acrylic acid ester copolymers and styrene-methacrylic acid ester copolymers. One or more selected from resins such as styrene resins, polypropylene resins, styrene resins, silicone resins, phenol resins, aliphatic or alicyclic hydrocarbon resins can be mentioned.

The content of the polyester resin in the toner particles is preferably 30% by mass or more, more preferably 50% by mass or more, still more preferably 60% by mass or more, still more preferably 70% by mass or more, from the viewpoint of fixability. Then, it is preferably 95% by mass or less, more preferably 90% by mass or less, and further preferably 85% by mass or less.

The content of the binder resin in the liquid developer is preferably 15% by mass or more, more preferably 20% by mass or more, and preferably less than 50% by mass, more preferably 45% by mass or less, still more preferably. It is 40% by mass or less, more preferably 30% by mass or less.

As the colorant, dyes, pigments and the like used as colorants for toner can be used. For example, carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rodamine-B base, solvent red 49, solvent red 146, solvent blue 35, quinacridone, carmin 6B, isoindoline, disazoero, etc. .. In the present invention, the toner particles may be either black toner or color toner.

From the viewpoint of improving the image density, the content of the colorant is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 15 parts by mass or more with respect to 100 parts by mass of the binder resin. Then, from the viewpoint of improving the pulverizability of the toner to reduce the particle size, improving the low-temperature fixability, and improving the dispersion stability of the toner particles to improve the storage stability, 100 masses of the binder resin It is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, still more preferably 50 parts by mass or less, still more preferably 30 parts by mass or less.

In addition to the binder resin and colorant, the toner particles include mold release agents, charge control agents, charge control resins, magnetic powders, fluidity improvers, conductivity modifiers, reinforcing fillers such as fibrous substances, and antioxidants. Additives such as an agent and a cleaning property improving agent may be appropriately contained.

As a method for producing toner particles, a method obtained by melt-kneading a toner raw material containing a binder resin and a colorant and crushing the obtained melt-kneaded product, preferably wet crushing, an aqueous binder resin dispersion liquid and an aqueous system Examples thereof include a method of mixing the colorant dispersion liquid and combining the binder resin particles and the colorant particles, or a method of stirring the water-based binder resin dispersion liquid and the colorant at high speed. From the viewpoint of improving developability and fixability, a method of melt-kneading the toner raw material and then pulverizing, preferably wet pulverizing is preferable.

First, it is preferable that the toner raw material containing the binder resin, the colorant, the additive used if necessary, etc. is mixed in advance with a mixer such as a Henschel mixer, a super mixer, a ball mill, etc., and then supplied to the kneader. A Henschel mixer is more preferable from the viewpoint of improving the dispersibility of the colorant in the binder resin.

Next, the melt kneading of the toner raw material can be performed using a known kneader such as a closed kneader, a uniaxial or biaxial kneader, or a continuous open roll kneader. In the present invention, an open roll type kneader is preferable from the viewpoint of improving the dispersibility of the colorant and improving the yield of toner particles after pulverization.

Next, after cooling the melt-kneaded product to a extent that it can be pulverized, toner particles can be obtained through a pulverization step and, if necessary, a classification step and the like.

The crushing step may be divided into multiple steps. For example, the melt-kneaded product may be roughly pulverized to about 1 to 5 mm and then further pulverized.

The volume median particle diameter (D ₅₀ ) of the toner particles obtained in this step is preferably 3 μm or more, more preferably 4 μm or more, and preferably 15 μm from the viewpoint of improving the productivity of the wet pulverization step described later. Hereinafter, it is more preferably 12 μm or less. The volume median particle size (D ₅₀ ) means a particle size in which the cumulative volume frequency calculated by the volume fraction is 50% calculated from the smaller particle size. It is preferable that the toner particles are further refined by wet pulverization or the like after being mixed with the dispersant and the insulating liquid.

The content of the toner particles to be subjected to wet pulverization is preferably 30 parts by mass or more, more preferably 40 parts by mass or more, and further preferably 50 parts by mass or more with respect to 100 parts by mass of the insulating liquid from the viewpoint of pulverization efficiency. Yes, and from the viewpoint of improving dispersion stability, it is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, still more preferably 70 parts by mass or less, still more preferably 60 parts by mass or less.

As the dispersant in the present invention, a basic dispersant having a basic nitrogen-containing group is preferable, and an amino group-containing copolymer is more preferable.

The amino group-containing copolymer in the present invention includes monomer A having an amino group and formula (II):

(In the formula, R ¹ is a hydrogen atom or a hydrocarbon group having 1 or more and 5 or less carbon atoms, preferably a methyl group, and R ² is a hydrocarbon group having 1 or more and 22 carbon atoms or less, which may have a substituent. , Preferably an alkyl group having 1 to 22 carbon atoms or an alkenyl group having 2 to 22 carbon atoms)
A polymer of a monomer containing the monomer B represented by is preferable.

As the monomer A having an amino group, the formula (III):
CH ₂ = C (R ⁵ ) COYR ⁶ NR ³ R ⁴ (III)
(In the formula, R ³ and R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 or more and 4 or less carbon atoms, and they may be bonded to each other to form a ring structure, and R ⁵ Indicates a hydrogen atom or an alkyl group having 1 or more and 5 or less carbon atoms, preferably a methyl group, R ⁶ indicates an alkylene group having 2 or more and 4 or less carbon atoms, and Y indicates -O- or -NH-).
A monomer having an amino group represented by, or an acid neutralized product (tertiary amine salt) or a quaternary ammonium salt of this monomer is preferable. Preferred acids for obtaining the above acid neutralized products include hydrochloric acid, sulfuric acid, nitrate, acetic acid, formic acid, maleic acid, fumaric acid, citric acid, succinic acid, adipic acid, sulfamic acid, toluenesulfonic acid, lactic acid, pyrrolidone-. Examples include 2-carboxylic acid and succinic acid. Preferred quaternary agents for obtaining the above quaternary ammonium salt include alkyl halides such as methyl chloride, ethyl chloride, methyl bromide and methyl iodide, dimethyl sulfate, diethyl sulfate, di-n-propyl sulfate and the like. General alkylating agents of.

In the formula (III), R ³ and R ⁴ are each independently preferably an alkyl group having 1 or more and 4 or less carbon atoms, and NR ³ R ⁴ is preferably a tertiary amino group. Specific examples of R ³ and R ⁴ include a methyl group, an ethyl group, a propyl group, an isopropyl group and the like, and a methyl group is preferable.

Examples of R ⁶ include an ethylene group, a propylene group, a butylene group and the like, and an ethylene group is preferable.

^{Specific examples of the monomer in which NR 3} R ⁴ is a tertiary amino group in the formula (III) (monomer having a tertiary amino group) include a (meth) acrylate having a dialkylamino group and a dialkylamino group ( Meta) acrylamide and the like can be mentioned. In addition, "(meth) acrylic acid ester" indicates that the case of acrylic acid ester and methacrylic acid ester, and "(meth) acrylamide" indicates the case of both acrylamide and methacrylamide.

Examples of the (meth) acrylic acid ester having a dialkylamino group include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dipropylaminoethyl (meth) acrylate, diisopropylaminoethyl (meth) acrylate, and dibutylaminoethyl (dibutylaminoethyl). Examples thereof include one or more selected from the group consisting of meta) acrylate, diisobutylaminoethyl (meth) acrylate, and dit-butylaminoethyl (meth) acrylate.

Examples of (meth) acrylamide having a dialkylamino group include dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide, dipropylaminopropyl (meth) acrylamide, diisopropylaminopropyl (meth) acrylamide, and dibutylaminopropyl (meth). Examples thereof include one or more selected from the group consisting of acrylamide, diisobutylaminopropyl (meth) acrylamide, and dit-butylaminopropyl (meth) acrylamide.

Among these, (meth) acrylic acid ester having a dialkylamino group is preferable from the viewpoint of small particle size, low viscosity, storage stability, and low temperature fixability, and dimethylaminoethyl (meth) acrylate or diethylaminoethyl (meth) is preferable. ) Acrylate is more preferable.

The monomer B is represented by the above formula (II), and in the above formula (II), the carbon number of the alkyl group and the alkenyl group represented by ^{R 2 is low viscosity, storage stability, and low temperature.} From the viewpoint of fixability, it is preferably 10 or more, more preferably 12 or more, and from the viewpoint of adsorptivity to toner particles, it is 22 or less, preferably 20 or less. The alkyl group or alkenyl group of R ² may be a straight chain or a branched chain, and may have a substituent such as a hydroxyl group.

Therefore, ^{it is preferable that the monomer B contains at least the monomer B2 in which R 2} is an alkyl group or an alkenyl group having 10 or more and 22 or less carbon atoms.

In the monomer B, R ² is a monomer B1 which is an alkyl group having 1 or more and 9 or less carbon atoms or an alkenyl group having 2 or more and 9 carbon atoms or less, and a monomer B2 which is an alkyl group or an alkenyl group having 10 or more and 22 carbon atoms or less. The molar ratio of (monomer B1 / monomer B2) is preferably 0.1 or less, more preferably 0.07 or less, still more preferably 0.05 or less, still more preferably 0.03 or less, from the viewpoints of low viscosity, storage stability, and low temperature fixability. , More preferably 0.01 or less, 0 or more, and preferably 0.

Specific examples of monomer B include methyl (meth) acrylate, ethyl (meth) acrylate, (iso) propyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (iso or tertiary) butyl (meth) acrylate, and the like. 2-Ethylhexyl (meth) acrylate, (iso) octyl (meth) acrylate, (iso) nonyl (meth) acrylate, (iso) decyl (meth) acrylate, (iso) undecyl (meth) acrylate, (iso) dodecyl (meth) ) Acrylate, (iso) tridecyl (meth) acrylate, (iso) tetradecyl (meth) acrylate, (iso) pentadecyl (meth) acrylate, (iso) hexadecyl (meth) acrylate, (iso) heptadecyl (meth) acrylate, (iso) ) Octadecyl (meth) acrylate, (iso) nonadecil (meth) acrylate, (iso) icosyl (meth) acrylate, (iso) eicosyl (meth) acrylate, (iso) henicosyl (meth) acrylate, (iso) docosyl (meth) Examples include acrylate. One or more of these can be used. Here, "(iso or tertiary)" and "(iso)" mean that both the case where these groups are present and the case where they are not present are included, and when these groups are not present. Indicates that it is normal. Further, "(meth) acrylate" indicates that the case of both acrylate and methacrylate is included.

The mass ratio of monomer A to monomer B (monomer A / monomer B) is preferably 20/80 or more, more preferably 35/65 or more, still more preferably 45/55 or more, from the viewpoint of improving the chargeability of the toner. Yes, and from the viewpoint of improving the dispersion stability of the toner particles and improving the storage stability, and from the viewpoint of increasing the resistance of the liquid developer, it is preferably 80/20 or less, more preferably 65/35 or less, still more preferable. Is 55/45 or less.

Examples of the monomer other than the monomer A and the monomer B include a monomer having a polysiloxane chain.

The total content of monomer A and monomer B in all the monomers used in the amino group-containing copolymer is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, 100% by mass. It is less than or equal to mass%, preferably 100% by mass.

The polymerization of Monomer A and Monomer B is carried out by heating to about 40 to 140 ° C. in a solvent in the presence of a polymerization initiator such as 2,2'-azobis (2,4-dimethylvaleronitrile). Can be made to.

Examples of the dispersant other than the amino group-containing copolymer include polyallylamine, olefin / vinylpyrrolidone copolymer, aliphatic amine and salts thereof.

The content of the amino group-containing copolymer in the dispersant is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably 97% by mass or more, still more preferable. Is 100% by mass.

The amine value of the dispersant is 50 mgKOH / g or higher, preferably 70 mgKOH / g or higher, more preferably 90 mgKOH / g or higher, still more preferably 105 mgKOH / g or higher, and more preferably 105 mgKOH / g or higher, from the viewpoint of fixability to the plastic film. From the viewpoint of solubility in an insulating liquid, improvement of dispersion stability of toner particles to improve storage stability, and high resistance of a liquid developer, the amount is 300 mgKOH / g or less, preferably 250 mgKOH. It is / g or less, more preferably 220 mgKOH / g or less, still more preferably 200 mgKOH / g or less.

The content of the dispersant is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and further, from the viewpoint of improving the dispersion stability of the toner particles and improving the storage stability with respect to 100 parts by mass of the toner particles. It is preferably 3 parts by mass or more, preferably 10 parts by mass or less, more preferably 8.5 parts by mass or less, and further preferably 7 parts by mass from the viewpoint of improving the chargeability of the toner and increasing the resistance of the liquid developer. Parts or less, more preferably 5 parts by mass or less.

The insulating liquid in the present invention means a liquid through which electricity does not easily flow, but in the present invention, the conductivity of the insulating liquid is preferably 1.0 × 10 ^-11 S / m or less, more preferably 7.0. It is × 10 ^-12 S / m or less, and preferably 1.0 × 10 ^-13 S / m or more.

The insulating liquid in the present invention has a low viscosity and preferably contains a saturated aliphatic hydrocarbon from the viewpoints of pulverizability, handleability in an image forming apparatus, and fixability.

The carbon number of the saturated aliphatic hydrocarbon is preferably 10 or more, more preferably 11 or more from the viewpoint of improving the handleability in the image forming apparatus, and improves the fixability while suppressing the deformation of the plastic film. From the viewpoint of making the film, it is preferably 14 or less, more preferably 13 or less.

The saturated aliphatic hydrocarbon may be a straight chain or a branched chain, but is preferably a straight chain from the viewpoint of improving the handleability in the image forming apparatus.

Therefore, suitable linear saturated aliphatic hydrocarbons having 10 or more and 14 or less carbon atoms in the present invention are n-decane, n-undecane, n-dodecane, n-tridecane, and n-tetradecane.

The content of the saturated aliphatic hydrocarbon in the insulating liquid is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably 100% by mass. It is even more preferred to use only% by weight, i.e., saturated aliphatic hydrocarbons.

Examples of insulating liquids other than saturated aliphatic hydrocarbons include unsaturated aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, and polysiloxanes.

The temperature of the initial distillate of the insulating liquid is 190 ° C. or higher, preferably 200 ° C. or higher, from the viewpoint of improving the handleability in the image forming apparatus, and the fixing property while suppressing the deformation of the plastic film. From the viewpoint of improving the temperature, it is 240 ° C. or lower, preferably 220 ° C. or lower.

The difference between the initial distilling point and the dry point of the insulating liquid is 15 ° C or less from the viewpoint of improving the handling property in the image forming apparatus and suppressing the deformation of the plastic film at the time of fixing while improving the fixing property. Yes, preferably 10 ° C. or lower, more preferably 5 ° C. or lower.

The liquid developer is obtained by dispersing toner particles in an insulating liquid. From the viewpoint of reducing the particle size of the toner particles, it is preferable to disperse the toner particles in an insulating liquid and then wet-pulverize the toner particles to obtain a liquid developer.

In the production of the liquid developer of the present invention, the dispersant is preferably mixed with the insulating liquid together with the toner particles.

As a method of mixing the toner particles, the dispersant, and the insulating liquid, a method of stirring with a stirring / mixing device or the like is preferable.

The stirring / mixing device is not particularly limited, but a high-speed stirring / mixing device is preferable from the viewpoint of improving the productivity and storage stability of the toner particle dispersion liquid.

By mixing with the high-speed stirring and mixing device, the toner particles are pre-dispersed, the toner particle dispersion liquid can be obtained, and the productivity of the liquid developer by the next wet grinding is improved.

From the viewpoint of improving the image density, the solid content concentration of the toner particle dispersion is preferably 20% by mass or more, more preferably 30% by mass or more, still more preferably 33% by mass or more, and stable dispersion of toner particles. From the viewpoint of improving the properties and the storage stability, it is preferably 50% by mass or less, more preferably 45% by mass or less, and further preferably 40% by mass or less.

The content of the toner particles in the toner particle dispersion is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 30 parts by mass with respect to 100 parts by mass of the insulating liquid from the viewpoint of high-speed printability. More than parts, more preferably 40 parts by mass or more, still more preferably 50 parts by mass or more, and from the viewpoint of improving dispersion stability, preferably 100 parts by mass or less, more preferably 80 parts by mass or less, still more preferably. It is 70 parts by mass or less, more preferably 60 parts by mass or less.

Wet pulverization is a method of mechanically pulverizing toner particles dispersed in an insulating liquid in a state of being dispersed in the insulating liquid.

From the viewpoint of improving the image density, the solid content concentration of the liquid developer is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 20% by mass or more, and the dispersion stability of the toner particles. From the viewpoint of improving storage stability, the content is preferably 50% by mass or less, more preferably 45% by mass or less, still more preferably 40% by mass or less, still more preferably 30% by mass or less.

The volume median particle diameter (D ₅₀ ) of the toner particles in the liquid developer is preferably 0.5 μm or more, more preferably 1 μm or more, still more preferably 1.5 μm or more, from the viewpoint of reducing the viscosity of the liquid developer. From the viewpoint of improving the image quality of the liquid developer, it is preferably 5 μm or less, more preferably 3 μm or less, and further preferably 2.5 μm or less.

The content of the toner particles in the liquid developer is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more, and the dispersion stability of the toner particles is stable from the viewpoint of high-speed printing. From the viewpoint of sex, it is preferably 45% by mass or less, more preferably 40% by mass or less, and further preferably 35% by mass or less.

The content of the insulating liquid in the liquid developer is preferably 50% by mass or more, more preferably 55% by mass or more, still more preferably 60% by mass or more, and from the viewpoint of dispersion stability of the toner particles. From the viewpoint of high-speed printing, it is preferably 90% by mass or less, more preferably 85% by mass or less, and further preferably 80% by mass or less.

Since the liquid developer of the present invention has excellent fixability on a resin film, it is suitably used for printing on a plastic film. When printing on a plastic film, it is usually necessary to surface-treat the resin film with an anchor agent in advance, but if the liquid developer of the present invention is used, it is possible to print directly on the untreated plastic film.

Examples of the plastic film include films such as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyethylene, ethylene / vinyl acetate copolymer, polypropylene, cellulose acetate, polyester (polyethylene terephthalate, polybutylene terephthalate, etc.), and polycarbonate. Of these, polyethylene terephthalate (PET) film is preferred.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The physical properties of the resin and the like were measured by the following methods.

[IV value of PET]
It can be calculated by dissolving in a mixed solvent having a phenol / tetrachloroethane (mass ratio) of 60/40 at a concentration of 4 g / L, measuring with an Ubbelohde viscometer, and calculating according to the following formula.
IV = (-1 + √ (1 + 4kη)) / (2kC)
[In the formula, k = 0.33, C = 0.004 g / mL, and η = (t1 / t0) -1 (t0: number of seconds of solvent only falling, t1: number of seconds of sample solution falling). ]

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

[Maximum endothermic temperature of resin]
Using the differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan Co., Ltd.), weigh 0.01 to 0.02 g of the sample in an aluminum pan, and cool down from room temperature (25 ° C) to 10 ° C. Cool to 0 ° C at / min and maintain at 0 ° C for 1 minute. Then, the temperature is measured at a heating rate of 10 ° C./min. Of the observed endothermic peaks, the temperature of the peak with the largest peak area is defined as the maximum endothermic temperature.

[Resin glass transition temperature]
Using the differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan), weigh 0.01 to 0.02 g of the sample in an aluminum pan, raise the temperature to 200 ° C, and then cool down from that temperature. Cool to 0 ° C at 10 ° C / min. Next, the sample is heated at a heating rate of 10 ° C./min, and the endothermic peak is measured. The temperature at the intersection of the extension of the baseline below the maximum endothermic peak temperature and the tangent line indicating the maximum slope from the rising portion of the peak to the peak of the peak is defined as the glass transition temperature.

[Acid value of resin]
Measure based on the method of JIS K 0070: 1992. However, only the measurement solvent is changed from the mixed solvent of ethanol and ether specified in JIS K0070 to the mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)).

[Number average molecular weight and weight average molecular weight of resin]
The number average molecular weight is determined by the gel permeation chromatography (GPC) method by the following method.
(1) Preparation of sample solution Dissolve the sample in tetrahydrofuran at 40 ° C so that the concentration becomes 0.5 g / 100 mL. Next, this solution is filtered using a PTFE type membrane filter "DISMIC-25JP" (manufactured by Toyo Filter Paper Co., Ltd.) having a pore size of 0.20 μm to remove insoluble components, and used as a sample solution.
(2) Molecular weight measurement Using the following measuring device and analytical column, flow tetrahydrofuran as an eluent at a flow rate of 1 mL per minute to stabilize the column in a constant temperature bath at 40 ° C. 100 μL of the sample solution is injected therein and measurement is performed. The molecular weight of the sample is calculated based on a calibration curve prepared in advance. The calibration curve at this time includes several types of monodisperse polystyrene (A-500 (5.0 × 10 ² ), A-1000 (1.01 × 10 ³ ), A-2500 (2.63 × 10 ³ ), manufactured by Toso Co., Ltd.). A-5000 (5.97 × 10 ³ ), F-1 (1.02 × 10 ⁴ ), F-2 (1.81 × 10 ⁴ ), F-4 (3.97 × 10 ⁴ ), F-10 (9.64 × 10 ⁴ ), Use F-20 (1.90 × 10 ⁵ ), F-40 (4.27 × 10 ⁵ ), F-80 (7.06 × 10 ⁵ ), F-128 (1.09 × 10 ⁶ )) as standard samples. The molecular weight is shown in parentheses.
Measuring device: HLC-8220GPC (manufactured by Tosoh Corporation)
Analytical column: TSKgel GMH _XL + TSKgel G3000H _XL (manufactured by Tosoh Corporation)

[Volume medium particle size of toner particles before mixing with insulating liquid]
Measuring machine: Coulter Multisizer II (manufactured by Beckman Coulter Co., Ltd.)
Aperture diameter: 100 μm
Analysis software: Coulter Multisizer AccuComp version 1.19 (manufactured by Beckman Coulter Co., Ltd.)
Electrolyte: Isoton II (manufactured by Beckman Coulter Co., Ltd.)
Dispersion solution: Emalgen 109P (manufactured by Kao Co., Ltd., polyoxyethylene lauryl ether, HLB (griffin): 13.6) was dissolved in an electrolytic solution to adjust to 5% by mass. Is added and dispersed for 1 minute with an ultrasonic disperser (machine name: US-1, manufactured by SND Co., Ltd., output: 80 W). Then, 25 mL of the electrolytic solution is added and further dispersed with an ultrasonic disperser for 1 minute to prepare a sample dispersion.
Measurement conditions: To 100 mL of the electrolytic solution, add the sample dispersion so that the particle size of 30,000 particles can be measured in 20 seconds, measure 30,000 particles, and measure the volume from the particle size distribution. Determine the medium particle size (D ₅₀ ).

[Amine value of dispersant]
Measured by the method of ASTM D2074. However, chloroform is used as the dissolution solvent of the sample, and 0.1 mol / L acetic acid perchlorate standard solution is used as the titration solution.

[Conductivity of insulating liquid]
Put 25 g of insulating liquid into a 40 mL glass sample tube "Screw No. 7" (manufactured by Maruemu Co., Ltd.), and use a non-aqueous conductivity meter "DT-700" (manufactured by Dispersion Technology) to attach the electrodes. Immerse in an insulating liquid and measure 20 times at 25 ° C to calculate the average value and measure the conductivity. The smaller the value, the higher the resistance.

[Insulating liquid initial retention point]
Measure by the normal pressure method of JIS K 2254.

[Dry point of insulating liquid]
Measure by the normal pressure method of JIS K 2254.

[Viscosity of liquid developer at 25 ° C]
Put 6 to 7 mL of the measuring solution in a 10 mL screw tube, and use the rotary vibration viscometer "Viscomate VM-10A-L" (manufactured by SEKONIC Corporation, detection terminal: made of titanium, φ8 mm) at the tip of the detection terminal. Fix the screw tube at the position where the liquid level comes 15 mm above the part, and measure the viscosity at 25 ° C.

[Volume medium particle size of toner particles in liquid developer (D ₅₀ )]
Using the laser diffraction / scattering particle size measuring device "Mastersizer 2000" (manufactured by Malvern), Isopar L (manufactured by Exxon Mobile, isoparaffin, viscosity at 25 ° C, viscosity 1 mPa · s) is added to the measuring cell, and the scattering intensity is increased. _{The volume median particle size (D 50} ) is measured under the conditions of a particle refractive index of 1.58 (imaginary part 0.1) and a dispersion medium refractive index of 1.42 at a concentration of 5 to 15%.

Resin production example 1
The raw materials and esterification catalysts shown in Table 1 were placed in a 5-liter four-necked flask equipped with a thermometer, a stainless stir bar, a flow-down condenser and a nitrogen introduction tube, and placed in a mantle heater in a nitrogen atmosphere for 180. The temperature was raised to ° C., the reaction was carried out for 2 hours, and then the temperature was gradually raised to 230 ° C. at a rate of 5 ° C./h. Then, the reaction was carried out at 230 ° C. for 3 hours, cooled to 220 ° C., and then reacted at 8 kPa to a desired softening point to obtain polyester resins (resins A1 to A5, A7 to A10, A12).

Resin production example 2
Place the raw materials other than sebacic acid and the esterification catalyst shown in Table 1 in a 5-liter four-necked flask equipped with a thermometer, a stainless stir bar, a flow-down condenser and a nitrogen introduction tube, and place the mantle heater in a nitrogen atmosphere. The temperature was raised to 235 ° C., and the reaction was carried out for 5 hours. Then, the mixture was cooled to 210 ° C., sebacic acid was added, the reaction was carried out at normal pressure for 1 hour, and then the reaction was carried out at 8 kPa to a desired softening point to obtain a polyester resin (resin A6).

Resin production example 3
A 5 liter volume of the raw materials and esterification catalyst shown in Table 1 equipped with a thermometer, a stainless steel stirring rod, a fractionation tube through which hot water at 98 ° C is passed, a flow-down condenser, and a nitrogen introduction tube. In a four-necked flask, the temperature was raised to 180 ° C in a mantle heater in a nitrogen atmosphere, the reaction was carried out for 2 hours, and then the temperature was gradually raised to 230 ° C at a rate of 5 ° C / h. .. Then, the reaction was carried out at 230 ° C. for 3 hours, cooled to 220 ° C., and then reacted at 8 kPa to a desired softening point to obtain a polyester resin (resin A11).

Example of Dispersant Production 100 g of a solvent (methyl ethyl ketone) was placed in a 2 L four-necked flask equipped with a cooling tube, a nitrogen introduction tube, a stirrer and a thermocouple, and the inside of the reaction vessel was replaced with nitrogen gas. The inside of the reaction vessel was heated to 80 ° C., and the mixture of the raw material monomer and the polymerization initiator shown in Table 2 was added dropwise over 2 hours to carry out the polymerization reaction. After completion of the dropping, the reaction was carried out at 80 ° C. for another 3 hours. The solvent was distilled off at 80 ° C. to obtain amino group-containing copolymers (dispersants D1 to D5) having the physical characteristics shown in the table.

Examples 1-10 and Comparative Examples 1-3
Rotate 80 parts by mass of the binder resin and 20 parts by mass of the colorant "ECB-301" (manufactured by Dainichi Seika Kogyo Co., Ltd., phthalocyanine blue 15: 3) shown in Table 3 in advance using a 20 L Henschel mixer. After stirring and mixing at a frequency of 1500 r / min (peripheral speed 21.6 m / sec) for 3 minutes, the mixture was melt-kneaded under the conditions shown below.

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

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

35 parts by mass of the obtained toner particles and insulating liquid "Cactus Normal Paraffin N-12D" (manufactured by JXTG Energy Co., Ltd., n-dodecane, conductivity: 6.1 × 10 ^-12 S / m, initial distillation point: 209 ° C , Dry point: 212 ° C) 63.9 parts by mass and 1.1 parts by mass of the dispersant shown in Table 3 are placed in a 1 L polyethylene container and cooled with ice using "TK Robomix" (manufactured by Primix Co., Ltd.). The mixture was stirred at a rotation speed of 7,000 r / min for 30 minutes to obtain a toner particle dispersion having a solid content concentration of 36% by mass.

Next, the obtained toner particle dispersion liquid was rotated by a 6-cylinder sand mill "TSG-6" (manufactured by Imex Co., Ltd.) at a volume filling rate of 60% by volume using zirconia beads having a diameter of 0.8 mm. Wet pulverization was performed at 1300 r / min (peripheral speed 4.8 m / sec) _{until the volume medium particle size (D 50) shown in the table was reached.} After removing the beads by filtration, 40 parts by mass of the insulating liquid "Cactus Normal Paraffin N-12D" (manufactured by JXTG Energy Co., Ltd.) was added to 100 parts by mass of the filtrate to dilute it, and the solid content concentration was 26% by mass. A liquid developer having the physical properties shown in Table 3 was obtained.

Test example [Fixability]
A bar coater (tabletop coating machine TC-1 manufactured by Mitsui Denki Seiki Co., Ltd.) was used on the untreated surface of the PET film (Futamura Chemical Co., Ltd., biaxially stretched polyethylene terephthalate film, FFE2001 # 25). A liquid developer was applied so that the film thickness after drying was 3.5 μm, and the film was dried at 120 ° C. for 3 minutes to fix it. Immediately after fixing, the mending tape "Scotch Mending Tape 810" (manufactured by 3M Japan Ltd., width 18 mm) was attached to the coating film, and a weight of 190 g was reciprocated 5 times from the top of the tape. Then, the pasted tape is vigorously peeled off, and finally the image density before and after the tape peeling is measured using a colorimetric system (Spectroeye manufactured by X-rite), and the ratio of the two (after peeling / before sticking × 100). ) Was calculated as the retention rate. The results are shown in Table 3.

Based on the above results, these were compared with the liquid developer of Comparative Example 1 containing a polyester resin not using PET, Comparative Example 2 having a low acid value of the polyester resin, and Comparative Example 3 containing a dispersant having a low amine value. It can be seen that the liquid developer of Examples 1 to 10 having the above requirements is excellent in fixability to a plastic film. Further, from the comparison of Examples 2, 5 and 6, it can be seen that the fixability is improved by using PET having a low IV value.

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

Claims (7)

A liquid developer containing toner particles containing a binder resin and a colorant, a dispersant, and an insulating liquid, wherein the binder resin is a weight of a raw material containing an alcohol component, a carboxylic acid component, and polyethylene terephthalate. A liquid developer which is a condensate polyester resin, wherein the acid value of the polyester resin is 15 mgKOH / g or more and 70 mgKOH / g or less, and the amine value of the dispersant is 50 mgKOH / g or more and 300 mgKOH / g or less. The liquid developer according to claim 1, wherein the alcohol component contains an aliphatic diol. The liquid developer according to claim 1 or 2, wherein the amount of polyethylene terephthalate in the raw material is 5 mol or more and less than 60 mol with respect to a total of 100 mol of the alcohol component and the ethylene glycol unit in the polyethylene terephthalate. The liquid developer according to any one of claims 1 to 3, wherein the IV value of polyethylene terephthalate is 0.40 or more and 0.80 or less. The dispersant is monomer A having an amino group and formula (II) :.

(In the formula, R ¹ indicates a hydrogen atom or a hydrocarbon group having 1 or more and 5 or less carbon atoms, and R ² indicates a hydrocarbon group having 1 or more and 22 or less carbon atoms which may have a substituent).
The liquid developer according to any one of claims 1 to 4, which contains an amino group-containing copolymer which is a polymer of a monomer containing the monomer B represented by. The liquid developer according to any one of claims 1 to 5, which is used for printing on a plastic film. Use of the liquid developer according to any one of claims 1 to 6 in printing on a plastic film.