JP4557897B2 - Binder resin for toner - Google Patents

Description

  The present invention relates to a binder resin for toner used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, and the like, and an electrophotographic toner containing the binder resin.

  In recent years, there has been a demand for a binder resin for toner that can be fixed at a lower temperature in response to demands for speeding up and downsizing of the apparatus. As the binder resin for toner, vinyl resins and polyester resins are widely used. From the viewpoint of low-temperature fixability, polyester resins are preferred. In order to improve the low-temperature fixability, it is known that lowering of the softening point and glass transition point of the resin is effective, but on the other hand, offset resistance, blocking resistance and the like are lowered. Therefore, the combined use of a low softening point resin and a high softening point resin achieves both of these performances. However, when the same type of resin is used in combination, the resins are compatible with each other, making it difficult to achieve both of the above performances, and the glass transition point of the resin is about 50 ° C. at the lowest.

In order to improve this and use a resin having a lower softening point and a lower glass transition point, an incompatible resin is encapsulated (see Patent Document 1) to obtain a resin composition having a domain-matrix structure (Patent Document) 2), binder resins in which an addition polymerization resin is finely dispersed in a condensation polymerization resin (see Patent Document 3), and the like have been studied.
JP-A-6-130713 JP-A-6-342225 JP 2005-258221 A

  However, as described above, when the glass transition point is lowered, the blocking resistance and the like tend to be lowered. In addition, in the binder resin in which the addition polymerization resin is finely dispersed in the condensation polymerization resin, the anti-blocking property is improved, but the pulverization property is deteriorated and the productivity of the resin and toner is likely to be lowered. .

  An object of the present invention is to provide a binder resin for toner having excellent low-temperature fixability without impairing grindability, and an electrophotographic toner containing the binder resin.

The present invention
[1] A binder resin for toner composed of a condensation polymerization resin (resin a) that forms a continuous phase and an addition polymerization resin (resin b) that forms a dispersed phase, and the glass transition point of the resin b is − A binder resin for toner having a glass transition point of the binder resin at 30 to 35 ° C., having a glass transition point of 45 to 65 ° C., and not having a glass transition point of the binder resin at 35 ° C. or lower, and [2] The present invention relates to an electrophotographic toner containing a binder resin for toner.

  The binder resin for toner of the present invention and the electrophotographic toner containing the binder resin exhibit an effect that both the pulverization property and the low-temperature fixability are excellent.

  The binder resin for toner of the present invention comprises a condensation polymerization resin (hereinafter also referred to as resin a) that forms a continuous phase and an addition polymerization resin (hereinafter also referred to as resin b) that forms a dispersed phase. The glass transition point of b and the binder resin itself having the resin b have a glass transition point in a specific temperature range. Thereby, excellent low-temperature fixability is exhibited without impairing the grindability.

  The reason why the pulverizability of the binder resin of the present invention is improved is that the conventional binder resin composed of the condensation polymerization resin and the addition polymerization resin is the glass transition point of the condensation polymerization resin and the addition polymerization resin. The binder resin of the present invention has an average of the glass transition point of the condensation polymerization resin and the glass transition point of the addition polymerization resin, whereas it has two glass transition points respectively assigned to the glass transition point. Since both have at least one glass transition point in the vicinity, that is, 45 to 65 ° C., preferably 47 to 60 ° C., more preferably 50 to 55 ° C., both resins are regarded as one kind of resin. It is considered that the addition polymerization resin is very finely dispersed in the condensation polymerization resin. Therefore, from the viewpoint of the dispersibility of the addition polymerization resin, the binder resin of the present invention is a glass transition point belonging to the addition polymerization resin, that is, a binder resin having no glass transition point at 35 ° C. or lower. The binder resin has a single glass transition point, and the glass transition point is preferably in the temperature range. As a method of increasing the dispersibility of the resin b so that the glass transition points of the resin a and the resin b are averaged and both resins can be regarded as one kind of resin, a method using a large amount of both reactive monomers described later, In the binder resin production process, there may be mentioned a method of reacting at a high temperature after the addition polymerization reaction. From the viewpoint of adjusting the glass transition point, etc., in the binder resin production process, the reaction is carried out at a high temperature after the addition polymerization reaction. The method of making it preferable is.

  The glass transition point of the resin b is as low as -30 to 35 ° C, preferably -20 to 30 ° C, more preferably -10 to 25 ° C, and still more preferably 0 to 25 ° C. In the binder resin of the present invention, since the resin b having a low glass transition point is finely dispersed, the glass transition point of the resin a part is high, but the low glass transition point is maintained as a whole resin. Is done. The glass transition point of the resin b can be adjusted by a known method in consideration of the raw material monomer species and the ratio thereof. For example, referring to `` Polymer Handbook '' (published by INTERSCIENCE), styrene, methyl methacrylate, etc. as raw material monomers that increase the glass transition point of the resin, butyl acrylate as raw material monomers that lower the glass transition point of the resin, 2-ethyl acrylate or the like can be used as appropriate.

  In the binder resin for toner of the present invention, from the viewpoint of dispersibility of the addition polymerization resin, the dispersed phase having a diameter of 0.5 μm or less in the resin cross section is preferably 90% or more of the entire cross-sectional area of the dispersed phase, and 95% or more. More preferred is 98% or more. Here, the diameter in the resin cross section represents the dispersed particle diameter of the dispersed phase observed in the cross section, and is obtained as an average value of the major axis and the minor axis of the particle. Here, the diameter of the dispersed phase and the area ratio of the dispersed phase were determined by cutting a resin having a diameter of about 0.2 mm into a thickness of 100 to 300 nm with a microtome, and then obtaining the obtained flakes by a transmission scanning electron microscope (for example, JEOL (Japan It can be measured by “JEM-2000” (manufactured by Electronics Co., Ltd.) and image analysis by a well-known method.

  The binder resin of the present invention comprising the resin a and the resin b is prepared by melt-kneading each resin in the presence of an initiator or the like, if necessary, dissolving and mixing each resin in a solvent. Although it may be produced by any method such as polymerization of a raw material monomer mixture, preferably, a polycondensation reaction and an addition polymerization reaction are performed using the raw material monomer of resin a and the raw material monomer of resin b. This is a resin obtained by performing the method (Japanese Patent Laid-Open No. 7-98518).

  The resin a is preferably at least one selected from the group consisting of polyester, polyester-polyamide and polyamide, and more preferably polyester.

  As a raw material monomer for polyester, an alcohol component composed of a divalent or higher alcohol and a carboxylic acid component composed of a divalent or higher carboxylic acid compound are used.

  Examples of the dihydric alcohol include polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, (I):

(In the formula, RO is an alkylene oxide, R is an alkylene group having 2 or 3 carbon atoms, x and y are positive numbers indicating the average number of moles of alkylene oxide added, and the sum of x and y is 1-16. (Preferably 1.5 to 5.0)
Aromatic diols such as alkylene oxide adducts of bisphenol A represented by: aliphatic diols such as ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, neopentyl glycol, polyethylene glycol, polypropylene glycol; hydrogen Additive bisphenol A etc. are mentioned.

  As the alcohol component, an alkylene oxide adduct of bisphenol A represented by the formula (I) is preferable. The content of the alkylene oxide adduct of bisphenol A is preferably 50 mol% or more, more preferably 80 mol% or more, and further preferably 100 mol% in the alcohol component.

  Examples of the trihydric or higher polyhydric alcohol include sorbitol, pentaerythritol, glycerin, trimethylolpropane and the like.

  Divalent carboxylic acid compounds include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid; oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, Aliphatic dicarboxylic acids such as succinic acid substituted with alkyl groups having 1 to 20 carbon atoms such as adipic acid, dodecenyl succinic acid, octyl succinic acid or the like, or alkenyl groups having 2 to 20 carbon atoms, preferably 8 to 16 carbon atoms; And anhydrides of these acids and alkyl (C1-3) esters of these acids.

  Among these, terephthalic acid, isophthalic acid, alkenyl succinic acid, adipic acid, fumaric acid and maleic acid are preferable. The total content of these suitable divalent dicarboxylic acid compounds is preferably 50 mol% or more, more preferably 80 mol% or more, and even more preferably 100 mol% in the divalent carboxylic acid compound.

  Examples of the trivalent or higher polyvalent carboxylic acid compounds include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid and acid anhydrides thereof, and lower alkyls. (C1-C3) ester etc. are mentioned, Among these, trimellitic acid is preferable.

  The content of the trivalent or higher polyvalent carboxylic acid compound is preferably 5 to 50 mol%, more preferably 10 to 45 mol% in the carboxylic acid component.

  Furthermore, from the viewpoint of molecular weight adjustment and the like, a monovalent alcohol and a monovalent carboxylic acid compound may be appropriately contained in the alcohol component and / or carboxylic acid component as long as the effects of the present invention are not impaired.

  Examples of the raw material monomer for forming an amide component in polyester-polyamide or polyamide include polyamines such as ethylenediamine, pentamethylenediamine, hexamethylenediamine, diethylenetriamine, iminobispropylamine, phenylenediamine, xylylenediamine, and triethylenetetramine. , Aminocarboxylic acids such as 6-aminocaproic acid and ε-caprolactam, and aminoalcohols such as propanolamine, among which hexamethylenediamine and ε-caprolactam are preferable.

  The glass transition point of the resin a is preferably 50 to 80 ° C., more preferably 55 to 75 ° C., and further preferably 60 to 70 ° C. from the viewpoint of grindability. The glass transition point of the resin a can be easily adjusted by the raw material monomer species and the ratio thereof, the catalyst species, the reaction conditions, and the like. When the glass transition point of the resin a is in the above range, the glass transition point of the binder resin of the present invention is the above temperature range from the viewpoint of low temperature fixability and grindability, and the glass transition point of the resin a. The following is preferable.

  The resin b is preferably a vinyl resin obtained by radical polymerization reaction.

  Examples of the raw material monomer for the vinyl resin include styrene compounds such as styrene and α-methylstyrene; ethylenically unsaturated monoolefins such as ethylene and propylene; diolefins such as butadiene; halovinyls such as vinyl chloride; vinyl acetate; Vinyl esters such as vinyl propionate; alkyl (1-18) esters of (meth) acrylic acid, esters of ethylenic monocarboxylic acids such as dimethylaminoethyl (meth) acrylate; vinyl ethers such as vinyl methyl ether Vinylidene halides such as vinylidene chloride; N-vinyl compounds such as N-vinylpyrrolidone, and the like. From the viewpoint of reactivity, grindability and charge stability, styrene, butyl acrylate, 2-ethylhexyl acrylate and Methyl methacrylate is preferred, styrene and / or Meth) alkyl esters of acrylic acid, a raw material monomer in the vinyl resin, 50 wt% or more, and more preferably preferably is contained 80 to 100 wt%.

  In addition, when polymerizing the raw material monomer of the vinyl resin, a polymerization initiator, a crosslinking agent, or the like may be used as necessary.

  The weight ratio of the resin a to the resin b (resin a / resin b) in the binder resin of the present invention is preferably 50/50 to 95/5 from the viewpoint of achieving both low-temperature fixability and pulverizability, and 60/40 to 95/5 is more preferable, and 70/30 to 90/10 is more preferable.

  The weight ratio of the raw material monomer of the resin a to the raw material monomer of the resin b (the raw material monomer of the resin a / the raw material monomer of the resin b) is preferably 55/45 to 95/5 from the viewpoint of forming a continuous phase with the resin a. 60/40 to 95/5 is more preferable, and 70/30 to 90/10 is more preferable.

  The binder resin of the present invention preferably has, as a structural unit, a monomer that reacts with both the raw material monomer of resin a and the raw material monomer of resin b (hereinafter referred to as a bireactive monomer). Therefore, in the present invention, the condensation polymerization reaction and the addition polymerization reaction are preferably performed in the presence of both reactive monomers. As a result, the resin a and the resin b are partially bonded via the both reactive monomers, and a resin in which the resin b is more finely and uniformly dispersed in the resin a is obtained.

  Both reactive monomers have at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an epoxy group, a primary amino group and a secondary amino group in the molecule, preferably a hydroxyl group and / or carboxyl. A monomer having a group, more preferably a carboxyl group and an ethylenically unsaturated bond is preferred. Specific examples of the both reactive monomers include, for example, acrylic acid, methacrylic acid, fumaric acid, maleic acid and the like, and these hydroxyalkyl (1 to 3 carbon atoms) esters may be used. In view of the above, acrylic acid, methacrylic acid and fumaric acid are preferable.

  In the present invention, among the two reactive monomers, a monomer having two or more functional groups (polycarboxylic acid or the like) and a derivative thereof are used as a raw material monomer for the resin a, and a monomer having one functional group (monocarboxylic acid or the like) and The derivative is treated as a raw material monomer for the resin b. The amount of the amphoteric monomer used is preferably 1 to 30 mol with respect to 100 mol of the raw material monomer of the resin a excluding the amphoteric monomer. From the viewpoint of further increasing the dispersibility of the resin b, the binder resin is produced. In the process, in the method of reacting at a high temperature after the addition polymerization reaction, 1.5 to 20 mol is more preferable, and 2 to 10 mol is more preferable, and after the addition polymerization reaction, the amount of both reactive monomers is increased while keeping the temperature constant. In the method to be used, 4-15 mol is more preferable, and 5-10 mol is further more preferable.

  In the present invention, the condensation polymerization reaction and the addition polymerization reaction are performed in the same reaction vessel. In addition, the progress and completion of each polymerization reaction do not need to be simultaneous in time, and the reaction temperature and time may be appropriately selected according to each reaction mechanism to advance and complete the reaction.

  As a method for producing the binder resin of the present invention, specifically, a method having a step of performing a condensation polymerization reaction by raising the reaction temperature after completing the addition polymerization reaction in the presence of the raw material monomer of the resin a More specifically, the step (A) of performing a condensation polymerization reaction in parallel with the addition polymerization reaction under a temperature condition suitable for the addition polymerization reaction, and the addition polymerization reaction while maintaining the reaction temperature under the above-mentioned conditions A method comprising a step (B) for completing the step, and then a step (C) for further raising the reaction temperature and further performing a polycondensation reaction is preferred.

  In the step (A), it is preferable that the mixture containing the raw material monomer of the resin a is dropped and reacted in the mixture containing the raw material monomer of the resin a.

  Here, the temperature condition suitable for the addition polymerization reaction depends on the kind of the polymerization initiator used, but a temperature range of 50 to 180 ° C. is preferable. Further, the temperature range for further conducting the condensation polymerization reaction by raising the reaction temperature is preferably 190 to 270 ° C, more preferably 235 to 250 ° C, and further preferably 235 to 240 ° C, from the viewpoint of further improving the dispersibility of the resin b. More preferably. In this way, a binder resin in which two types of resins are effectively mixed and dispersed can be obtained by a method in which two independent reactions proceed in parallel in a reaction vessel.

  The binder resin of the present invention may contain a release agent. The release agent may be mixed with the binder resin and contained in the binder resin, but the binder resin of the present invention is mixed with the raw material monomer of the resin a and the raw material monomer of the resin b in the same reaction vessel. When the polycondensation reaction and the addition polymerization reaction are carried out in (1), the dispersibility of the mold release agent can be enhanced by carrying out the polycondensation reaction and the addition polymerization reaction in the presence of the mold release agent. The content of the release agent is preferably 0.5 to 50 parts by weight, more preferably 1.0 to 40 parts by weight, and even more preferably 1.5 to 30 parts by weight with respect to 100 parts by weight of the raw material monomer of the binder resin.

  Examples of the release agent contained in the binder resin of the present invention include low molecular weight polypropylene, low molecular weight polyethylene, low molecular weight polypropylene polyethylene copolymer, aliphatic hydrocarbon waxes such as microcrystalline wax, paraffin wax, and Fischer-Tropsch wax, and These oxides, fatty acid amides, fatty acids, higher alcohols, fatty acid metal salts and the like can be mentioned, and among these, aliphatic hydrocarbon waxes are preferable from the viewpoint of releasability and stability.

  The softening point of the binder resin for toner of the present invention is preferably from 100 to 160 ° C, more preferably from 125 to 150 ° C, and even more preferably from 130 to 145 ° C, from the viewpoints of fixability and grindability. The softening point of the binder resin can be easily adjusted by adjusting the raw material monomer composition, the polymerization initiator, the catalyst amount, etc., or selecting the reaction conditions.

  Furthermore, the present invention provides an electrophotographic toner containing the toner binder resin and a colorant.

  In the toner of the present invention, a low softening point resin and a high softening point resin are preferably used in combination as a binder resin from the viewpoint of low-temperature fixability. The softening point of the low softening point resin is preferably 80 to 120 ° C., more preferably 85 to 115 ° C. from the viewpoint of low-temperature fixability, and the softening point of the high softening point resin is from the viewpoint of offset resistance. The temperature is preferably higher than 120 ° C and not higher than 160 ° C, more preferably 130 to 155 ° C. The difference in softening point between the low softening point resin and the high softening point resin is preferably 20 to 60 ° C, more preferably 30 to 50 ° C.

  Accordingly, it is preferable that a resin having a high softening point or a resin having a low softening point is further contained as a binder resin depending on the softening point of the binder resin for toner of the present invention. Preferably, the resin having a high softening point is the binder resin of the present invention. When the resin of the present invention is used in combination with a low softening point resin as a high softening point resin, the ratio of both (resin of the present invention / low softening point resin) is preferably 95/5 to 50/50, and 90/10 to 55 / 45 is more preferred.

  In the toner of the present invention, the binder resin used in combination with the toner binder resin of the present invention is for conventional toners such as polyester, vinyl resin, epoxy resin, polycarbonate, polyurethane, and a hybrid resin composed of two or more resins. Any resin known as a binder resin may be used, but in the toner of the present invention, a hybrid resin composed of two or more kinds of resins is preferable.

  As the colorant, all of dyes and pigments used as toner colorants can be used, such as carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine-B base, Solvent Red 49, Solvent Red 146, Solvent Blue 35, Quinacridone, Carmine 6B, Disazo Yellow and the like can be used alone or in combination of two or more. The toner of the present invention is a black toner, color Either toner or full color toner may be used. The content of the colorant is preferably 1 to 40 parts by weight and more preferably 3 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

  The toner of the present invention further includes a release agent, a charge control agent, a magnetic powder, a conductivity modifier, an extender pigment, a reinforcing filler such as a fibrous substance, an antioxidant, an anti-aging agent, a fluidity improver, Additives such as a cleaning property improving agent may be appropriately contained.

  As the release agent, low molecular weight polypropylene, low molecular weight polyethylene, low molecular weight polypropylene polyethylene copolymer, aliphatic hydrocarbon waxes such as microcrystalline wax, paraffin wax, Fischer-Tropsch wax and their oxides, carnauba wax, Examples include ester waxes such as montan wax, sazol wax and their deoxidized wax, fatty acid amides, fatty acids, higher alcohols, fatty acid metal salts, etc. Among these, from the viewpoint of releasability and stability Therefore, an aliphatic hydrocarbon wax is preferable.

  The melting point of the release agent is preferably 60 to 120 ° C, more preferably 100 to 120 ° C, from the viewpoint of offset resistance and durability.

  The content of the release agent is preferably 0.5 to 10 parts by weight and more preferably 1 to 5 parts by weight with respect to 100 parts by weight of the binder resin.

  Charge control agents include nigrosine dyes, triphenylmethane dyes containing tertiary amines as side chains, quaternary ammonium salt compounds, polyamine resins, imidazole derivatives and other positively chargeable charge control agents and metal-containing azo dyes, copper Examples include negatively chargeable charge control agents such as phthalocyanine dyes, metal complexes of alkyl derivatives of salicylic acid, and boron complexes of benzylic acid.

  The content of the charge control agent is preferably 0.1 to 5 parts by weight and more preferably 0.5 to 2 parts by weight with respect to 100 parts by weight of the binder resin.

Magnetic powders include ferromagnetic materials such as cobalt, iron and nickel, alloys of metals such as cobalt, iron, nickel, aluminum, lead, magnesium, zinc and manganese, Fe ₃ O ₄ , γ-Fe ₃ O ₄ , cobalt Examples thereof include metal oxides such as added iron oxide, various ferrites such as Mn-Zn ferrite and Ni-Zn ferrite, magnetite and hematite. Furthermore, those surfaces may be treated with a surface treatment agent such as a silane coupling agent or a titanate silane coupling agent, or may be polymer-coated.

  The primary average particle size of the magnetic powder is preferably 0.05 to 0.5 μm, more preferably 0.1 to 0.3 μm, from the viewpoint of dispersibility.

  In the case of a magnetic toner, the content of magnetic powder is preferably 30% by weight or more, more preferably 30 to 60% by weight in the toner. The magnetic powder may be contained as a black colorant.

The method for producing the toner may be any conventionally known method such as a kneading and pulverization method using the binder resin of the present invention as one of the raw materials, a phase inversion emulsification method, an emulsion dispersion method, and a suspension polymerization method. The kneading and pulverizing method is preferable because of easy production. For example, in the case of a pulverized toner by a kneading and pulverizing method, a binder resin, a colorant, and the like are uniformly mixed with a mixer such as a Henschel mixer, and then melt-kneaded with a hermetic kneader or a uniaxial or biaxial extruder. It can be produced by cooling, pulverization and classification. The volume median particle size (D ₅₀ ) of the toner is preferably 3 to 15 μm, more preferably 4 to 8 μm. In the present specification, the volume-median particle size (D50) means a particle size at which the cumulative volume frequency calculated by the volume fraction is 50% calculated from the smaller particle size.

  The toner containing the binder resin obtained according to the present invention can be used for both one-component developing toner and two-component developing toner. However, since the toner of the present invention has excellent low-temperature fixability, The toner is preferably a magnetic one-component developing toner that is difficult to achieve the fixing property.

[Softening point of resin]
Using a flow tester (Shimadzu Corp., CFT-500D), a 1 g sample was heated at a heating rate of 6 ° C / min, and a 1.96 MPa load was applied by a plunger, and extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. . 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 taken as the softening point.

(Glass transition point of resin (Tg))
Measurement was performed using a differential scanning calorimeter (Pyris6DSC manufactured by Perkin Elmer). First, set the sample temperature to -70 ° C and let stand for 30 minutes, then measure the temperature up to 200 ° C at a heating rate of 10 ° C / min. Peaks from the baseline extension below the maximum peak temperature of the heat of fusion and from the peak rising part The temperature at the point of intersection with the tangent showing the maximum inclination to the top of the glass transition point is taken as the glass transition point. In the case where there are two or more peaks at the glass transition point, the glass transition point calculated by the Fox method from the composition of the raw material monomers of the addition polymerization resin can be used as an aid in determining the peak assignment.

[Melting point of wax]
Using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., DSC210), the sample was heated to 200 ° C and then cooled to 0 ° C at a temperature decrease rate of 10 ° C / min. The maximum peak temperature of heat of fusion is the melting point.

[Volume-median particle diameter of toner (D ₅₀ )]
Measuring machine: Coulter Multisizer II (Beckman Coulter, Inc.)
Aperture diameter: 100 μm
Measurement particle size range: 2-60μm
Analysis software: Coulter Multisizer AccuComp version 1.19 (Beckman Coulter)
Electrolyte: Isoton II (Beckman Coulter, Inc.)
Dispersion: Emulgen 109P (manufactured by Kao Corporation, polyoxyethylene lauryl ether, HLB: 13.6) 5% electrolyte dispersion condition: 10 mg of measurement sample is added to 5 ml of dispersion, and dispersed for 1 minute with an ultrasonic disperser. Then, 25 ml of the electrolytic solution is added, and further dispersed with an ultrasonic disperser for 1 minute.
Measurement conditions: Add 100 ml of electrolyte and dispersion in a beaker, measure 30,000 particles at a concentration that can measure the particle size of 30,000 particles in 20 seconds, and determine the volume-median particle size ( determine the D _50).

Resin production example 1
The raw material monomer and polymerization initiator of resin b (vinyl resin) shown in Table 1 are put into a dropping funnel, and the raw material monomer and esterification catalyst of resin a (polyester) are connected to a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple. The mixture was placed in a 5-liter four-necked flask equipped and stirred at 160 ° C. in a nitrogen atmosphere, and the mixture of the raw material monomer of resin b and the polymerization initiator was added dropwise over 1 hour from the dropping funnel. After aging the addition polymerization reaction for 2 hours while maintaining the temperature at 160 ° C., the temperature is raised to 230 ° C. and the condensation polymerization reaction is performed until the desired softening point is reached, thereby forming a dispersed phase with the resin a that forms a continuous phase. Resins A to C consisting of b were obtained.

  In Table 1, the Tg of the resin a is a resin obtained by polycondensation of the raw material monomer of the resin a and the bireactive monomer alone, that is, the raw material monomer of the resin a, the bireactive monomer, and the esterification catalyst. Is the glass transition point of the resin obtained by the condensation polymerization reaction until the desired softening point is reached. The Tg of the resin b is determined by the Fox method from the composition of the raw material monomers. This is the calculated glass transition point.

Resin production example 2
The raw material monomer of resin b (vinyl resin) and the polymerization initiator shown in Table 2 are put in a dropping funnel, and the raw material monomer of resin a (polyester) other than trimellitic anhydride, wax and esterification catalyst are introduced into a nitrogen inlet tube, dehydrated Place in a 5 liter four-necked flask equipped with a tube, stirrer, and thermocouple, stir at 160 ° C. in a nitrogen atmosphere, and stir the mixture of resin b raw material monomer and polymerization initiator from the dropping funnel over 1 hour. And dripped. After aging the addition polymerization reaction for 2 hours while maintaining the temperature at 160 ° C., the temperature was raised to 235 ° C. for 4 hours, followed by reaction at 240 ° C. for 2 hours. Thereafter, trimellitic anhydride was added and a condensation polymerization reaction was performed at 230 ° C. until a desired softening point was reached, thereby obtaining resins D and E consisting of a resin a forming a continuous phase and b forming a dispersed phase.

  In Table 2, the Tg of the resin a is a resin obtained by polycondensation of the raw material monomer of the resin a and the bireactive monomer alone, that is, the raw material monomer of the resin a, the bireactive monomer, and the esterification catalyst. The mixture was heated to 235 ° C and allowed to react for 4 hours, then reacted at 240 ° C for 2 hours, and trimellitic anhydride was added, followed by condensation polymerization at 230 ° C until the desired softening point was reached. The Tg of the resin b is the glass transition point calculated by the Fox method from the composition of the raw material monomers.

Resin production example 3
The raw material monomer of resin b (vinyl resin) and the polymerization initiator shown in Table 2 are put into a dropping funnel, and the raw material monomer of resin a (polyester), wax and esterification catalyst are introduced into a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermoelectric device. The mixture was placed in a 5-liter four-necked flask equipped with a pair, and the mixture of the raw material monomer of resin b and the polymerization initiator was added dropwise over 1 hour from a dropping funnel while stirring at 160 ° C. in a nitrogen atmosphere. After aging the addition polymerization reaction for 2 hours while maintaining the temperature at 160 ° C., the temperature is raised to 230 ° C. and the condensation polymerization reaction is performed until the desired softening point is reached, thereby forming a dispersed phase with the resin a that forms a continuous phase. Resin F consisting of b was obtained.

  In Table 2, the Tg of the resin a means the Tg of the resin a, a resin obtained by polycondensing the raw material monomer of the resin a and the both reactive monomers alone, that is, the raw material monomer of the resin a, both This is the glass transition point of the resin obtained by mixing the reactive monomer and the esterification catalyst, raising the temperature to 230 ° C., and allowing the condensation polymerization reaction to reach the desired softening point, and the Tg of the resin b is the raw material It is the glass transition point calculated by the Fox method from the monomer composition.

Examples 1 to 4, Comparative Examples 1 and 2
100 parts by weight of binder resin shown in Table 3, 54 parts by weight of magnetic powder “MTS106HD” (manufactured by Toda Kogyo Co., Ltd.), 1.0 part by weight of charge control agent “T-77” (manufactured by Hodogaya Chemical Co., Ltd.), and Table 3 After sufficiently mixing the wax with a Henschel mixer, the kneaded portion was melt kneaded using a co-rotating twin screw extruder having a total length of 1560 mm, a screw diameter of 42 mm, and a barrel inner diameter of 43 mm. The heating temperature in the roll was 140 ° C., the roll rotation speed was 150 r / min, the feed rate of the mixture was 20 kg / hour, and the average residence time was about 18 seconds.
The obtained kneaded material was rolled with a cooling roll, mechanically pulverized, and classified to obtain a powder having a volume-median particle size (D ₅₀ ) of 6 μm.

  To 100 parts by weight of the obtained powder, 1.5 parts by weight of hydrophobic silica “R-972” (manufactured by Nippon Aerosil Co., Ltd.) and 1 part by weight of strontium titanate “TiSr” (manufactured by Fuji Titanium) are added as external additives. The magnetic toner was obtained by mixing with a Henschel mixer.

Example 5
The same procedure as in Example 1 was performed except that 4 parts by weight of the colorant “ECB-301” (manufactured by Dainichi Seika Co., Ltd.) was used instead of the magnetic powder “MTS106HD” and strontium titanate “TiSr” was not used. A non-magnetic toner was obtained.

Test Example 1 [Crushability]
Toner pulverized with a 3 mm mesh (mesh opening: 3 mm) screen mounted on a rotochplex using an I-2 type pulverizer (Nippon Pneumatic Co., Ltd.), the target volume-median particle size (D ₅₀ ) is 5.5 μm And was pulverized at a pulverization pressure of 0.5 Pa. From the grinding speed, grindability was evaluated according to the following evaluation criteria. The results are shown in Table 3.

〔Evaluation criteria〕
A: The target toner can be obtained at a pulverization speed of 5 kg / hr or more.
○: The target toner can be obtained at a pulverization rate of 3 kg / hr or more and less than 5 kg / hr.
X: The target toner is obtained at a pulverization speed of 3 kg / hr or less. Alternatively, the target toner cannot be obtained even at a pulverization rate of 3 kg / hr or less.

Test Example 2 [low temperature fixability]
A magnetic one-component developing device “Laser Jet 4200” (manufactured by Hewlett-Packard) is used for the magnetic toners of Examples 1 to 4 and Comparative Examples 1 and 2, and a non-magnetic one-component is used for the non-magnetic toner of Example 5. A developing device “AR-505” (manufactured by Sharp Corporation) was used, and 250 g of toner was mounted on the developing device to obtain an unfixed image (2 cm × 12 cm) with a toner adhesion amount of 0.6 mg / cm ² .

Using the fixer (fixing speed: 200 mm / sec), the non-magnetic one-component developing device “AR-505” (manufactured by Sharp Corporation) was improved so that the fixer can be fixed off-line. Then, a fixing test was performed while the temperature of the fixing roll was gradually increased from 100 ° C. to 240 ° C. by 10 ° C. As the fixing paper, “CopyBond SF-70NA” (manufactured by Sharp Corporation, 75 g / m ² ) was used.

  “UNICEF Cellophane” (Mitsubishi Pencil Co., Ltd., width: 18mm, JISZ-1522) was pasted on the image fixed at each temperature, passed through the fixing roll of the fixing machine set to 30 ° C., and then the tape was peeled off. The optical reflection density of the image after tape peeling was measured using a reflection densitometer “RD-915” (manufactured by Macbeth). Measure the optical reflection density of the image before applying the tape in advance, and the ratio of that value (after peeling the tape / before applying the tape) first exceeds 80% as the minimum fixing temperature. The low-temperature fixability was evaluated according to the evaluation criteria. The results are shown in Table 3.

〔Evaluation criteria〕
A: The minimum fixing temperature is less than 180 ° C.
○: The minimum fixing temperature is 180 ° C. or higher and lower than 200 ° C.
X: The minimum fixing temperature is 200 ° C. or higher.

  From the above results, it can be seen that the toners of Examples 1 to 5 achieve both pulverization and low-temperature fixability. On the other hand, in Comparative Example 1, in which the glass transition point of the resin a is lowered by using a soft acid monomer having no benzene ring skeleton, the grindability is lacking, and the glass transition point of the resin a is low. In Comparative Example 2, which is high and the resin b is not dispersed, the low-temperature fixability is lacking.

  The binder resin for toner of the present invention is used as a binder resin for toner used for developing a latent image formed in electrophotography, electrostatic recording method, electrostatic printing method and the like.

Claims (8)

A binder resin for toner comprising a condensation polymerization resin (resin a) forming a continuous phase and an addition polymerization resin (resin b) forming a dispersed phase, and the glass transition point of the resin b is -30 to 30. A binder resin for toner that has a glass transition point of the binder resin at 45 to 65 ° C. and does not have a glass transition point of the binder resin at 35 ° C. or lower.   The binder resin for toner according to claim 1, wherein a weight ratio of the resin a to the resin b (resin a / resin b) is 50/50 to 95/5.   Using the raw material monomer of resin a and the raw material monomer of resin b in a weight ratio of 55/45 to 95/5 with respect to the raw material monomer of resin a and the raw material monomer of resin a, addition reaction and addition in the same reaction vessel The binder resin for toner according to claim 1, which is obtained by performing a polymerization reaction.   The binder resin for toner according to claim 3, which is obtained by a method comprising a step of performing a condensation polymerization reaction at 235 to 250 ° C. after completing the addition polymerization reaction in the presence of the raw material monomer of the resin a.   The binder resin for toner according to claim 1, wherein the glass transition point of the resin a is 50 to 80 ° C., and the glass transition point of the binder resin is a temperature not higher than the glass transition point of the resin a.   An electrophotographic toner comprising the toner binder resin according to claim 1. The electrophotographic image according to claim 6, wherein the binder resin contains two types of resins having different softening points, and the resin having a higher softening point is the binder resin for toner according to any one of claims 1 to 5. Toner. The toner for electrophotography according to claim 7, wherein the softening point of the resin having the lower softening point is 80 to 120 ° C, and the softening point of the resin having the higher softening point is higher than 120 ° C and not higher than 160 ° C.