JP5060072B2 - Toner for electrophotography - Google Patents

Description

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

With the development of electrophotographic technology, it is desired to develop a small particle size toner having excellent fixability. On the other hand, styrene acrylic resin, polyester, and the like are known as toner binder resins. Polyester is excellent in durability and fixability, but has a defect that offset tends to occur. Thus, for the purpose of improving offset resistance, a toner containing a resin obtained by polymerizing a raw material monomer of a condensation polymerization resin such as polyester and a raw material monomer of an addition polymerization resin such as styrene and an acrylic monomer is provided. (See Patent Documents 1 and 2).
JP-A-7-98517 JP 2004-85605 A

  However, due to the further increase in speed and energy saving of recent machines, it has been found that conventional binder resins for toner are insufficient for market demand. That is, it is very difficult to maintain sufficient fixing strength due to shortening of the fixing time in the fixing process and lowering of the heating temperature supplied from the fixing machine. Particularly in high-speed continuous printing, low-temperature fixability and offset resistance tend to be insufficient.

  An object of the present invention is to provide an electrophotographic toner excellent in fixability and offset resistance.

  Conventionally, attempts have been made to achieve both low-temperature fixability and durability of toner, but satisfactory performance could not be obtained. However, in the combined use of two types of composite resins having different softening points, in the present invention, by increasing the glass transition point derived from the addition polymerization resin unit of the composite resin having the lower softening point, the polyester having the same softening point is used. Low molecular weight compared to the above, can secure low-temperature fixability, while lowering the glass transition point derived from the addition polymerization resin unit of the composite resin having a higher softening point, polyester of the same softening point It has been found that since the molecular weight can be increased as compared with the above, offset resistance can be ensured, and both the low temperature fixability and the offset resistance can be compatible with each other.

  That is, the present invention is an electrophotographic toner comprising, as a binder resin, a resin (A) and a resin (B) having a softening point higher than that of the resin (A) by 5 ° C. or more. ) And resin (B) is a composite resin obtained by polymerizing at least a raw material monomer of a condensation polymerization resin and a raw material monomer of an addition polymerization resin, and a glass transition derived from the addition polymerization resin unit of the resin (A) The present invention relates to an electrophotographic toner having a point of 80 to 100 ° C. and a glass transition point derived from an addition polymerization resin unit of resin (B) of −50 to 40 ° C.

  The toner for electrophotography of the present invention is excellent in fixability and has an excellent effect that the occurrence of offset is suppressed.

  The present invention is an electrophotographic toner containing a resin (A) and a resin (B) having a softening point higher than that of the resin (A) by 5 ° C. or more, wherein the resin (A) and the resin (B) are at least a condensation polymerization type. It is a composite resin obtained by polymerizing a raw material monomer of a resin and a raw material monomer of an addition polymerization resin, and has a characteristic that the glass transition point derived from the addition polymerization resin unit of each composite resin has a specific value. .

  Resin (A) and resin (B) are composite resins obtained by polymerizing at least a raw material monomer of a condensation polymerization resin and a raw material monomer of an addition polymerization resin.

  As the condensation polymerization resin component, from the viewpoint of low-temperature fixability of the toner, the raw material monomer for forming polyester, alcohol component, carboxylic acid component and amide component obtained by condensation polymerization of alcohol component and carboxylic acid component is condensed. It is preferably at least one selected from the group consisting of a polyester / polyamide obtained by polymerization and a polyamide obtained by polycondensing raw material monomers for forming a carboxylic acid component and an amide component. Then, polyester is more preferable.

  The polyester is not particularly limited, and can be obtained by polycondensing a raw material monomer containing an alcohol component composed of a divalent or higher alcohol and a carboxylic acid component composed of a divalent or higher carboxylic acid compound.

  As the dihydric or higher alcohol, from the viewpoint of storage stability of the toner, the formula (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 added mole number of alkylene oxide, and the sum of x and y is 1 to 16) , Preferably 1-10, more preferably 1.5-5)
An alkylene oxide adduct of bisphenol A represented by The content of the alkylene oxide adduct of bisphenol A is preferably 50 mol% or more, more preferably 60 mol% or more, and further preferably 80 mol% or more in the alcohol component.

  Examples of the alkylene oxide adduct of bisphenol A represented by the formula (I) include polyoxyethylene-2,2-bis (4-hydroxyphenyl) propane and other ethylene oxide adducts having 2 carbon atoms, such as polyoxypropylene Examples thereof include propylene oxide adducts having 3 carbon atoms such as -2,2-bis (4-hydroxyphenyl) propane.

  The alcohol components other than the alkylene oxide adduct of bisphenol A include ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, neopentyl glycol, polyethylene glycol, polypropylene glycol, bisphenol A, hydrogenated bisphenol A, and sorbitol. , Pentaerythritol, glycerol, trimethylolpropane and the like.

  Examples of the divalent or higher carboxylic acid compound include adipic acid, fumaric acid, maleic acid, succinic acid (for example, n-dodecenyl succinic acid, isododecenyl succinic acid, n-dodecyl succinic acid, isooctenyl succinic acid, Aliphatic carboxylic acids such as isooctyl succinic acid and the like, succinic acid substituted with alkyl groups having 1 to 20 carbon atoms or alkenyl groups having 2 to 20 carbon atoms, phthalic acid, isophthalic acid, terephthalic acid, 1,2, 4-Benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, aromatic carboxylic acids such as pyromellitic acid, anhydrides of these acids and lower alkyl (C1-3) esters, etc. Is mentioned. Such acids, anhydrides of these acids, and alkyl esters of these acids are collectively referred to herein as carboxylic acid compounds.

  The polyester is preferably a crosslinked polyester obtained using a trivalent or higher monomer as the alcohol component and / or carboxylic acid component from the viewpoint of the softening point and grindability. The content of the trivalent or higher monomer is preferably 2 to 20 mol%, more preferably 4 to 18 mol% in the total amount of the alcohol component and the carboxylic acid component. As the trivalent or higher monomer, 1,2,4-benzenetricarboxylic acid (trimellitic acid) and its anhydride are preferable.

  The alcohol component may contain a monovalent alcohol, and the carboxylic acid component may contain a monovalent carboxylic acid compound as appropriate from the viewpoints of molecular weight adjustment and offset resistance improvement.

  The polycondensation of the alcohol component and the carboxylic acid component can be performed, for example, in an inert gas atmosphere at a temperature of 180 to 250 ° C. using an esterification catalyst if necessary.

  The polyester / polyamide is obtained by using a raw material monomer for forming an amide component in addition to the alcohol component and the carboxylic acid component, and polycondensing these raw material monomers. The polyamide is obtained by using the carboxylic acid component described above. In addition to the above, a raw material monomer for forming an amide component is used, and these raw material monomers are subjected to condensation polymerization.

  Examples of the raw material monomer used to form the amide component include various known polyamines, aminocarboxylic acids, aminoalcohols, etc., preferably hexamethylenediamine and ε-caprolactam.

  The above raw material monomers also include those normally classified as ring-opening polymerization monomers, but these are hydrolyzed by condensation due to the presence of water or the like produced by the condensation polymerization reaction of other monomers. Therefore, it is considered to be included in the raw material monomer of the condensation polymerization resin in a broad sense.

  On the other hand, raw material monomers for addition polymerization resins used in addition polymerization reactions 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; vinyl esters such as vinyl acetate and vinyl propionate; alkyl (carbon number 1 to 18) esters of (meth) acrylic acid, ethylenic monocarboxylic acids such as dimethylaminoethyl (meth) acrylate Examples include esters; vinyl ethers such as vinyl methyl ether; vinylidene halides such as vinylidene chloride; and N-vinyl compounds such as N-vinylpyrrolidone. Styrene is used from the viewpoint of lowering the molecular weight of the combined system with the polymerization resin and improving the fixability. In particular, the content of styrene in the resin (A) is preferably 90% by weight or more, more preferably 95% by weight or more, more preferably in the raw material monomer of the addition polymerization resin. It is 98 weight% or more, More preferably, it is substantially 100 weight%.

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

  The addition polymerization reaction can be performed by a conventional method, for example, in the presence of a polymerization initiator, a crosslinking agent, or the like, in the presence of an organic solvent or in the absence of a solvent. For example, the temperature condition is preferably 110 to 200 ° C., More preferably, it is 140-170 degreeC.

  Examples of the organic solvent used in the addition polymerization reaction include xylene, toluene, methyl ethyl ketone, and acetone. The amount of the organic solvent used is preferably about 10 to 50 parts by weight with respect to 100 parts by weight of the raw material monomer of the addition polymerization resin.

  Resin (A) and / or resin (B) is added to the raw material monomer of the condensation polymerization resin and the raw material monomer of the addition polymerization resin from the viewpoint of improving the dispersibility of additives such as a release agent in the toner. Further, a resin (hybrid resin) obtained by using a compound (both reactive monomers) capable of reacting with both the raw material monomer of the condensation polymerization resin and the raw material monomer of the addition polymerization resin is preferable. Therefore, in the present invention, the condensation polymerization reaction and the addition polymerization reaction are preferably carried out in the presence of both reactive monomers. As a result, the hybrid resin has a partial condensation polymerization resin component and addition polymerization resin component. The addition polymerization resin component is more finely and uniformly dispersed in the condensation polymerization resin component.

  As the both reactive monomers, in the molecule, 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, preferably a hydroxyl group and / or A compound having a carboxyl group, more preferably a carboxyl group, and an ethylenically unsaturated bond is preferred. By using such a bireactive monomer, the dispersibility of the resin that becomes the dispersed phase can be further improved. . Both reactive monomers are preferably at least one selected from the group consisting of acrylic acid, methacrylic acid, fumaric acid, maleic acid and maleic anhydride, but from the viewpoint of reactivity, acrylic acid, methacrylic acid and Fumaric acid is more preferred.

  In the present invention, the both reactive monomers are handled as raw material monomers for the condensation polymerization resin. The amount of the both reactive monomers used is preferably 1 to 20 mol% and more preferably 5 to 15 mol% in the carboxylic acid component which is a raw material monomer for the condensation polymerization resin.

  In the present invention, the composite resin is obtained by performing the condensation polymerization reaction and the addition polymerization reaction in parallel in the same reaction vessel, but the progress and completion of the condensation polymerization reaction and the addition polymerization reaction are simultaneous in time. It is not necessary, and the reaction temperature and time may be appropriately selected according to each reaction mechanism to advance and complete the reaction. The condensation polymerization reaction and the addition polymerization reaction can be performed by the above-described methods.

  In the present invention, the weight ratio of the condensation polymerization resin to the addition polymerization resin, that is, the weight ratio of the condensation polymerization resin raw material monomer to the addition polymerization resin raw material monomer (condensation polymerization resin raw material monomer / addition polymerization resin). The raw material monomer) is preferably 55/45 to 95/5, more preferably 60/40 to 95/5, since the continuous phase is preferably a condensation polymerization resin and the dispersed phase is an addition polymerization resin. 70/30 to 90/10 is more preferable.

  From the viewpoint of improving the fixability, the toner of the present invention preferably contains a release agent. From the viewpoint of improving the dispersibility of the wax, the resin (A) and / or the resin (B) is a wax. A resin obtained by polymerizing a raw material monomer of a condensation polymerization resin and a raw material monomer of an addition polymerization resin containing styrene in the presence of styrene.

  Examples of the wax include aliphatic hydrocarbon waxes such as low molecular weight polypropylene, low molecular weight polyethylene, low molecular weight polypropylene polyethylene copolymer, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax, and oxides thereof, carnauba wax, and montan wax. , Ester waxes such as 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, Aliphatic hydrocarbon waxes are preferred.

  The amount of the wax added is preferably 20 parts by weight or less, more preferably 10 parts by weight or less, with respect to 100 parts by weight of the total amount of raw material monomers used for the production of the resin (A) or resin (B).

  The addition timing of the wax is not particularly limited, and may be at the beginning of the polymerization or in the middle of the polymerization reaction.

  The softening point of the resin (A) and the resin (B) is higher in the resin (B), and the difference is 5 ° C. or higher, preferably 10 ° C. or higher, from the viewpoint of low-temperature fixability and offset resistance of the toner. Preferably it is 20-60 degreeC.

  The softening point of the resin (A) is preferably 80 ° C. or higher and lower than 110 ° C., more preferably 85 to 105 ° C., and still more preferably 90 to 100 ° C., from the viewpoint of low-temperature fixability. On the other hand, the softening point of the resin (B) is preferably 110 to 150 ° C, more preferably 115 to 145 ° C, and still more preferably 120 to 140 ° C, from the viewpoint of hot offset resistance. In the present specification, the softening point is measured by the method described in Examples described later.

  The glass transition point derived from the addition polymerization resin unit of the resin (A) is 80 to 100 ° C., preferably 85 to 100 ° C., more preferably 90 to 100 ° C. On the other hand, the glass transition point derived from the addition polymerization resin unit of the resin (B) is -50 to 40 ° C, preferably -50 to 35 ° C, more preferably -50 to 30 ° C. Further, since the glass transition point derived from the addition polymerization resin unit of the resin (A) and the resin (B) satisfies the relationship derived by the Fox method, a known method is considered in consideration of the raw material monomer species and the ratio thereof. Can be adjusted. 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 addition, in this specification, a glass transition point is calculated by the method as described in the below-mentioned Example.

  The weight ratio of the resin (A) to the resin (B) (resin (A) / resin (B)) is preferably 20/80 to 80/20, more preferably 30 from the viewpoint of low-temperature fixability and offset resistance. / 70 to 70/30, more preferably 40/60 to 60/40.

  The total content of the resin (A) and the resin (B) is preferably 50 to 100% by weight, more preferably 80 to 100% by weight, and still more preferably 90 to 100% by weight in the binder resin. desirable. In addition to the resin (A) and the resin (B), other binder resins may be contained within a range not impairing the effects of the present invention. Examples of the binder resin include epoxy resins, polycarbonates, polyurethanes, and styrene-acrylics. Examples thereof include resins.

  In addition to the binder resin, the toner of the present invention includes a colorant, a release agent, a charge control agent, a magnetic powder, a conductivity regulator, an extender pigment, a reinforcing filler such as a fibrous substance, an antioxidant, and an anti-aging agent. In addition, additives such as a fluidity improver and a cleaning property improver may be appropriately contained.

  As the colorant, dyes and pigments used as toner colorants can be used. 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, etc., and these can be used alone or in admixture of two or more. The toner of the present invention includes black toner, color toner, Any of full-color toners may be used. The content of the colorant is preferably 1 to 40 parts by weight and more preferably 2 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

  As the mold release agent, the above-mentioned wax can be exemplified. Among these, aliphatic hydrocarbon waxes and ester waxes are preferable from the viewpoint of releasability and stability, and these may be contained alone or in admixture of two or more. The content of the release agent is preferably 0.1 to 20 parts by weight and more preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the binder resin. From the viewpoint of improving dispersibility, the release agent may be used together with the resin raw material monomer during the production of the binder resin, and may be internally added to 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 powder includes 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 and cobalt Metal oxides such as added iron oxide, various ferrites such as Mn—Zn ferrite and Ni—Zn ferrite, magnetite, hematite and the like can be used alone or in combination. Furthermore, the surface of these magnetic components 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.

  When the toner of the present invention is a magnetic toner, the content of the magnetic powder is preferably 10 to 90 parts by weight with respect to 100 parts by weight of the binder resin from the viewpoint of the dispersibility of the magnetic powder and the charging environment. 20 to 80 parts by weight is more preferable, and 30 to 70 parts by weight is more preferable. Further, a known colorant such as carbon black or phthalocyanine blue may be used in combination for adjusting the color and the charge amount.

The toner of the present invention can be produced by a known method such as a kneading and pulverizing method, a spray drying method, or a polymerization method, but is preferably produced by a kneading and pulverizing method from the viewpoint of productivity and dispersibility of the colorant. . As a general method of the kneading and pulverization method, for example, a binder resin, and a release agent, a charge control agent, an additive such as magnetic powder, and the like are uniformly mixed with a mixer such as a Henschel mixer and a ball mill, Examples of the method include melt kneading with a closed kneader or a single or twin screw extruder, cooling, pulverizing, and classification. Furthermore, a fluidity improver such as hydrophobic silica may be added to the coarsely pulverized product in the production process or the surface of the obtained toner, if necessary. The volume median particle size (D ₅₀ ) of the toner of the present invention is preferably 3 to 15 μm, more preferably 4 to 8 μm. In the present invention, the volume-median particle size (D ₅₀ ) means a particle size at which the cumulative volume frequency calculated by the volume fraction is 50% when calculated from the smaller particle size.

  The toner of the present invention can be used alone as a developer or mixed with a carrier as a two-component developer, but contains magnetic powder from the viewpoint of good dispersibility of the toner additive. It can be suitably used as a magnetic one-component developing toner. In addition, the toner of the present invention can be suitably used for a high-speed machine having a linear speed of 200 mm / sec (A4 paper 40 sheets / min) or more, more preferably 250 to 300 mm / sec.

[Softening point of resin]
Using a flow tester (Shimadzu Corporation, CFT-500D), a 1 g sample was heated at a heating rate of 6 ° C / min, and a load of 1.96 MPa 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 addition polymerization resin unit]
The glass transition point of the addition polymerization resin unit is calculated from the composition of the raw material monomer by the Fox formula shown below. The Fox formula is shown, for example, in Kyoritsu Shuppan Co., Ltd., Basics of Polymer Properties, pages 311-312 (issued February 1, 1993).
When the addition polymerization resin unit to be calculated is composed of monomer 1 and monomer 2,

(In the formula, Tg is the glass transition point (K) of the addition polymerization resin unit, Tg ₁ and Tg ₂ are the glass transition points (K) of the homopolymers of monomers 1 and 2, and W ₁ and W ₂ are the total amount of monomer 1) Shows the weight ratio of monomers 1 and 2)
Calculated by
The homopolymer Tg described in Polymer Handbook, pages III-64 to III-85 (INTERSCIENCE, published in 1965) can be used as the homopolymer Tg of the addition polymerization monomer. In addition, when there is only one type of monomer of the addition polymerization resin unit, the calculation can be performed by omitting the second term (W ₂ / Tg ₂ ) on the right side of the above formula, and there are three types of addition polymerization resin units. Even in the case of the above monomers, the glass transition point can be similarly calculated based on the Fox equation. For example, when the addition polymerization resin unit to be calculated is composed of monomer 1, monomer 2, and monomer 3,

(In the formula, Tg is the glass transition point (K) of the addition polymerization resin unit, Tg ₁ , Tg ₂ , Tg ₃ are the glass transition points (K) of the homopolymers of monomers ₁ , ₂ , and ₃ , W ₁ , W ₂ W ₃ represents the weight ratio of monomers 1, 2, and 3 when the total amount of monomers is 1.
Can be calculated.

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

[Volume-median particle size of toner (D ₅₀ )]
Measuring machine: Coulter Multisizer II (Beckman Coulter, Inc.)
Aperture diameter: 100μm
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) is dissolved in the electrolytic solution to a concentration of 5% by weight to obtain a dispersion.
Dispersion conditions: 10 mg of a measurement sample is added to 5 mL of the above dispersion, and dispersed for 1 minute with an ultrasonic disperser, then 25 mL of electrolyte is added, and further dispersed for 1 minute with an ultrasonic disperser. Prepare a dispersion.
Measurement conditions: By adding the sample dispersion to 100 mL of the electrolytic solution, the particle size of 30,000 particles is adjusted to a concentration that can be measured in 20 seconds, and then 30,000 particles are measured, Determine the volume-median particle size (D ₅₀ ).

Resin production examples 1-7
Raw material monomer of polyester other than trimellitic anhydride and acrylic acid shown in Table 1 and 15 g of tin octoate as esterification catalyst, 4 liters of 10 liters equipped with nitrogen introduction tube, dehydration tube, stirrer and thermocouple The flask was placed in a flask and subjected to a condensation polymerization reaction at 230 ° C. for 8 hours. Further, the reaction is carried out at 8 kPa for 1 hour, Fischer-Tropsch wax “Sazol H105” (manufactured by Sazol) shown in Table 1 is added, and after cooling to 160 ° C., acrylic acid and vinyl resin raw material monomers shown in Table 1 And the mixture of the polymerization initiator was dripped over 1 hour with the dropping funnel. After dropping, the addition polymerization reaction was aged for 1 hour while maintaining the temperature at 160 ° C., then the temperature was raised to 200 ° C. and maintained at 10 kPa for 1 hour to remove the vinyl resin monomer. Thereafter, trimellitic anhydride shown in Table 1 was added and reacted for 1 hour, and then a crosslinking reaction was performed at 40 kPa until a predetermined softening point was reached to obtain a resin.

Toner Production Examples 1-7 (Examples 1-5 and Comparative Examples 1-2)
The toner materials shown in Table 2 were stirred and mixed with a Henschel mixer, and then melt-kneaded using a co-rotating twin screw extruder having a total kneading part length of 1560 mm, a screw diameter of 42 mm, and a barrel inner diameter of 43 mm. The rotation speed of the roll was 200 r / min, the heating temperature in the roll was 120 ° C., the feed rate of the mixture was 10 kg / hour, and the average residence time was about 18 seconds. The obtained kneaded product was rolled and cooled with a cooling roller, then pulverized with a jet mill, and classified to obtain a toner having a volume-median particle size (D ₅₀ ) of 5 μm.

Test Example 1 [Fixability]
Mount 250g of the toner in Table 2 on "Laser Jet4200" (manufactured by HP), print a solid image without fixing, and gradually increase the temperature of the fixing roll for each unfixed image from 80 ° C to 10 ° C. A test was conducted in which the sample was stored in a constant temperature bath at 100 ° C. for 15 seconds. “UNICEF Cellophane” (Mitsubishi Pencil Co., Ltd., width: 1.8 mm, JISZ-1522) was attached to the obtained fixed image, passed through a fixing roll set at 30 ° C., and then the tape was peeled off. The optical reflection density before and after the tape was peeled was measured using a reflection densitometer “RD-915” (manufactured by Macbeth Co.), and the ratio between the two (after tape peeling / before tape sticking) was initially 90%. The temperature of the fixing roll that exceeds the minimum fixing temperature is set.

[Evaluation criteria for fixability]
: Less than 110 ° C ○: More than 110 ° C, less than 130 ° C ×: More than 130 ° C

Test Example 2 [Offset resistance]
The toner was mounted in the same manner as in Test Example 1, and an image of 2 cm × 12 cm and 0.6 mg / cm ² was formed without fixing. For the obtained image, the fixing machine of the copier “AR-505” (manufactured by Sharp Corporation) is improved so that the total fixing pressure of the offline fixing machine is 392 Pa (fixing speed 250 mm / sec: A4 paper) 50 copies / minute) was used, and a fixing test was performed on “CopyBond SF-70NA” (75 g / m ² , manufactured by Sharp Corporation) while gradually increasing the fixing temperature from 100 ° C. to 240 ° C. in 10 ° C. increments. The offset was visually observed, and the temperature at which the offset occurred was evaluated according to the following evaluation criteria. The results are shown in Table 2.

[Evaluation criteria for offset]
◎: 90 ℃ or more ○: 70 ℃ or more, less than 90 ℃ △: 50 ℃ or more, less than 70 ℃ ×: less than 50 ℃

  From the above results, it can be seen that the toners of the examples have good fixability and offset resistance.

Toner Production Example 8 (Example 6)
In Toner Production Example 1, in the same manner as in Toner Production Example 1, except that 5 parts by weight of a colorant “ECB301” (manufactured by Dainichi Seika Co., Ltd.) is added to 100 parts by weight of the binder resin instead of magnetic powder. A non-magnetic toner was obtained. The obtained toner was tested for fixability and offset resistance in the same manner as described above, and as a result, good results were obtained. For the image evaluation of toner evaluation, “Microline 5400” (manufactured by Oki Data Corporation) was used instead of “Laser Jet4200”.

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

Claims (3)

An electrophotographic toner comprising, as a binder resin, a resin (A) and a resin (B) having a softening point higher than that of the resin (A) by 5 ° C. or more, the resin (A) and the resin (B) Is a composite resin obtained by polycondensation of at least the raw material monomer of the condensation polymerization resin and addition polymerization of the raw material monomer of the addition polymerization resin, and the glass transition derived from the addition polymerization resin unit of the resin (A) The point is calculated by the Fox equation, the glass transition point is 80 to 100 ° C., and the glass transition point derived from the addition polymerization resin unit of the resin (B) is calculated by the Fox equation The glass transition point is −50 to 40 ° C., the raw material monomers of the condensation polymerization resin are an alcohol component and a carboxylic acid component, and the addition monomer of the addition polymerization resin is a styrene compound and an ethylenic monocarbohydrate. At least one selected from ester le or Ranaru group phosphate, wherein the addition polymerization resin of the resin (A) raw material monomer is contained styrene 90 wt% or more (provided that the polycondensation resin When using a compound capable of reacting with both the raw material monomer and the raw material monomer of the addition polymerization resin (both reactive monomers), the usage amount of both reactive monomers is treated as the usage amount of the raw material monomer of the condensation polymerization resin). The weight ratio of the resin (A) to the resin (B) (resin (A) / resin (B)) is 20/80 to 80/20, and the softening point of the resin (A) is 80 ° C. or higher and lower than 110 ° C. An electrophotographic toner in which the softening point of the resin (B) is 110 to 150 ° C. Resin (A) and / or the resin (B) is obtained by further polymerizing in the presence of with any compound capable of reacting the raw material monomers of the raw material monomer and the addition polymerization resin of the polycondensation resin, according to claim 1 serial mounting electrophotographic toner. Resin (A) and / or the resin (B) is obtained by polymerizing the raw material monomers of the raw material monomer and the addition polymerization resin polycondensation resin in the presence of a wax according to any one of claims 1 or 2 Toner for electrophotography.