JP4699191B2 - Crosslinked polyester for toner - Google Patents

Description

  The present invention relates to a crosslinked polyester 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 a toner containing the polyester.

  Along with the development of electrophotographic technology, toners with excellent fixability and storage stability (blocking resistance) are required, and toners containing polyester resin with 1,3-propanediol as an essential component as an alcohol component (patented) Reference 1) has been reported. In Patent Document 1, aliphatic alcohols containing 1,3-propanediol, carboxylic acids such as terephthalic acid and trimellitic acid are combined as constituent components.

  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.

  On the other hand, if the softening point of the resin is lowered in order to improve the low-temperature fixability, not only the offset occurs but also the glass transition point is inevitably lowered, resulting in poor storage stability such as toner aggregation. Result.

Further, as is apparent from the offset resistance evaluation method in Patent Document 1, by applying oil to the fixing roller, offset resistance can be ensured even with a polyester having a low softening point (patent). In the recent market where there is a tendency to reduce the size of the device, the installation of an oil application device will increase the size of the device. Therefore, ensuring anti-offset properties by applying oil is a modern trend. It is not suitable.
JP 2002-169331 A

  An object of the present invention is to provide a crosslinked polyester for toner excellent in low-temperature fixability, offset resistance in oilless fixing and storage stability, and a toner containing the polyester.

  The present invention is a crosslinked polyester for toner obtained by condensation polymerization of an alcohol component and a carboxylic acid component in the presence of a tin (II) compound having no Sn-C bond, wherein the alcohol component is 1 1,2-propanediol, 1,3-propanediol and glycerin, and the molar ratio of 1,2-propanediol (1,2-PD) to 1,3-propanediol (1,3-PD) The present invention relates to a crosslinked polyester for toner having (1,2-PD / 1,3-PD) of 70/30 to 99/1, and a toner containing the crosslinked polyester for toner.

  The toner of the present invention is excellent in both low-temperature fixability and storage stability, and has an excellent effect that it can exhibit good offset resistance even in oil-less fixing.

  The crosslinked polyester for toner according to the present invention comprises a divalent alcohol such as 1,2-propanediol and 1,3-propanediol in the presence of a tin (II) compound having no Sn-C bond, and a trivalent It is obtained by condensation polymerization of an alcohol component containing glycerin, which is a polyhydric alcohol, and a carboxylic acid component. In the present invention, the crosslinked polyester means that the content of the trihydric or higher polyhydric alcohol and / or trihydric or higher carboxylic acid compound in the total amount of the alcohol component and the carboxylic acid component is 1 to 40 mol%, preferably Polyester which is 5-30 mol%.

  The 1,2-propanediol having 3 carbon atoms used for the alcohol component in the present invention is effective for improving low-temperature fixability as compared with alcohol having 2 or less carbon atoms, and compared with alcohol having 4 or more carbon atoms. It is effective in preventing deterioration of storage stability accompanying a decrease in glass transition point. Furthermore, in the present invention, since 1,2-propanediol is used in combination with linear 1,3-propanediol, the glass transition point of the polyester can be kept high. In addition, the linear 1,3-propanediol imparts flexibility to the molecular chain, so that low temperature fixability can be ensured while maintaining offset resistance in oilless fixing.

  The molar ratio of 1,2-propanediol (1,2-PD) to 1,3-propanediol (1,3-PD) (1,2-PD / 1,3-PD) is low temperature fixability and storage From the viewpoint of achieving compatibility, the ratio is 70/30 to 99/1, preferably 75/25 to 95/5, more preferably 77/23 to 85/15.

  The alcohol component may contain an alcohol other than 1,2-propanediol, 1,3-propanediol and glycerin as long as the effects of the present invention are not impaired. The total content of 1,3-propanediol is preferably 60 to 100 mol%, more preferably 70 to 100 mol%, still more preferably 80 to 100 mol%, and more preferably 90 to 100 mol in the divalent alcohol component. Further preferred. Examples of divalent alcohol components other than 1,2-propanediol and 1,3-propanediol include alkylene oxide adducts of bisphenol A, ethylene glycol, hydrogenated bisphenol A, sorbitol, or alkylenes thereof (2 to 4) Oxide (average added mole number: 1 to 16) adduct and the like. The content of the divalent alcohol component is preferably 60 to 95 mol%, more preferably 65 to 90 mol% in the alcohol component.

  Furthermore, the alcohol component of the polyester of the present invention contains glycerin, which is a trivalent alcohol that acts as a crosslinking agent. Conventionally, cross-linking with trimellitic anhydride, which is suitably used as a trivalent or higher monomer, did not have sufficient fixing and offset resistance, but glycerin not only acts as a cross-linking agent but also fixed at low temperatures. It is also effective for improving the performance. From this viewpoint, the content of glycerin is preferably 1 to 40 mol%, more preferably 5 to 35 mol% in the alcohol component.

  Examples of trihydric or higher alcohols other than glycerin include pentaerythritol and trimethylolpropane.

  On the other hand, the carboxylic acid component preferably contains an aliphatic dicarboxylic acid compound having 2 to 4 carbon atoms. Examples of the aliphatic dicarboxylic acid compound having 2 to 4 carbon atoms include adipic acid, maleic acid, malic acid, succinic acid, fumaric acid, citraconic acid, itaconic acid, and anhydrides of these acids. Among these, it is more preferable that at least one aliphatic dicarboxylic acid compound selected from the group consisting of succinic acid, fumaric acid, citraconic acid, itaconic acid and anhydrides of these acids is contained. Since these aliphatic dicarboxylic acid compounds impart flexibility to the molecular chain, they are effective in improving low-temperature fixability. In the present invention, itaconic acid is preferable among the aliphatic dicarboxylic acid compounds.

  The content of the aliphatic dicarboxylic acid is preferably 0.5 to 20 mol% and more preferably 1 to 15 mol% in the carboxylic acid component from the viewpoint of improving the low-temperature fixability and suppressing the decrease in the glass transition point.

  The carboxylic acid component preferably contains rosin from the viewpoint of low-temperature fixability and charging environment stability. The rosin having a polycyclic aromatic ring can reduce the water absorption of conventional aliphatic alcohol polyesters, improve the environmental stability of charging, and further improve the low-temperature fixability.

  In the present invention, rosin is a natural resin obtained from pine, and the main component thereof is a resin such as abietic acid, neoabietic acid, parastrinic acid, pimaric acid, isopimaric acid, sandaracopimaric acid, dehydroabietic acid, etc. Acids and mixtures thereof.

  Rosin is roughly classified into tall rosin obtained from tall oil obtained as a by-product in the process of producing pulp, gum rosin obtained from raw pine ani, wood rosin obtained from pine stumps, etc. From the viewpoint of fixability, tall rosin is preferred.

  In addition, a modified rosin such as a disproportionated rosin or a hydrogenated rosin may be used, but in the present invention, from the viewpoint of low-temperature fixability and storage stability, a so-called raw rosin that is not modified may be used. preferable.

  The rosin is preferably a purified rosin from the viewpoint of improvement in storage stability and odor.

  The purified rosin in the present invention is a rosin whose impurities are reduced by the purification process. Main impurities include 2-methylpropane, acetaldehyde, 3-methyl-2-butanone, 2-methylpropanoic acid, butanoic acid, pentanoic acid, n-hexanal, octane, hexanoic acid, benzaldehyde, 2-pentylfuran, 2 , 6-dimethylcyclohexanone, 1-methyl-2- (1-methylethyl) benzene, 3,5-dimethyl-2-cyclohexene, 4- (1-methylethyl) benzaldehyde and the like. In the present invention, among these, the peak intensity detected as a volatile component by the headspace GC-MS method of three types of impurities, 2-methylpropane, pentanoic acid and benzaldehyde, can be used as an indicator of purified rosin. . The reason why the volatile component, not the absolute amount of impurities, is used as an indicator is that the use of the purified rosin in the present invention makes the odor one of the problems of improvement over the conventional polyester using the rosin.

That is, the purified rosin in the present invention has a peak intensity of hexanoic acid of 0.8 × 10 ⁷ or less and a peak intensity of pentanoic acid of 0.4 × 10 ⁷ or less under the measurement conditions of the headspace GC-MS method described later. Rosin having a peak intensity of benzaldehyde of 0.4 × 10 ⁷ or less. Furthermore, from the viewpoint of storage stability and odor, the peak intensity of hexanoic acid is preferably 0.6 × 10 ⁷ or less, and more preferably 0.5 × 10 ⁷ or less. The peak intensity of pentanoic acid is preferably 0.3 × 10 ⁷ or less, and more preferably 0.2 × 10 ⁷ or less. The peak intensity of benzaldehyde is preferably 0.3 × 10 ⁷ or less, and more preferably 0.2 × 10 ⁷ or less.

Further, from the viewpoint of storage stability and odor, it is preferable that n-hexanal and 2-pentylfuran are reduced in addition to the above three substances. peak intensity of n- hexanal is preferably 1.7 × 10 ⁷ or less, more preferably 1.6 × 10 ⁷ or less, further preferably 1.5 × 10 ⁷ or less. The peak intensity of 2-pentylfuran is preferably 1.0 × 10 ⁷ or less, more preferably 0.9 × 10 ⁷ or less, and further preferably 0.8 × 10 ⁷ or less.

  As a purification method of rosin, known methods can be used, and methods such as distillation, recrystallization, extraction and the like can be mentioned, and purification by distillation is preferable. As the distillation method, for example, the method described in JP-A-7-286139 can be used, and examples thereof include vacuum distillation, molecular distillation, steam distillation, etc., but purification by vacuum distillation is preferable. For example, distillation is usually performed at a still temperature of 200 to 300 ° C. at a pressure of 6.67 kPa or less, and methods such as ordinary simple distillation, thin film distillation, rectification, etc. are applied. On the other hand, 2 to 10% by weight of a high molecular weight substance is removed as a pitch component, and at the same time, 2 to 10% by weight of an initial fraction is simultaneously removed.

  The softening point of the purified rosin is preferably 50 to 100 ° C, preferably 60 to 90 ° C, and more preferably 65 to 85 ° C. Further, the impurities contained in the rosin are removed by purification. The softening point of the purified rosin in the present invention means the softening point measured when the rosin is once melted and naturally cooled in an environment of a temperature of 25 ° C. and a relative humidity of 50% for 1 hour by the method described later. To do.

  Further, the acid value of the purified rosin is preferably 100 to 200 mgKOH / g, more preferably 130 to 180 mgKOH / g, and further preferably 150 to 170 mgKOH / g.

  The content of the purified rosin is preferably 2 to 50 mol%, more preferably 5 to 40 mol%, further preferably 10 to 30 mol% in the carboxylic acid component.

  Further, the carboxylic acid component may contain a carboxylic acid compound other than the aliphatic carboxylic acid compound and rosin as long as the effect of the present invention is not impaired, and ensures storage stability (that is, glass transition). From the viewpoint of ensuring the point), it is preferable that an aromatic dicarboxylic acid such as phthalic acid, isophthalic acid or terephthalic acid is contained. The content of the aromatic dicarboxylic acid is preferably 40 to 95 mol%, more preferably 50 to 95 mol%, still more preferably 60 to 80 mol% in the carboxylic acid component.

  Examples of the trivalent or higher polyvalent carboxylic acid compounds include trimellitic acid, pyromellitic acid and anhydrides and alkyl (carbon number 1 to 3) esters of these acids. Among these, trimellitic acid and Their derivatives (anhydrides and alkyl (C1-3) esters) are preferred.

  The polyester of the present invention is obtained by polycondensing the alcohol component and the carboxylic acid component in the presence of a tin (II) compound having no Sn-C bond. Since the polyester of the present invention uses such a tin (II) compound as a catalyst, it has a high glass transition point and good storage stability. This is because when a tin (II) compound having no Sn-C bond is used as a catalyst during the polycondensation reaction of the polyester, metal coordination occurs between molecules, so that the glass transition point of the resulting polyester is increased. Presumed to be.

  Examples of the tin (II) compound having no Sn—C bond include a tin (II) compound having a Sn—O bond, a tin (II) compound having a Sn—X (X represents a halogen atom) bond, and the like. Preferably, a tin (II) compound having a Sn-O bond is more preferable.

Examples of the tin (II) compound having an Sn-O bond include tin (II) oxalate, tin (II) diacetate, tin (II) dioctanoate, tin (II) dilaurate, tin (II) distearate, diolein Tin (II) carboxylate having a carboxylic acid group having 2 to 28 carbon atoms such as tin (II) acid; dioctyloxy tin (II), dilauroxy tin (II), distearoxy tin (II), dioleoxy tin (II), etc. Dialkoxytin (II) having an alkoxy group having 2 to 28 carbon atoms; tin (II) oxide; tin (II) sulfate and the like having a Sn—X (X represents a halogen atom) bond include chloride. Tin (II), tin (II) halides such as tin (II), and the like can be mentioned. Among these, (R ¹ COO) ₂ Sn (where R ¹ represents a fatty acid tin (II) represented by an alkyl group or an alkenyl group having 5 to 19 carbon atoms, and (R ² O) ₂ Sn (where R ² is 6 to ² carbon atoms) A dialkoxytin (II) represented by 0 (which represents an alkyl group or an alkenyl group) and a tin (II) oxide represented by SnO, and a fatty acid tin (II) represented by (R ¹ COO) ₂ Sn And tin oxide (II) is more preferable, and tin (II) dioctanoate, tin (II) distearate and tin (II) oxide are more preferable.

  The existing amount of the tin (II) compound is preferably 0.01 to 1.0 part by weight, and more preferably 0.1 to 0.5 part by weight with respect to 100 parts by weight of the total amount of the alcohol component and the carboxylic acid component.

  In addition, as a catalyst, you may use together the titanium compound of the grade which does not inhibit the effect of this invention. When used together, the addition amount of the titanium compound is preferably 0.01 to 0.1 parts by weight, more preferably 0.01 to 0.05 parts by weight, with respect to 100 parts by weight of the total amount of the alcohol component and the carboxylic acid component.

  The softening point of the polyester is preferably 90 to 165 ° C, more preferably 120 to 165 ° C, further preferably 130 to 155 ° C, and further preferably 140 to 155 ° C, from the viewpoints of fixability, storage stability, and durability. The softening point can be easily adjusted by, for example, the polymerization time.

  Further, the glass transition point of the polyester is preferably 50 to 70 ° C, more preferably 55 to 65 ° C, from the viewpoints of fixability, storage stability, and durability. The acid value is preferably 1 to 50 mgKOH / g, more preferably 20 to 40 mgKOH / g, from the viewpoints of chargeability and environmental stability.

  The polyester of the present invention may be a modified polyester. Modified polyester refers to polyester grafted or blocked with phenol, urethane or the like.

  By using the polyester of the present invention as a binder resin for toner, it is possible to obtain a toner having excellent low-temperature fixability and storage stability and good offset resistance even in oilless fixing. In the toner of the present invention, a known binder resin, for example, a vinyl resin such as styrene-acrylic resin, an epoxy resin, a polycarbonate, a polyurethane, or the like is used in combination as long as the effects of the present invention are not impaired. However, the content of the polyester of the present invention is preferably 70% by weight or more, more preferably 80% by weight or more, still more preferably 90% by weight or more, and substantially 100% by weight in the binder resin. More preferred

  By using the polyester obtained by the present invention as a binder resin for toner, it is possible to obtain a toner excellent in both low-temperature fixability and storage stability.

  The toner of the present invention preferably contains a release agent. Mold release agents include polypropylene wax, polyethylene wax, synthetic wax such as Fischer Tropu, coal wax such as montan wax, petroleum wax such as paraffin wax, wax such as alcohol wax, carnauba wax, rice wax, and candelilla. Natural ester waxes such as wax may be mentioned, and these may be used alone or in admixture of two or more.

  The content of the release agent is preferably 1 to 10 parts by weight and more preferably 2 to 5 parts by weight with respect to 100 parts by weight of the binder resin.

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

  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, and the toner of the present invention may be either a black toner or a color toner. 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.

The toner of the present invention may be a toner obtained by any conventionally known method such as a melt-kneading method, an emulsion phase inversion method, or a polymerization method, but from the viewpoint of productivity and dispersibility of the colorant, A pulverized toner obtained by a melt kneading method is preferred. In the case of pulverized toner by melt kneading method, raw materials such as binder resin, colorant, charge control agent, etc. are uniformly mixed with a mixer such as a Henschel mixer, then a sealed kneader, a single or twin screw extruder, open It can be produced by melt-kneading with a roll-type kneader or the like, cooling, pulverizing and classifying. The volume median particle size (D ₅₀ ) of the toner is preferably 3 to 15 μm. In the present specification, 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 as a one-component developing toner or as a two-component developer mixed with a carrier.

  Since the toner of the present invention is excellent in fixability, it can be suitably used in a heat roll method in which the occurrence of offset is a problem, and color toners also exhibit good offset resistance in oilless fixing. . The oilless fixing is a method using a fixing device having a heat roll fixing device that does not include an oil supply device. The oil supply device has an oil tank and has a mechanism for quantitatively applying oil to the surface of the heat roll, as well as a device having a mechanism for bringing a roll pre-impregnated with oil into contact with the heat roll, etc. including.

[Softening point of resin]
Using a flow tester (Shimadzu Corporation, CFT-500D), a 1 g sample is heated at a heating rate of 6 ° C / min, and a 1.96 MPa load is 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.

[Softening point of rosin]
(1) Sample preparation 10g of rosin is melted on a hot plate at 170 ° C for 2 hours. After that, it is naturally cooled for 1 hour in an open state at a temperature of 25 ° C. and a relative humidity of 50%, and then ground for 10 seconds in a coffee mill (National MK-61M).
(2) Measurement Using a flow tester (Shimadzu Corporation, CFT-500D), a 1g sample was heated at a heating rate of 6 ° C / min, and a load of 1.96MPa was applied by a plunger, with a diameter of 1mm and a length of 1mm. Extrude from 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 taken as the softening point.

[Glass transition point of resin]
Using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., DSC210), weigh 0.01 to 0.02 g of the sample into an aluminum pan, raise the temperature to 200 ° C, and from that temperature to 0 ° C at a rate of 10 ° C / min. The temperature of the cooled sample is raised at a heating rate of 10 ° C / min, and the temperature at the intersection of the base line extension below the maximum peak temperature of endotherm and the tangent that indicates the maximum slope from the peak rise to the peak apex To do.

[Acid value of resin and rosin]
Measured according to the method of JIS K0070. However, only the measurement solvent was changed from the mixed solvent of ethanol and ether specified in JIS K0070 to a mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)).

[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).

Example of purification of rosin 1000 g of tall rosin was added to a 2000 ml distillation flask equipped with a fractionation tube, reflux condenser and receiver, and distilled under a reduced pressure of 13.3 kPa. A purified rosin was obtained by collecting as a fraction and used in Examples described later.

  20 g of purified rosin was pulverized with a coffee mill (National MK-61M) for 5 seconds, and 0.5 g was measured in a headspace vial (20 ml) after passing through a 1 mm sieve. Table 1 shows the results of sampling the headspace gas and analyzing the impurities in the purified rosin by the headspace GC-MS method.

[Measurement conditions for headspace GC-MS method]
A. Headspace sampler (Agilent, HP7694)
Sample temperature: 200 ℃
Loop temperature: 200 ° C
Transfer line temperature: 200 ° C
Sample heating equilibration time: 30min
Bayal pressurized gas: Helium (He)
Bayal pressurization time: 0.3min
Loop filling time: 0.03min
Loop equilibration time: 0.3min
Injection time: 1min

B. GC (Gas Chromatography) (Agilent, HP6890)
Analytical column: DB-1 (60m-320μm-5μm)
Carrier: Helium (He)
Flow rate condition: 1ml / min
Inlet temperature: 210 ° C
Column head pressure: 34.2kPa
Injection mode: split
Split ratio: 10: 1
Oven temperature condition: 45 ℃ (3min) -10 ℃ / min-280 ℃ (15min)

C. MS (mass spectrometry) (Agilent, HP5973)
Ionization method: EI (electron impact) method Interface temperature: 280 ℃
Ion source temperature: 230 ° C
Quadrupole temperature: 150 ° C
Detection mode: Scan 29-350m / s

Example 1
The alcohol component, terephthalic acid and esterification catalyst shown in Table 2 were placed in a 5-liter four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a rectifying column, a stirrer and a thermocouple. After the condensation polymerization reaction at 10 ° C. for 10 hours, the reaction was performed at 230 ° C. and 8.0 kPa for 1 hour. After cooling to 180 ° C, itaconic acid was added and heated to 220 ° C, reacted at normal pressure for 4 hours, then purified rosin was added and reacted at normal pressure for 10 hours, then trimellitic anhydride An acid was added and reacted at normal pressure for 1 hour, and then reacted at 220 ° C. and 20 kPa to the desired softening point to obtain a polyester.

Example 2
The alcohol component, terephthalic acid and esterification catalyst shown in Table 2 were placed in a 5-liter four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a rectifying column, a stirrer and a thermocouple. After the condensation polymerization reaction at 10 ° C. for 10 hours, the reaction was performed at 230 ° C. and 8.0 kPa for 1 hour. Later, itaconic acid was added and reacted at normal pressure while raising the temperature to 210 ° C. over 2 hours. Then, trimellitic anhydride was added and reacted at normal pressure for 1 hour, then 220 ° C. and 20 kPa. The polyester was obtained by reacting to the desired softening point.

Example 3, Comparative Example 2 and Comparative Example 3
The alcohol component, terephthalic acid and esterification catalyst shown in Table 2 were placed in a 5-liter four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a rectifying column, a stirrer and a thermocouple. After the condensation polymerization reaction at 10 ° C. for 10 hours, the reaction was performed at 230 ° C. and 8.0 kPa for 1 hour. After cooling to 220 ° C., trimellitic anhydride was added and reacted at normal pressure for 1 hour, and then reacted at 220 ° C. and 20 kPa to the desired softening point to obtain a polyester.

Comparative Example 1
Place the alcohol components, terephthalic acid and esterification catalyst shown in Table 2 in a 5-liter four-necked flask equipped with a nitrogen inlet tube, dehydrator tube, stirrer and thermocouple, and at 230 ° C for 10 hours under a nitrogen atmosphere. After the condensation polymerization reaction, the reaction was carried out at 230 ° C. and 8.0 kPa for 1 hour. After cooling to 180 ° C., itaconic acid was added, the temperature was raised to 210 ° C. over 5 hours, and the reaction was carried out at 210 ° C. and 10 kPa to the desired softening point to obtain a polyester.

Example of Toner Production 100 parts by weight of polyester obtained in each of Examples and Comparative Examples, 4 parts by weight of carbon black “MOGUL L” (Cabot), negative charge control agent “Bontron S-34” (Orient Chemical) (Made by Kogyo Co., Ltd.) 1 part by weight and 1 part by weight of polypropylene wax NP-105 (Mitsui Chemicals Co., Ltd.) were mixed thoroughly with a Henschel mixer, and then the roll rotation speed was 200 r / min using a co-rotating twin screw extruder. The mixture was melt-kneaded at a heating temperature in the roll of 80 ° C. The obtained melt-kneaded product was cooled and coarsely pulverized, then pulverized with a jet mill and classified to obtain a powder having a volume median particle size (D ₅₀ ) of 8.0 μm.

  To 100 parts by weight of the obtained powder, 1.0 part by weight of “Aerosil R-972” (manufactured by Nippon Aerosil Co., Ltd.) as an external additive was added and mixed with a Henschel mixer to obtain a toner.

Test Example 1 [Low-temperature fixability and offset resistance]
The toner is mounted on the printer “Page Presto N-4” (Casio Computer Co., Ltd., fixing: contact fixing method, developing method: non-magnetic one-component developing method, developing roll diameter: 2.3 cm), and the toner adhesion amount is 0.6 mg / An unfixed image was obtained by adjusting to cm ² . Fixing the unfixed image obtained by using the AR-505 (sharp) copier, a fixing machine that can be fixed outside the machine (fixing speed: 200 mm / s, nip Using a width: 4 mm, load: 7 kg / 370 mm, silicone oil not applied), fixing the unfixed image while increasing the temperature of the fixing roll from 100 ° C to 240 ° C in 5 ° C increments, and performing a fixing test .

  The image obtained at each fixing temperature was pasted with `` UNICEF Cellophane '' (Mitsubishi Pencil Co., Ltd., width 18 mm, JISZ-1522), passed through the fixing roll of the fixing machine set to 30 ° C., and then the tape was applied. The optical reflection density before and after peeling and tape peeling was measured using a reflection densitometer “RD-915” (manufactured by Macbeth). The fixing roller temperature at which the ratio between the two (after peeling / before peeling) first exceeded 90% was set as the minimum fixing temperature, and the low-temperature fixing property was evaluated according to the following evaluation criteria. Also, the hot offset occurrence temperature was confirmed at the same time, and the offset resistance was evaluated according to the following evaluation criteria. The results are shown in Table 2.

[Evaluation criteria for low-temperature fixability]
◎: Minimum fixing temperature is less than 150 ° C ○: Minimum fixing temperature is 150 ° C or more and less than 170 ° C △: Minimum fixing temperature is 170 ° C or more and less than 180 ° C ×: Minimum fixing temperature is 180 ° C or more

[Evaluation criteria for offset resistance]
◎: Hot offset generation temperature is 240 ° C or higher ○: Hot offset generation temperature is 230 ° C or higher and lower than 240 ° C △: Hot offset generation temperature is 190 ° C or higher and lower than 230 ° C ×: Hot offset generation temperature is lower than 180 ° C

Test Example 2 [Preservation]
4 g of toner was allowed to stand for 72 hours in an environment of a temperature of 50 ° C. and a relative humidity of 60%, and the presence or absence of toner aggregation was visually observed, and the storage stability was evaluated according to the following evaluation criteria. The results are shown in Table 2.

〔Evaluation criteria〕
A: No aggregation of toner is observed.
○: One or two particles of toner aggregation are observed.
Δ: 3-5 aggregated toner particles are observed.
X: Toner aggregation particles of 6 or more are observed.

Test Example 3 [Charging stability]
40 g of the obtained toner was mixed with 960 g of a resin-coated ferrite carrier to prepare a developer, and each developer was left at high temperature and high humidity (temperature 35 ° C., relative humidity 85%) for 1 day. The triboelectric charge before and after standing was measured by the blow-off method, and the charging stability was evaluated according to the following evaluation criteria. The results are shown in Table 2.

〔Evaluation criteria〕
Charge amount change before and after standing (charge amount difference before and after leaving / charge amount before leaving × 100) is very good, being within 10%.
○: Greater than 10% and within 20%, which is good.
Δ: It is larger than 20% and within 30%, and can be used in practice.
X: It is larger than 30% and is defective.

  From the above results, the toner containing the crosslinked polyesters of Examples 1 to 3 in which 1,2-propanediol and 1,3-propanediol are blended at a specific ratio and glycerin is used contains the polyester of the comparative example. It can be seen that both the fixing property and the storage property are achieved at a higher level as compared with the toner, and the storage property is excellent. In particular, it can be seen that Example 1 containing purified rosin obtained extremely excellent results in charge stability.

  The crosslinked polyester 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 (5)

In the presence of tin (II) carboxylate having a carboxylic acid group having 2 to 28 carbon atoms or dialkoxytin (II) having an alkoxy group having 2 to 28 carbon atoms , an alcohol component and a carboxylic acid component are subjected to polycondensation. Cross-linked polyester for toner obtained, wherein the alcohol component contains 1,2-propanediol, 1,3-propanediol and glycerin, and 1,2-propanediol (1,2-PD) A crosslinked polyester for toner having a molar ratio of 1,3-propanediol (1,3-PD) (1,2-PD / 1,3-PD) of 70/30 to 99/1.   The crosslinked polyester for toner according to claim 1, which has a softening point of 120 to 165 ° C.   The crosslinked polyester for toner according to claim 1 or 2, wherein the carboxylic acid component contains an aliphatic dicarboxylic acid compound having 2 to 4 carbon atoms.   The crosslinked polyester for toner according to any one of claims 1 to 3, wherein the carboxylic acid component contains a purified rosin. Claim 1-4 toner comprising a toner for crosslinking polyester according to any one.