JP4493080B2 - Polyester for toner - Google Patents

Description

  The present invention relates to a polyester for toner suitable as 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 a toner containing the polyester.

In order to cope with energy saving in recent years, a toner containing a wax and having a wide offset resistance range and excellent fixability has been studied. However, polyester, which is a binder resin with excellent fixing properties, is inherently low in compatibility with wax and it is difficult to disperse the wax uniformly and stably in the resin. It tends to adhere to the equipment, and durability such as image distortion due to a decrease in chargeability tends to be reduced. Therefore, a toner binder composition (see Patent Document 1) in which the difference between the physical properties of the binder resin and the wax is adjusted, and a polyester in which wax is internally added as the binder resin, and further, the outflow start temperature and the outflow end temperature of the toner are set. A toner adjusted to a specific range (see Patent Document 2) has been reported, and although some effect has been obtained, further improvement in performance is desired.
JP-A-7-301951 (Claim 1) JP 2002-148844 A (Claim 1)

  An object of the present invention is to provide a polyester for a toner in which a wax is dispersed with an appropriate particle size and is excellent in both fixability and durability, and a toner containing the polyester.

  The present invention is a polyester for toner in which a wax is dispersed in a polyester, and the polyester is used as a raw material monomer of the formula (I):

(In the formula, R is an alkylene group having 2 or 3 carbon atoms, x and y are positive numbers, and the sum of x and y is 1 to 16)
A polyester obtained by using an alcohol component containing 90 mol% or more of an alkylene oxide adduct of bisphenol A represented by the formula: wherein the wax contains 50 wt% or more of a polyolefin wax, and the wax is contained in the polyester. Polyester for toner having a softening point of 130 to 160 ° C. and a toner containing the polyester for toner, which is contained in an amount of 0.1 to 5% by weight and dispersed with a volume average dispersion diameter of 3 to 30 μm About.

  The polyester for toner according to the present invention is suitable for use as a toner binder resin because the wax is dispersed in the polyester with an appropriate particle size and is excellent in both fixability and durability.

  The polyester for toner of the present invention is a highly durable polyester obtained by using an alcohol component containing, as a main component, an alkylene oxide adduct of bisphenol A having polarity, in which a wax is dispersed in a polyester. In addition, since the highly hydrophobic polyolefin wax is appropriately dispersed, the durability can be improved without deteriorating the fixing property.

  The polyester is obtained by condensation polymerization of both components using an alcohol component composed of alcohol and a carboxylic acid component composed of a carboxylic acid compound as raw material monomers.

  As the alcohol component, in the present invention, as described above, from the viewpoint of compatibility between fixing property and durability, the formula (I):

(Wherein R is an alkylene group having 2 or 3 carbon atoms, x and y are positive numbers, and the sum of x and y is 1 to 16, preferably 1.5 to 5.0)
An alcohol component containing 90 mol% or more of an alkylene oxide adduct of bisphenol A represented by the formula:

  Specific examples of the alkylene oxide adduct of bisphenol A represented by the formula (I) include polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.2 ) -2,2-bis (4-hydroxyphenyl) propane and the like.

  The content of the alkylene oxide adduct of bisphenol A is 90 mol% or more, preferably 95 to 100 mol%, more preferably 100 mol% in the alcohol component.

  Divalent alcohols 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, hydrogenated bisphenol A, and the like. Can be mentioned.

  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 or alkenyl groups having 2 to 20 carbon atoms such as adipic acid, dodecenyl succinic acid and octyl succinic acid; anhydrides of these acids and their Alkyl (C1-C3) ester of an acid etc. are mentioned. Among these, aromatic dicarboxylic acid compounds are preferable from the viewpoints of durability, fixability, and dispersibility of the colorant.

  The content of the aromatic dicarboxylic acid compound is preferably 50 to 100 mol%, more preferably 80 to 100 mol%, and particularly preferably 100 mol% in the divalent carboxylic acid component.

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

  In the polyester of the present invention, a trivalent or higher monomer is preferably used as one kind of raw material monomer. From the viewpoint of durability, the content of the trivalent or higher monomer, that is, the trivalent or higher polyhydric alcohol and the polyvalent carboxylic acid compound, preferably the trivalent or higher polyvalent carboxylic acid compound is 1 in each component. -40 mol% is preferable and 10-30 mol% is more preferable.

  Furthermore, from the standpoint of molecular weight adjustment and the like, a monovalent alcohol or a monovalent carboxylic acid compound may be appropriately contained within a range not impairing the effects of the present invention.

  In the present invention, the wax contains polyolefin wax such as polyethylene wax, polypropylene wax, polypropylene polyethylene copolymer wax and the like. Polyolefin wax has low reactivity with polyester and has a hydrophobic group as a main component, and therefore contributes to improvement of fixing property as well as offset resistance.

  The content of the polyolefin wax is 50% by weight or more, preferably 80 to 100% by weight, and more preferably 100% by weight in the total amount of the wax.

  Examples of the wax other than the polyolefin wax include carnauba wax, ester wax such as beeswax, beeswax, whale wax, and montan wax, and amide wax such as fatty acid amide wax.

  The melting point of the wax is preferably 75 to 140 ° C, more preferably 100 to 140 ° C, from the viewpoint of offset resistance and durability.

  The content of the wax in the polyester is 0.1 to 5% by weight, preferably 0.5 to 3% by weight.

  For example, the polyester of the present invention is obtained by polycondensing a raw material monomer comprising an alcohol component and a carboxylic acid component at 150 to 280 ° C. in the presence of wax, in an inert gas atmosphere, and optionally in the presence of an esterification catalyst. Obtained. The addition timing of the wax is not particularly limited, and the wax may be added in the middle of the reaction even if the wax is present from the beginning of the condensation polymerization reaction.

  The softening point of the polyester of the present invention is 130 to 160 ° C., preferably 135 to 160 ° C., more preferably 140 to 155 ° C., and still more preferably 145 to 150 ° C., from the viewpoint of compatibility between fixability and durability. is there. In addition, the glass transition point is preferably 70 ° C. or higher, more preferably 70 to 80 ° C., from the viewpoints of durability and blocking resistance. The acid value of the polyester is preferably 1 to 30 mgKOH / g.

  Furthermore, the number average molecular weight of the polyester of the present invention is preferably from 3,000 to 5,000, more preferably from 3,300 to 4,500, from the viewpoint of achieving both fixability and durability. The weight average molecular weight is preferably from 50,000 to 1,000,000, more preferably from 200,000 to 900,000, and particularly preferably from 400,000 to 700,000.

  In addition, if the volume average dispersion diameter of the wax in the polyester of the present invention is too large, the dispersion diameter of the wax is not appropriate even when the resin and the colorant are melt-kneaded, and are crushed at the wax interface when pulverized. When the wax is exposed on the toner surface and the toner is likely to be fused, if it is too small, the exposure amount on the toner surface becomes too small, and the fixing property and offset resistance are lowered. From this viewpoint, the volume average dispersion diameter of the wax is 3 to 30 μm, preferably 3 to 10 μm, and more preferably 4 to 7 μm. The dispersion diameter of the wax can be adjusted by the addition timing of the wax, the kind of raw material monomer, the stirring strength when polymerizing the raw material monomer, the cooling rate after polymerization, and the like.

  The toner of the present invention containing, as a binder resin, the polyester of the present invention in which wax is dispersed with an appropriate particle size has excellent durability. Therefore, the toner of the present invention can be suitably used as a two-component developing toner that requires particularly high durability.

  The toner of the present invention further includes a colorant, a charge control agent, a conductivity regulator, an extender pigment, a reinforcing filler such as a fibrous substance, an antioxidant, an anti-aging agent, a fluidity improver, and a cleaning property improver. Such additives may be appropriately contained.

  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.

  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 toner production method may be any conventionally known method such as a kneading and pulverizing method, a phase inversion emulsification method, and a polymerization method. For example, in the case of a pulverized toner by a kneading and pulverizing method, the polyester of the present invention is included. Binder resin, colorant, charge control agent, etc. are uniformly mixed with a mixer such as a Henschel mixer, then melt-kneaded with a closed kneader, a single or twin screw extruder, an open roll kneader, etc., and cooled. , Pulverized and classified.

[Softening point of resin (Tm)]
Using a Koka type flow tester (manufactured by Shimadzu Corporation, CFT-500), a 1 g sample was heated at a heating rate of 6 ° C./min, a load of 1.96 MPa was applied by a plunger, a diameter of 1 mm, A nozzle with a length of 1 mm is pushed out, and this draws a plunger drop amount (flow value) -temperature curve of the flow tester. When the height of the S-shaped curve is h, the temperature corresponding to h / 2 (resin The temperature at which half of the effluent flowed out) is taken as the softening point.

[Glass transition point (Tg) of resin and melting point of wax]
Using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., DSC210), the temperature was raised to 200 ° C., and the sample cooled from that temperature to 0 ° C. at a temperature lowering rate of 10 ° C./min was measured at a temperature rising rate of 10 ° C./min. When a wax is used as a sample, the maximum peak temperature is taken as the melting point. When a resin is used as a sample, the glass transition point is defined as the temperature at the intersection of the base line extension below the maximum peak temperature and the tangent showing the maximum slope from the peak rising portion to the peak apex.

[Acid value of the resin]
The acid value was measured according to the method of JISK0070.

[Molecular weight distribution of resin]
Weigh 0.04 g of resin in a 20 ml sample tube, add 20 ml of tetrahydrofuran, place on a ball mill bed and stir for 1 hour to dissolve the resin sufficiently. This solution was added to a 2 μm fluororesin filter (manufactured by Sumitomo Electric Industries, Ltd.). FP-200) to remove undissolved components to obtain a sample solution.
Tetrahydrofuran is allowed to flow at a flow rate of 1 ml / min as a lysis solution, and the column is stabilized in a constant temperature bath at 40 ° C. 100 μl of the sample solution is injected therein and measurement is performed. The molecular weight of the sample is calculated based on a calibration curve prepared using a monodisperse polystyrene prepared in advance as a standard sample.
Measuring device: CO-8010 (manufactured by Tosoh Corporation)
Analysis column: GMHLX + G3000HXL (manufactured by Tosoh Corporation)

[Volume average dispersion diameter of wax]
To a 50 ml sample tube, 0.5 g of polyester and 20 ml of tetrahydrofuran were added, and the mixture was placed on a ball mill carrier and stirred for 1 hour to sufficiently dissolve the resin, thereby preparing a sample solution in which wax was dispersed. This sample solution is diluted until the wax has a measurable concentration, and the dispersion diameter of the wax particles is measured using a Shimadzu laser diffraction particle size distribution analyzer “SALD-2000J” (manufactured by Shimadzu Corporation). The volume average value is obtained.
In addition, when the resin insoluble content is confirmed in the solution, a 1N potassium hydroxide (KOH) aqueous solution is dropped, and ultrasonic irradiation is repeatedly performed until the resin insoluble content disappears, and measurement is performed.

Examples 1 and 3 and Comparative Examples 1 to 4, 6, and 8 (Example 3 is a reference example)
The amount of the alcohol component shown in Table 1, the carboxylic acid component excluding trimellitic anhydride, the wax, and the catalyst are placed in a 5-liter four-necked flask until the reaction rate reaches 90% at 230 ° C. in a nitrogen atmosphere. After making it react, it was made to react at 8.3 kPa for 1 hour. Then, it cooled to 210 degreeC, the trimellitic anhydride was thrown in, and after making it react at normal pressure for 1 hour, it was made to react to a desired softening point at 200 kPa, and polyester was obtained. In the present invention, the reaction rate means a value of reaction water amount (mol) / theoretical water generation amount (mol) × 100.

Example 2
The amount of the alcohol component shown in Table 1, the carboxylic acid component excluding trimellitic anhydride and fumaric acid, the wax and diisopropoxytitanium triethanolamate were placed in a 5-liter four-necked flask and placed under a nitrogen atmosphere. After reacting at 90 ° C. until the reaction rate reached 90%, the reaction was performed at 8.3 kPa for 1 hour. Then, it cooled to 180 degreeC, the fumaric acid and the hydroquinone were added, it heated up to 210 degreeC over 3 hours, and was made to react at 8.3 kPa for 1 hour. Thereafter, trimellitic anhydride and hydrogen were added and reacted at normal pressure for 1 hour, and then reacted at 200 kPa to a desired softening point to obtain a polyester.

Comparative Examples 5 and 7
The amount of the alcohol component shown in Table 1, the carboxylic acid component excluding trimellitic anhydride, the wax, and the catalyst were placed in a 5-liter four-necked flask, heated to 180 ° C. in a nitrogen atmosphere, and then over 5 hours. The temperature was raised to 230 ° C. After reacting at 230 ° C. until the reaction rate reached 90%, it was cooled to 200 ° C., trimellitic anhydride was added, and the reaction was carried out at 200 kPa to the desired softening point to obtain a polyester.

  Softening point (Tm), glass transition point (Tg), acid value (Av), volume average dispersion diameter of wax, number average molecular weight (Mn), and weight average molecular weight (Mw) of polyesters obtained in Examples and Comparative Examples Is shown in Table 2.

Test example 1
For each example and comparative example, 100 parts by weight of polyester, 4 parts by weight of carbon black “MOGUL-L” (manufactured by Cabot), and 1 weight of negative charge control agent “Bontron S-34” (manufactured by Orient Chemical Industries) After thoroughly mixing the parts with a Henschel mixer, melt kneading using a co-rotating twin-screw extruder with a heating temperature in the roll of 100 ° C., cooling and coarsely pulverizing the resulting mixture, then pulverizing with a jet mill, Classification was performed to obtain a powder having a volume average particle diameter of 8.0 μm.
To 100 parts by weight of the obtained powder, 0.1 part by weight of hydrophobic silica “TS-530” (manufactured by Cabot, average particle diameter: 8 nm) is added as an external additive, and mixed with a Henschel mixer to obtain a toner. It was.

As a non-magnetic one-component developing device, toner was mounted on “Page Presto N-4” (manufactured by Casio Computer Co., Ltd.) equipped with a stainless steel developing roll (roll diameter: 2.3 cm), and transfer was performed. The image was a solid solid image of 8 cm square at 2 cm from the center of the top edge of the A4 blank paper. The obtained unfixed image was fixed by an external fixing machine equipped with a fixing roller set at 170 ° C.
A load of 500 g was placed on a sand eraser having a bottom surface of 15 mm × 7.5 mm, and rubbed 5 times on the fixed solid image. Before and after rubbing, the four points inside the square square 2 cm in length and breadth were measured with a reflective Macbeth densitometer (RD914, manufactured by Macbeth Co., Ltd.), the average value of each was calculated, and the fixing rate calculated from the following formula was used. Furthermore, the fixability was evaluated according to the following evaluation criteria. The results are shown in Table 2.
Fixing rate (%) = (Image density after rubbing) / (Image density before rubbing) × 100

〔Evaluation criteria〕
A: Fixing rate is 95% or more B: Fixing rate is 80% or more and less than 95% X: Fixing rate is less than 80%

Test example 2
A developer obtained by mixing 3 parts by weight of toner and 97 parts by weight of a silicone-coated ferrite carrier (manufactured by Kanto Denka Kogyo Co., Ltd.) having an average particle size of 90 μm is mounted on “Pretail 550” (manufactured by Ricoh) and printed. After continuously printing 3000 images with a rate of 5%, a solid image was printed, the obtained image was visually observed, and durability was evaluated according to the following evaluation criteria. The results are shown in Table 2.

〔Evaluation criteria〕
A: A uniform solid image was obtained.
○: Blur was seen in the solid image.
X: White streaks were observed in the solid image.

  From the above results, in comparison with Comparative Examples 1 to 8, in Examples 1 to 3, a polyester having a specific resin composition and having a wax having a polyolefin wax as a main component dispersed appropriately is used as a binder resin. It can be seen that a toner excellent in both fixability and durability can be obtained.

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

Claims (5)

A polyester for toner in which a wax is dispersed in a polyester, wherein the polyester is a raw material monomer of the formula (I):

(In the formula, R is an alkylene group having 2 or 3 carbon atoms, x and y are positive numbers, and the sum of x and y is 1 to 16)
A polyester obtained by using an alcohol component containing 90 mol% or more of an alkylene oxide adduct of bisphenol A represented by the formula: wherein the alkylene oxide adduct of bisphenol A is polyoxypropylene (2.2) -2 , 2-bis (4-hydroxyphenyl) propane (BPA-PO) and polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane (BPA-EO), and their moles The ratio (BPA-PO / BPA-EO) is 90/10 to 75/25, the wax is a polyolefin wax, and the wax is contained in the polyester in an amount of 0.1 to 5% by weight. A polyester for toner having a softening point of 135 to 155 ° C., dispersed at a volume average dispersion diameter of 10 μm. As one of the raw material monomer, a trivalent or higher polyvalent carboxylic acid compound according to claim 1 Symbol placement for toner polyester obtained using. Claim 1 or 2 for toner polyester according glass transition point of 70 ° C. or higher. The number average molecular weight of 3,000 to 5,000, according to claim 1 to 3 for a toner polyester according to any weight average molecular weight of 50,000 to 1,000,000. Claim 1-4 toner comprising a toner polyester according to any one.