JP2003186250A - Electrophotographic toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide electrophotographic toners which excel in the rising property of electrostatic charge and hardly give rise to fogging and a method of manufacturing the same. <P>SOLUTION: The electrophotographic toners containing a binder resin and coloring agents and further containing an inorganic tin (II) compound and the method of manufacturing the electrophotographic toners having a process step of mixing at least the binder resin, the coloring agents and the inorganic tin (II) compound. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention 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 and the like, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, it has been demanded to improve the charge rising property of a two-component toner mainly from the viewpoint of increasing the speed of a copying machine and the non-magnetic one-component toner from the viewpoint of downsizing. Therefore, improvement of various charge control agents has been studied, for example, organic tin (IV) which is colorless and has good thermal stability.
Regarding the compound, JP-A-63-101856,
A large number of reaction products of dioctyltin oxide or dibutyltin oxide with 1,4-butanediol are reported in JP-A-61-272758 and the like. However, even if such an organotin compound is used, sufficient charge rising property cannot be obtained, and fog is observed,
Further improvements are desired.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic toner which is excellent in charge rising property and is less likely to cause fog, and a method for producing the same.

[0004]

The present invention relates to (1) an electrophotographic toner containing a binder resin and a colorant, which further contains an inorganic tin (II) compound. The present invention relates to a toner, and (2) a method for producing an electrophotographic toner having a step of mixing at least a binder resin, a colorant, and an inorganic tin (II) compound.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is characterized by the fact that an inorganic tin (II) compound has been found to be completely new in finding that it is very effective in improving the charge rising property required for toner. In the present invention, the inorganic tin compound means
It refers to a compound having no Sn-C bond.

Although the mechanism by which the inorganic tin (II) compound exerts such a remarkable effect is unknown, the inorganic tin (II) compound
Inorganic tin (II), which is greatly affected by the deviation of the electron density between Sn-X (X represents O, halogen atom, etc.) bonds of the compound, and further improves the compatibility with the binder resin, especially polyester It is presumed that the uniform dispersion of the particles has further improved the charge rising property.

The inorganic tin (II) compound is preferably a compound having a Sn-O bond, a compound having a Sn-X (X represents a halogen atom) bond, and the like, more preferably a compound having a Sn-O bond.

Examples of compounds having a Sn--O bond include tin (II) oxalate, tin (II) acetate, tin (II) octoate,
Tin (II) carboxylate having 2 to 28 carbon atoms such as tin (II) laurate, tin (II) stearate, tin (II) oleate;
Dialkoxy tin (II) having 2 to 28 carbon atoms such as dioctyloxy tin (II), dilauroxy tin (II), distearoxy tin (II), dioleyloxy tin (II); tin (II) sulfate, tin (II) oxide, etc. However, examples of the compound having a Sn—X (X represents a halogen atom or the like) bond include tin (II) chloride, tin (II) halide such as tin (II) bromide, and the like. , From the standpoint of charging effect and catalytic ability,
(R ¹ COO) ₂ Sn (wherein R ¹ represents an alkyl or alkenyl group having 5 to 19 carbon atoms) fatty acid and tin having 6 to 20 carbon atoms represented by (II) and (R _² O) ² Sn (Wherein R ² represents an alkyl group or an alkenyl group having 6 to 20 carbon atoms) and a dialkoxy tin (II) having 6 to 20 carbon atoms is preferable, and a fatty acid tin (II) having 6 to 20 carbon atoms is preferable. Is more preferable, and saturated fatty acid tin (II) having 8 to 18 carbon atoms is particularly preferable.

The content of the inorganic tin (II) compound is preferably 0.001 to 5 parts by weight, more preferably 0.05 to 2 parts by weight, based on 100 parts by weight of the binder resin.

Examples of the binder resin in the present invention include polyester, styrene-acrylic resin, epoxy resin, polycarbonate, polyurethane, and hybrid resin in which two or more resin components are partially chemically bonded. Then, polyester and a hybrid resin composed of a polyester component and a vinyl-based resin component, in which the effects of the present invention are remarkably exhibited, are preferable, and polyester is more preferable. The content of the polyester in the binder resin is preferably 50 to 100% by weight, more preferably 9
0 to 100% by weight, particularly preferably 100% by weight.

In the production of polyester, an alcohol component composed of a divalent or higher polyhydric alcohol and a carboxylic acid component composed of a divalent or higher polycarboxylic acid compound are used as raw material monomers.

Examples of the divalent polyhydric alcohol include polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane and polyoxyethylene (2.2).
Aromatic diols such as alkylene (carbon number 2 to 4) oxide adducts (average addition mole number 1.5 to 6) of bisphenol A such as -2,2-bis (4-hydroxyphenyl) propane, ethylene glycol, propylene Aliphatic diols such as glycol, neopentyl glycol, 1,4-butanediol, 1,3-butanediol, and 1,6-hexanediol are mentioned.

Examples of trihydric or higher polyhydric alcohols include sorbitol, pentaerythritol, glycerol and trimethylolpropane.

Examples of the divalent carboxylic acid compound include aromatic dicarboxylic acids such as phthalic acid, terephthalic acid and isophthalic acid, sebacic acid, fumaric acid, maleic acid, adipic acid,
Aliphatic dicarboxylic acids such as azelaic acid, dodecenyl succinic acid and dodecyl succinic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, and anhydrides of these acids, alkyl (C 1 to C 3) esters and the like can be mentioned.

Examples of the trivalent or higher polyvalent carboxylic acid compound include aromatic carboxylic acids such as 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid and pyromellitic acid. And derivatives of such acid anhydrides and alkyl (C1 to C3) esters.

In the present invention, among the above-mentioned raw material monomers, an aromatic diol and / or an aromatic carboxylic acid compound having a valence of 2 or more is preferable because of its remarkable charge rising property. Bisphenol A as an aromatic diol
The propylene oxide adduct is preferably terephthalic acid, isophthalic acid, phthalic acid and trimellitic acid, and more preferably terephthalic acid and trimellitic acid as the divalent or higher valent aromatic carboxylic acid compound.

When any one of the aromatic diol and the aromatic carboxylic acid compound is contained, the content thereof in the alcohol component or the carboxylic acid component is preferably 40 to 40.
100 mol%, more preferably 80 to 100 mol%, and when both are contained, preferably 20 to 100 mol%, more preferably 60 to 1 in all raw material monomers.
It is 00 mol%. Aromatic diols and aromatic carboxylic acid compounds are preferable even if either one is used, but particularly when an alkylene oxide adduct of bisphenol A and an aromatic dicarboxylic acid compound are used in combination,
Due to the resonance effect of the benzene ring contained in both compounds, the electric charge is allowed to exist stably, and the rise of charging is improved, which is preferable. However, even if two kinds of resins obtained by using any one of them as a raw material monomer are mixed, such an effect by the combined use of both can be obtained.

The polyester contains an alcohol component and a carboxylic acid component in an inert gas atmosphere at 180 to 250.
It can be produced by condensation polymerization at a temperature of ° C, if necessary under reduced pressure.

Further, in the present invention, the hybrid resin may be obtained from two or more kinds of resins as raw materials, but may be obtained from one kind of resin and another kind of resin as a raw material monomer. May be obtained from a mixture of raw material monomers of two or more resins, but in order to efficiently obtain a hybrid resin, one obtained from a mixture of raw material monomers of two or more resins Is preferred.

Therefore, as the hybrid resin, two raw material monomers of the polymerization type resin having independent reaction paths, preferably a raw material monomer of the polyester and a raw material monomer of the vinyl type resin are mixed to carry out the two polymerization reactions. The resin obtained by this is preferable, and specifically, the hybrid resin described in JP-A-10-087839 is preferable.

The softening point of the binder resin is preferably 90 to 170 ° C, more preferably 95 to 150 ° C. The glass transition point is preferably 50 to 130 ° C, more preferably 50 to 80 ° C.

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

Further, the toner of the present invention preferably contains a charge control agent. As a charge control agent,
Nigrosine dye, triphenylmethane dye containing tertiary amine as a side chain, quaternary ammonium salt compound, polyamine resin, positive charge control agent such as imidazole derivative and metal-containing azo dye, copper phthalocyanine dye, alkyl salicylate Examples thereof include negatively chargeable charge control agents such as metal complexes of derivatives and boron complexes of benzylic acid. The toner of the present invention may have either a positive charging property or a negative charging property, and a positive charging control agent and a negative charging control agent may be used in combination.

The content of the charge control agent is preferably 0.01 to 10 parts by weight, based on 100 parts by weight of the binder resin, and 0.1.
1 to 3 parts by weight is more preferable.

Further, in the toner of the present invention, a releasing agent, a fluidity improver, a conductivity modifier, an extender pigment, a reinforcing filler such as a fibrous substance, an antioxidant, an antiaging agent, a cleaning improver. Additives such as may be appropriately blended.

Examples of the releasing agent include natural ester waxes such as carnauba wax and rice wax, synthetic waxes such as polypropylene wax, polyethylene wax, Fischer Tropsch, coal wax such as montan wax, and waxes such as alcohol wax. These may be contained alone or in combination of two or more.

The toner of the present invention contains at least a binder resin,
It can be manufactured through a step of mixing a colorant and an inorganic tin (II) compound. The raw materials may be mixed by mixing two of the three types in advance and then mixing the remaining one, but it is preferable to mix all of them at the same time. The method for producing the toner may be any conventionally known method such as a kneading and pulverizing method and an emulsion phase inversion method, but the kneading and pulverizing method is preferable because mixing can be easily performed. For example, in the case of a pulverized toner obtained by a kneading pulverization method, a binder resin, a colorant, an inorganic tin (II) compound, etc. are uniformly mixed with a mixer such as a ball mill, and then a closed kneader or a single-screw or twin-screw extruder. It can be manufactured by melt-kneading with, etc., cooling, pulverizing and classifying. In the emulsion phase inversion method, a binder resin, a colorant, an inorganic tin (II)
After the compound or the like is dissolved or dispersed in an organic solvent, water is added to form an emulsion, which is then separated and classified for production. The volume average particle diameter of the toner is 3 to 15
μm is preferred. On the surface of the toner, a fluidity improver such as hydrophobic silica may be added as an external additive.

The electrophotographic toner of the present invention is used alone as a developer when it contains magnetic fine powder, or as a non-magnetic one-component developer when it does not contain magnetic fine powder.
Alternatively, it may be mixed with a carrier and used as a two-component developer.

[0029]

[Example] [Softening point] Enhanced flow tester "CFT-"
500D "(manufactured by Shimadzu Corporation), while heating 1 g of the sample at a temperature rising rate of 6 ° C./min, a load of 1.96 MPa is applied by a plunger to obtain a diameter of 1 mm and a length of 1 m.
The nozzle of m is pushed out to draw the plunger drop amount (flow value) -temperature curve of the flow tester, and when the height of the S-shaped curve is h, the temperature corresponding to h / 2 (half of the resin) Is the softening point.

[Glass Transition Point] Differential Scanning Calorimeter “DSC
210 "(manufactured by Seiko Denshi Kogyo Co., Ltd.) was used to raise the temperature to 200 ° C., and the temperature of the sample cooled to 0 ° C. at the temperature decreasing rate of 10 ° C./minute was measured at the temperature increasing rate of 10 ° C./minute. The glass transition point is defined as the temperature at the intersection of the extension line of the baseline below the peak temperature and the tangent line showing the maximum slope from the rising portion of the peak to the peak of the peak.

Production Example of Resin A Propylene oxide adduct of bisphenol A (2.
2 mol) 71.3 parts by weight (54 mol%), terephthalic acid 28.7 parts by weight (46 mol%) and dibutyltin oxide.
Twenty-five parts by weight was reacted at 235 ° C. in a nitrogen atmosphere until a desired softening point was reached to obtain a resin A. Resin A
Had a softening point of 101.8 ° C and a glass transition point of 64.2 ° C.

Production Example of Resin B Propylene oxide adduct of bisphenol A (2.
2 mol) 37.0 parts by weight (25 mol%), ethylene oxide adduct of bisphenol A (2.2 mol) 34.
4 parts by weight (25 mol%) and 18.4 parts by weight of fumaric acid (37.5 mol%) under nitrogen atmosphere at 180 ° C. to 21 ° C.
After heating to 0 ° C over 4 hours, trimellitic anhydride 1
0.1 part by weight (12.5 mol%) was added, and 8.3 was added.
The reaction was performed at kPa until the desired softening point was reached to obtain Resin B. Resin B had a softening point of 115.5 ° C and a glass transition point of 57.5 ° C.

Production Example of Resin C 9.1 parts by weight of ethylene glycol (17.6 mol%),
28.4 parts by weight (38.7 mol%) of neopentyl glycol and 45.9 parts by weight (33.3 mol%) of terephthalic acid were heated from 180 ° C. to 230 ° C. over 8 hours under a nitrogen atmosphere, After reacting for 2 hours, 200 ℃
Then, 16.6 parts by weight (10.4 mol%) of trimellitic anhydride was added and the reaction was continued until the desired softening point was reached.
Resin C was obtained. Resin C had a softening point of 112.8 ° C and a glass transition point of 65.5 ° C.

Examples 1 to 8 100 parts by weight of the binder resin shown in Table 1 and polyethylene wax "NP-055" (Mitsui Chemicals, melting point: 145 ° C)
2 parts by weight, carbon black "MOGUL-L" (manufactured by Cabot) 4 parts by weight, negatively chargeable charge control agent "Bontron S-34" (manufactured by Orient Chemical Industry Co., Ltd.) 1 part by weight,
The tin compound shown in Table 1 was charged into a Henschel mixer, and stirred and mixed at a tank temperature of 40 ° C. for 3 minutes to obtain a mixture. The obtained mixture is melt-kneaded using a co-rotating twin-screw extruder with a heating temperature of 100 ° C. in a roll, and the resulting kneaded product is cooled and coarsely pulverized, then pulverized and classified by a jet mill to obtain a volume average. A powder having a particle size of 7.5 μm was obtained.

100 parts by weight of the obtained powder and hydrophobic silica "TS-530" (manufactured by Cabot Co., average particle size: 8 n)
m) 0.7 part by weight was mixed with stirring by a Henschel mixer for 3 minutes to obtain a toner.

Example 9 Instead of the negatively chargeable charge control agent, a positively chargeable charge control agent "Bontron P-51" (manufactured by Orient Chemical Industry Co., Ltd.)
A toner was obtained in the same manner as in Example 1 except that was used.

Example 10 Example 1 except that no negatively chargeable charge control agent was used.
A toner was obtained in the same manner as in.

Comparative Example 1 Except that the tin compound was not added together with the binder resin and the like,
A toner was obtained in the same manner as in Example 1.

Comparative Example 2 A toner was obtained in the same manner as in Example 1 except that 0.5 part by weight of dibutyltin oxide was used as the tin compound instead of tin (II) octoate.

Comparative Example 3 Except that the tin compound was not added together with the binder resin and the like,
In the same manner as in Example 1, a powder having a volume average particle size of 7.5 μm was obtained. 100 parts by weight of the obtained powder and tin octoate (I
I) 0.5 parts by weight and hydrophobic silica "TS-530"
0.7 parts by weight (manufactured by Cabot Corp., average particle diameter: 8 nm) were mixed with stirring by a Henschel mixer for 3 minutes to obtain a toner.

Test Example 1 [Evaluation of Charge Rising Property] 0.6 g of toner and 19.4 g of silicone ferrite carrier (manufactured by Kanto Denka Kogyo Co., Ltd., average particle size: 90 μm) were mixed at 250 r / min using a ball mill,
Mixing time 15 seconds, 30 seconds, 60 seconds, 120 seconds, 300
The charge amount in seconds was measured using a q / m meter (manufactured by EPPING). The charge rising property was evaluated using the relative value of the charge amount at the mixing time of 15 seconds with respect to the maximum charge amount throughout. The results are shown in Table 1.

Test Example 2 [Evaluation of Undercoat Fogging] Toner was applied to "Page Presto N-4" (manufactured by Casio Computer Co., Ltd.) equipped with a developing roll made of stainless steel (roll diameter: 2.3 cm) as a non-magnetic one-component developing device. Implement A
A 2 cm square solid image was formed at 2 cm from the center of the top of the 4 blank paper. Next, (1) From the center of the upper end to the circumference distance of the developing roller from 7.2 cm to 2
In the part where the fog can be seen by the solid image below cm,
Inside a square of 2 cm square, each corner is 0.5c in length and width
Color point difference meter “CR-3” for 4 points inside m by L ^* a ^* b ^* method
21 ”(manufactured by Minolta Co., Ltd.) and the average value was calculated. Then, (2) image densities at a total of 4 points were measured in the same manner at a distance of 4 cm and 8 cm to the left and right from the center at a distance of 10.2 cm from the upper end of the image center, and the average value was calculated. The difference (ΔE) between the two values (1) and (2) was determined by the following formula, and the degree of fog generation was evaluated according to the following evaluation criteria. The results are shown in Table 1.

[0043]

[Equation 1]

[In the formula, L ₁ , a ₁ and b ₁ represent each measured value in (1), and L ₂ , a ₂ and b ₂ represent each measured value in (2). ]

[Evaluation Criteria] ⊚: ΔE is less than 0.5 ○: ΔE is 0.5 or more and less than 1 ×: ΔE is 1 or more and less than 3 XX: ΔE is 3 or more

[0046]

[Table 1]

From the above results, it is clear that, in comparison with the toners of the examples, all the toners of the comparative examples lack the charge rising property and are apt to cause fog. As a result, the effect of improving the charge buildup cannot be obtained with organic tin such as dibutyltin oxide, and even when an inorganic tin (II) compound is used, it is not possible to add the inorganic tin (II) compound externally to the toner surface. It can be seen that the dispersibility is poor and the effect cannot be obtained.

[0048]

According to the present invention, it is possible to provide an electrophotographic toner which is excellent in the rising property of charging and is less likely to cause fogging, and a method for producing the same.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masayuki Maruta             1334 Minato Minato, Wakayama Kao Corporation             Within (72) Inventor Eiji Shirai             1334 Minato Minato, Wakayama Kao Corporation             Within F-term (reference) 2H005 AA01 AA06 CA08 CA25 CB07                       DA01

Claims (6)

[Claims] 1. An electrophotographic toner comprising a binder resin and a colorant, which further comprises an inorganic tin (II) compound. 2. The toner for electrophotography according to claim 1, wherein the inorganic tin (II) compound is a tin compound having a Sn—O bond. 3. The inorganic tin (II) compound has 2 to 28 carbon atoms.
The toner for electrophotography according to claim 1, which is at least one selected from the group consisting of tin (II) carboxylate and dialkoxy tin (II) having 2 to 28 carbon atoms. 4. The binder resin is polyester.
3. The electrophotographic toner according to any one of 3 to 3. 5. The toner for electrophotography according to claim 1, further comprising a charge control agent. 6. A method for producing an electrophotographic toner, which comprises a step of mixing at least a binder resin, a colorant, and an inorganic tin (II) compound.