JP2003241418A - Agent for improving low temperature fixing property and blocking resistance for toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an agent for improving low temperature fixing property and blocking resistance having excellent effects to lower the fixing temperature of a toner and to prevent blocking, and to provide a binder resin containing the agent for improving low temperature fixing property and for blocking resistance, and to provide a toner containing the binder resin and having excellent low temperature fixing property and blocking resistance. <P>SOLUTION: As for the agent for improving low temperature fixing property and blocking resistance of a toner, polyglycerides containing two or more kinds of fatty acids as the structural fatty acids are used. The low temperature fixing property and blocking resistance of a toner are improved by blending the above polyglycerides in the toner. <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 a polyglycerin fatty acid ester having the effect of improving low-temperature fixing property and blocking resistance of a toner used for developing an electrostatic image in electrophotography and the like. The present invention relates to a binder resin and a toner contained therein.

[0002]

2. Description of the Related Art A plain paper copier by electrophotography,
Toner is used as a developer for laser printers and the like. The toner manufacturing method includes a mechanical pulverization method, a polymerization method, a powder mist drying method, and the like, each having its own characteristics. However, in terms of safety, stability of quality and production efficiency,
Most toners are currently produced by mechanical grinding. The mechanical pulverization method is a method in which each component such as a binder resin and a colorant is melt-kneaded in a binder resin, pulverized and classified to produce a toner. Since the particles are mechanically made into fine particles, the particle diameter of the toner particles becomes non-uniform. If the particle size is non-uniform,
Since the fluidity and triboelectrification property of the toner deteriorate, it is difficult to obtain a good delicate image. On the other hand, the polymerization method is a method capable of improving the uniformity of particles, and since a uniform spherical toner is obtained, it is possible to manufacture a toner having a higher performance function than the conventional pulverized toner. The polymerization method is a method of obtaining a toner by polymerizing a monomer mixture containing a polymerizable monomer, a colorant, a charge control agent, a release agent, etc. in an aqueous dispersion medium containing a dispersion stabilizer. Is.

By the way, with the recent spread of personal computers, as toners for laser printers and digital multifunction machines,
The items required for toners have become more sophisticated, such as being able to contribute to energy saving, being able to handle faster printing and copying, and being able to deal with full-colorization. The part that consumes the most energy in a copying machine or printer is the fixing process of toner to paper, but it is necessary to lower the fixing roll temperature in the fixing process in order to save energy. Further, since the amount of heat applied to the paper in the fixing step is naturally limited, it is necessary to lower the paper surface temperature in order to speed up various machines, and from this point, low temperature fixing is required. On the other hand, it is possible to lower the fixing temperature of the toner on the paper by lowering the glass transition temperature of the binder resin, but by lowering the glass transition temperature,
There is a blocking problem where the toner solidifies in the machine.

As a method for solving the contradictory problems of imparting the low-temperature fixability and preventing blocking, a method of blending a low molecular weight ester compound having a melting point of 50 to 150 ° C. with a binder resin (Japanese Patent Laid-Open No. 63-66563). And a method of blending polyglycerin partial ester (Japanese Patent Laid-Open No. 4-19
4948) and the like have been proposed, but these methods cannot be said to have improved low-temperature fixability due to poor heat-melting characteristics but poor adhesion to paper.
Further, since it is premised that all toners are manufactured by a pulverizing method, they are not suitable for manufacturing by a polymerization method. Further, a capsule toner having a core-shell structure in which toner particles are coated with a polymer having a high glass transition temperature has been proposed (JP-A-59-62870, JP-A-6-11899). This method can be applied to both the pulverization method and the polymerization method, but if the glass transition temperature of the toner particles is lowered in order to lower the fixing temperature, the toner characteristics cannot be sufficiently secured, and higher performance and finer At present, the demand for images is not fully met.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to improve the low-temperature fixing property and the blocking resistance, which are excellent in the effect of lowering the fixing temperature of the toner and preventing blocking, regardless of the method for producing the toner. To provide the agent. Another object of the present invention is to provide a binder resin containing a low-temperature fixing property and a blocking resistance improving agent and a binder resin, and to provide a toner excellent in low-temperature fixing property and blocking resistance.

[0006]

As a result of intensive studies conducted by the present inventors to solve the above problems, the constituent fatty acids consist of two or more kinds of saturated fatty acids and unsaturated fatty acids having 8 to 22 carbon atoms. By polyglycerin fatty acid ester,
The inventors have found that the above problems can be solved.

The present invention also relates to the low temperature fixability of the above toner,
The present invention is intended for a binder resin using a polyglycerin fatty acid ester as a blocking resistance improver and a toner containing the binder resin.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The constituent fatty acids of the polyglycerin fatty acid ester in the present invention are saturated fatty acids and unsaturated fatty acids having 8 to 22 carbon atoms, and it is preferable to mix two or more kinds of saturated fatty acids having 14 to 22 carbon atoms.

The polyglycerin used in the polyglycerin fatty acid ester of the present invention may have an average degree of polymerization of 2 or more calculated from the hydroxyl value, preferably in the range of 2 to 15.

The esterification ratio of the fatty acid to the polyglycerol of the polyglycerol fatty acid ester of the present invention is 10
If it is at least 50% by weight, it has the effect of improving the low temperature fixability and blocking resistance of the toner, but preferably 70% by weight.
That is all. Particularly, 90% by weight or more is desirable for the toner produced by the polymerization method. If the esterification rate is less than 90% by weight, the polymerization process such as suspension polymerization or emulsion polymerization may be affected, and the effect of the present invention cannot be expected.

The polyglycerin fatty acid ester of the present invention is 3 parts by weight to 100 parts by weight of the binder resin.
35 parts by weight are compounded. If the blending amount is less than 3 parts by weight, the low temperature fixing property and blocking resistance of the toner are hardly improved.

Examples of the binder resin in the present invention include, but are not limited to, styrene / acrylic copolymer resin, epoxy resin, polystyrene resin, polyester resin and polycarbonate resin.

The toner of the present invention may be what is generally called a "toner" in which a colorant, an antistatic agent, a release agent and the like are dispersed in a binder resin, which is a one-component toner or a two-component toner. It may be a component toner. Further, it may be magnetic or non-magnetic. If necessary, additives for toner such as silicon dioxide, metal soap and polyolefin wax may be added.

Further, the method for producing a toner in which the polyglycerin fatty acid ester of the present invention can be used can be applied without limitation, such as mechanical pulverization method, powder mist drying method, polymerization method and microcapsule method. .

[0015]

EXAMPLES Next, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The polyglycerin used this time is
Diglycerin S, Polyglycerin # 500, # 750
(All manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.), and the average degree of polymerization calculated from the hydroxyl value is 2, 6 and 10, respectively. Less than,
An example and a comparative example of the present invention are shown. However, part and%
Is weight basis unless otherwise specified.

(Synthesis of polyglycerin fatty acid ester)
100g of polyglycerin # 500 and 12 of palmitic acid
3 g of behenic acid and 326 g of behenic acid were placed in a reaction vessel and reacted at 240 ° C. under a catalyst and nitrogen stream, and the esterification rate was about 95%
Polyglycerin octapalmitate / behenate was obtained. Similarly, those produced by changing the type of fatty acid and the molar ratio of fatty acid to polyglycerin are shown in Table 1.
It was shown to.

[0017]

[Table 1]

Example 1 80.5 parts of styrene and n-
Core monomer consisting of 19.5 parts of butyl acrylate, 7 parts of carbon black, 1 part of antistatic agent, 0.3 part of divinylbenzene, 0.5 part of polymethacrylic acid ester macromonomer, pentaerythritol tetramyristate 15 And 15 parts of polyglycerin octapalmitate / behenate were added, mixed and dissolved to obtain a polymerizable monomer composition for core. All the adjustment of the polymerizable monomer composition for cores was performed at room temperature.

On the other hand, at room temperature, an aqueous solution prepared by dissolving 9.5 parts of magnesium chloride in 250 parts of ion-exchanged water was gradually added under stirring with an aqueous solution prepared by dissolving 5.8 parts of sodium hydroxide in 50 parts of ion-exchanged water. Thus, a magnesium hydroxide colloidal dispersion was prepared. The preparation of this dispersion was carried out at room temperature.

The above polymerizable monomer composition for core was added to the magnesium hydroxide colloidal dispersion obtained above at room temperature and stirred until the droplets became stable. After adding 6 parts of t-butyl peroxyneodecanoate as a polymerization initiator thereto, 15,000 rpm using an Ebara Milder
High-shear stirring was performed for 30 minutes at the number of revolutions of 1. to granulate the droplets of the monomer mixture. An aqueous dispersion of the granulated monomer mixture was placed in a 10 L reactor, and the polymerization reaction was started at 60 ° C. Next, at room temperature, 3 parts of methyl methacrylate and 30 parts of ion-exchanged water were finely dispersed by an ultrasonic emulsifier to obtain an aqueous dispersion of a polymerizable monomer for shell. The polymerizable monomer for the shell and ammonium persulfate as a water-soluble initiator.
Dissolve 3 parts in 65 parts distilled water, put in a reactor,
After continuing the polymerization for a period of time, the reaction was stopped to obtain an aqueous dispersion of toner particles.

While stirring the aqueous dispersion of the core-shell type polymer particles obtained above at room temperature, acid washing is carried out with sulfuric acid, water is separated by filtration, and 500 parts of ion-exchanged water is newly added. It was made into a slurry and washed with water. Then, dehydration and water washing were repeated several times at room temperature to filter the solid content, and then the product was dried at 45 ° C. for a whole day and night to obtain polymer particles. To 100 parts of this polymer particle, 0.6 part of colloidal silica hydrophobized at room temperature was added and mixed by using a Hensyl mixer to prepare a polymerization toner.

Example 2 The polyglycerin octapalmitate / behenate used in Example 1 was replaced with polyglycerin tetrastearate / oleate. A toner was obtained in the same manner as in Example 1 except for the above.

Comparative Example 1 The polyglycerin octapalmitate / behenate used in Example 1 was replaced with polyglycerin octastearate. A toner was obtained in the same manner as in Example 1 except for the above.

Comparative Example 2 The polyglycerin octapalmitate / behenate used in Example 1 was replaced with polyglycerin tetraoleate. Otherwise, Example 1
A toner was obtained in the same manner as in.

(Comparative Example 3) The polyglycerin octapalmitate / behenate used in Example 1 was replaced with polyglycerin monopalmitate / behenate. A toner was obtained in the same manner as in Example 1 except for the above.

(Comparative Example 4) The polyglycerin octapalmitate / behenate used in Example 1 was replaced with polyglycerin monostearate. A toner was obtained in the same manner as in Example 1 except for the above.

Comparative Example 5 The polyglycerin octapalmitate / behenate used in Example 1 was not used. A toner was obtained in the same manner as in Example 1 except for the above.

(Embodiment 3) A vinyl-based copolymer comprising styrene component 80%, methyl methacrylate 5%, n-butyl acrylate 15%, and divinylbenzene 0.2% as a crosslinkable monomer according to a conventional method for pulverized toner. A polymer was produced.
25 parts of this vinyl-based copolymer, 10 parts of polyglycerin octapalmitate / behenate, 60 parts of magnetite,
2 parts polypropylene wax, 2 parts carbon black,
1 part of the antistatic agent was pulverized and mixed in a ball mill. afterwards,
The mixture was melt-kneaded with a roll mill, cooled, coarsely pulverized, and then finely pulverized with a jet mill to obtain a toner composition. Further, 0.3 part of hydrophobic silica fine powder was added to this toner composition to prepare a pulverized toner.

Example 4 The polyglycerin octapalmitate / behenate used in Example 3 was replaced with polyglycerin tetrastearate / oleate. A toner was obtained in the same manner as in Example 3 except for the above.

Comparative Example 6 The polyglycerin octapalmitate / behenate used in Example 3 was replaced with polyglycerin octastearate. A toner was obtained in the same manner as in Example 3 except for the above.

(Comparative Example 7) The polyglycerin octapalmitate / behenate used in Example 3 was replaced with polyglycerin monostearate. A toner was obtained in the same manner as in Example 3 except for the above.

Comparative Example 8 The polyglycerin octapalmitate / behenate used in Example 3 was not used. A toner was obtained in the same manner as in Example 3 except for the above.

(Test Method) In this example, the following method was used for evaluation. (Low-temperature fixing property) A commercially available non-magnetic one-component developing type printer (8) modified so that the temperature of the fixing roll portion can be changed.
The fixing test was conducted using a sheet machine. The fixing test was performed by changing the temperature of the fixing roll of the modified printer, measuring the fixing ratio of the toner at each temperature, and determining the temperature-fixing ratio relationship. The fixing rate was calculated from the ratio of the image density before and after the tape peeling operation in the solid black area of the test paper printed by the modified printer. That is, assuming that the image density before peeling the tape is before ID and the image density after the tape peeling is after ID, the fixing ratio can be calculated from the following equation. Fixing rate (%) = (after ID / before ID) x 1
00 Here, the tape peeling operation is a series of operations in which an adhesive tape is attached to a measurement portion of a test paper, adhered at a constant pressure, and then the adhesive tape is peeled in a direction along the paper at a constant speed. Further, the image density was measured using a reflection type image density measuring device. In this fixing test, the fixing roll temperature at a fixing rate of 80% was evaluated as the fixing temperature of the developer. The results are shown in Table 2.

(Blocking resistance) After the toner is put in a hermetically sealed container and hermetically sealed, the container is submerged in a constant temperature water bath maintained at a temperature of 55 ° C. After 8 hours, the container is taken out from the constant temperature water tank, and the toner in the container is transferred onto a 42-mesh sieve. At this time, the toner is gently taken out from the container and carefully transferred onto the sieve so that the aggregation structure of the toner in the container is not destroyed. Then, using a powder measuring machine, after vibrating for 30 seconds under the condition of strength of 4.5, the state of the toner remaining on the sieve was observed. The case where aggregation (cake formation) is not observed in the toner particles is indicated by ◯, and the case where aggregation is observed is indicated by x. The results are shown in Table 2.

[0035]

[Table 2]

[0036]

As is clear from Table 2, the toner to which the polyglycerin fatty acid ester of the present invention is added was excellent in both the low temperature fixing property and the blocking resistance improving effect.
Therefore, by blending the polyglycerin fatty acid ester of the present invention in a specific amount, a toner excellent in low-temperature fixing property and blocking resistance can be obtained and can be suitably used in an image forming apparatus for high-speed printing.

Claims (4)

[Claims] 1. A polyglycerin fatty acid ester, which is used as a low-temperature fixing property and blocking resistance improving agent for a toner. 2. The polyglycerin fatty acid ester according to claim 1, wherein the constituent fatty acids of the polyglycerin fatty acid ester are selected from two or more kinds of saturated fatty acids and unsaturated fatty acids having 8 to 22 carbon atoms. 3. A binder resin for a toner containing the polyglycerin fatty acid ester according to claim 1 or 2. 4. A toner using the binder resin according to claim 3.