JPH0769633B2 - Method for manufacturing toner for electrostatic image development - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is for electrostatic image development used for developing an electrostatic latent image formed in electrophotography, electrostatic printing, electrostatic recording or the like. The present invention relates to a toner manufacturing method.

[Background of the Invention]

For example, in electrophotography, generally, an electrostatic latent image is formed on a latent image carrier made of a photoconductive photoreceptor by charging and exposure, and then this electrostatic latent image is coated with a colorant in a binder resin. The toner image obtained is developed with fine particle toner contained therein, and the obtained toner image is transferred onto a support such as transfer paper and fixed to form a visible image.

As a method for fixing the toner image, various means have been conventionally used, but the heat roller fixing method is preferable among them.
The heat roller fixing method is a method of fixing a toner image on a support by transporting a support such as paper carrying a toner image so as to come into contact with a heated roller. According to this method, it is advantageous in terms of safety and also in terms of energy saving and less heat loss.

However, recently, due to the demand for downsizing of high-speed copying machines or copying machines, it has been strongly desired to develop a toner capable of fixing at a lower temperature than ever before. That is, in a high-speed copying machine, when a large number of sheets are continuously copied, the heat of the heat roller is absorbed by the transfer paper and the heat supply cannot be made in time, and as a result, the temperature of the heat roller lowers and fixing failure tends to occur. In a small copying machine, it is necessary to reduce the capacity of the heater for heating the heat roller to make it a more energy-saving and compact copying machine. However, if the capacity of the heater for heating is reduced, it takes time to heat the heat roller. As a result, the waiting time becomes long, or if continuous copying is performed, heat supply cannot be made in time, and as a result, the temperature of the heat roller is lowered and fixing failure is likely to occur.

On the other hand, when the heat roller fixing method is adopted, the toner comes into contact with the surface of the heat roller in a molten state during fixing, but when the viscoelasticity of the molten toner is too small or too large, a part of the molten toner is A so-called offset phenomenon occurs in which the toner is transferred and adhered to the surface of the heat roller, and this is transferred again to the transfer paper that is sent next to stain the image. The offset phenomenon includes under-offset that occurs when the toner is insufficiently heated and hot offset that occurs when the toner is excessively heated. Therefore, as the toner, the minimum fixable temperature at which fixing is possible is low, and the fixable temperature within the non-offset temperature range where the offset phenomenon does not occur above the minimum fixing temperature (under offset occurrence temperature and above hot offset occurrence temperature) It is preferable that the area is wide.

Further, in the toner, it can exist stably as a powder without aggregating under the use or storage environment conditions,
That is, excellent blocking resistance is required.

In response to such a request, the following techniques have been conventionally proposed.

(1) A technique of using a resin containing a mutually immiscible crystalline polymer and an amorphous polymer as the binder resin, and the proportion of the crystalline polymer being 70 to 95% by weight (Japanese Patent Application Laid-Open No. 2004-242242). Akira
59-3446).

(2) A technique of using three types of resins that are incompatible with each other as the binder resin (JP-A-57-32447).

[Problems to be solved by the invention]

However, the above technique has the following problems.

That is, in the above technique (1), since the proportion of the crystalline polymer is large, there is a problem in that the pulverization process is poor in the pulverization step, which is one of the toner production steps, and the toner yield is low.

Further, in the above technique (2), when the number average molecular weight Mn of the amorphous polymer is, for example, 10,000 or more, the pulverizability is poor and the toner yield is lowered. On the other hand, when a crystalline polymer having a small number average molecular weight Mn is used, the compatibility with the amorphous polymer is increased, the crystallinity of the resin is lowered, and the blocking resistance is deteriorated.

[Object of the Invention]

The present invention has been made based on the above circumstances, and an object thereof is to produce a toner for electrostatic image development capable of producing a toner excellent in low-temperature fixing property, offset resistance and blocking resistance. To provide a method.

[Means for solving problems]

The present invention provides a method for producing an electrostatic image developing toner, which comprises a kneading step of kneading a toner raw material containing a binder resin, and a crushing step of crushing a kneaded product obtained by the kneading step, wherein the binder The resin contains a block copolymer or a graft copolymer in which a crystalline polyester and an amorphous vinyl polymer having a functional group that forms a bond with the crystalline polyester are chemically bonded. A heat treatment step of heat-treating the kneaded product obtained by the kneading step is added between the kneading step and the crushing step.

[Advantageous effects of the invention]

According to the present invention, since a specific binder resin is used and a specific heat treatment step is added, a toner excellent in low-temperature fixing property, offset resistance, and blocking resistance can be manufactured.

That is, since the binder resin contains a block copolymer or a graft copolymer of a crystalline polyester and an amorphous vinyl polymer, it has a low minimum fixing temperature and can be fixed without an offset phenomenon. Since a toner having a wide fixing temperature range can be obtained and a heat treatment step is added between the kneading step and the crushing step, the heat treatment step increases the crystallinity of the crystalline polyester in the binder resin. As a result, the melting peak of the binder resin becomes sharp and the blocking resistance of the toner is improved.

On the other hand, when the heat treatment step is not added, the crystallinity of the binder resin is low, so that the melting peak of the binder resin becomes dull and the blocking resistance of the toner deteriorates.

Further, there is known a technique (Japanese Unexamined Patent Publication No. 56-52758) in which the toner is spheroidized by performing a heat treatment after the crushing process, not before the crushing process. In the technique, the toner is aggregated by the heat treatment. Therefore, there is a problem that the yield of the toner is lowered as a result. In the present invention, since the heat treatment step is added before the crushing step as described above, such a problem does not occur.

[Specific configuration of the invention]

 The configuration of the present invention will be specifically described below.

In the kneading step, other toner raw materials are added to a binder resin containing a specific block copolymer or graft copolymer, which will be described in detail later, and these are sufficiently kneaded while heating.

The kneading temperature may be a temperature at which the toner raw material melts,
A temperature 10 to 20 ° C. lower than the softening point of the binder resin is preferable.

As an apparatus used in the kneading step, an ordinary kneading apparatus can be used, and for example, a two-roll type kneading machine, a twin-screw extruder or the like can be used.

After the kneading process as described above is completed, it is necessary to cool the kneaded product in order to pulverize the kneaded product. In the present invention, a heat treatment process is added before the pulverization process. There are various modes of heat treatment, and the heat treatment method is not particularly limited. For example, the following heat treatment methods can be adopted.

(1) After the completion of the kneading step, in the process of cooling the kneaded material from the kneading temperature to the crushing temperature for the crushing step, the kneaded material is lower than the kneading temperature and higher than the crushing temperature by an appropriate heating means. Incubate at temperature for a period of time and then cool to milling temperature.

(2) After the completion of the kneading step, the kneaded product is once cooled from the kneading temperature to the crushing temperature, and then the kneaded product is heated to a temperature lower than the kneading temperature and higher than the crushing temperature by an appropriate heating means, and the temperature is increased. Incubate for a period of time and then cool again to the milling temperature.

The heat treatment temperature may be lower than the kneading temperature and higher than the crushing temperature, but is preferably not higher than the melting point of the crystalline polyester in the binder resin.

The heat treatment time is about 10 minutes to 10 hours, but 1 hour to 3 hours
Time is preferable.

As an apparatus used in the heat treatment step, for example, an oven can be used. For example, when an oven is used, the kneaded product immediately after the completion of the kneading step can be taken out of the kneading device, transferred to the oven, and the inside of the oven can be kept at a constant temperature for heat treatment.

After the heat treatment process as described above is completed, the kneaded product is cooled to the crushing temperature and then subjected to the crushing process.

The temperature when subjected to the pulverizing step, i.e., the pulverizing temperature, is not particularly limited, but in the present invention, since a binder resin containing a specific block copolymer or graft copolymer is used, for example, about 10 to 30 ° C. It is possible to sufficiently pulverize under a normal atmospheric temperature, and it is possible to economically produce a toner.

The crushing device is not particularly limited, and a normal crushing device can be used. Specifically, for example, a jet mill or the like can be used.

The crushing process may be performed in multiple stages. For example, by finely pulverizing the kneaded material in the first pulverizing step, then further finely pulverizing it in the second pulverizing step, and then classifying it, finely divided toner powder can be obtained.

The toner powder thus obtained has an average particle size of, for example, 9 to
It is preferably about 15 μm. Further, in order to improve the characteristics of the toner, an appropriate additive may be externally added to and mixed with the toner powder.

The binder resin used as a toner raw material in the present invention is a block copolymer or graft obtained by chemically bonding a crystalline polyester and an amorphous vinyl polymer having a functional group that forms a bond with the crystalline polyester. It contains a copolymer.

As the functional group of the amorphous vinyl polymer, for example, a carboxyl group, a hydroxyl group, an amino group, an epoxy group and the like are preferable. Examples of the monomer having such a functional group include acrylic acid, β, β-dimethylacrylic acid, α-ethylacrylic acid, methacrylic acid, fumaric acid, itaconic acid, maleic acid, crotonic acid, hydroxyethyl methacrylate,
Acryloyloxyethyl monosuccinate, N-hydroxyethyl acrylamide, N-methylol acrylamide, p-aminostyrene, glycidyl methacrylate and the like can be mentioned. The monomer having such a functional group should be used in a proportion of 0.1 to 20 mol%, preferably 0.5 to 10 mol% in the monomer composition for obtaining the amorphous vinyl polymer. Is preferred.

In the amorphous vinyl polymer, the vinyl polymer constituting the main part thereof is not particularly limited, and examples thereof include polystyrene, polymethyl methacrylate, polymethyl acrylate, polyvinyl chloride, polyvinyl acetate, polyacrylonitrile, and these Examples thereof include copolymers. In particular, styrene polymers, acrylic polymers, styrene
Acrylic copolymers are preferred, and examples of the styrene-based monomer or acrylic-based monomer used to form such a polymer include styrene, o-methylstyrene, m-
Methyl styrene, p-methyl styrene, α-methyl styrene, p-ethyl styrene, 2,4-dimethyl styrene,
pn-butyl styrene, p-dodecyl styrene, p-
Methoxystyrene, p-phenylstyrene, p-crossstyrene, methyl acrylate, ethyl acrylate,
n-butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, methyl methacrylate, ethyl methacrylate, n
-Propyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, dimethylaminoethyl methacrylate and the like can be mentioned. These monomers can be used alone or in combination of two or more kinds.

The amorphous vinyl polymer preferably has a ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn of 3.5 or more, particularly 5.0 or more. And the weight average molecular weight Mw is 1
It is preferable that the number average molecular weight Mn is 2,000 or more and the number average molecular weight Mn is 2,000 or more. Further, it preferably has two or more peaks in its molecular weight distribution. The measurement of this molecular weight distribution is
Gel permeation chromatography (GPC)
Can be done by. And, it is preferable that at least one peak molecular weight is 100,000 to 1,000,000 and at least one other peak molecular weight is 2,000 to 20,000. When such an amorphous vinyl polymer is used, the under-offset generation temperature can be lowered and the hot-offset generation temperature can be increased, so that the fixable temperature range becomes extremely wide. In addition, the amorphous vinyl polymer has a softening point Tsp of 100 to 150 by an elevated flow tester.
Those at ℃ are preferred.

The weight average molecular weight Mw and the number average molecular weight Mn are values measured by gel permeation chromatography (GPC) as follows.

That is, at a temperature of 40 ° C., a solvent (tetrahydrofuran or the like) is caused to flow at a flow rate of 1.2 ml per minute, and 3 mg of a sample solution of tetrahydrofuran having a concentration of 0.2 g / 20 ml is injected as a sample weight for measurement. When measuring the molecular weight of the sample, the measurement conditions are selected so that the logarithm of the molecular weight and the count number of the calibration curve made by the monodisperse polystyrene standard samples of several kinds of samples have a linear range. The reliability of the measurement results can be confirmed by the fact that the NBS706 polystyrene standard sample obtained under the above measurement conditions has a weight average molecular weight Mw of 28.8 × 10 ^{4 and a} number average molecular weight Mn of 13.7 × 10 ⁴ . Any GPC column may be used as long as it satisfies the above conditions. For example, TSK-GEL, GMH (manufactured by Toyo Soda Co., Ltd.)
Etc. can be used. The solvent and the measurement temperature are not limited to the above and may be changed appropriately.

The glass transition point Tg of the amorphous vinyl polymer is 50 to 100 ° C,
Particularly, 50 to 85 ° C is preferable. If the glass transition point Tg is too small, the blocking resistance tends to deteriorate, and the glass transition point Tg
When is too large, the fixability is likely to deteriorate. The glass transition point Tg of this amorphous vinyl polymer was measured in the state where it was not bound to the crystalline polyester.
Here, the glass transition point Tg is the differential scanning calorimetry (DS
According to C), it is the value obtained from the intersection of the baseline and the endothermic peak slope when 10 mg of the sample is heated at a constant heating rate (10 ° C / min).

The crystal control polyester has a crystal structure in at least a part of the polyester, and includes a homopolymer or copolymer in which at least one component is crystalline, that is, partially crystallized, and is sharp and clear. It shows a melting point, and in the solid state at a temperature equal to or lower than the melting point, it shows clouding due to a crystallized portion.

As such crystalline polyester, polyalkylene polyester is particularly preferable from the viewpoint of low temperature fixability and fluidity. Specifically, for example, polyethylene sebacate, polyethylene adipate, polyethylene suberate, polyethylene succinate, polyethylene-p- (carbophenoxy) undecaate, polyhexamethylene oxalate, polyhexamethylene sebacate, polyoctamethylene dodecanedioate. , Polyoctamethylene dedocandioate, polynonamethylene azelate, polydecamethylene adipate, polydecamethylene azelate, polydecamethylene oxalate, polydecamethylene sebacate, polydecamethylene succinate, polydecamethylene dodecanedio Ate, polydecamethylene octadecanedioate, polytetramethylene sebacate, polytrimethylene dodecanedioate, polytrimethylene octadadecanedioate, poly Li methylene Ok The rate, polyhexamethylene - decamethylene - sebacate, polyoxyethylene decamethylene-2-methyl-1,3-propane - can be exemplified dodecanedioate like.

The melting point Tm of the crystalline polyester is 50 to 120 ° C., especially 50 to 1
00 ° C is preferred. If the melting point Tm is too low, blocking resistance tends to deteriorate, and if the melting point Tm is too high, low temperature fixability tends to deteriorate. The melting point Tm of this crystalline polyester was measured in a state where it was not bound to the amorphous vinyl polymer. Here, the melting point Tm means a melting peak value when 10 mg of a sample is heated at a constant heating rate (10 ° C./min) according to a differential scanning calorimetry (DSC).

The crystalline polyester has a weight average molecular weight Mw of 5,000 to 50,000 and a number average molecular weight Mn of 2,000 to 20,000.
Are preferred.

The proportion of the crystalline polyester is 3 to 50% by weight, particularly 5 to 5% by weight in the block copolymer or the graft copolymer.
40% by weight is preferred. If the proportion of the crystalline polyester is too small, the low temperature fixability tends to deteriorate, and conversely if the proportion is too large, the offset resistance tends to deteriorate.

It is preferable that the crystalline polyester and the amorphous vinyl polymer are substantially incompatible. The term "substantially incompatible" means
It means that the crystalline polyester and the amorphous vinyl polymer are not sufficiently dispersed. Specifically, for example, SP value by the method of Fedose [RF Fedors, Polym. Eng. Sci., 14 ,
(2) 147 (1974)] is greater than 0.5.

In order to obtain a block copolymer or a graft copolymer obtained by chemically bonding a crystalline polyester and an amorphous vinyl polymer, for example, a coupling reaction between terminal functional groups present in each polymer is used. Allows direct binding to each other in a head-to-tail fashion. Alternatively, it can be bonded to the terminal functional group of each polymer by a bifunctional coupling agent, for example, a urethane bond formed by the reaction of a polymer having a hydroxyl group as a terminal group and diisocyanate, and a hydroxyl group as a terminal group. An ester bond formed by the reaction of a polymer which is a group with a dicarboxylic acid or the reaction of a polymer whose terminal group is a carboxyl group and a glycol, a polymer whose terminal group is a hydroxyl group and phosgene,
It can be bound by other bonds or the like formed by reaction with dichlorodimethylsilane.

Examples of such coupling agents include difunctional isocyanates such as hexamethylene diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, tolidine diisocyanate, naphthylene diisocyanate, isophorone diisocyanate and xylylene diisocyanate; for example ethylenediamine, hexamethylenediamine, phenylenediamine and the like. Bifunctional carboxylic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid, terephthalic acid, and isophthalic acid; for example, ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, cyclohexanediene Bifunctional alcohols such as methanol and p-xylylene glycol; for example, terephthalic acid chloride, isophthalic acid It may include, for example, diisothiocyanate, Bisuketen, other bifunctional coupling agents such as bis-carbodiimide; Rorido, adipic acid chloride, difunctional acid chlorides such as sebacic acid chloride.

The coupling agent is 1 to 10% by weight, particularly 2 to 10% by weight based on the total amount of the crystalline polyester and the amorphous vinyl polymer.
It is preferably used in a proportion of 7% by weight. When the proportion of the coupling agent is too large, the softening point of the resulting block copolymer or graft copolymer becomes too high, and the low-temperature fixability tends to deteriorate, and when it is too small, the offset resistance tends to deteriorate.

In the present invention, the above specific block copolymer or graft copolymer is used as the binder resin, but other resins may be used in combination. However, the proportion of the block copolymer or graft copolymer in the binder resin is preferably 30% by weight or more, and particularly preferably 50 to 100% by weight.

As other toner raw materials used together with the binder resin, there are various additives such as colorants and charge control agents, which can be used if necessary.

Examples of colorants include carbon black, nigrosine dye, aniline blue, chalco oil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, Mixtures of these and others can be used.

Examples of the charge control agent include nigrosine dyes, metal-containing azo dyes, metal complexes and the like.

In order to make the viscoelasticity of the toner during melting more suitable,
Alternatively, in order to further improve the fixing property, the melting point is 50 to
It is preferable to use a wax at about 150 ° C. by kneading with a binder resin. Specifically, liquid or solid paraffin, low molecular weight polyolefin such as polyethylene or polypropylene, fatty acid metal salt, fatty acid ester, partially saponified fatty acid ester, higher fatty acid, higher alcohol, silicone varnish, amide wax, aliphatic fluorocarbon. Moreover, the modified body etc. can be used.

In addition, in order to improve the fluidity of the toner or to polish the surface of the latent image carrier to a new surface,
Inorganic fine particles and the like may be externally added to and mixed with the toner powder. Examples of such inorganic fine particles include silica, alumina, titania, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, chromium oxide, Cerium oxide, red iron oxide, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide,
Examples thereof include fine particles of silicon nitride. Silica fine particles are particularly preferable. The primary particle size of the inorganic fine particles is, for example,
5 mμ to 2 μm, particularly about 5 mμ to 500 mμ are preferable. The addition ratio is 0.01 to 5% by weight of the toner, especially 0.01 to 2.
About 0% by weight is preferable.

In the case of obtaining a magnetic toner, magnetic particles may be further added to the binder resin and the kneading step may be performed. Such magnetic fine particles include, for example, ferromagnetic metals such as iron, nickel and cobalt, alloys containing these metals, compounds of ferromagnetic metals such as ferrite and magnetite, and containing no ferromagnetic element, but appropriately heat-treated. Examples thereof include alloys exhibiting ferromagnetism, for example, alloys of the type called Heusler alloys such as manganese-copper-aluminum and manganese-copper-tin, or fine particles such as chromium dioxide. The average particle size of the magnetic fine particles is preferably about 0.1 to 1 μm. The addition amount of the magnetic fine particles is usually about 20 to 70% by weight of the toner raw material.

〔Example〕

Examples of the present invention will be specifically described below, but the present invention is not limited to these examples.

<Crystalline polyester> (1) Crystalline polyester 1 Polyhexamethylene sebacate (weight average molecular weight Mw = 1
4,000, melting point Tm = 64 ℃) (2) Crystalline polyester 2 Polyethylene sebacate (weight average molecular weight Mw = 12,800,
(Melting point Tm = 72 ° C.) <Amorphous vinyl polymer> (1) Amorphous vinyl polymer 1 Put 30 g of toluene in a separable frast of 1 volume,
Among them, as a monomer for high molecular weight components, styrene 19.5
g (65 parts by weight) and 10.5 g of ethylhexyl methacrylate
(35 parts by weight) and benzoyl peroxide 0.06 g (0.2 parts by weight)
Was added to suspend and disperse the gas, and the gas phase in the flask was replaced with nitrogen gas. Then, the temperature was raised to 80 ° C. and the temperature was maintained for 15 hours to carry out the first stage polymerization. Incidentally, the weight average molecular weight Mw in the homopolymer of the high molecular weight component monomer is 30
The glass transition temperature Tg is 0,000 and 53 ° C.

Then, the reaction system was cooled to a temperature of 40 ° C., and 95 g (95 parts by weight) of styrene was added as a monomer for the low molecular weight component.
Then, 5 g (5 parts by weight) of α-ethylacrylic acid and 4 g (4 parts by weight) of benzoyl peroxide were added, and stirring was continued for 2 hours at a temperature of 40 ° C, and then the temperature was raised again to 80 ° C. The temperature was maintained at that temperature for 8 hours to carry out the second stage polymerization. The weight average molecular weight Mw of the homopolymer of the monomer for the low molecular weight component is 6,000 and the glass transition point Tg is 63 ° C.

After that, the system was cooled to separate a solid matter, and after repeating dehydration and washing, it was dried to obtain an amorphous vinyl polymer 1 having a carboxyl group consisting of a high molecular weight component and a low molecular weight component.

This amorphous vinyl polymer 1 has two peaks in its molecular weight distribution, and the peak molecular weight on the high molecular weight side is 281,
The peak molecular weight on the low molecular weight side was 800 and 4,470. The glass transition point Tg was 62 ° C and the softening point Tsp was 139 ° C.

(2) Amorphous vinyl polymer 2 85 parts by weight of styrene, 10 parts by weight of n-butyl methacrylate, 5 parts by weight of acryloyloxyethyl monosuccinate, 4 parts by weight of benzoyl peroxide, and 100 parts of toluene.
The mixture was placed in a separable flask having a capacity of 1 containing parts by weight, the gas phase in the flask was replaced with nitrogen gas, the temperature was raised to 80 ° C., and the temperature was maintained for 15 hours to carry out polymerization. Then, toluene was distilled off by an aspirator and a vacuum pump to obtain an amorphous vinyl polymer 2 which was a styrene-acrylic resin having a carboxyl group.

This amorphous vinyl polymer 2 has one peak in the molecular weight distribution, has a weight average molecular weight Mw of 71,000 and a ratio Mw / Mn.
Value is 7.5, glass transition point Tg is 67 ℃, softening point Tsp is 123 ℃
Met.

<Graft Copolymer> A total of 100 parts by weight of the crystalline polyester and the amorphous vinyl polymer in the combinations and proportions shown in Table 1 below and p-
0.05 parts by weight of toluenesulfonic acid and 100 parts by weight of xylene were placed in a separable flask having a capacity of 3 l, and the temperature was set at 150.
Each graft copolymer was obtained by refluxing at 0 ° C. for 1 hour, and then distilling off xylene with an aspirator and a vacuum pump.

<Examples 1 to 4> In each example, 100 parts by weight of a binder resin made of the copolymer shown in Table 1 below, 10 parts by weight of carbon black "Mogal L" (manufactured by Cabot), and polypropylene "Viscol". 3 parts by weight of "660P" (manufactured by Sanyo Kasei Co., Ltd.) and 3 parts by weight of "Wax E" (manufactured by Hoechst Co., Ltd.) were used, and the softening point of the binder resin was measured using a twin-screw extruder.
Kneading was performed at a temperature 10 ° C lower. Immediately after the completion of the kneading step, the kneaded product was set in an oven and heat-treated at a temperature shown in Table 1 for 2 hours. After the heat treatment step, the heat-treated kneaded product is cooled to room temperature, then coarsely pulverized by a Willey mill, finely pulverized by a jet mill, and then classified by an air classifier to obtain colored fine particles having an average particle diameter of 11 μm. Obtained.

Toners 1 to 4 were manufactured by externally adding and mixing hydrophobic silica fine powder "Aerosil R-972" (manufactured by Nippon Aerosil Co., Ltd.) to the colored fine particles at a ratio of 0.8% by weight.

<Examples 5 to 8> In each example, the binder resin shown in Table 1 below.
100 parts by weight, carbon black "Mogal L" (manufactured by Cabot) 10 parts by weight, and polypropylene "Viscor"
3 parts by weight of "660P" (manufactured by Sanyo Kasei Co., Ltd.) and 3 parts by weight of "Wax E" (manufactured by Hoechst) were mixed and kneaded in the same manner as in Example 1. After completion of the kneading step, once cooled to room temperature, then set the cooled kneaded product in the oven,
It heat-processed for 2 hours at the temperature shown in Table 1 below. After completion of the heat treatment step, the heat treated kneaded product is cooled to room temperature,
Then, coarse pulverization was performed using a Willey mill, fine pulverization was performed using a jet mill, and classification was performed using an air classifier to obtain colored fine particles having an average particle size of 11 μm.

Toners 5 to 8 were manufactured by externally adding and mixing hydrophobic silica fine powder "Aerosil R-972" (manufactured by Nippon Aerosil Co., Ltd.) to the colored fine particles in a ratio of 0.8% by weight.

<Comparative Examples 1 to 3> In each Comparative Example, the binder resin shown in Table 1 below is shown.
100 parts by weight, carbon black "Mogal L" (manufactured by Cabot) 10 parts by weight, and polypropylene "Viscor"
3 parts by weight of "660P" (manufactured by Sanyo Kasei Co., Ltd.) and 3 parts by weight of "Wax E" (manufactured by Hoechst) were mixed and kneaded in the same manner as in Example 1. After the completion of the kneading step, the kneaded product was cooled to room temperature, then coarsely pulverized by a Wiley mill, further finely pulverized by a jet mill, and then classified by an air classifier to obtain colored fine particles having an average particle diameter of 11 μm.

Comparative toners 1 to 3 were produced by externally adding and mixing hydrophobic silica fine powder "Aerosil R-972" (manufactured by Nippon Aerosil Co., Ltd.) to the colored fine particles in a ratio of 0.8% by weight.

<Evaluation> (1) Melting start temperature With respect to each of the above-mentioned toners, the temperature at which melting starts is measured.

(2) Toner aggregation rate After tapping each of the above toners 500 times with a tap denser, the toner is left to stand in an atmosphere of 55 ° C. for 2 hours,
Then, the mixture was fractionated with a 48-mesh sieve, and the proportion of aggregates remaining on the sieve was measured.

(3) Minimum fixing temperature 5 parts by weight of each toner described above and electrophotographic copying machine "U-Bix 16"
00 "(manufactured by Konishi Rokusha Kogyo Co., Ltd.) is mixed with 95 parts by weight of a carrier to prepare each developer, and each developer is not fixed onto the transfer paper by the electrophotographic copying machine" U-Bix 1600 ". The operation of forming a toner image and fixing this unfixed toner image at a linear velocity of 140 mm / sec by a heat roller fixing device adopting a heat roller fixing method is performed at each temperature by changing the set temperature of the heat roller by 5 ° C. Repeatedly, the obtained fixed image was rubbed with the same paper as the transfer paper by a Ken labor tester,
The lowest setting temperature of the heat roller for the fixed image showing sufficient rubbing resistance was defined as the lowest fixing temperature. The fixing device used here does not have a silicone oil supply mechanism.

(4) Hot offset generation temperature Similar to the measurement of the minimum fixing temperature, an unfixed toner image is formed on the transfer paper, and this unfixed toner image is fixed by a similar heat roller fixing device at a linear velocity of 140 mm / sec. After performing the treatment, the blank transfer paper is sent to the heat roller fixing device under the same conditions and the operation of visually observing whether or not toner stains occur is repeated by changing the set temperature of the heat roller, The lowest set temperature at which the toner was contaminated was defined as the hot offset generation temperature.

The above results are shown in Table 1 below.

As can be understood from the above results, in the toners 1 to 8 manufactured by applying the manufacturing method of the present invention, since the melting start temperature is appropriately low, sufficient low temperature fixability is exhibited, and the toner aggregation rate is high. Small and with good blocking resistance,
The hot offset generation temperature is high and the offset resistance is sufficient. After all, it is excellent in all of the low temperature fixing property, the offset resistance, and the blocking resistance.

On the other hand, Comparative Toners 1 and 2 were manufactured without passing through the heat treatment process, so that the melting start temperature was considerably low, the toner aggregation rate was high, and the blocking resistance was poor.

Further, in Comparative Toner 3, since the binder resin is composed only of the amorphous vinyl polymer, the minimum fixing temperature is high and the low temperature fixing property is poor.

Claims (4)

[Claims] 1. A method for producing an electrostatic image developing toner, comprising: a kneading step of kneading a toner raw material containing a binder resin; and a crushing step of crushing a kneaded product obtained by the kneading step. The binder resin contains a block copolymer or a graft copolymer in which a crystalline polyester and an amorphous vinyl polymer having a functional group that forms a bond with the crystalline polyester are chemically bonded. And a heat treatment step of heat-treating the kneaded product obtained by the kneading step is added between the kneading step and the pulverizing step. 2. The heat treatment in the heat treatment step is a treatment for keeping the temperature of the kneaded product obtained in the kneading step constant during the process from the kneading step to the crushing step. Item 6. A method for producing a toner for developing an electrostatic image according to item. 3. The ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn of the amorphous vinyl polymer is 3.5 or more. A method for producing a toner for developing an electrostatic image as described above. 4. The electrostatic image developing toner according to claim 1, wherein the amorphous vinyl polymer has two or more peaks in its molecular weight distribution. Production method.