JPH0453431B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for manufacturing a carrier that constitutes an electrostatic image developer together with toner. In particular, by coating the carrier core material with a specific resin, durability can be improved and high image quality can be achieved. The present invention relates to a method for producing a carrier for electrostatic image development, from which an image can be obtained. [Background of the Invention] In electrophotography, a photoreceptor made of a photoconductive element is given a uniform surface charge in a dark place, an electrostatic image is formed by imagewise exposure, and this electrostatic image is developed. A visible image is formed. Generally, methods for developing such electrostatic images are broadly classified into wet developing methods and dry developing methods. The wet development method uses a liquid developer made by dispersing various pigments and dyes as fine particles in an insulating organic liquid, while the dry development method uses carbon black in a natural or synthetic resin. This is a developing method that uses a fine powder, called a toner, which contains a colorant such as the following dispersed therein. In addition to the so-called bristle brush method, impression method, and powder cloud method using a developer containing only the above-mentioned toner as a main component, this dry development method includes a method in which the above-mentioned toner is mixed with a carrier made of iron powder or glass beads, etc. There are the so-called magnetic brush method and the cascade method, which use the body as a developer. By these developing methods, electrostatic particles such as toner particles having electric charge contained in the developer adhere to the electrostatic image to form a visible image. This visible image is transferred directly onto a photoreceptor or onto paper or other image support by heat pressure, solvent vapor, etc., and then fixed. The present invention relates to a developer carrier used in the magnetic brush method and cascade method among the above-mentioned development methods, that is, a carrier for imparting a desired charge to the toner by being stirred together with the toner. Generally, carriers are broadly classified into conductive carriers and insulating carriers. Oxidized or unoxidized iron powder is usually used as the conductive carrier, but in a developer containing this iron powder carrier, the triboelectric charging properties of the toner are unstable, and the formation by the developer is unstable. There is a drawback that fog occurs in the visible image. That is, as toner particles adhere to the surface of the iron powder carrier particles as a developer is used, the current resistance of the carrier particles increases and the bias current decreases, and the triboelectric charging properties become unstable, resulting in the formation of toner particles. The image density of the visible image decreases and fog increases. Therefore, if a developer containing an iron powder carrier is used for continuous copying with an electronic copying device, the developer deteriorates after a few copies, making it necessary to replace the developer early, making it difficult to continue producing good images. I can't get it. A typical example of an insulating carrier is one in which the surface of a carrier core material made of a ferromagnetic material such as iron, nickel, or ferrite is uniformly coated with an insulating resin. In a developer using this insulating carrier, toner particles are less likely to fuse to the carrier surface than in the case of a conductive carrier, and at the same time, the frictional electrification between the toner and the carrier can be controlled, resulting in increased durability. is relatively excellent. It also has the advantage that it can be used in restricted electronic copying machines. However, in this insulating carrier, the coating layer covering the surface of the carrier core material has sufficient abrasion resistance (durability),
The coating layer must have good anti-sticking properties to prevent the formation of a toner film on the carrier surface, and the desired charging state of size and polarity can be obtained by friction with the specific toner used with the carrier. chargeability) is required. That is, the insulating carrier is rubbed against other carrier particles, toner particles, the container wall, etc. in the developing device, but when the coating layer is worn away by this friction,
The stability of charging characteristics caused by friction with the toner is lost, and as a result, it is not possible to impart a desired charging state to the toner particles. Furthermore, even if the coating layer of the insulating carrier has sufficient friction resistance, if its adhesion to the core material is poor, the coating layer will peel off or crumble due to the friction described above, and the charging characteristics will similarly deteriorate. become lost. Furthermore, if toner adheres to the surface of the coating layer to form a film, the charging characteristics will become unstable. In either case, it becomes necessary to quickly replace the entire developer with a new one. [Problems to be solved by the invention] Conventionally, as a technique for solving such drawbacks, the
No. 53-40452 proposes a carrier coated with a crystalline fluoropolymer, and states that it provides excellent durability and adhesion. However, it has been found that the above coated carrier also has the following problems. In recent years, there has been a call for increased speed in carrier manufacturing, and mass production has become strongly desired. However, in the conventional fluidized bed method, in which the coating liquid is sprayed while the carrier core material is suspended and fluidized, when trying to increase the amount of coating liquid to increase the production speed, the carriers tend to stick to each other, resulting in coating I had to limit the amount of liquid. Therefore, it was found that this fluidized bed method was unable to increase the manufacturing speed and was ultimately unsuitable for mass production. Therefore, the present inventor has discovered that as a method excellent in mass production, it is sufficient to apply shearing force when spraying the coating liquid while floating or flowing the carrier core material. However, in the case of the carrier described in Japanese Patent Publication No. 53-40452, the coating resin has high crystallinity, so when a large shearing force is applied, the crystalline polymer is stretched and fibrillated (stringy). As a result, a uniform coating film could not be obtained, resulting in unstable triboelectrification and poor durability. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for producing a carrier for electrostatic image development, which is excellent in mass production, has excellent durability and chargeability, is free from fogging, and is capable of increasing image density. [Means for Solving the Problems] The carrier for electrostatic image development according to the present invention, which can achieve the above object, comprises a crystalline polyvinylidene fluoride polymer and the polyvinylidene fluoride polymer on a carrier core material. Production of a carrier for electrostatic image development, the main component of which is a polymer consisting of a polymer blend with a second polymer that inhibits crystallinity, and which forms a coating layer in which the heat of fusion of the polymer is 30 mJ/mg or less. In the method, by spraying or immersing the coating liquid in the coating liquid while floating or flowing the carrier core material and applying a rotational force, or
The method is characterized in that a coating layer is formed on the carrier core material while applying shearing by supplying a high-pressure jet stream. The present invention will be explained in detail below. The coating layer of the carrier of the present invention is mainly composed of a polymer made of a polymer blend of a crystalline polyvinylidene fluoride polymer and a second polymer that inhibits the crystallinity of the polyvinylidene fluoride polymer. Examples of crystalline polyvinylidene fluoride-based polymers include polyvinylidene fluoride, copolymers of polyvinylidene fluoride and trifluorochloroethylene, copolymers of polyvinylidene fluoride and tetrafluoroethylene, and polyvinylidene fluoride and hexafluoropropylene. Examples include copolymers with. The second polymer that inhibits the crystallinity of the crystalline polyvinylidene fluoride polymer is not particularly limited, but is preferably amorphous and has a high Tg (glass transition temperature), such as methyl methacrylate polymer, fluoromethacrylate polymer, etc. Combination etc. is desirable. When it is desired to use a strongly negatively chargeable toner as a positively chargeable toner, it is preferable to use a fluorine-based polymer as the second polymer because it has high triboelectric chargeability and is stable. In the present invention, the polymer constituting the carrier coating layer has a heat of fusion of 30 mJ/mg or less. Here, the heat of fusion refers to the amount of heat required to melt a polymer from a solid state, and is determined as follows. First, a blend sample consisting of a crystalline polyvinylidene fluoride polymer and a second polymer that inhibits the crystallinity of the polyvinylidene fluoride polymer was cast in a 5% solution, dried, and then melted for 30 minutes at a temperature above the melting point. A sample for measurement is prepared by annealing at a temperature below (at a temperature close to the melting point). The obtained measurement sample was tested using SSC-580 manufactured by Seiko Electronics Industries
With type DSC, the sample weight is approximately 7 mg and the heating temperature is 10
Measure the heat of fusion (mJ/mg) in °C/min. The heat of fusion determined by the above method can be controlled by appropriately selecting the polymer blend ratio of the crystalline polyvinylidene fluoride polymer and the second polymer that inhibits the crystallinity of the polyvinylidene fluoride polymer. can. The blend ratio at which the heat of fusion of the blended polymer of the present invention is 30 mJ/mg or less varies depending on the type of polymer to be blended, but for example, in the case of a blend of polyvinylidene fluoride resin and polymethyl methacrylate resin. , the former is
95 parts by weight or less, and the latter is 5 parts by weight or more. In addition, from the viewpoint of maintaining good charging properties, the former is
The latter is 50 parts by weight or more (preferably 70 parts by weight or more), and the latter is 50 parts by weight or less (preferably 30 parts by weight or less). In the present invention, the carrier coating layer is mainly composed of the polymer having the heat of fusion of 30 mJ/mg or less,
When using a polymer with a heat of fusion exceeding 30 mJ/mg,
The resulting carrier has a highly crystalline resin, which causes fibrillation, making it impossible to obtain a uniform coating film, resulting in unstable triboelectrification and insufficient durability. The coating layer of the carrier of the present invention contains a polymer made of the above-mentioned polymer blend, but it is also possible to contain a third component etc. as necessary within the scope of the purpose of the present invention. The content of the third component is 0 to 30% by weight
is preferred. In producing the carrier of the present invention, a coating liquid is prepared by dissolving the above polymer composition in an organic solvent,
By spraying or immersing the coating liquid into the coating liquid while floating or flowing the carrier core material, or by applying rotational force, or by supplying a high-pressure jet flow, the coating liquid is applied onto the carrier core material while applying shear. After forming the coating layer, the carrier of the present invention is obtained by further heating or standing. In the present invention, "applying shear" means to forcefully apply a force to break the adhesion or cohesion of the carriers. As a method of applying force to break the adhesion, as described above, rotational force is applied. Examples include methods of supplying high-pressure jet flow. Specific examples of methods for applying rotational force include, for example, the tumbling fluidized bed coating method and the Henschel mixer method. The tumbling fluidized bed coating method uses a tumbling fluidized bed coating device "Spiracoater" equipped with a rotating disk.
(manufactured by Okada Seiko Co., Ltd.), the carrier core material is rolled by the centrifugal force of a rotating disk and moved to the circumference of the disk, and the pressurized gas flow rising at the circumference of the disk moves the carrier core material into equilibrium. In this method, the carrier core material is raised to a height, and then the coating liquid is spray-coated by the time the core material falls onto the rotating disk again, and this application is repeated to form a coating layer on the carrier core material. If there is agglomerated carrier, it can be sieved to finally obtain the carrier of the present invention having a desired film thickness. In the Henschel mixer method, for example, the carrier core material is immersed in a concentrated coating liquid in a Henschel mixer, and then the Henschel mixer is rotated to agitate the carrier core material. In this method, the solvent is evaporated to form a coating layer on the carrier core material. If there is agglomerated carrier, it can be sieved to finally obtain the carrier of the present invention having a desired film thickness. The organic solvent used in the above production may be any solvent as long as it dissolves the polymer according to the present invention, but examples include acetone, ketones such as methyl ethyl ketone, tetrahydrofuran, dioxane,
Dimethyl sulfoxide or a mixed solvent thereof is used. In the present invention, the thickness of the carrier coating layer is
Range of 0.05μm to 20μm, preferably 0.1μm to 2μm
is within the range of If the thickness of the coating layer is 20μm or less, the solvent will not remain in the coating layer for a long time and will not have a negative effect on charging properties.If the thickness of the coating layer is 0.05μm or more, charging due to pinholes will be stable. There are no problems with durability or durability due to friction. The material of the carrier core material in the present invention is as follows:
Materials commonly used as carrier core materials can be used, such as sand, glass, metal, etc.
In particular, substances that are strongly magnetized in the direction of a magnetic field.
For example, metals that exhibit ferromagnetism, such as ferrite and magnetite, iron, cobalt, and nickel, or alloys or compounds containing these metals, and materials that do not contain ferromagnetic elements but exhibit ferromagnetism through appropriate heat treatment. Examples of suitable alloys include alloys called Heusler alloys such as manganese-copper-aluminum or manganese-copper-tin, and chromium dioxide. The particle size of these carrier core materials is 30 to 1000 μm, preferably 50 to 500 μm.
The carrier of the present invention has an absolute value of 5 to 5 under normal usage conditions with respect to the toner used together with it.
Preferably, it provides a charge of 40 μC/g. The carrier of the present invention can constitute a two-component developer with any toner. Among these, preferred toners include those using polyester resin or styrene/acrylic resin as a binder. Polyester resin is obtained by polycondensation of alcohol and carboxylic acid, and the alcohols used include, for example, ethylene glycol, diethylene glycol, triethylene glycol,
Diols such as 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,4-bis(hydroxymethyl)cyclohexane, and bisphenol A, etherified bisphenols such as hydrogenated bisphenol A, polyoxyethylenated bisphenol A, and polyoxypropylenated bisphenol A;
Other dihydric alcohol monomers may be mentioned. Examples of carboxylic acids include maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, and malonic acid. Examples include acids, anhydrides of these acids, dimers of lower alkyl esters and linoleic acid, and other divalent organic acid monomers. As the polyester resin that can be used in the present invention, it is preferable to use not only a polymer made only of the above difunctional monomers but also a polymer containing a component made of trifunctional or higher polyfunctional monomers. It is. Examples of trivalent or higher polyhydric alcohol monomers that are such polyfunctional monomers include sorbitol, 1,2,3,6-hexanetetrol,
1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2,4-butanetriol,
1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5
-trihydroxymethylbenzene, and others. In addition, as trivalent or higher polyvalent carboxylic acid monomers,
For example, 1,2,4-benzenetricarboxylic acid,
1,3,5-benzenetricarboxylic acid, 1,2,
4-cyclohexanetricarboxylic acid, 2,5,7
-Naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-
Mention may be made of methylenecarboxypropane, tetra(methylenecarboxyl)methane, 1,2,7,8-octanetetracarboxylic acid, Empol trimer acid, anhydrides of these acids, and others. It is desirable that the above-mentioned polyfunctional monomer component is contained in a proportion of 20 to 30 mol% in each of the alcohol component or acid component as a structural unit in the polymer. As for styrene/acrylic resin, JP-A-50
-Contains the α,β-unsaturated ethylenic monomer described in Publication No. 134652 as a structural unit, and has a weight average molecular weight (Mw)/number average molecular weight (Mn) of 3.5
~40 resins can be used. It is desirable that the polyester resin or styrene/acrylic resin is contained in an amount of 30 to 95% by weight based on the total amount of the toner. To produce a toner, the binder contains a colorant and, if necessary, various additives, and is mixed using a ball mill or the like, kneaded,
The toner used in the present invention can be obtained through the steps of pulverization and classification. In addition, it can also be obtained by a manufacturing method other than the above, such as spray drying, interfacial polycondensation, suspension polycondensation, or solution polycondensation. The particle size of the toner obtained by the above method is 1 to
The thickness is 50 μm, preferably 5 to 30 μm. Specific examples of colorants contained in toner include:
For example, carbon black, nigrosine dye, aniline blue, calco oil blue, chrome yellow, ultramarine blue, methylene blue,
Mention may be made of rose bengal, phthalocyanine blue, or mixtures thereof. Further, the above-mentioned toner may contain fine powder of hydrophobic silica or fatty acid metal salt. Regarding fine silica powder, see Japanese Patent Publication No. 54-16219 and No. 54-
Although it is described in Japanese Patent No. 16220, a preferable example is "Aerosil" manufactured by Nippon Aerosil Co., Ltd.
Examples include "R972" and "Silica D-17". Examples of fatty acid metal salts include metal salts of maleic acid and zinc, magnesium, calcium, etc.;
Stearic acid and zinc, cadmium, barium,
Metal salts with lead, iron, nickel, cobalt, copper, aluminum, magnesium, etc.; dibasic lead stearate; oleic acid with zinc, magnesium,
Metal salts of iron, cobalt, copper, lead, calcium, etc.; metal salts of palmitic acid and aluminum, calcium, etc.; lead caprylate; lead caproate; metal lead of linoleic acid and zinc, cobalt, etc.; calcium ricinoleate metal salts of ricyleic acid and zinc, cadmium, etc., and mixtures thereof. The content is 0.01 to 10% by weight based on the toner. As the addition method, a so-called external addition method is preferably used. Further, examples of additives that may be added as necessary include offset inhibitors, charge control agents, and the like. The developer is obtained by mixing the carrier of the present invention and the toner, and the mixing ratio is that of the carrier.
It is preferably 0.5 to 20 parts by weight per 100 parts by weight. [Effects of the Invention] The carrier of the present invention has a coating layer as its main component, a crystalline fluorine-based polymer having a heat of fusion of 30 mJ/mg or less, and a second substance that inhibits the crystallinity of the fluorine-based polymer. Because it uses a polymer consisting of a polymer blend, a uniform coating film can be obtained even when large shear forces are applied.
Therefore, high-quality images can be obtained, and the triboelectric charging properties are very stable during long-term use, resulting in excellent durability. [Examples] Examples of the present invention will be described below, but the embodiments of the present invention are not limited thereto. (Manufacture of carriers) First, carriers A to I and comparative carriers A to C were manufactured as follows. (Carrier A) Polyvinylidene fluoride “KF Polymer #1000”
(manufactured by Kureha Chemical Co., Ltd.) and 4 g of polymethyl methacrylate "Delpet 80N" (manufactured by Asahi Kasei Industries, Ltd.) were dissolved in 500 ml of acetone-methyl ethyl ketone (1:4) mixed solvent to prepare a coating liquid. The core material is spherical ferrite “F-
100 (manufactured by Nippon Tetsuko Co., Ltd.) (1 kg) was coated using a fluidized rolling coating device "Spira Coater" (manufactured by Okada Seiko Co., Ltd.) at a disc rotation speed of 200 rpm to produce carrier A. In addition, when the heat of fusion of the coating resin of Carrier A was measured, it was 26 mJ/mg. (Carrier B) Carrier B was produced in the same manner as in Carrier A except that a coating liquid was prepared using 14 g of the polyvinylidene fluoride "KF Polymer #1000" and 6 g of the polymethyl methacrylate "Delpet 80N". The heat of fusion of the coating resin of Carrier B was 19 mJ/mg. (Carrier C) Polyvinidene fluoride “KF Polymer #1000”
19g and the following polymer (a) (intrinsic viscosity 0.50dl/g) 1
Carrier C was produced in the same manner as Carrier A, except that the coating liquid was prepared according to Example 1.g. The heat of fusion of the carrier C coating resin was 30 mJ/mg. Polymer (a): (Carrier D) 18g of "KF Polymer #1000", 2g of Polymer (a)
Carrier D was manufactured in the same manner as Carrier C except that a coating liquid was prepared as Example 1.g. The heat of fusion of the carrier D coating resin was 25 mJ/mg. (Carrier E) 16g of "KF Polymer #1000", 4g of Polymer (a)
Carrier E was manufactured in the same manner as Carrier C except that a coating liquid was prepared as Example 1.g. The heat of fusion of the carrier E coating resin was 20 mJ/mg. (Carrier F) 14g of "KF Polymer #1000", 6g of Polymer (a)
Carrier F was manufactured in the same manner as Carrier C except that a coating liquid was prepared as Example 1.g. The heat of fusion of the coating resin of Carrier F was 15 mJ/mg. (Carrier G) 12g of "KF Polymer #1000", 8g of polymer (a)
Carrier G was manufactured in the same manner as Carrier C except that a coating liquid was prepared as Example 1. The heat of fusion of the coating resin of Carrier G was 10 mJ/mg. (Carrier H) Vinylidene fluoride/ethylene tetrafluoride copolymer obtained by reacting vinylidene fluoride and ethylene tetrafluoride at a molar ratio of 85:15 (intrinsic viscosity 0.92
dl/g) 18g and the following polymer (b) (intrinsic viscosity 0.61
Carrier H was manufactured in the same manner as Carrier A except that the coating liquid was prepared using 2 g (dl/g). The heat of fusion of Carrier H's coating resin is 28 m
J/mg. Polymer (b): (Carrier I) “KF Polymer #1000” 16g and “Delpet
Prepare a coating liquid by dissolving 4g of ``80N'' in 100ml of acetone-methyl ethyl ketone (1:4) mixed solvent, and immerse 1kg of spherical ferrite ``F-100'', which is a carrier core material, in this coating liquid. The container was kept warm at 60° C., rotated for 30 minutes at an impeller rotation speed of 1000 rpm, dried and sieved to produce Carrier I. In addition, when the heat of fusion of the coating resin of Carrier I was measured, it was 20 mJ/mg. Comparison carrier A Polyvinylidene fluoride “KF Polymer #1000”
Comparative carrier A was produced in the same manner as carrier A except that only 20 g of polymethyl methacrylate "Delpet 80N" was used. In addition, when the heat of fusion of the coating resin of Comparative Carrier A was measured, it was 38 mJ/mg. Comparison carrier B Polyvinylidene fluoride “KF Polymer #1000”
18g and polymethyl methacrylate "Delpetu"
Comparative carrier B was manufactured in the same manner as carrier A except that 2 g of ``80N'' was used to prepare the coating liquid.
was manufactured. In addition, when the heat of fusion of the coating resin of Comparative Carrier B was measured, it was 32 mJ/mg. Comparative Carrier C Comparative Carrier C was produced in the same manner as in Carrier A except that the coating solution was prepared using only 20 g of the vinylidene fluoride/tetrafluoroethylene copolymer obtained in the production of Carrier H. In addition,
When the heat of fusion of the coating resin of Comparative Carrier C was measured, it was 35 mJ/mg. (Evaluation of carriers) Carriers A to I of the present invention and comparative carriers A to
When C was observed using an electron microscope, it was found that uniform coating films were formed in all of carriers A to H of the present invention, but fibrillation of the coating resin was observed on the surfaces of comparative carriers A to C. (Production of toner) 180 g of 1,4-butanediol, 307 g of terephthalic acid, and 45 g of isophthalic acid were placed in a round-bottomed flask equipped with a thermometer, a stainless steel stirrer, a glass nitrogen gas inlet tube, and a flowing condenser. The flask was placed in a mantle heater, and nitrogen gas was introduced from the nitrogen gas introduction tube to raise the temperature while maintaining an inert atmosphere inside the flask. Then, add 0.05 g of dibutyltin oxide and raise the temperature to 200 ml while monitoring the reaction at the softening point.
The reaction was carried out at ℃ to produce a polyester resin. 100 parts by weight of this polyester resin, 10 parts by weight of carbon black "Regal 660R" (manufactured by Cabot), low molecular weight polypropylene "Viscol"
2 parts by weight of ``660P'' (manufactured by Sanyo Chemical Industries, Ltd.) and 2 parts by weight of ethylene bisstearoylamide ``Hoechstwax C'' (manufactured by Hoechst Corporation) were mixed in a ball mill, and through the steps of kneading, pulverization and classification, an average particle size of 11 μm was obtained. Toner particles were prepared by mixing 0.4% by weight of hydrophobic silica differential powder "Aerosil R-812" (manufactured by Nippon Aerosil Co., Ltd.) and 0.1% by weight of zinc stearate. (Examples and Comparative Examples) Carriers A to I of the present invention and comparative carriers A to
C was mixed with toner at a toner concentration of 3.5 wt%, and a total of 9 types of developers according to the present invention and a total of 3
A comparative developer was prepared. Next, the electrophotographic copying machine "U-
Bix 2500MR (manufactured by Konishiroku Photo Industry Co., Ltd.) was used to make continuous copies of up to 50,000 copies of each developer, and the occurrence of fogging after every 5,000 copies was investigated. Table 1 shows the results at the initial stage, after 10,000 copies, after 30,000 copies, and after 50,000 copies. In the table, "charge amount" is the amount of triboelectric charge per gram of toner measured by a known blow-off method, and "fogging" is the black area ratio of the portion of the copied image that corresponds to the white area of the original image. The evaluation was based on the values measured with a halftone dot analyzer "Sakura Area Duck-100" (manufactured by Konishiroku Photo Industry Co., Ltd.). Note that long runs were discontinued when the black ground area ratio exceeded 0.7%, as fogging was significant.

[Table] As is clear from Table 1 above, the developer using the carrier of the present invention had no or almost no fog up to 50,000 copies, and even after 50,000 copies, high image density and good images were obtained. On the other hand, when using a developer using a comparative carrier, fogging occurred during continuous use and the image quality deteriorated significantly.

Claims (1)

[Claims] 1. On the carrier core material, the main component is a polymer consisting of a polymer blend of a crystalline polyvinylidene fluoride polymer and a second polymer that inhibits the crystallinity of the polyvinylidene fluoride polymer, and In a method for producing a carrier for electrostatic image development that forms a coating layer with a heat of fusion of 30 mJ/mg or less, rotational force is applied by spraying a coating liquid or immersing the carrier core material in the coating liquid while floating or flowing the carrier core material. 1. A method for producing a carrier for electrostatic image development, characterized in that a coating layer is formed on a carrier core material while shearing the carrier core material by applying shear or by supplying a high-pressure jet flow.