JPH02187771A - Polyolefin type resin coated carrier - Google Patents

Abstract

PURPOSE:To prevent deterioration in image quality even at the time of successive copying and to improve durability and resistance to spent production by incorporating specified fine particles and a >=90% carrier core material in a polyolefin resin coated layer having a rugged structure on the surface. CONSTITUTION:The polyethylene resin coating layer has the rugged structure on the surface, and this layer contains the fine particles having a load controlling function and/or fine electrically conductive particles as additives and the carrier core material in a content of >=90%. The surface-rugged polyethylene resin coated carrier exhibits an effect when electric resistance, coating ratio, filling rate, and specific gravity are each in the prescribed range, dependent on the relationship of the carrier core material and the coating layer. The electrifiability effects of each component and the toner are synergistically enhanced by adding the load giving fine particles, and the resistance of the carrier is properly lowered by adding the fine conductive particles, and leakage and storage of electric charge are executed in good balance, and deterioration of an image is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a carrier used in a two-component development system, and more particularly to a carrier coated with a polyolefin resin.

Conventional technology Conventionally, as an electrostatic latent image development method for electrophotography, by mixing insulating non-magnetic toner and carrier particles,
A two-component development system is known in which toner is triboelectrically charged and a developer is conveyed and brought into contact with an electrostatic latent image for development.

The granular carrier used in such a two-component development method has the following properties: prevention of toner filming on the carrier surface, formation of a uniform surface of the carrier, prevention of surface oxidation, prevention of deterioration of moisture sensitivity, extension of developer life, and photosensitivity. It is usually coated with an appropriate material for reasons such as protection from scratches or abrasion caused by carriers on the body, control of charge polarity, or adjustment of charge amount.

As such a coating material, a carrier to which polyolefin resin is applied is known (for example, Japanese Patent Laid-Open No. 52
-154639, JP-A-54-35735, etc.).

JP-A-52-154639 discloses that a carrier whose surface is coated with polyethylene resin can be obtained by heating and melting polypropylene resin or the like in a suitable solvent and spraying the molten resin onto a carrier core material. do.

Japanese Unexamined Patent Publication No. 54-35735 discloses a coated carrier in which coating material powder is adhered to the surface of carrier particles and fixed by heating to a temperature higher than the melting point of the coating material.

However, carriers whose surfaces are coated with polyolefin resin as described above have poor durability, such as poor adhesion between the coating layer and the carrier, and the coating material peeling off when continuously copied. be. Further, the above manufacturing method has drawbacks such as difficulty in controlling the film thickness.

Problems to be Solved by the Invention The present invention is based on the polyol-3 resin, which does not deteriorate in image quality even after continuous copying and has excellent durability and spent resistance. It can be seen that it has Conventionally, there is no carrier that has such a convex portion on the surface of the carrier, and the convex portion is made of polyethylene resin.

For reference, the second photo shows the particle structure of the carrier provided with the thermosetting acrylic resin coating layer by spray drying.
As shown in the figure. FIG. 2 is a photograph of the carrier obtained in Comparative Example 4, which will be described later, magnified 1500 times using a reflection electron microscope. Although the photograph in Figure 2 was taken at a higher magnification than that in Figure 1, the surface is smooth, and it can be seen that there is a clear difference in its structure compared to the surface in Figure 1. Although a thermosetting acrylic resin coated carrier is shown in Figure 2, the surface structure of a carrier simply coated with polyethylene resin by spray drying, fusion bonding, etc. is similar to that shown in Figure 2. Therefore, repeated use of such a carrier as a developer causes insufficient durability (peeling of the coating layer), an increase in the amount of spent toner, and a decrease in image quality.

The purpose of the present invention is to provide a reflex resin-coated carrier.

Means for Solving the Problems The present invention comprises a polyolefin resin coating layer having an uneven surface structure, the resin coating layer containing as an additive fine particles having charge control ability and/or conductive fine particles, and a carrier. The present invention relates to a polyolefin resin-coated carrier having a core material content of 90% or more.

The carrier of the present invention is coated with a polyolefin resin, and is characterized by the form of the polyolefin resin coating layer. For ease of understanding, FIG. 1 shows a photograph showing the particle structure of the carrier of the present invention having a polyethylene resin coating layer. Hereinafter, in this specification, the term polyethylene will be used to represent the term polyolefin, and a carrier having a polyethylene resin coating layer will be described. FIG. 1 shows a photograph of a carrier obtained in Carrier Production Example 1, which will be described later, magnified 1000 times using a reflection electron microscope.

Although it is difficult to directly define such a convex portion, the following formula [
11 In formula 1, the outer periphery represents the outer periphery of the projected image of the carrier particles, and the area represents the average value of the projected areas of the carrier particles. ], the value is 130 to 200
, preferably 140-170. The S value represents the degree of unevenness on the particle surface, and the greater the degree of unevenness of the surface state, the further the value becomes from 100. If the value is less than 130, the coating layer will inevitably become thinner and the electrical resistance will decrease, resulting in carrier development. Moreover, if it is larger than 200, fluidity will be impaired and the coating layer will be likely to peel off.

In the present invention, the shape factor S refers to the average value measured by an image analyzer (Luzex 5000, manufactured by Nippon Regulator Co., Ltd.), but in general, there is no large difference in the measurement of the shape factor S depending on the model. However, this does not mean that the measurement must be performed with the above-mentioned model in particular.

A polyethylene resin-coated carrier with an uneven surface is
Furthermore, the electrical resistance, coverage rate, filling rate, specific gravity, etc. obtained by the relationship between the carrier core material and the structure of the coating layer have values within a certain range, and the objectives and effects of the present invention are more effective within that range. can be achieved.

The carrier core material should be at least 20 μm (average particle diameter) in order to prevent carrier adhesion (scattering) to the electrostatic latent image carrier, and to prevent carrier streaks and other deterioration in image quality. From the viewpoint of prevention, use one with a maximum value of 1100p. Specific materials include those known as two-component carriers for electrophotography, such as metals such as ferrite, magnetite, iron, nickel, and cobalt, and these metals and zinc, antimony, aluminum, lead, tin, bismuth, beryllium, and manganese. , alloys or mixtures with metals such as selenium, tungsten, zirconium, and vanadium; metal oxides such as iron oxide, titanium oxide, and magnesium oxide; nitrides such as chromium nitride and vanadium nitride; and carbides such as silicon carbide and tungsten carbide. and ferromagnetic ferrite, as well as mixtures thereof, etc. can be applied.

The surface of the carrier of the present invention is preferably covered with polyethylene resin by at least 70%, preferably at least 90%, more preferably at least 95%. If the coverage is less than 70%, the characteristics of the carrier core material itself (unstable environmental resistance, decreased electrical resistance, unstable charging) will be strongly visible through the background, making it impossible to take advantage of the advantages of the resin coating.

The filling rate of the carrier core material is set to about 90 wL% or more, preferably 95 wt% or more. The filling rate is expressed as something that indirectly defines the thickness of the resin coating layer of the carrier. If the carrier filling rate is less than 90 wt%, the coating layer becomes too thick, and even if it is actually applied to a developer, Problems such as peeling off of the coating layer, increase in the amount of charge, etc., which do not satisfy the durability and charge stability required of the developer, and poor fine line reproducibility and decrease in image density occur in terms of image quality. .

It is also possible to indirectly express the thickness of the polyethylene resin coating layer in terms of specific gravity. The specific gravity of the carrier of the present invention is greatly influenced by the type of carrier core material, but as long as the carrier core material is used, the specific gravity is 3.5 to 7°5, preferably 4.0 to 6.
．． 0, more preferably a value within the range of about 4°0 to 5.5. If the value is outside this range, the same problems as those caused by the carrier not being coated with an appropriate filling rate will occur as described above.

The electrical resistance of the polyethylene resin coating layer having an uneven surface according to the present invention is set to about lXl0' to 1xlOI4Ω·c+n, preferably 10' to 10”Ω·c+++1, more preferably IO! to 1012Ω·c1R. Electrical resistance If it is less than lXl0'Ω·cIR, carrier development will occur and the image quality will deteriorate.If it is larger than lXl0″Ω·cm, the toner will be excessively charged and proper image density will not be obtained. It can be considered that the electrical resistance indirectly expresses the polyethylene resin coverage rate and carrier filling rate described above.

Additives such as fine particles having a charge imparting function or conductive fine particles are added to the carrier-coated polyethylene layer of the present invention.

Fine particles with a charge imparting function include CrO2, Fe
203% F e3o 4s Iro ts Mn
Oz-, MoO2sNbOx, PtO2, Tie,,T
i20. ,Ti,O,,Wo 2,V to s,A
Metal oxides such as l*os, MgO1Si02, ZrO2, BeO, Nigrosine base, Subiron black T
Specific examples include dyes such as RH.

Examples of conductive fine particles include carbon black, carbon black such as acetylene black, and SiCSiC1T1C.
Carbides such as X% ZrC, BN% NbN.

Examples include nitrides such as TiN and ZrN, and magnetic powders such as ferrite magnetite.

Addition of metal oxides, metal fluorides, and metal nitrides is effective in further increasing chargeability. It is believed that such an effect is produced by the synergistic charging effects of each component and the toner due to contact between the toner and a complex interface composed of these compounds, polyethylene, and the core material.

Addition of carbon black is effective in improving developability and obtaining images with high image density and clear contrast. It is thought that this is because the addition of conductive fine particles such as carbon black lowers the electrical resistance of the carrier appropriately, and the leakage and accumulation of charges are performed in a well-balanced manner.

One of the characteristics of conventional binder type carriers is that they have excellent halftone reproducibility and gradation reproducibility, but in the case of the coated carrier of the present invention, magnetic powder is added to the polyethylene resin coating layer. As a result, a carrier with excellent gradation reproducibility can be obtained. This is thought to be because the addition of magnetic powder to the polyethylene coating layer resulted in a surface composition similar to that of the binder-type carrier, and the chargeability and specific gravity approached those of the binder-type carrier.

Addition of borides and metal carbides has an effect on the rise of charging.

Regarding the size, amount, etc. of the additive, a particular method is suitable as long as it satisfies the various properties of the carrier of the present invention, such as unevenness, coverage, electrical resistance, etc. described herein.

This publication is hereby incorporated by reference as part of this specification. That is, the polyethylene coating layer contains (1) a highly active catalyst component that contains titanium and/or zirconium and is soluble in a hydrocarbon solvent, (2) a product obtained by contacting a carrier core material in advance, and (2) an organoaluminum compound. It can be formed by polymerizing ethylene on the surface of the carrier core material. Furthermore, when fine particles having a charge imparting function or conductive fine particles are added, these additives may be added and present at the time of forming the polyethylene coating layer.

This polyethylene forming method forms a polyethylene coating layer directly on the surface of the carrier core material, so the resulting film has excellent strength and durability.

In particular, the weight average molecular weight of polyethylene is 5.0×10”
~5.0XlO', preferably 1. OXl'0'~4.
5XIO'% more preferably 5.0XIO' to 4.0X
When it is IO', the polyethylene resin layer can have excellent resin strength and adhesion to the carrier.

Although not limited, in relation to the preferable method for manufacturing the carrier of the present invention described later, the size of the fine particles should be, for example, a particle size that can be uniformly dispersed into a slurry without agglomerating in dehydrated hexane. Specifically, the average particle size is 2 to 0.01 μm, preferably 1 to 0.01 μm.
It is sufficient that the thickness is about 01 μm.

Further, the amount of the micrometer particles added cannot be specified in part as described above, but it is 0.1 wL% to 60 wt%, preferably 1.9 wt% to the coated polyethylene resin. 40 wt% is appropriate.

In particular, when the filling rate of the carrier is as low as about 90 wt% and the thickness of the coating layer is relatively thick, when continuous copying of fine lines is performed using such a carrier, a problem arises in that the reproducibility decreases. Such problems are solved by adding the above additives.

The production of the carrier of the present invention is not particularly limited,
Known methods can be applied, but for example, as described in JP-A-60-106808, in order to further enhance the adhesion between the polyethylene resin layer and the carrier core material, conditions such that the molecular weight is low at the initial stage of polymerization are used. It is effective to carry out the polymerization at

As long as the coating film formed on the carrier surface satisfies the same conditions as the polyethylene resin coating layer on the carrier surface, such as uneven structure, coverage rate, filling rate, electrical resistance, etc. Also applicable are olefinic resins such as polypropylene.

The carrier according to the present invention is mixed with a known toner and used as a two-component developer.

Carrier Production Example 1 (1) Preparation of titanium-containing catalyst component In a flask with an internal volume of 500 m12 purged with argon, 200 m of dehydrated n-hebutane was added at room temperature. 2 and magnesium stearate 159 (25 mmol), which had been previously dehydrated at 120° C. under reduced pressure (2 mmHg), were added to form a slurry. After 0.449 (2.3 mmol) of titanium tetrachloride was added dropwise with stirring, the temperature was started to rise, and the mixture was reacted under reflux for 1 hour to obtain a viscous and transparent solution of the titanium-containing catalyst component.

(2) Activity evaluation of titanium-containing catalyst components In an argon-substituted autoclave with an internal volume of 1a, 400 mQ of dehydrated hexane, 0.8 mmol of triethylaluminum, 0.8 mmol of diethylaluminum chloride, and the titanium-containing catalyst obtained in (1) above. Collect 0.001℃ mole of titanium atom as the component, add it, and heat to 90℃.
The temperature rose to . At this time, the system internal pressure is 1.5 kg/c
It was m2G. Next, hydrogen was supplied and 5.5 kg
/cm2G, the total pressure is 9-5 kg/cm2G.
Ethylene was continuously supplied so as to be maintained at cm"G, and polymerization was carried out for 1 hour to obtain 70 g of polymer. The polymerization activity was 365&9/g・Ti/Hr, and the MFR of the obtained polymer ( The melt flowability (JIS K7210) at 190° C. and a load of 2.16 kg was 40.

(3) Reaction of titanium-containing catalyst component and filler and polymerization of ethylene When dehydrated hexane is used at room temperature at 500 m<+ and 200°0 in an argon-substituted autoclave with an inner volume of 1 g, the ferrite surface is thinly covered with polyethylene and trioxidized. Molybdenum was observed to be uniformly dispersed in the polyethylene. In addition, when this composition was measured by TGA (thermal balance), the total content of ferrite and molybdenum trioxide was 95.8%, and when calculated from the amount charged, the content of ferrite, polyethylene, and molybdenum trioxide was 22%.
．． The weight ratio was 5:1:0, 1O.

Carrier Production Example 2 In an autoclave with an internal volume IQ that was purged with argon, in the same manner as in Production Example 1 (3), the titanium-containing catalyst component prepared in Production Example 1 (1) was added to 450 g of ferrite as titanium atoms. .02 mmol was added and the reaction was carried out for 1 hour. After that, add carbon black (etchen black E) from the upper nozzle of the autoclave.
C, manufactured by Lion Akzo Co., Ltd.) 0°229 was added. Naori-Bon black was dried under reduced pressure at 200° C. for 1 hour and made into a slurry with dehydrated hexane. Then triethyl aluminum 2
．． 450 g of sintered ferrite powder F-300H (manufactured by Nippon Tetsuko Co., Ltd., average particle size 60 μm) dried under reduced pressure (2 Hg) for 3 hours at 0 mm was added, and stirring was started. Next, the temperature was raised to 40°C, and 0.02 mmol of the titanium-containing polymerization catalyst component (1) was added as titanium atoms, and the reaction was carried out for about 1 hour. Thereafter, 2.0 g of molybdenum trioxide (manufactured by Shin Nippon Metal Co., Ltd., average particle size: 0.4 μm) was charged from the upper nozzle of the autoclave.

The molybdenum trioxide used was one that had been dried under reduced pressure at 200° C. for 1 hour and made into a slurry with dehydrated hexane. Then triethyl aluminum 2.
0 mmol and 2.0 mmol of diethylaluminium chloride were added, and the temperature was raised to 90°C. The system internal pressure at this time was 1.5 kg7 cm2G. Next, hydrogen was supplied and the pressure was increased to 2 kg/cm"G, and the total pressure was increased to 6 to 9.
Polymerization was carried out for 58 minutes while continuously supplying ethylene so as to maintain the pressure at 7 cm"G, and a total amount of 472 g of a polyethylene composition containing ferrite and molybdenum trioxide was obtained.

The dried powder had a uniform gray color and was observed under an electron microscope. 2.0 mmol of diethylaluminum chloride was added and the temperature was raised to 90°C. The system internal pressure at this time is 1.5k
g/cm"G. Next, hydrogen was supplied, and 9/cm"G was added to 2.
After increasing the pressure to cm2G, polymerization was carried out for 45 minutes while continuously supplying ethylene to maintain the total pressure at 6 kg/cm"G, to obtain a total amount of 472 g of a polyethylene composition containing ferrite and carbon black. Dry powder. was uniformly black, and electron microscopy revealed that the ferrite surface was thinly covered with polyethylene, and carbon black was uniformly dispersed in the polyethylene.

In addition, when this composition was measured by TGA (thermal balance), the ferrite content was 95.3 wt%, and when calculated from the amount charged, the weight ratio of ferrite, polyethylene, and carbon black was 21:l:0.01. Ta.

The conditions and results are shown in Table 1.

Carrier Production Example 3 In Carrier Production Example 2, polymerization was carried out in the same manner as in Production Example 2 except that the amount of carbon black was as shown in Table 1. The conditions and results are shown in Table 1.

Carrier Production Example 4 In a argon-substituted autoclave with an inner volume of 1Q, 50% of dehydrated hexane
0 mQ, and 450 g of ferrite was charged. Next, 1.0 mmol of diethylaluminium chloride was added with stirring, and after treatment at 40°C for 30 minutes, Production Example 1
The titanium-containing catalyst component prepared in (1) was added in an amount of 0.02 mmol as titanium atoms, and the reaction was carried out for 1 hour.

Thereafter, magnetite was dried at 200°C for 3 hours under reduced pressure (2mmHg) RB-BL fine particles (manufactured by Titan Kogyo Co., Ltd.)
7.5 g of triethylaluminum and 2.0 mmol of triethylaluminum were added, and the temperature was raised to 90°C. At this time, the system internal pressure is 1
, 5 kg/cm2G. Next, hydrogen was supplied and the pressure was increased to 1.7kg/cm2G, and then ethylene was continuously supplied to maintain the total pressure at 3.2 kg/cm2G. Polymerization was carried out for 1 minute to obtain a composition with a total amount of 495 g.The dried composition powder contained free 11, L
Polymerization was carried out in the same manner as in Production Example 2, except that 4.39% of each of the above components was added.

The conditions and results are shown in Table 1.

Carrier Production Example 9 In the same manner as in Carrier Production Example 1, the titanium-containing catalyst component prepared in Production Example 1 (1) was added to 450 g of ferrite in an argon-substituted autoclave with an internal volume of IQ. 0.01 mmol was added and the reaction was carried out for 1 hour. Then, pour carbon black (Ketchen black E) from the upper nozzle of the autoclave.
C, manufactured by Lion Akzo Co., Ltd.) 0.469 was added. The Naori-Pon black used was one that had been dried under reduced pressure at 200° C. for 1 hour and made into a slurry with dehydrated hexane. Thereafter, 1.0 mmol of triethylaluminum and 1.0 mmol of diethylaluminum chloride were added, and the temperature was raised to 90°C. At this time, the system internal pressure is 1
, 5 kg7 cm"G. Next, 1-butene 3
7.5 mmol (2,19) was introduced, then hydrogen was supplied, the pressure was increased to 97 cm"G, and the total pressure was increased to 6729
The presence of fine magnetite powder was hardly observed, and observation using an electron microscope confirmed that fine magnetite powder was uniformly dispersed in the polyethylene on the ferrite (60 μm) surface. When this composition was measured by TGA (thermal balance), the content of ferrite and magnetite was 92.4 wt%, and when calculated from the amount charged, the weight ratio of ferrite (60 μm), polyethylene, and fine magnetite powder was 12:1. :0.2.

The conditions and results are shown in Table 1.

Carrier Production Example 5 Polymerization was carried out in the same manner as in Production Example 4, except that the amount of magnetite fine powder RBBL (manufactured by Titan Kogyo Co., Ltd.) was changed to 6.6 g.

The conditions and results are shown in Table 1.

Carrier Production Examples 6 to 8 In Carrier Production Example 2, silicon carbide (manufactured by Ibiden Co., Ltd.), zinc oxide (23-, produced by Sakai Chemical Industry Co., Ltd.), and conductive were used instead of carbon black, respectively. Titanium oxide (manufactured by Mitsubishi Metals Co., Ltd.) at 11.7,/cm'G
Polymerization was carried out for 33 minutes while continuously supplying ethylene so as to maintain the temperature of 469 g of a polyethylene composition containing ferrite and carbon black. The dried powder had a uniform black color, and electron microscopy revealed that the ferrite surface was thinly covered with polymer, and the carbon black was uniformly dispersed in the polymer.

When this composition was measured by TGA (thermal balance) and converted from the amount charged, the weight ratio of ferrite, polymer, and carbon black was 97:4:O', l. Furthermore, when the polymer from which ferrite and carbon black were removed by Soxhlet extraction (solvent: xylene) was analyzed by rR, it was confirmed that it was a polyethylene copolymer containing 8 wt % of butene.

Carrier Production Examples 10 and 11 In Carrier Production Example 2, stannous fluoride (manufactured by Morita Chemical Industries, Ltd.) and silicon nitride (manufactured by Japan Shinkinzoku Co., Ltd.) were used instead of carbon black, respectively. 1.19.
Polymerization was carried out in the same manner as in Production Example 2 except that 5.2 g of each was added.

The conditions and results are shown in Table 1.

(Hereinafter, blank spaces) Carrier Production Examples 12 to 33 Carriers were produced in the same manner as Carrier Production Example 1, except that the following additives were added instead of molybdenum trioxide.

Detailed manufacturing conditions are shown in Table 1.

The manufacturers of the above additives are as follows.

Molybdenum trioxide (Moss): manufactured by Nippon Shinkinzoku Co., Ltd. Zinc oxide (ZnO): 23-; manufactured by Sakai Chemical Industry Co., Ltd. Ferrous fluoride (F eF): Nakeda Kagaku Kogyo Co., Ltd. ): Titanium nitride (T)
iN): Titanium boride (TiB2) manufactured by Nippon Shinkinzoku Co., Ltd.
): Same as above Silicon carbide (SiC): Showa Denko K.K.
Acetylene black manufactured by Denki Kagaku Kogyo Co., Ltd.: Magnetite powder RB-BL manufactured by Denki Kagaku Kogyo Co., Ltd.: Titanium dioxide (Tioz) manufactured by Titanium Kogyo Co., Ltd.: R830; Magnesium oxide (MgO) manufactured by Ishihara Sangyo Co., Ltd.: 500 -IW; Asahi Glass (
Magnesium fluoride (MgFz) manufactured by Kado Kagaku Kogyo Co., Ltd.: Silicon nitride (StsN4) manufactured by Barade Kagaku Kogyo Co., Ltd. Zirconium boride (ZrBz) manufactured by Honjo Metal Co., Ltd.: Same as above Tungsten carbide (WC): Same as above Ketchen Black E
C: Ferrite powder MFP-2 manufactured by Lion Akzo Co., Ltd.
: Manufacture example 34 of carrier manufactured by TDK Corporation In the same manner as in manufacturing example 1 of the carrier, the titanium-containing catalyst prepared in (1) of manufacturing example 1 was added to 450 g of ferrite in an argon-substituted autoclave with an internal volume of H2. The components were added in an amount of 0.01 mmol in terms of titanium atoms, and the reaction was carried out for 1 hour. After that, carbon black (Ketchen black) is added from the upper nozzle of the autoclave.
black) EC.

0.509 (manufactured by Lion Akzo) was used. Naori-
The pom black used was one that had been dried under reduced pressure at 200° C. for 1 hour and made into a slurry with dehydrated hexane. Thereafter, 1.0 mmol of triethylaluminum and 1.0 mmol of diethylaluminum chloride were added, and the temperature was raised to 90°C. The system internal pressure at this time is 1,5
kg7 cm”G.Next, 1-butene37.
5 mmol (2.1 g) was introduced, then hydrogen was supplied,
After increasing the pressure to 2 hg/cm2c, the total pressure was increased to 6729/cm2c.
Polymerization was carried out for 28 minutes while continuously supplying ethylene so as to maintain the temperature at cm''G, and a total amount of 467 g of a polyethylene composition containing ferrite and carbon black was obtained.

The dried powder had a uniform black color, and electron microscopy revealed that the ferrite surface was thinly covered with polymer, and the carbon black was uniformly dispersed in the polymer. In addition, when this composition was measured by TGA (thermal balance), the weight ratio of ferrite, polymer, and carbon black was 27:1:0.03. Furthermore, when the polymer from which ferrite and carbon black were removed by Soxhlet extraction (solvent: xylene) was analyzed by IH, it was confirmed that it was a polyethylene copolymer containing 8 wt % of butene.

Carrier Production Example 35 Carrier Production Example 23 was carried out under the same conditions except that spherical iron powder (manufactured by Kanto Denka Kogyo Co., Ltd., 5T-60, average particle size 65 μm) was used as the core material.

The ferrite filling rate (wt%) of the carriers obtained in Carrier Production Examples 1 to 35 (however, the filling rate of iron powder in Example 35), specific gravity, and weight average molecular weight of the polyethylene resin layer (M
W), electrical resistance (Ω·c+n), and coverage (%) are shown in Table 2 below.

Note that the ferrite filling rate (wt%) was calculated from the weight ratio of 7 erite determined by TGA.

Specific gravity measurement is ・Electronic balance: Sensitivity 0, 1 mg.

・Vicnometer: A pycnometer with a Gerussac thermometer specified in JIS R3501 (glassware for analytical chemistry), internal volume 50+++L ・Thermostatic water tank: Capable of maintaining water temperature at 23±0.5℃.

The measurement was carried out using a measuring device equipped with the following procedure.

■The mass of the pre-dried vicinometer is O8lt.
Weigh accurately to the ng digit.

■Fill the vicnometer with sufficiently degassed n-hebutane and keep it in a constant temperature water bath at 23 ± 0.5°C for 1 hour.
Align the liquid surface accurately with the marked line.

Take it out of the constant-temperature water tank, wipe the outside water completely, and then
Weigh the mass accurately to the order of O, 1m9.

■Next, after emptying the vicinometer, sample lO~1
59 sample, weigh it again accurately to the nearest 0.1 mg, and subtract the result from (2) to determine the mass of the sample.

■ Gently add 20 to 30 mQ of degassed n-heptane to the pycnometer containing the sample to completely cover the sample, and then gently remove air from the liquid in a vacuum desiccator.

0 Next, the n-
Fill with hebutane and keep in a constant temperature water bath at 23±0.5°C for 1 hour. After accurately aligning the liquid surface with the marked line, take it out, wipe off the water from the outside, and measure its mass in O, l.
Weigh accurately to the digit of rr+9.

■Specific gravity is calculated using the following formula.

Place the sample so that the diameter is 50 mm, and the mass is 895° 4 g.
An electrode with a diameter of 20 mm and a guard electrode with an inner diameter of 38 mm and an outer diameter of 42 mm were mounted, and the current value after 1 minute when a DC voltage of 500 V was applied was read and converted to the volume resistivity P of the sample.

The measurement environment was a temperature of 25 degrees C1 and a relative humidity of 55±5%, and the measurements were repeated five times and the average was taken.

In the present invention, the carrier coverage rate is measured using an image analyzer (Luzex 5000; manufactured by Nippon Regulator Co., Ltd.)
This is the average value measured by the above-mentioned model, but in general, when measuring the I coverage rate, there is no significant difference depending on the model used for measurement, so it does not mean that the measurement must be performed with the above model. In other words, a carrier image obtained by a reflection electron microscope is taken into an image analyzer, and this is used to measure the area of the part covered by the coating layer of the core material, and the proportion of that amount to the total area of the projected image of the particle is calculated. It was taken as the coverage rate.

Alternatively, on a carrier photograph obtained using a reflection electron microscope, the carrier particles of interest and their S = a-d
/ (b-c+a) where S: specific gravity.

a: Mass of sample (g).

b: Immersion liquid up to the marked line of the pycnometer Mass (g) when filled with

C: Pycnometer mark containing sample Quality when filled with immersion liquid up to the line Amount (9).

d: Specific gravity of the immersion liquid at 23°C.

The weight average molecular weight of the polyethylene resin coating layer was determined by gel permeation chromatography (GPC) under the following conditions.

Measuring device: Waters ALC-GPCl 50
C Column Nido-So T S K HM+GMHX
2 Solvent nitrichlorobenzene Temperature = 135°C Concentration = 5wrg/1OII112 Injection amount: 400μC Flow rate: 1μQ/min Electrical resistance is 1 mm thick on a metallic circular electrode.

There is also a method of copying the portion covered by the core material coating layer observed on the particles onto a tracing paper or the like, cutting out each portion, weighing it, and calculating the coverage rate from the weight ratio.

(Hereafter, blank space) ・Polyester resin 100 (softening point, 130°C; glass transition point, 60°C, AV25.0H
V38) ・Carbon black 5 (manufactured by Mitsubishi Kasei Corporation, MA#8) ・Dye 3 (manufactured by Odogaya Chemical Industry Co., Ltd., Spiron Black TRH) After thoroughly mixing the above materials in a ball mill, the mixture was heated to 140C. The mixture was kneaded on three heated rolls. After cooling the kneaded material,
It was coarsely ground using a feather mill and further finely ground using a jet mill. Next, air classification was performed to obtain a fine powder with an average particle size of 13 μm (toner A).

Toner Production Example 2 [(+) Chargeable Toner (Toner B
) Toner B was produced using the same method as in Toner Production Example 1 with the following composition.

Ingredients 1 part of ``Hayabusa'', styrene-n-butyl 100 methacrylate resin (softening point, 132°C; glass transition point, 60°C), carbon black 5 (manufactured by Mitsubishi Kasei Corporation, MA#8) Nigrosine dye 3 (Bontron N-01, manufactured by Orient Chemical Co., Ltd.) Example 1 A developer with a toner mixing ratio of 7 wt % was obtained using the carrier obtained in Carrier Production Example 1 and Toner B.

The toner charge amount at this time was +18.4 μC/g, and then a printing durability test was conducted using this developer.

EP-4902 (manufactured by Minolta Camera Co., Ltd.) was used as a copying machine. During the 500,000-sheet printing cycle, there were no major fluctuations in the toner charge amount or image density, and these were stable.

During printing, the amount of spent toner was measured at each point of 100,000 sheets, 300,000 sheets, and 500,000 sheets, and the reproducibility of fine lines was evaluated. To determine the amount of spent toner, sample the developer, separate the developer into toner and carrier using the blow-off method, immerse the isolated carrier in 20 ml of ethanol for 2 hours, filter it, and measure the absorbance at 500 nm of the filtrate. Measure with a spectrophotometer. Separately, a calibration curve is obtained for the dye component in the toner, and the amount of dye in the toner eluted is calculated from the absorbance at 500 nm. From this value and the proportion of dye contained in the toner, the amount of spent toner (mg/ca) is determined as the amount of toner fixed on the carrier.
Find rrier 1 g).

However, the amount of spent toner determined in this manner was almost 0, 0 m9/carrier l9, or was outside the range of the calibration curve, and thus showed a negative value. This shows that spent toner did not occur with this carrier after all. Table 3 summarizes the presence or absence of spent toner.

The reproducibility of fine lines was evaluated using a black line with a line width of 50 μm and a reflection density of 1.5. Some parts are missing (
(Large); Lines with extremely thin or missing lines were ranked as those that were rarely reproduced.

On the other hand, after storing this developer for 24 hours under high temperature and high humidity conditions of 35° and 185% RH, the toner charge amount was measured and showed a value of +18.1 μC/g. This shows that this carrier has excellent environmental friendliness.

Examples 2 to 35 Example 1 except for using the carrier and toner shown in Table 3
A developer was prepared and evaluated in the same manner as described above. However, when Toner A was used, the copying machine used for the printing durability test was EP-570.
2 (manufactured by Minolta Camera Co., Ltd.).

The results are shown in Table 3.

Comparative Example 1 A thermosetting resin coated carrier (acrylic resin coated carrier, F141-3040, Japanese iron powder (
Co., Ltd., average particle size 53.2 μm, S value 115, core material filling rate 99.3 wt%). Using this carrier and toner A, a developer with a toner mixing ratio of 7 wt % was obtained. The toner charge amount at this time was 11.7 μC/g. Furthermore, the toner charge amount attenuated significantly under high temperature and high humidity conditions.

Next, a printing durability test was conducted in the same manner as in Example 1 using this developer. During printing of 500,000 sheets, the toner charge amount decreased with the number of copies. As a result of examining the amount of spent toner at each time point of 100,000 copies, 300,000 copies, and 500,000 copies, it was found that the amount of spent toner gradually increased as the number of copies was made, as shown in Table 3. This confirms the cause of the decrease in toner charge amount during printing, and also indicates that this carrier has poor spent resistance. These results are summarized in Table 3 together with the results of the environmental tests.

Comparative example 2 Low density polyethylene (high wax 220P.

Mitsui Petrochemical Co., Ltd.) was heated and dissolved in toluene (2%
Solution) Using an iron powder carrier (AT = 50, manufactured by Kanto Denka Kogyo Co., Ltd., average particle size 50 μm) as a core material, 1
．． The coating was carried out so that a coating of 0 wt% was obtained.

The carrier thus obtained had an S value of 120, a core filling rate of 99.0 wt%, and an electrical resistance value of 1.

4XIO'Ω·cm, and the specific gravity was 5.0.

Using this carrier and toner A, the toner mixing ratio is 7w.
A developer of t% was obtained. The toner charge amount at this time is -18
．． At 2 μC/9.

Next, a printing company test was conducted in the same manner as in Example 1 using this developer. During printing of 500,000 sheets, both the number of copies and thin line areas (for example, 100 in a line chart)
The reproducibility of areas such as μm (density 1.2) or 5-point type (density 0.9) was poor. Since this is a characteristic of uncoated carriers, it suggests peeling of the coating layer.

Furthermore, the amount of spent toner of 0.0 g/1 g of carrier means that either no spent toner was generated or that the coating layer peeled off. These results are summarized in Table 3.

Comparative Example 3 Using the same material as in Comparative Example 2, the core material was 5.9
A carrier was obtained by setting conditions such that a coating of wt% was achieved.

The carrier thus obtained had an S value of 124, a core filling rate of 95.0 wt%, and an electrical resistance value of 5°2XIO.
Ω·cm, and the specific gravity was 4.6.

Using this carrier and toner B, the toner mixing ratio is 7w.
A developer of t% was obtained. At this time, the toner charge amount is +26
．． It was 8μ/C/9. However, like Comparative Example 1, the reproducibility of fine lines during printing was poor.

These results are also summarized in Table 3.

Comparative Example 4 Acrylic resin solution with solid ratio of 2% (Acrydec A405
; manufactured by Dainippon Ink Co., Ltd.) with 3% molybdenum trioxide (manufactured by Nippon Metal Co., Ltd., average particle size 0.4 μm) added to the solid content, and thoroughly dispersed by ultrasonic waves. was used as the coating liquid. Sintered ferrite powder (F-300
H, manufactured by Nippon Tetsuko Co., Ltd., average particle size 60 μl 11), was applied to the core material using a spira coater (manufactured by Kaida Seiko Co., Ltd.) so that a coating of 10 wt % was obtained. Thereafter, the temperature in the system was raised to 150° C. to cure the resin, thereby obtaining a carrier coated with a thermosetting acrylic resin.

Ferrite filling rate 90.3% S value 197 Carrier specific gravity 3.61 Resin layer MW (GPC value) 6.4XI O' additive
None Carrier electrical resistance 1.0Xlo”Ω・cm Coverage rate
A carrier having the characteristics of 100% was obtained.

A developer was prepared using this carrier and toner A, and Example 1
The results were shown in Table 3.

(Hereafter, blank space) The S value of the carrier obtained in this way is 118, the core material filling rate is 99.2 wt%, and the electrical resistance value is 4.3 x l Q
The resistance was 10Ω·cm, and the specific gravity was 5.07.

Using this carrier and toner B, the toner mixing ratio is 7W.
A developer of L% was obtained. At this time, the toner charge amount is +12
．． It was 1 μC/g. However, during the printing durability test, the toner charge amount decreased as the number of printing sheets increased. Apart from this, it was confirmed that toner was becoming spent.

Comparative Example 5 Ethylene polymerization conditions without adding additives Ferrite charge amount 450g Catalyst addition amount [Ti] 0.02 mmol Polymerization conditions Time 51 minutes Temperature 90°C Pressure Ethylene 6ky/cm2G Hydrogen 3
kg/cm2G Yield: 500g The carrier of the present invention was produced in the same manner as in Carrier Production Example 1. Effects of the Invention The carrier of the present invention has excellent electrostatic properties, spent resistance, charging stability, and environmental resistance, and is of high quality. Effective for image formation,
Their effectiveness is maintained even after continuous long-term use of the carrier.

[Brief explanation of the drawing]

FIG. 1 is a photograph showing the structure of carrier particles of the present invention coated with a polyethylene resin coating layer having an uneven structure on the surface. FIG. 2 is a photograph showing the particle structure of a carrier having a polyacrylic resin coating layer formed by spray drying.

Claims (1)

[Scope of Claims] 1. A polyolefin resin coating layer having an uneven surface structure, the resin coating layer containing fine particles having charge control ability and/or conductive fine particles as an additive, and a carrier core material. A polyolefin resin-coated carrier having a content of 90% or more. 2. The surface unevenness is calculated using the following formula: S = {(outer circumference)^2/area} x (1/4π) x 100[
2. The carrier according to claim 1, wherein the outer circumference represents the outer circumference of a projected image of the carrier particles, and the area represents the average value of the projected area of the carrier particles. 3. The carrier according to claim 1, wherein the polyolefin resin is a polyethylene resin.