JPS62121462A - Electrostatic image developing carrier - Google Patents

Abstract

PURPOSE:To obtain the titled carrier having always stable triboelectrifiability independent of humidity, and capable of forming a good image by treating a silicone resin coating layer having a condensation reaction type after curing it, with a coupling agent. CONSTITUTION:The coating film of the condensation reaction type silicone resin is formed on the surface of the core material of the carrier followed by curing it, and then the obtd. cured layer is treated with the coupling agent to form the coating layer. As the condensation reaction type silicone resin, a thermosetting type silicone resin and a cold setting type silicone resin may be used. As the coupling agent, the silane type or a titanium type coupling agnet is used. As the silane coupling agent having an alkoxy group or a chlorine atom forms a silanol group by hydrolysing it, said coupling agent has good reactivity to a hydroxy group contd. in the cured layer of the condensation reaction type silicone resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrostatic method used together with a toner to develop an electrostatic latent image formed in electrophotography, electrostatic printing, electrostatic recording, etc. The present invention relates to a carrier for electrostatic image development, and particularly relates to a resin-coated carrier for electrostatic image development having a 1ν layer made of a condensation reaction type silicone resin.

[Background of the invention]

In recent image forming methods, methods using electrostatic latent images are widely used. In electrophotography, for example, an electrostatic latent image is formed by imparting a uniform electrostatic charge to a photoconductive photoreceptor and then performing imagewise exposure. Such an electrostatic latent image is developed with a developer, and the resulting toner image is transferred to transfer paper or fixed as it is to form a visible image.

To develop an electrostatic latent image, a two-component developer consisting of toner and a carrier containing a magnetic substance is used, and the developer is made to stand on the surface of a developer carrier by magnetic force to form a magnetic plan. However, there is a widely used method in which the toner particles in the magnetic plan are electrostatically attached to the electrostatic latent image on the latent image carrier by rubbing the surface of the latent image carrier with this magnetic brush. .

As carriers used in such development methods, carriers made of particles of ferromagnetic materials such as iron, ferrite, and magnetite are conventionally known, but when such carriers are used, the carrier and toner are The toner material tends to transfer and adhere to the surface of the carrier particles due to friction with the carrier particles, which may reduce the triboelectric charging properties of the carrier, or the ferromagnetic particles described above have high hygroscopicity, so in a humid environment, the carrier may There are problems such as a decrease in triboelectric charging properties.

[Problems to be solved by the invention]

In order to eliminate these problems, a carrier has been developed in which the surfaces of the above-mentioned ferromagnetic particles are coated with a resin. A carrier formed by coating the surface of a carrier core material with a silicone resin has good surface slipperiness and can effectively prevent toner substances from adhering to the surface of carrier particles. Among silicone resins, condensation reaction type silicone resins in particular have greater strength, better adhesion, and are less expensive than other peroxide curing reaction type and addition reaction type silicone resins. It is preferable as

However, in such a condensation reaction type silicone resin-coated carrier, after the condensation reaction type silicone resin is cured, water-absorbing hydroxyl groups remain and are oriented on the surface of the coating layer, so the triboelectric charging ability of the carrier increases depending on the humidity. (There is a problem that it is difficult to form a good image depending on the environmental conditions. In other words, if the triboelectric charging ability of the carrier is within an appropriate range under normal quality conditions) However, under high humidity conditions, the amount of moisture absorbed by the carrier coating layer is large, reducing the triboelectric charging ability, and as a result, the number of toner particles with an insufficiently charged amount increases, resulting in lη staining due to toner scattering. On the other hand, under low humidity conditions, the amount of moisture absorbed by the carrier coating layer is small and the triboelectric charging ability is lower than under normal humidity conditions. As a result, the number of toner particles with an excessively charged amount increases, and the electrostatic adhesion between the toner and the carrier increases, making it difficult for the toner to separate from the carrier, causing the toner to adhere to the electrostatic image on the latent image carrier. There is a problem that the amount of adhesion decreases, resulting in lower image density.

[Purpose of the invention]

The present invention has been made based on the above circumstances, and its purpose is to have stable triboelectric charging ability under high humidity or low humidity, similar to that under normal humidity, and to have It is an object of the present invention to provide a carrier for electrostatic image development that can stably form good images regardless of the situation.

[Means for solving problems]

The carrier for electrostatic image development of the present invention has a coating layer mainly made of a condensation reaction type silicone resin, and the coating layer is treated with a coupling agent after curing of the condensation reaction type silicone resin. It is characterized by

According to this structure, since the coating layer is mainly made of a condensation reaction type silicone resin, the surface has good slipperiness and can effectively prevent toner substances from adhering to the surface of the carrier particles. Since the condensation reaction type silicone resin is treated with a coupling agent after curing, the hydroxyl remaining in the condensation reaction type silicone resin layer after curing may react with the hydrophilic groups of the cambling agent. The lipophilic groups of the coupling agent are oriented on the surface of the rgI layer, and as a result, the triboelectric charging ability of the carrier is always stable regardless of the level of humidity. Note that curing in the present invention refers to curing generally referred to in thermosetting resins.

The present invention will be explained in detail below.

In the present invention, a coating film of a condensation reaction type silicone resin is provided on the surface of the carrier core material and cured, and then the cured layer is treated with a coupling agent to form a coating layer, which allows electrostatic image development. Get a carrier for.

Examples of the condensation reaction type silicone resin used to form the coating layer in the present invention include those that are cured by the reactions shown in (1) and (2) below.

■Heating dehydration condensation reaction R+ Rz -O-5i-OH+ HO-5i O-heating
11 ■ Room temperature humidity hardening reaction R, R2 05i-OX + XO-5i-0-l -2HOX l In the formula 1, OX represents an alkoxy group, a ketoxime group, an acetoxy group, an aminoxy group, etc.

Particularly preferred among such condensation reaction type silicone resins are those in which the substituent is a methyl group. The coating layer obtained from the condensation reaction type silicone resin in which the substituent is a methyl group has a dense structure (8) It is possible to obtain a carrier with considerably good aqueous property and better moisture resistance.

As the condensation reaction type silicone resin used in the present invention, either a heat-curable silicone resin or a room temperature-curable silicone resin can be used. When using a heat-curing silicone resin, it is necessary to heat it at about 200 to 250°C, and when using a room-temperature-curing silicone resin, it is not necessary to heat it to a particularly high temperature for curing. However, in order to accelerate curing, 15
You may heat within the range of 0-220 degreeC.

Room temperature curable silicone resin is a silicone resin that cures at a temperature of about 20 to 25 degrees Celsius or slightly higher than this in a normal atmosphere.
It does not require temperatures exceeding ℃.

Examples of commercially available condensation reaction type silicone resins include the following.

rSR-2410J <manufactured by Tomu Silicone Co., Ltd.) r
SR-2411J (manufactured by Tomu Silicone Co., Ltd.) rK
R-255J (manufactured by Shin-Etsu Chemical Co., Ltd.) rKR-271
J (manufactured by Shin-Etsu Chemical Co., Ltd.) rKR-152J (manufactured by Shin-Etsu Chemical Co., Ltd.) rKR-251J (manufactured by Shin-Etsu Chemical Co., Ltd.) rKR-220J (manufactured by Shin-Etsu Chemical Co., Ltd.) In the formation of the coating layer, a condensation reaction type silicone resin is used. These may be used alone or in combination, or a mixture of the condensation reaction type silicone resin and other resins may be used as long as the effects of the present invention are not lost. The addition ratio varies depending on the type of condensation reaction type silicone resin and other resins, and cannot be further specified, but in general, it is preferably 10 parts by weight or less per 100 parts by weight of condensation reaction type silicone resin. Examples include acrylic resin, styrene resin, epoxy resin, urethane resin, polyamide resin, polyester resin, acetal resin, polycarbonate resin, phenol resin, vinyl chloride resin, vinyl acetate resin, cellulose resin, polyolefin resin, and copolymer resins thereof. , compounded resins, etc.

In the present invention, in forming the coating layer, after the condensation reaction type silicone resin is cured, the cured layer is treated with a coupling agent, and specific treatment methods include, for example, the following methods.

(1) Water-in-liquid method Add a coupling agent with a concentration of approximately 0.1 to 0.5% to a constant p.
Hydrolyze by injecting and dissolving H into water or water-solvent with sufficient stirring. After immersing the carrier material with a cured layer of condensation-reactive silicone resin in this solution,
Water is removed by filtration or squeezing and thoroughly dried at 120-130°C.

(2) Organic solvent method A small amount of water and a hydrolysis catalyst (Hα or CHzCOOI
A coupling agent is dissolved in an organic solvent (alcohol, Hensen, halogenated hydrocarbon) containing I).

The carrier material on which the cured layer of condensation reaction type silicone resin has been formed is heated to 7 tatami mats for 7 nights, filtered or squeezed to remove the solvent, and thoroughly dried at 120 to 130°C.

(3) Spray method While vigorously stirring the carrier material on which the cured layer of condensation reaction type silicone resin has been formed, an aqueous solution or solvent solution of the coupling agent is sprayed.

Water or solvent is removed at 120-130°C.

The cassoplating agent that can be used in the present invention is not particularly limited, but includes, for example, a silane coupling agent or a titanium coupling agent. Silane coupling agents having good reactivity with hydroxyl groups in the layer are preferable, and in particular, silane coupling agents having an alkoxy group or chloro group are suitable for use in the cured layer of condensation reaction type silicone resins because they hydrolyze to produce silanol groups. has better reactivity with hydroxyl groups.

As the silane coupling agent, for example, the following formula -a (
1) can be mentioned.

General formula +11 X, SiY.

(X represents an alkoxy group, an acetoxy group, or a chlorine atom, m represents an integer of 1 to 3, and Y represents a methyl group, or a chlorine atom, an amino group, a vinyl group, a glycidoxy group, a mercapto group, a methacryl group, or a ureido group. represents a hydrocarbon group having at least one or two types of 177-1 =, and n represents an integer of 3 to 1. Specific substances of the silane coupling agent represented by the above general formula (11) are as follows. We can mention things like.

(Things with a vinyl group) cu2=cllsicZff CHHz=Cf1Si (OCJs) aCIl□=
CIICHzSiα.

CIIz=CIICILzSi(C1h)cIzC11
2= CIICHzSi (C1l:+) zclC1
1z=CIICHzSi(OCzlls)iCJ=
CH31 (OCzl140Cf13)! (C1h=C
IICIlz)zsicIz(CHz=CH)zSi(
OCtlls)z(CL = C)I) zsiOcJ
sHC/ ・CIIzCHzCIIzSi(OCR*)
ffCl1z=CH5i(OCOCHs)sCIl□
=CHSi(OCH3)+ (having a chlorine atom) fuc)IzCIIz(JlzSi (OCH3) 5
CICH2CHzCHtSi C0CHz) tCHl (Those where Y is a methyl group) CToSi(OCHi) :I C1l+Si (OCzlls) 3 (CII*)SiC/z (CH,) zsiclt (C1h)isic/ (Those with a glycidoxy group) (Merca Put (having a group) 11sclIzcHzcHzsi (OCHi) 3113
GHzGHzc) IzSi (OCtlls) zll
sctlzcHzc)IzSi(OCL)! CHz (having methacrylic group) CH3 (C11,1)zC=CC00C1hCHzCHzSi
α2C11゜(CHz)zc冨C-C00CII□CIl□CHzS
i (OCtl+) 3CI.

CHz I-CC00CIIzCII□CIIzSi(
OCHi) xCHl CIl□=CC00CH2CII2N''α-C1h
C) IzGHzCHzSi (OCIh) y(
having a ureido group) NlI□C0NI-IC) lzcH2cllzsi (
OCR)+5113 (containing an amino group) N112CII□C1l□C1125i (OCII
,).

Nll□CII□CII□CIl□Si (OCzHs
) 3CI'h NlI□CII□CIl. C1l+Si (OClh)
2CL CloudyNHzCH,CH,NHCl1zCHzCIhSi(O
CHi)zNlI□C0N)ICII□C)11□C1
l□5t(OCtHs)sNlhCHzCHzNHCH
zCHzCHzSi(OCllt)sNHzCthe)
IJHCHzCHJHCHzCHzCtltSi(OC
II 3) 3CJsOCOCHzCHtNHCHzC
1hCIl□5i(OCth)zCJsOCOCHzC
H□N11CHzCHzNHCHzCHzCtl□Si
(OCH3)+CJsOCOC1hCHtNHCIhC
HtNHCHtCHJHCII□CHfN)I-CIh
CHzCHzSi(OCll+)3CH30COCHz
CHyoNHCtlgcHJHCHxcHICHzsi(
QC) 13) IC code H5 N-CHtCIl, CH□5i (OCHs) 3ztls CHl lIOcHzclI□ N-CII□CIl□CIl□Si (OCth) 3
110CII2CI+! (CH30)zsi(JItC)IgCL NHCH
2(C)IJ)3SiCHzlHhCHi NHCH
z(CtHsO)ssic)IiCIlzCHzCH (C!H5O)ssicHzcHtcHzCH3NHC
HzCHzCHtSi(OCzHs) yNHz(CH
zCHJH)zcHzclhcll□5i(OCH3)
tCHJIICONIICH□CHzCl(zSi (
OCII3) s(CM, )*5iNH5i (CH3
)*Also, examples of titanium-based coupling agents include those represented by the following general formulas (1) to (2).

General formula■ Ti(OR’)a-(0-X　R”)llGeneral formula■ (CH,)11-.

General formula ■ (R' O) group, alkenyl group, cyclic alkyl group, and X is II II 11 /-C-, -
P--0-Pl\CH or O-8-, X' represents ○, C-ri represents an acetylacetonato group, n represents an integer from 1 to 3, m is 1 or 2, p represents O or l, and q represents an integer from 4 to 20. ) General formula ■ Tj(OR)-(OR')n-,, L- (In general formula ■, R and R' each have a hydrogen atom and a carbon atom number of 3 to 20
represents a substituted or unsubstituted alkyl group or aryl group, L represents a phosphorus ligand, and n and m each represent an integer of 0 to 4. ) General formula ■ (In the general formula ■, R represents a substituted or unsubstituted alkyl group having 3 to 20 carbon atoms, and p represents an integer of 4 to 20.) Specifically, the following can be mentioned.

C1,0 \ (I CHOTi(OCC+Jas)z CHz (C1hCHzCllzClh O) zTi (O
CC+ yll+s) CHz Tomi CI-C00-C11C
Hz II 1 o CL H, COO I II II C1h=C-COOCI CHs tl+c OCHs Ti (OCHGHz) 4 CL Ti (OC+12CI+2CIIZ(:113) 4
Ti(0-C)It-CM-C4H*)szlls Ti(0-C,,If,,).

CH.

C11, -C11-0-Ti (0-C, II, NH-C
f11. Nibun.

(C1h(CHz)aO) 2 Ti [0CJ-
N(CzH-Off)z ) z The above coupling agents may be used alone or in combination of two or more. The amount of these coupling agents used is preferably 0.1% by weight or more based on the weight of the carrier. If this ratio is too small, the treatment effect of the coupling agent will not be obtained and the triboelectric charging ability will increase depending on the humidity level (this may change). Varies depending on the type of
In addition, since it is possible to remove the coupling agent used in excess, it is preferably about 3% by weight or less, although this cannot be said in general.

As the carrier core material, for example, magnetic metals such as iron, steel, nickel, and cobalt, magnetic oxides such as ferrite and magnetite, copper, carborundum, glass beads, and others can be used. When the carrier core material is a magnetic material, it is possible to obtain a carrier that provides a developer suitable for magnetic brush development. As such carrier core material, those having a weight average particle diameter of 1 to 1000 nm are usually used, and those having a weight average particle diameter of 5 to 200 microns are particularly preferred.

The carrier of the present invention can be prepared by applying a coating solution prepared by dissolving a condensation reaction type silicone resin in a solvent to the surface of a carrier core material, and then usually heating and drying to remove the solvent by volatilization. It can be produced by curing the coating film during or after drying, and then treating the surface of the cured layer with a coupling agent.

Specific coating methods using the coating liquid include an immersion method in which powder of the carrier core material is immersed in the coating liquid, a spray method in which the coating liquid is sprayed onto the carrier core material, a method in which the carrier core material is suspended with fluidized air, Examples include the fluidized bed method in which the coating liquid is sprayed onto the carrier core material in a floating state, and the method in which the carrier core material is transferred onto the surface where the coating liquid is present. In particular, the fluidized helad method is used. In some cases, a uniform coating film can be formed on the surface of the carrier core material, and a coating layer can be stably formed. Regarding the coating method using the fluidized bed method, for example, Japanese Patent Application Laid-Open No. 54-1550
It is described in Publication No. 49.

Other additives may be added to the coating solution for forming the coating layer as necessary, and the solvent is not particularly limited as long as it dissolves the condensation reaction type silicone resin, but examples include toluene and xylene. Aromatic hydrocarbons such as;
Ketones such as acetone and methyl ethyl ketone; tetrahydrofuran, dioxane, higher alcohols, or mixed solvents thereof can be used.

The temperature when curing the coating film is, for example, 150 to 280°C.
That's about it. When using a room temperature curable silicone resin, it is not necessary to particularly heat it when curing it, but if necessary, it may be heated to about 150 to 220°C, for example, to increase the mechanical strength of the coating layer. Good too. Furthermore, during drying, metal soaps such as lead, iron, cobalt, manganese, and zinc such as octylic acid and naphthenic acid may be used as drying accelerators, and organic amines such as ethanolamine are also effective as drying accelerators. Can be used.

The thickness of the coating layer thus obtained is usually 0.1 to 10x
, preferably 0.3 to 5 n.

Further, the average particle size of the carrier of the present invention is, for example, 1 to 1000.
μl, preferably about 5 to 200 n.

The toner constituting the developer together with the carrier of the present invention is not particularly limited, and any known toner can be used.

〔Example〕

Examples of the present invention will be described below, but the present invention is not limited thereto.

Example 1 10 parts by weight of silicone resin liquid rsR-2411J (manufactured by Toray Silicone Co., Ltd.) was added to spherical ferrite particles with an average particle diameter of 100 nm (manufactured by Nippon Tetsuko Co., Ltd.) at a temperature of 80°C using a fluidized bed apparatus. Spray on the weight part,
The mixture was further heat-treated at 200° C. for 1 hour, and the aggregates were sieved to obtain a carrier material having a cured layer of silicone resin. This will be referred to as "carrier material A."

Next, 1 part by weight of N-phenyl-gamma-aminopropyltrimethoxysilane was injected and dissolved into an acetic acid aqueous solution containing 200 parts by weight of water and 1.2 parts by weight of acetic acid with sufficient stirring.

After immersing 100 parts by weight of carrier material A in this treatment liquid,
The water was removed by filtration and dried at 120° C. for 2 hours to obtain a carrier according to the present invention.

This will be referred to as "Career 1."

Example 2 4 parts by weight of water were added to 150 parts by weight of methanol, and 3 parts by weight of hexamethyldisilazane was further dissolved therein.

After immersing 100 parts by weight of carrier material A in this treatment liquid,
Filter to remove solvent and incubate at 60°C for 1 hour, then at 120°C.
The carrier was dried for 1 hour to obtain a carrier according to the present invention. This will be referred to as "Career 2."

Comparative Example 1 The carrier material A obtained in Example 1 was
”.

Example 3 In Example 1, silicone resin liquid rSR-2411
Silicone resin liquid rKR-255J (manufactured by Shin-Etsu Chemical Co., Ltd.) instead of J (manufactured by Toray Silicone Co., Ltd.)
A carrier material having a cured layer of silicone resin was obtained in the same manner except that 4 parts by weight was used. This will be referred to as "carrier material B."

Using this carrier material B, a carrier according to the present invention was obtained in the same manner as in Example 1 except that γ-aminopropyltrimethoxysilane was used instead of N-phenyl-γ-aminopropyltrimethoxysilane. This will be referred to as "Career 3."

Comparative Example 2 The carrier material B obtained in Example 3 was
”.

Experimental Example 0 Styrene-acrylic copolymer 100 parts by weight (styrene: n-butyl acrylate = 15:25, weight average molecular weight: 12X10''') 0 Carbon blank
10 parts by weight "Mogul LJ (manufactured by Caponoto) Q low molecular weight polypropylene 3 parts by weight [Viscol 660PJ (manufactured by Sanyo Chemical Industries, Ltd.) or more substances were mixed, melted and kneaded, then pulverized and classified to obtain an average particle size of 12
A toner particle powder of .mu.

Said carriers 1 to 3 and comparative carrier 1. 3.5 parts by weight of the above toner was mixed with 96.5 parts by weight of each of No. 2 to prepare a total of five types of developers.

For each of these developers, a high-temperature, high-humidity atmosphere (hereinafter referred to as "atmosphere I") with a temperature of 30° C. and a relative humidity of 80% was used.
,) and an atmosphere with a temperature of 10°C and a relative humidity of 20% (hereinafter referred to as "atmosphere ■"), a frictional charging test and a photocopying test using a modified electrophotographic copying machine rU-Bix2500J (manufactured by Konishiroku Photo Industry Co., Ltd.) were conducted. went.

In the triboelectric charging test, the developer was shaken for 20 minutes to be tribocharged to 1γ, and then the charge IQ (〆/g) per 1 g of toner was determined to be 7111 using a known blow-off method. In the actual copying test, the maximum image density Dmax of the formed copy image was measured.

Note that this maximum image density Dmax is the relative degree of darkness of the copied image when the image density of the original image is 1.3.

These results are shown in Table 1.

As can be understood from the results in Table 1, with the developer using carriers 1 to 3 according to the present invention, good triboelectric charging properties can be stably obtained regardless of the humidity level. The concentration was sufficiently high in both high and low humidity conditions.

On the other hand, the developers using Comparative Carriers 1 and 2, which were not treated with a coupling agent, had unstable triboelectric charging properties that varied greatly depending on the humidity, and were unstable under low humidity. The density of the copied image was low (so that a good image could not be obtained).Furthermore, in the actual copying test conducted in Atmosphere I, fogging was observed in the obtained copied image.

〔Effect of the invention〕

As explained in detail above, in the carrier of the present invention, since the coating layer mainly consists of a condensation reaction type silicone resin,
The surface has good slipperiness and can effectively prevent toner substances from adhering to the carrier particle surface, and this coating layer is treated with a coupling agent after the condensation reaction type silicone resin is cured. The hydroxyl groups remaining in the condensation-reactive silicone resin layer after curing react with the hydrophilic groups of the cambling agent, and the lipophilic groups of the coupling agent become oriented on the surface of the coating layer. The triboelectric charging ability of the carrier is always stable regardless of the humidity level, and appropriate tribocharging ability can be obtained under high or low humidity as well as under normal humidity, ultimately regardless of the environmental conditions. Therefore, it is possible to stably form a good image.

−；Yu,lnee’ r−

Claims (1)

[Scope of Claims] 1) It has a coating layer mainly made of a condensation reaction type silicone resin, and the coating layer is treated with a coupling agent after curing of the condensation reaction type silicone resin. A carrier for electrostatic image development. 2) The carrier for electrostatic image development according to claim 1, wherein the coupling agent is a silane coupling agent.