JPH02150858A - Toner for electrostatic charge development - Google Patents

Abstract

PURPOSE:To improve not only flowability but the rise of electrostatic charge as well by incorporating fine nonmagnetic inorg. particles treated with metal alkoxide into the toner. CONSTITUTION:The toner contains at least the fine nonmagnetic inorg. particles treated with the metal alkoxide expressed by the formula I. In the formula, M denotes a metal ion; R denotes a lower alkyl group; n denotes the oxidation number of the metal ion. The fine nonmagnetic inorg. particles are used by being externally added to the toner and the amt. of the particles to be added is 0.01 to 5wt.% of the toner. There is no effect of adding the fine nonmagnetic inorg. particles if the amt. of the particles to be added is less than 0.01wt.%. Toner splashing increases and ground fogging arises if the amt. exceeds 5wt.%. Namely, the toner is improved in the flowability and the electrostatic characteristics, such as rise of electrostatic charge, if the fine nonmagnetic inorg. particles treated with the metal alkoxide are added to the toner.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a toner used as a developer for developing electrostatic images in electrophotography.

Prior Art and Problems In direct or indirect electrophotographic development systems, a desired electrostatic charge pattern (latent image) is formed on the surface of a photoconductor, and on this latent image,
A developer containing a colored powder (toner) having an opposite charge is brought into contact with the toner, and the toner is attached to obtain a visible image.

The latent image is developed by a cascade development method or a magnetic brush development method using a mixed developer of toner and carrier, or by a touchdown development method or a non-magnetic two-component development method using a developer consisting only of toner. Usually, in order to increase the fluidity of these toners,
Fine particles of silica, alumina, titanium oxide, etc. are added to the toner, and the addition of these fine particles is also effective in preventing toner aggregation in the hopper and developing device and improving toner cleaning performance.

However, since the i-free fine particles used as a fluidizing agent are numerically hydrophilic, under high temperature and high humidity conditions, the amount of charge decreases and toner scattering and background fogging occur. For this reason, it is known that these inorganic fine particles are subjected to hydrophobization treatment (for example, No. 0823720617, JP-A-48-4
7345, Japanese Unexamined Patent Publication No. 48-47346, Japanese Patent Publication No. 54-20344). Despite its strength, there were problems with charging buildup, etc.

JP-A-48-47345 and JP-A-48-47
No. 346 discloses the use of a fine powder of silicon dioxide which has been subjected to a hydrophobization treatment.

Although the silanol groups on the surface of silicon dioxide particles are made to react with organosilicon compounds to make them hydrophobic, the degree of hydrophobicity and chargeability are not sufficient. decreases.

Japanese Patent Publication No. 54-20344 discloses a negatively chargeable toner using fine hydrophobic silica powder. for example,
Although silica in which the silanol group of silica is substituted with a hydrophobic group such as a methyl group has excellent negative chargeability, the rise of charging is insufficient, and there are problems in contact development methods, high-speed development methods, etc.

Problems to be Solved by the Invention It is an object of the present invention to solve the above-mentioned problems and provide a toner that is excellent not only in fluidity but also in the rise of charging.

Means for solving the problem, that is, the object of the present invention can be achieved by including in a toner at least nonmagnetic inorganic fine particles treated with a metal alkoxide.

Inorganic fine particles include those commonly used as fluidizing agents, such as silicon dioxide, aluminum silicate, magnesium silicate, titanium dioxide, alumina, calcium carbonate, barium titanate, zinc oxide, or mixtures thereof. Non-magnetic microparticles can be used. Even among the inorganic fine particles conventionally used as a fluidizing agent, those having magnetism are undesirable because they are liberated from the toner and adhere to the developing sleeve or carrier.

These inorganic fine particles have an average particle size of 1 mμ to 2 μm, preferably 5 mμ to 1, um, and are treated with lOO'C! before being treated with a metal alkoxide. It is preferable to perform the heat treatment at a temperature higher than that.

The metal alkoxide for treating the non-magnetic inorganic fine particles has the following maximum [■1: M(OR)n-[I] [where M represents a metal ion, R represents a lower alkyl group, and n represents a metal ] indicates the oxidation number of the ion.

In formula [I], M represents a metal ion, specifically Li
, Be, B, Na%Mg, AQ%Si, P, KsCaS
Ti, V, Fe, Ga, Ge1YSZr, Nb.

Sn%5bSLa, Hf%Ta, W, CeSNd15m
.

These are metal ions such as Gd, Ho, and Er%Yb. Preferably, metal ions such as Si and Ti are used.

R1 represents a lower alkyl group such as methyl, ethyl, propyl, butyl.

n indicates the oxidation number of the metal ion M.

- Specific examples of metal alkoxides represented by maximum [I] include Li (OE t), Be (OE L), B
(OEth, Na(OEt), Mg(OEt),,
A l(Oi −P r)i, 5i(OEt) P(
OEt)x, P O(OMe)z, K(OEl), ca
(oEt)z, Ti(O4-Pr),,V(Oi-P
r) 4% Fe(OE t) 3, Ca(OE t
), ,Ge(OE t),.

Y(Oi-Pr)3, Zr(OL-Bu)IZr(On
-Bu),.

Nb(OEt), %5n(OL-Bu) 5n(On
-Bu) S b(OE t)s, S b(OE t)
x, La (○1-Pr),, Hf (OE L)4. T
a(OE t)s, W(OE t)s, Ca(Oi-P
r),, N d(Oi P r)s, S m(Oi
-P r)3, Gd(Oi P r)i, Ho(Oi
-P r)x, E r(Oi -P r)s, Yb(
Examples include OiPr)i.

As a method for treating inorganic fine particles with a metal alkoxide, first, the metal alkoxide is added to an alcohol (e.g., ethanol) solvent together with water and an acid (e.g., hydrochloric acid), and the ratio of [water]/[metal alkoxide] is 0.1 to 50. good tl
, < is t~30. Add so that the [acid]/[metal alkoxide] ratio becomes 0.001-1, and heat to 20°C to 90°C to prepare a homogeneous mixed solution. Next, inorganic fine particles are added to this solution, and while uniformly mixed and stirred, the temperature of the solution is maintained at 20 to 80°C to promote hydrolytic condensation of the metal alkoxide and gel the solution on the surface of the inorganic fine particles. , take the sample out of the solution tank and heat it to an appropriate temperature (100~
Heat treatment is performed at 500°C). At this time, the alkyl group in the metal alkoxide group should be eliminated. If alkyl remains, fluidity and moisture resistance will be adversely affected.

Other methods include spraying the above solution or a solution of the metal alkoxide itself while rolling the inorganic fine particles in a transfer fluidized tank or the like, followed by heat treatment. In this case, a metal alkoxide solution may be attached to the sample surface, or the metal alkoxide may be gasified and attached.

Alternatively, a method may be used in which the inorganic fine particles and the metal alkoxide-alcohol-water dispersion solution are spray-dried in a gas phase by a method such as a spray drying method, and then subjected to heat treatment.

The inorganic fine particles may be further treated with a coupling agent to impart hydrophobicity.

The use of a treatment agent as a hydrophobizing agent is also effective in suppressing changes in properties due to environmental conditions, especially humidity. As such a hydrophobizing agent, various coupling agents such as silane type, titanate type, amine type, fluorine type, etc. are used. Examples of silanes include chlorosilane, alkylsilane, alkoxysilane, and silazane. Specifically, for example, ・CH35iCQs ・(CHs)zs ICQ2 ・(CH3)3 SiCQ ・CHs Si(OCH3)3 ・CHs SI(OCHx CH3)3・(CH3)
3 S i(OCH3) ・(CHs)x S j(OCHi)z・(C1(s)
zsi(OCH2CHx)z・5i(OCH2CHx)
* ・S i(OCH3)1 ・CH3(H) S +(OCH3)2・CH1(H)
S i(○C82CH3)2・(CH3)! (H)S
i(OCH2CH3)・(◎)! s i(o CH3
)2 ・◎S i(OCH2CH3)3 ・(◎)2Si(OCH2CH,).

・◎S i(OCH3)1 ・(◎), 5iCI22 ・(◎)! CHi S s CQ ・◎5iC123 ・(◎XCHx)SiCI2z ・(CHx):+5iNH5i(CHx)z・CH3(
CHx)+□S i(CHsXo CH1)2・CH3
CCH Itsi(○CH3)3・CHx(CHz)
+ySi(OC2Hs)s・CHx(CHz)xSi(
CHx)zc(2・CHscc Hz)+y S sc
c Hx)zcQ・CHs(CHz)+tSi(CHs
)(jlz·CH, (CH,), 5iCI23, etc.

In the titanate series, for example, H (C8H17) - 0 しTi・[P ÷ Kano C + 5Hzr)z
OH]zCHi-CI-0-Ti +0-C-C+7)
! 36]3 etc. can be mentioned.

As an amine coupling agent, HzN(CH2)2N H(CH2)3S i(OC
H3) 3・H, N(CH,), NH(CH,), S
i(CH3XOCHL)2 ・HzN(CH2)2NH(CHz)3Si(OCHx
)x・H2N(CHt)zNH(CHz)zNH(CH
z)ssi(OCHx)z ・H2N(CHz)asi(OCHl)i・C1HsN
H(CH2)3S i(OCH3))・H! N @
S l(OCH3) 3・H2N CH2CHx N
HCH2◎CH2CH,Si(OCHx)s ・H2NCH,◎CHzCHzSi(OCHxh・(
Mention may be made of XH2CH2CQ3 and mixtures thereof.

Examples of fluorine-based coupling agents include fluorine-based silane coupling agents, such as: ・CF 3 (CH2) 25 <CQ3 ・CF 3 (CF Ri6 SiCQs・CF 3 (C
F z)s(CH2)2S icL・CF 3(CF
2)? (CHz)251c(is・CF s(CF ri7CH2CHzS i(OCHs)s・CF 3(CF
z)y(CHz)zs i(CHs')CQs・CF
3(CH2)zsi(OCH3)t・CFs(CHz)
2si(CHiXOCHx)z・CF Yu(CF Ri1(
CH2)2 Si(OCHs)3・CFx(CFz)
s(CHz)zsi(OCHx)x・CFs(CFz)
scONH(CH2)zsi(OCzHsh・CF 3
(CF 2) ICOO (CHz) zs i (OCHs)
s・CF! (CF 2) 7 (CHz) ts i (OC
H) h・CF s(CF z)7(CH2)is i(
CHxXOCHi)z・CF 3(CF ri7S Ox
N H(CHz)xs i(OCzHs)x・CF 3
(CF z)s(CHz)zs i(OCH3)! and mixtures thereof.

The type of toner to which the nonmagnetic inorganic fine particles obtained as described above are added is not particularly limited, but may be mixed and kneaded with, for example, a thermoplastic resin, a coloring agent, and/or a charge imparting agent; , a pulverization method toner obtained by crushing and classifying the toner, or a suspension polymerization toner obtained by dispersing a colorant and/or a charge-imparting agent in a monomer and polymerizing the same, or a colorant and a low softening point substance such as a wax. Alternatively, capsule toner in which a liquid containing a fixing resin is surrounded by a wall material (capsule shell) with a higher softening point than these, or photoconductive toner in which the surface is coated with a photoconductive substance, etc. Can be done.

The nonmagnetic inorganic fine particles are used before being externally added to the toner, and the amount added is 0.01 to 5% by weight, preferably 0.41 to 3% by weight, based on the toner.

When the amount added is less than 0.01% by weight, there is no effect of adding the non-magnetic inorganic fine particles, and when it is more than 5% by weight, toner scatters a lot and background fogging occurs.

According to the present invention, when non-magnetic inorganic fine particles treated with a metal alkoxide are added, charging characteristics such as toner fluidity and charging rise are improved. It is thought that one of the factors contributing to these improvements is the metal-centered network structure formed on the surface of the nonmagnetic inorganic fine particles and the properties of the central metal.

The present invention will be explained below with reference to Examples.

Production Example (2) A log of an ethanol water-hydrochloric acid mixed solution of metal alkoxide Si(OCxHs)a was prepared. 50 g of colloidal silica (AERO5IL200; manufactured by Nippon Aerosil Co., Ltd.) as inorganic fine particles was placed in a high-speed mixer, and the above mixed solution was gradually added to the mixer over about 5 minutes while stirring. After the addition, the contents of the mixer were stirred vigorously for an additional approximately 10 minutes. After heating the obtained mixed solution at a temperature of 120° C. in a constant temperature bath, the aggregated silica was crushed, and the obtained silica fine particles were designated as inorganic fine particles a.

Production example ■ Etal of metal colloid T1(oc!H5)4
The aqueous mixed solution is mixed with inorganic fine particle colloidal silica (AER).
O5IL 130 (manufactured by Nippon Aerosil Co., Ltd.) was sprayed, and then the temperature was gradually raised to 120°C. The obtained silica fine particles were used as inorganic fine particles.

Production example■ 3g of hexamethyldine lazan was added to tetrahydrofuran.
A solution was prepared by dissolving in g. As inorganic fine particles, 50 g of colloidal silica (AERO3IL 200; manufactured by Nippon Aerosil Co., Ltd.) was placed in a high-speed mixer, and the above mixed solution was gradually added to the mixer over about 5 minutes while stirring.

After the addition, the contents of the mixer were stirred vigorously for an additional approximately 10 minutes. After heating the obtained mixed solution at a temperature of 150° C. in a constant temperature bath, the aggregated silica was crushed, and the obtained silica inorganic fine particles were designated as inorganic fine particles C.

Carrier manufacturing ingredients: 1
Polyester resin 100 (softening point 123°C1 glass transition point 65°CXAV23.0HV40) Fe-Zn ferrite fine particles 500MFP
-2 (manufactured by TDK) Carbon black 2 (manufactured by Mitsubishi Chemical Industries, Ltd., AM#8) The above materials were thoroughly mixed and pulverized using a Henschel mixer, and then the cylinder part was heated to 180°C and the cylinder head part was heated to 170°C.
The mixture was melted and kneaded using an extrusion kneader set at °C. After cooling the kneaded material, it was coarsely ground using a feather mill, further finely ground using a jet mill, and then classified using a classifier to obtain a carrier having an average particle size of 60 μm.

Example ■ Styrene/n-butyl 100 parts by weight methacrylate copolymer resin (number average molecular weight run: 9,300, weight average molecular weight M
w: 213, 900 My, 'Mn: 23 Softening point 130°C, glass transition point 60°C) ・Carbon black MA#8 5 parts by weight (manufactured by Mitsubishi Chemical Corporation) ・Charge control agent Spiron black 2 parts by weight TRH (
(manufactured by Hodogaya Kogyo Co., Ltd.) ・Offset prevention agent Viscoel 5 parts by weight 550P
(Manufactured by Mitsubishi Chemical Industries, Ltd.) The above raw materials were mixed using a Henschel mixer, then kneaded using a twin-screw kneading extruder, and then cooled.

The kneaded material was coarsely pulverized, pulverized with a jet pulverizer, and then used with an air classifier to obtain a toner having a particle diameter of 5 to 25 μm (average particle size: 11.3 μm).

To the above toner lOO parts by weight, the hydrophobic fine particles a of Production Example ■
Add 0.15 parts by weight of
Toner A was obtained by processing at 0 rpm for 1 minute. A two-component developer was prepared by adding 64 parts by weight of the thus prepared toner A to 800 parts by weight of a binder-type carrier (carrier production example), and a charge amount measurement, an actual photographic test, and an environmental test were conducted. .

The amount of charge was -13.4 μC/g.

When the developer was subjected to a printing durability test using an electrophotographic copying machine EP-8702 (manufactured by Minolta Camera Co., Ltd.), clear images without fogging were obtained even after approximately 10,000 copies were made.

Furthermore, there was no fog even in a high temperature and high humidity environment (temperature: 35° C., humidity: 85%), and the result was very good.

Example ■ - Styrene/n-butyl 100 parts by weight Methacrylate/methacrylic acid group polymer resin (number average molecular weight Mn: 5,400, weight average molecular weight - Carbon black 5 parts by weight MA#100
(Manufactured by Mitsubishi Kasei Corporation) ・Offset prevention agent Viscole 5 parts by weight 550P
(manufactured by Mitsubishi Kasei Corporation) Charge control agent Nigrosine base 5 parts by weight EX (manufactured by Orient Chemical Co., Ltd.) Using the above raw materials in the same manner as in Example I, a toner of 5 to 25 μm (average particle size 10.1 μm) was obtained. .

To 100 parts by weight of the above toner, add 0.3 parts by weight of the hydrophobic fine particles of Production Example ①, and use a Henschel mixer 11000r.
Toner B was obtained by mixing for 1 minute at p.

Except that the thus obtained toner B was replaced with EP470Z (manufactured by Minolta Camera Co., Ltd.), evaluation was carried out in the same manner as in Example 2. The charge amount was +12.9 μC/g, and there was no fogging and was very good It was good.

Comparative Example ■ In Example I, Aerosil 2 was used instead of hydrophobic fine particles a.
Toner C was obtained in the same manner except that 00 (manufactured by Nippon Aerosil Co., Ltd.) was used.

As a result of evaluating the thus obtained toner C in the same manner as in Example I, the charge amount was -12.0 μC/g,
Also, in the printing durability test, capri occurred after 50,000 sheets.

The results of the above examples and comparative examples are shown in Table 1.

Table 1 Note that the larger the bulk specific gravity is, the better the toner fluidity is.

Effects of the Invention According to the present invention, when non-magnetic inorganic fine particles treated with a metal alkoxide are externally added to a toner, a toner with excellent fluidity and charge build-up can be obtained.

Patent applicant: Minolta Camera Co., Ltd. Representative patent attorney: Haka Aoyama (1 person)

Claims (1)

[Scope of Claims] 1. A toner for electrostatic charge development characterized by containing at least non-magnetic inorganic fine particles treated with metal alkoxide. 2. A claim that the metal alkoxide has the general formula [I]; M(OR)n... [I] [wherein M is a metal ion and R is a lower alkyl group n represents the oxidation number of the metal ion] The toner according to item 1. 3. The toner according to claim 1, wherein the inorganic fine particles are selected from the group consisting of silicon dioxide, aluminum silicate, magnesium silicate, titanium dioxide, alumina, calcium carbonate, barium titanate, zinc oxide, and mixtures thereof.