JPH10288858A - Binder for electrophotographic toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the electrophotographic toner binder capable of forming a sharp image even in a high-speed copying machine by using the toner binder made of a specified silicone type graft copolymer. SOLUTION: The electrophotographic toner binder is made of the silicone type graft copolymer obtained by copolymerizing an organopolysiloxane macromonomer represented by the formula with the other radically polymerizable monomer copolymerizable with this monomer. In the formula, R<1> is an oxygen atom or a methyl group; R<2> is a 1-6C univalent hydrocarbon group; (m) is an integer of 1-3; and (n) is an integer satisfying the following inequality: 20<=n<=200. As the monomer copolymerizable with this macromonomer, styrenes and their derivatives, acrylates and methacrylates are preferable from the view point of easiness in manufacture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binder for a dry toner used for developing an electrostatic image or a magnetic latent image, and more particularly to a binder for a dry toner having excellent high-speed fixability and good releasability from a rubber roll.

[0002]

2. Description of the Related Art A one-component toner or a two-component toner used in a dry development system is composed of components such as a binder resin, a colorant, and a charge control agent. In this case, since the binder resin is a main component in the toner, characteristics such as pulverizability and dispersibility of the colorant are required. Further, when incorporated in a toner, many properties such as fixing properties, anti-offset properties, anti-blocking properties, and electrical properties are required.

In particular, since it is necessary to increase the fixing speed with high-speed development, binder resins and various internal release agents having good releasability between a toner and a roll have been proposed. . For example, Japanese Patent Application Laid-Open No. 5-197202 proposes a block copolymer of dimethylpolysiloxane and an aromatic polyester. When this block copolymer is used, the blocking resistance is remarkably improved, but there is an industrial problem since the polyesterification reaction requires a high temperature and a long time. Accordingly, attempts have been made to use a polyester condensation-promoting catalyst such as an organotin compound to effect a low-temperature reaction, but such a tin compound is not safe. It has also been proposed to add a liquid having a low surface energy, for example, dimethyl silicone oil, as an internal release agent (see US Pat. No. 4,147,272).
However, in this case, contamination of the carrier particles by the silicone oil has been pointed out, and as a result, there has been a disadvantage that the frictional charge of the developer becomes insufficient and the charge becomes unstable.

Further, in recent years, there has been proposed a toner by a suspension polymerization method which does not require a pulverizing step for the purpose of improving the fluidity of the toner, making the triboelectric charge uniform, and sharpening the image (Japanese Patent Publication No. 51-148).
No. 95). In the suspension polymerization method, a polymerization reaction is carried out in an aqueous phase by uniformly dissolving or dispersing a polymerizable monomer, a colorant, a polymerization initiator and, if necessary, a crosslinking agent, a charge control agent, and other additives. As a result, toner particles having a desired particle size can be obtained. According to this method, the toner particles are formed simultaneously with the generation of the binder resin by polymerization, and further, since the pulverizing step is not included at all and the classification step can be omitted, energy can be saved, the process can be simplified, There are many advantages such as reduction of time and improvement of process yield.

In the toner obtained by the above suspension polymerization method, a toner containing a silicone oil has been proposed in order to satisfy both the offset resistance and the fixing property (see Japanese Patent Application Laid-Open No. 60-103355). . However, according to the polymerization method, the silicone oil tends to undergo phase separation with the progress of the polymerization of the styrene-based monomer, and the silicone oil oozes out of the particles, resulting in poor triboelectricity. Is also happening. In order to prevent oozing of silicone oil, a toner comprising a copolymer obtained by copolymerizing a silicone oil containing a radical polymerizable functional group (silicone macromonomer) and a styrene monomer has been proposed in Japanese Patent Application Laid-Open No. HEI 4-104. It is proposed in Japanese Patent No. 163464. In this method, methacryloyl group-containing dimethylpolysiloxane is used as a silicone-based macromonomer, but the polymerization conversion with the styrene-based monomer is not complete, so that the releasability from the fixing roll material can be imparted. When the silicone-based macromonomer is copolymerized (for example, 20% by weight or more), there is a problem that free silicone which is not copolymerized remains.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the problems of the prior art by preparing a copolymer in advance or by preparing a copolymer as in a suspension polymerization method. Regardless of whether the formation and the formation of toner particles are performed simultaneously, we have developed a graft copolymer of silicone-based macromonomer that exhibits excellent properties when used as a binder for electrophotographic toner and is easy to manufacture. Is to provide.

[0007]

The present inventors have made intensive studies to solve the problems of the prior art, and as a result, have found that a dimethylpolysiloxane having a 4-vinylphenyl group or a 4-isopropenylphenyl group bonded to a silicon atom. The present inventors have found that a copolymer obtained by graft copolymerization of siloxane is easy and suitable not only in physical properties but also in production, and completed the present invention. That is, the object of the present invention is to provide a silicone-based graft copolymer obtained by radical copolymerization of an organopolysiloxane compound represented by the following chemical formula 2 and another radical polymerizable monomer copolymerizable with the organopolysiloxane compound. Achieved by an electrophotographic toner binder comprising a polymer.

Embedded image (In the formula, R ¹ is a hydrogen atom or a methyl group, and R ² is a carbon atom 1
To 6 monovalent hydrocarbon groups, m is 1, 2 or 3, and n is
Represents an integer of 20 ≦ n ≦ 200. )

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The organopolysiloxane (hereinafter referred to as radically polymerizable silicone macromonomer) represented by the above formula (2) is obtained by combining a styryl-substituted chlorosilane compound represented by the following formula (3) with the following formula (4).
The dehydroxylation reaction of the terminal hydroxyl group-containing dimethylpolysiloxane compound represented by the following formula or a compound represented by the following formula 3 and a dimethylpolysiloxane compound containing Li at the terminal represented by the following formula 5 Can be obtained by a lithium chloride reaction according to a conventional method. If n in Chemical Formula 2 is less than 20, the releasability of the toner using the same will be insufficient, and if it exceeds 200, the copolymerizability will be poor,
Also, depending on the silicone content, the toner may become sticky, which is not preferable.

[0009]

Embedded image

Embedded image

Embedded image

Specific examples of the radical polymerizable silicone macromonomer represented by the above formula (2) are shown below.
One.

Embedded image

[0011]

Embedded image

Next, other radically polymerizable monomers copolymerizable with the radically polymerizable silicone macromonomer include styrene and its derivatives, acrylates and methacrylates from the viewpoint of offset resistance and fixing property.
In addition, it is preferred because the production of the copolymer is easy. In particular, copolymerization of styrene or a styrene derivative with the radically polymerizable silicone macromonomer is more preferable because a toner which is less affected by temperature and humidity and which can improve offset resistance can be obtained. Styrene or its derivatives preferably copolymerized include styrene, α-methylstyrene,
-Methylstyrene, 3-methylstyrene, 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene,
-Vinylanisole, 4-ethylstyrene, vinyltoluene and the like. These can be used alone or in combination of two or more.

Specific examples of the acrylate or methacrylate include methyl (meth) acrylate, ethyl (meth) acrylate, and n-butyl (meth) acrylate.
Alkyl (meth) acrylates such as acrylate and 2-ethylhexyl (meth) acrylate; and hydroxyalkyl (meth) such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (meth) acrylate ) Fluorine-substituted alkyl (meth) acrylates such as acrylates, trifluoropropyl (meth) acrylate, perfluorobutylethyl (meth) acrylate, and perfluorooctylethyl (meth) acrylate; glycidyl (meth) acrylate; -Epoxy group-containing (meth) acrylates such as epoxycyclohexylmethyl (meth) acrylate. These can be used alone or in combination of two or more.

Further, to the extent that the object of the present invention is not impaired,
Monomers other than the preferred radically polymerizable monomers can be copolymerized. Such radically polymerizable monomers include, for example, maleic acid, fumaric acid,
Acids such as acrylic acid and methacrylic acid, acrylamide,
Acrylamides such as N-methylol acrylamide,
3-trimethoxysilylpropyl (meth) acrylate, 3-triethoxysilylpropyl (meth) acrylate, 3-dimethoxymethylsilylpropyl (meth) acrylate, vinyltriethoxysilane, 4-vinylphenyltrimethoxyxylan, vinylmethyldimethoxysilane , 4-trimethoxysilyl-1-butene, 6-trimethoxysilyl-1-hexene and other radically polymerizable silane compounds, acrylonitrile, vinylpyridine, vinylpyrrolidone, vinyl acetate, vinyl chloride, vinyl alkyl ethers, Examples include radically polymerizable macromonomers such as polyoxyalkylene and polycaprolactone having one radically polymerizable group.

By copolymerizing the radically polymerizable silicone macromonomer described above with another radically polymerizable monomer, a silicone graft copolymer used in the binder of the present invention can be obtained. The mixing ratio of the silicone macromonomer and the other radical polymerizable monomer in the copolymerization is preferably (1 to 50) / (50 to 99) (% by weight). If the amount of the radically polymerizable silicone macromonomer exceeds 50% by weight, the fixability becomes poor, and the amount of free residual macromonomer due to a decrease in polymerization conversion increases, which is not preferable. If it is less than 1% by weight, almost no releasability can be expected.

For the copolymerization of the radical polymerizable silicone macromonomer with other radical polymerizable monomers, any of solution polymerization, bulk polymerization, emulsion polymerization, microsuspension polymerization, and suspension polymerization is applied. In particular, the microsuspension polymerization method and the suspension polymerization method have a high polymerization rate even when a large amount of a radically polymerizable silicone macromonomer is copolymerized, and have a preferable particle size simultaneously with the formation of the copolymer. This is preferable because toner particles having a diameter can be formed and the pulverizing step can be omitted. Since the emulsion polymerization method is copolymerized by diffusion of the monomer in water, it is difficult to copolymerize a large amount of a radically polymerizable silicone macromonomer having high hydrophobicity, and since the copolymer particle diameter is as small as 1 μm or less, In order to obtain toner particles having a required particle size, steps such as granulation, pulverization, and classification are required, which is not a preferable polymerization method, but the surface of the core particles containing no polysiloxane chain is used in the present invention. It is useful when modified with such a copolymer.

The suspension polymerization method and the microsuspension polymerization method can be carried out by a known method using an oil-soluble radical polymerization initiator, a suspending agent, a surfactant, a molecular weight modifier and the like. Examples of the oil-soluble radical polymerization initiator include organic peroxides such as benzoyl peroxide, dicumyl peroxide, and lauroyl peroxide; and 2,2'-azobis-.
(2-methylbutyronitrile), 2,2'-azobis-
Examples include azo compounds such as (2,4-dimethylvaleronitrile) and 2,2′-azobisisobutyronitrile. The amount of the oil-soluble radical polymerization initiator used is preferably 0.1 to 5 parts by weight based on 100 parts by weight of the total of the radically polymerizable silicone macromonomer and other radically polymerizable monomers.

As a suspending agent, polyvinyl alcohol,
Organic suspensions such as methylcellulose, carboxymethylcellulose, methylhydroxypropylcellulose, polyethylene oxide, polyacrylic acid, polyacrylate, gelatin, starch, etc., calcium phosphate, magnesium phosphate, barium sulfate, calcium carbonate, calcium metasilicate, bentonite And the like, and these are used alone or in combination. When the amount used is increased, the particle size of the copolymer decreases, but it is preferably 0.1 to 10 parts by weight based on 100 parts by weight of the total of the radical polymerizable silicone macromonomer and other radical polymerizable monomers.

The suspending agent can be used alone, but when used in combination with a surfactant described later, the amount used is small and the particle size can be easily controlled. As a surfactant,
Anionic surfactants such as sodium dodecylbenzenesulfonate, sodium lauryl sulfate and polyoxyethylene alkyl ether sulfate; nonionic surfactants such as polyoxyethylene alkyl ether and polyoxyethylene alkyl allyl ether; alkyl ammonium hydroxide And cationic surfactants such as alkylbenzylammonium salts. Further, as a method in which free surfactant does not remain in the toner, a radical polymerizable surfactant can be used. For example, JP-A-54-144317, JP-A-55-115419, and JP-A-62 34947, JP-A-58-203960, JP-A-4-53802, JP-A-62-104802, JP-A-49-40388, JP-A-52-134658,
Reactive surfactants described in JP-B-49-46291 and the like can be mentioned. The amount of the surfactant used is preferably 0.01 to 15 parts by weight based on 100 parts by weight of the total of the radical polymerizable silicone macromonomer and other radical polymerizable monomers.

In the solution polymerization method, polymerization is carried out in a solvent such as toluene, methyl ethyl ketone, or ethyl acetate using the above-described oil-soluble radical polymerization initiator. In the bulk polymerization method, polymerization is carried out with the above-mentioned oil-soluble radical polymerization initiator in the absence of a solvent. However, it is difficult to remove heat and such is not a preferable method. In the emulsion polymerization method, emulsion polymerization is carried out in an aqueous medium using the surfactant and a water-soluble radical polymerization initiator. As the water-soluble radical polymerization initiator, hydrogen peroxide water, potassium persulfate, inorganic peroxides such as ammonium persulfate, t-butyl hydroperoxide, organic peroxides such as t-butylperoxymaleic acid, 2,2′-azobis- (2-
An azobis compound such as (N-benzylamidino) propane hydrochloride is exemplified. Further, if necessary, a redox system using a reducing agent such as sodium acid sulfite, Rongalit, or L-ascorbic acid can also be used. The amount of the water-soluble radical polymerization initiator used is preferably 0.1 to 5 parts by weight based on 100 parts by weight of the total of the radically polymerizable silicone macromonomer and other radically polymerizable monomers.

In the above polymerization method, the polymerization temperature is from 10 to 90.
Polymerization can be carried out at a temperature of about 3 to 10 hours. After completion of the polymerization, the particle diameter is 1 in the case of the solution polymerization method or the emulsion polymerization method.
μm or less, the dispersion medium is removed by a known method such as spray drying, concentration under reduced pressure or dehydration after coagulation,
Necessary treatments such as washing with water, drying, pulverization or crushing, and classification are performed to obtain a particulate silicone-based graft copolymer. In the suspension polymerization method and the micro-suspension polymerization method, when a silicone-based graft copolymer is produced, fine particles such as a colorant, a charge control agent, and a magnetic material, which are components used in a toner, are previously contained in a radical polymerizable monomer. Powders can be added and dispersed. Furthermore, a radical polymerization initiator, an aqueous medium, a suspending agent or a surfactant are added,
Using a high-speed shearing stirrer such as a homomixer or a homogenizer, the mixture is suspended and polymerized to a preferable particle size.
Increasing the amount of suspending agent or surfactant, or applying high shear force, reduces the particle size. The particle size of the obtained toner is 2 to
What is necessary is just to superpose | polymerize by adjusting conditions so that it may be set to 50 micrometers. A more preferred particle size is 5 to 30 μm. When the particle size is less than 2 μm, the toner is too fine to handle easily, and the developer is bulky, which is not preferable. Also, if it exceeds 50 μm, the image quality is poor,
It is not preferable because the resolution is reduced.

Examples of colorants for toner include black pigments such as carbon black, yellow pigments such as zinc yellow, nickel titanium yellow and cadmium yellow, red pigments such as red iron, cadmium red and lead red, phthalocyanine blue and cobalt blue. Examples include blue pigments, white pigments such as titanium oxide, zinc white, and antimony white. Furthermore,
In order to adjust the charge amount of the toner, known charge control agents such as manganese such as naphthenic acid, salicylic acid, octylic acid, and higher fatty acids, and metal soaps such as iron salts, cobalt, nickel, lead, cerium, and calcium salts. Metal azo dyes, pyridine compounds, metal chelates of alkylsalicylic acid, various phosphate compounds, chromium complex compounds and the like are used. In addition, extenders such as silica, alumina, talc, barium carbonate, and clay can be added as necessary.

[0023]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.
All parts in the examples are parts by weight. <Production Example-1> A mixture of 30 parts of a macromonomer represented by the following [Chemical Formula 8], 70 parts of styrene, and 2 parts of azobisisobutyronitrile was added to 100 parts of toluene at 80 to 90 ° C under nitrogen aeration.
For 2 hours. After completion of the dropwise addition, the mixture was aged at 80 to 90 ° C. for 8 hours. Then, toluene was distilled off under reduced pressure, and the resulting copolymer was pulverized with a hammer mill to have a weight average molecular weight of 28,000.
Was obtained.

Embedded image

<Production Example 2> 70 parts of styrene, 25 parts of 2-ethylhexyl methacrylate, 5 parts of the macromonomer represented by the above formula, 0.05 part of dodecyl mercaptan, 5 parts of carbon black, methyltriphenylphosphonium tosylate 1 And a mixture of 4 parts of azobisisobutyronitrile were added to an aqueous solution obtained by dissolving 3 parts of Alcox R-1000 (trade name, manufactured by Meisei Chemical Co., Ltd .; polyethylene oxide) in 300 parts of ion-exchanged water. Was dispersed. This dispersion was charged into a polymerization vessel equipped with a stirrer, a condenser, a thermometer and a nitrogen gas inlet, and polymerized at 80 ° C. for 8 hours under nitrogen aeration to obtain a polymerized polymer suspension. The suspension was filtered, washed with water, dehydrated and dried to obtain a spherical fine particle toner having an average particle diameter of about 15 μm and a weight average molecular weight of the copolymer of about 30,000.

<Production Example 3> 80 parts of styrene, 10 parts of butyl acrylate, macromonomer 10 represented by the above [Chemical Formula 8]
Part, dodecyl mercaptan 0.05 part, carbon black 5
Parts, 1 part of methyltriphenylphosphonium tosylate,
Aqualon HS-20 (trade name, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd .; radical reactive surfactant) 0.1 part, Metroose 65SH400
A mixture of 5 parts (trade name, manufactured by Shin-Etsu Chemical Co., Ltd .; methyl cellulose) and 1 part of benzoyl peroxide was added to 300 parts of water, and emulsified with a homomixer. Stirrer this emulsion,
The mixture was charged into a polymerization vessel equipped with a condenser, a thermometer, and a nitrogen gas inlet, and polymerization was carried out at 80 ° C. for 6 hours under nitrogen aeration to obtain a polymerized polymer suspension. The suspension was filtered, washed with water, dehydrated and dried to obtain a spherical fine particle powder toner having an average particle diameter of about 7 μm and a weight average molecular weight of the copolymer of about 210,000.

<Production Example 4> A weight average was obtained in the same manner as in Production Example 1 except that the macromonomer represented by Chemical Formula 8 used in Production Example 1 was replaced with the macromonomer represented by Chemical Formula 9. A silicone-based graft copolymer having a molecular weight of 26,000 was obtained.

Embedded image

<Example-1> 100 parts of the silicone-based graft copolymer obtained in Production Example-1, 5 parts of carbon black,
A mixture of 1 part of methyltriphenylphosphonium tosylate was dispersed in a hot roll at 160 ° C., pulverized with a hammer mill, and further obtained with a jet mill to obtain a fine powder toner having an average particle size of about 20 μm. Using a ferrite carrier (Powdertech Co., Ltd.) with an average particle size of 150 μm and a developer whose toner concentration is adjusted to 0.5% by weight using the above toner, a dry two-component copying machine of magnetic brush development system (copying) (Speed: 60 sheets / min). When fog was examined after 50,000 copies, no fog was found and a clear image was obtained. No adhesion of toner was observed after 50,000 copies were made, and there was no stain on the fixing roll. Apply this developer to 50
The fluidity was not lost even when left open for 24 hours under the conditions of 98 ° C. and 98% RH.

Example 2 Using the ferrite carrier used in Example 1 and the spherical fine particle toner obtained in Production Example 2, a developer was prepared in which the toner concentration was adjusted to 0.5% by weight. Was evaluated in the same manner as described above. As a result, no fog or roll contamination was observed even after copying 50,000 sheets, and the fluidity was good.

Example 3 A developer was prepared in the same manner as in Example 2 except that the spherical fine particle powder toner obtained in Production Example 3 was used instead of the spherical fine particle powder toner obtained in Production Example 2. Was prepared, and the same evaluation as in Example 1 was performed. As a result, 5
Even after 10,000 copies, there was no fog or roll contamination, and the fluidity was good.

<Example-4> A developer was prepared in the same manner as in Example-1 using the ferrite carrier used in Example-1 and the silicone-based graft copolymer obtained in Production Example-4. Evaluation was performed in the same manner as in Example 1. As a result, 5
Even after 10,000 copies, there was no fog or roll contamination, and the fluidity was good.

<Comparative Example 1> A styrene-acrylic resin having a glass transition point of 63 ° C. (trade name, Hymer TB-9000, manufactured by Sanyo Chemical Industries, Ltd.) instead of the silicone-based graft copolymer obtained in Production Example-1 A finely pulverized toner was prepared in exactly the same manner as in Example 1 except for using, and the same evaluation as in Example 1 was performed. As a result, fog was examined after 10,000 copies, and fog was found and contamination of the roll was also observed. Also, the fluidity was considerably reduced.

[0032]

The toner using the binder of the present invention does not aggregate during storage and can maintain excellent fluidity. That is, the lubricity between toner particles is good, and it is hardly affected by humidity and temperature. Further, the releasability from the toner fixing rubber roll is remarkably excellent. Due to these characteristics, a clear image is formed even in a high-speed machine.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinji Miyadai 1-10 Hitomi, Matsuida-cho, Usui-gun, Gunma Prefecture Inside Silicone Electronics Materials Research Laboratory, Shin-Etsu Chemical Co., Ltd. (72) Inventor Hiroyuki Ohata Kitafu, Takefu-shi, Fukui 2-17-1733 Nissin Kagaku Kogyo Co., Ltd. (72) Inventor Masahide Hatanaka 2-17-17 Kitafu, Takefu City, Fukui Prefecture Nissin Kagaku Kogyo Co., Ltd.

Claims (4)

[Claims] 1. A copolymer obtained by radical copolymerization of an organopolysiloxane compound represented by the following formula 1 and another radical polymerizable monomer copolymerizable with the organopolysiloxane compound. For electrophotographic toner. Embedded image (In the formula, R ¹ is a hydrogen atom or a methyl group, and R ² is a carbon atom 1
To 6 monovalent hydrocarbon groups, m is 1, 2 or 3, and n is
Represents an integer of 20 ≦ n ≦ 200. ) 2. The binder for an electrophotographic toner according to claim 1, wherein the other radically polymerizable monomer copolymerizable with the organopolysiloxane compound represented by Chemical Formula 1 is a monomer selected from styrene and styrene derivatives. 3. The other radically polymerizable monomer copolymerizable with the organopolysiloxane compound represented by the chemical formula 1 is a monomer selected from acrylates and methacrylates, or styrene and styrene. 2. The binder for an electrophotographic toner according to claim 1, wherein a monomer selected from derivatives is added. 4. A copolymer obtained by suspension polymerization or microsuspension polymerization of an organopolysiloxane compound represented by the formula 1 and another radical polymerizable monomer copolymerizable with the organopolysiloxane compound in an aqueous medium. 4. The binder for an electrophotographic toner according to claim 1, comprising a polymer.