JPH10312082A - Binder resin for toner, toner for electrostatic charge development, and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner having good fixability to paper, capable of obtaining a clear image without a dropout of characters even in a humid environment, and having no blocking during production and storage. provide. SOLUTION: A toner for electrostatic charge development produced by a process of kneading a binder resin having a free acid group in a structure and containing an oil component, and a colorant, if necessary, together with other components. .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for electrostatic charge development, a binder resin for toner, and an image forming method using the toner, which are used for image formation by an electrophotographic method.

[0002]

2. Description of the Related Art In an electrophotographic copying machine or printer, toner temporarily adheres to an image carrier such as a photoconductor on which an electrostatic image is formed in a developing process, and is then transferred to a transfer paper in a transferring process. After that, the toner is fixed in a fixing step to form an image. The toner adhesion (development) to the image carrier includes so-called regular development in which the charge of the electrostatic image is opposite to the charge polarity of the toner, and reversal development in which both have the same polarity. The toner used in the development includes a two-component toner used together with the carrier and a one-component toner using only the toner as a developer.
Further, the one-component toner includes a one-component toner containing a magnetic substance and a non-magnetic one-component toner containing no magnetic substance. In the transfer step, an electrostatic transfer method is widely used, and as the method, a corona transfer method, a roller transfer method, a belt transfer method and the like are known. Electrophotographic image formation is performed by a combination of methods selected from these various developing methods or transfer methods.

As a method for producing a toner, a method of blending a binder resin with a necessary component such as a colorant and a charge controlling agent, kneading, kneading, pulverizing and classifying is widely used. The performance required of the toner is that when an image is formed, the image density is sufficient, there is no image fog, an image without image defects is obtained, or there is no toner scattering or filming on the photoconductor. , Good cleaning,
Long-term stable use, toner production process and storage,
There is a wide variety of problems, such as not causing blocking during transportation, and problems with production images, formed images, and equipment used. In order to satisfy such requirements, many proposals have been made regarding the properties of the materials to be melt-kneaded, the compounding formula, the kneading conditions, and the like. For example, attempts have been made to improve the adhesion between toner and paper by using a binder resin having an acid group in the structure. Also, it has been reported that when a toner is produced by melting and kneading a resin, a colorant, a magnetic powder and the like, an offset phenomenon can be prevented by adding a silicone oil (Japanese Patent Application Laid-Open No. 54-48245, Japanese Patent Application Laid-Open No. 54-48245). Kaisho 59
-197048). Alternatively, various external additives represented by silica have been proposed.

[0004]

However, these conventional methods do not always sufficiently satisfy the performance required for the toner. Further, depending on the development, transfer, and other methods employed in the image forming apparatus, sufficient effects cannot always be obtained. In particular, in a roller transfer method in which a toner layer is transferred directly to a recording paper through a conductive rubber roller or a dielectric roller having a dielectric layer provided on a conductive rubber, and the electric field generated thereby transfers the toner layer, a character is transferred in a process of transferring the toner. Missing defects often occur. This is related to the cohesive force or fluidity of the toners, and it is known that a toner having a low cohesive force between the toners and a good fluidity of the toner does not cause missing characters, but the factor is complicated. At present, there is no effective proposal for a solution to this problem. In particular, in the case of a toner employing a binder resin having an acid group, the occurrence of missing characters in roller transfer tends to be more apparent, and particularly in a humid environment, image defects may occur, and the image quality is fatal. is there. On the other hand, if the binder resin is reduced in particle size in order to improve the dispersibility of each component in the toner, the fluidity of the resin particles deteriorates, and bridging and adhesion to the apparatus wall surface in each step of toner production become severe. This lowers the productivity of the toner. Further, when the glass transition point of the resin is lowered for the purpose of fixing at a low temperature in response to the demand for energy saving in recent years, a new problem that blocking during transportation and storage is easily caused has arisen. The present invention has been made in view of the above circumstances, and an object of the present invention is to use a binder resin having an acid group, to have a good fixing property to paper, and to have a clear and dirty character without any voids even in a humid environment. It is an object of the present invention to provide a toner which can obtain a good image free from defects, has improved trouble during production, storage or transportation, and enables stable production.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that the above problems can be solved by using a binder resin containing oil in advance. Achieved. That is, the present invention
It is produced by a process of kneading a binder resin for a toner having an oil component and having a free acid group in a structure and a resin and a coloring agent together with other components as necessary. The present invention relates to a toner for charge development and an image forming method using the toner.

Hereinafter, the present invention will be described in detail. It is important for the binder resin for a toner of the present invention to contain an oil component in advance in the resin, whereby the oil is added when the binder resin and other components are kneaded, compared to the method disclosed in the above publication, The fluidity of the resin can be significantly improved. The binder resin for a toner containing the oil component according to the present invention can be obtained by producing the resin component, that is, by allowing the oil component to be present at the time of monomer polymerization.

The binder resin for a toner of the present invention is not particularly limited, and a conventionally known binder resin having an acid group in a structure is used. For example, a vinyl resin having an acid group, a polyester resin, or a mixed resin thereof may be used. The vinyl resin having an acid group is produced by copolymerizing one or more vinyl monomers with a monomer having a polymerizable unsaturated double bond and at least one carboxyl group. Examples of the vinyl monomer include styrene, α-methylstyrene, and o-methyl, m-methyl, p-methyl, p-methyl
-Ethyl group, 2,4-dimethyl group, p-butyl group, p-
Styrene derivatives having a hexyl group, a p-octyl group, a p-nonyl group, a p-decyl group, a p-methoxy group, a p-phenyl group, etc., acrylic esters represented by the general formula: CH ₂ CR-COOR Or methacrylic acid esters (where R represents hydrogen or a methyl group; R ′ represents a methyl group, an ethyl group, an n-butyl group, an isobutyl group, an s-butyl group, a t-butyl group, an n-pentyl group, n -Alkyl group such as hexyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, isononyl group, decyl group, dodecyl group, tridecyl group, stearyl group, docosyl group; cycloalkyl group such as cyclohexyl group; benzyl Aralkyl or aryl such as phenyl, phenyl, etc .; aralkyl such as methoxyethyl, ethoxyethyl, butoxyethyl, phenoxyethyl, etc. Represents a oxyalkyl or aryloxyalkyl group), vinyl esters such as vinyl acetate and vinyl propionate, acrylonitrile, methacrylonitrile, and the like, and is used as one type or a mixture of two or more types depending on the purpose. be able to.

The styrenic polymer or styrenic copolymer may be crosslinked or a mixed resin. Examples of the monomer having a polymerizable unsaturated double bond and at least one carboxyl group include unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid, α
-Substituted carboxylic acids such as chloroacrylic acid and α-bromoacrylic acid; unsaturated dicarboxylic acids such as fumaric acid, maleic acid, maleic anhydride and monobutyl maleate;
Examples thereof include anhydrides and half esters thereof. Among them, acrylic acid or methacrylic acid is preferred. The amount of these acid components is 0.1 to 30% by weight in the resin.
And more preferably 0.5 to 10% by weight.

As the polyester resin, a resin having a free acid group obtained by condensation polymerization of a divalent or higher carboxylic acid and a divalent or higher valent alcohol component is selected. Examples of the divalent carboxylic acid include maleic anhydride, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, and n-dodecyl. Succinic acid, n-dodecenyl succinic acid, isododecyl succinic acid, isododecenyl succinic acid, n-octyl succinic acid, n-octenyl succinic acid, and the like, and anhydrides thereof can also be used. Examples of the trivalent carboxylic acid include 1,2,4-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid,
2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) Examples thereof include methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, and empole trimer acid, and these acid anhydrides can also be used.

The dihydric alcohols include polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane and polyoxypropylene (3.3)-
2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2.0) -polyoxyethylene (2. 0) -2,2-
Bis (4-hydroxyphenyl) propane, etherified bisphenols such as polyoxypropylene (6) -2,2-bis (4-hydroxyphenyl) propane, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,4
-Butenediol, neopentyl glycol, 1,5-
Pentane glycol, 1,6-hexane glycol,
Use 1,5-pentane glycol, 1,6-hexane glycol, 1,4-cyclohexane dimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol A, bisphenol Z, hydrogenated bisphenol A, etc. can do. Examples of the trihydric alcohol include sorbitol, 1,2,3,6-hexanetetol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol,
1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,
3,5-trihydroxymethylbenzene and the like.

Among these resins having an acid group, the binder resin of the present invention is preferably a vinyl resin. In particular, a binder resin obtained by polymerizing a monomer containing styrene is preferable, and a binder resin obtained by polymerizing a monomer containing styrene and one or more acrylate or methacrylate is more preferable. The acid value of these resins is 1 to 30.
It is preferably mgKOH / g. The acid value of resin is resin 1
It indicates the number of mg of potassium hydroxide required to neutralize the acid content contained in g, and is measured by the method described in JIS K0070. Further, the glass transition temperature (Tg) of the resin is related to the fixing property of the toner, and is preferably 60 ° C. or lower in order to meet the demand for low-temperature fixing.

The oil in the present invention means a liquid which is liquid at normal temperature, does not dissolve in water, and has viscosity. That is, oil is a hydrophobic oily substance, for example, mineral oil, liquid paraffin, α-olefin oligomer, liquid polypropylene, liquid isobutylene, liquid polybutene, isoper L, isoper M, liquid chloroprene, silicone oil, spindle oil, vegetable oil, linseed oil And the like. An index indicating this viscosity is viscosity, and the viscosity (kinematic viscosity) of the oil used in the present invention is 1 to 1
Preferably, it is 000 centistokes (cs). Particularly preferred is 10 to 1,000 centistokes. In the present invention, the oil is preferably a silicone oil. As silicone oil,
Good release and release properties are preferred, but in addition to straight silicone oils such as dimethyl silicone oil, methyl phenyl silicone oil, and methyl hydrogen silicone oil, polyether-modified silicone oil, epoxy-modified silicone oil, and methacryl-modified silicone Oil, long-chain alkyl-modified silicone oil,
Various modified silicone oils such as a fluorine-modified silicone oil are exemplified. In the case of a vinyl resin, a silicone oil having a reactive vinyl group capable of reacting with a polymerizable monomer is also used. In the present invention, straight silicone oil is particularly preferred, and dimethyl silicone oil is more preferred. The oil content in the binder resin is desirably 0.01 to 10 parts by weight based on 100 parts by weight of the resin (excluding oil).

The polymerization method for producing the binder resin includes, for example, solution polymerization, suspension polymerization, bulk polymerization and emulsion polymerization. In the present invention, it is particularly preferable to produce a vinyl monomer by suspension polymerization. Then, at the time of the polymerization reaction, the oil is present in the system and polymerized to obtain a resin containing the oil. Specifically, there is a method of mixing and polymerizing an oil with a monomer from the beginning of the reaction, and a method of adding the oil in the middle of the polymerization reaction. A method of polymerizing after the reaction is preferred.

To produce a binder resin containing the oil of the present invention by polymerizing a vinyl monomer by suspension polymerization using a silicone oil as an oil, for example, a monomer, a silicone oil, a polymerization initiator (for example, benzoyl peroxide) , An azo compound, etc.), an oil phase to which a chain transfer agent is further added if necessary, and an aqueous phase to which a suspension stabilizer such as water and polyvinyl alcohol, and further, a dispersing aid is further added as necessary, are mixed and stirred. Make a droplet dispersion (suspension). The ratio of the oil phase to the aqueous phase is set by weight, and the aqueous phase is set to 10 or less, preferably 2 to 5 for 1 oil phase. The droplet dispersion is heated to a predetermined polymerization temperature and polymerized. Then, the polymer is separated by dehydrating the reaction mixture, washed with water if necessary, and dried to obtain a desired resin.

In order to improve the dispersibility of each component in the toner, the volume average particle size of the resin containing the oil is 1 mm.
The following is preferred. Glass transition point of resin (T
Since g) is related to the Tg of the toner, the temperature is desirably 60 ° C. or lower in view of the tendency of low-temperature fixing in recent years. If necessary, a toner component other than oil, for example, a colorant, a charge controlling agent, an additive such as a wax, a magnetic material, or the like may be added to the resin during the polymerization. The binder resin containing the oil component thus obtained is further added to the colorant and, if necessary, other components, and then kneaded to produce the toner of the present invention. The other components are appropriately selected from known ones such as a charge controlling agent, a magnetic powder, and a wax. At this time, a binder resin and a silicone oil may be further used in combination with the other components at the time of kneading.
The kneading is performed using a kneading machine such as a heating roll, a kneader, an extruder or the like. The kneaded composition is solidified by cooling, pulverized and classified to a desired particle size, and if necessary, an external additive such as silica is further added to obtain a toner.

The toner according to the present invention is a magnetic powder containing magnetic powder.
It can be applied to any formulation of a component toner, a non-magnetic one-component toner containing no magnetic powder, or a two-component toner used by mixing with a carrier. As the colorant used in the present invention, for example, carbon black, lamp black, iron black, ultramarine, nigrosine dye, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa Yellow G,
Rhodamine dyes, chrome yellow, quinacridone,
Any conventionally known dye or pigment such as benzidine yellow, rose bengal, triallylmethane dye, monoazo or disazo dye or pigment may be used alone or in combination.

In the toner of the present invention, the colorant
May have magnetism. In the case of magnetic toner, general
In this case, black or brown magnetic particles are used as a colorant. In the present invention
The magnetic particles used include the operating temperature of the copying machine, etc.
(Around 0 ° C. to 60 ° C.)
A ferromagnetic substance that exhibits ferromagnetism and the like.
Site (Fe_ThreeO_Four), Maghemite (γ-Fe
_TwoO_Three), An intermediate between magnetite and maghemite,
Light (MxFe_Three-XO_FourWhere M is Mn, Fe, C
o, Ni, Cu, Mg, Zn, Cd, etc. or mixed crystals thereof
Spinel ferrite and BaO.6Fe_TwoO_Three,
SrO.6Fe_TwoO_ThreeHexagonal ferrite, Y _ThreeFe
_FiveO₁₂, Sm_ThreeFe_FiveO₁₂Garnet-type oxides such as C
rO_TwoRutile oxides such as Fe, Mn, Ni, Co,
In metals such as Cr and other ferromagnetic alloys, 0 ° C to 6 ° C
Those exhibiting ferromagnetism or ferrimagnetism around 0 ° C
Magnetite, maghemite, and magne
Average particle size of intermediates such as tight and maghemite 3μm or less
Under, more preferably, about 0.05 to 1 μm fine particles
It is both efficient and cost-effective. The above magnetic particles are used alone
In addition to the above, two or more kinds can be used in combination.

The method for producing the toner is not particularly limited, and any conventionally known method can be employed. For example, a general manufacturing method is as follows. Components such as a colorant and, if necessary, a charge control agent are added to a binder resin containing oil, and the mixture is uniformly dispersed with a Henschel mixer or the like. Next, the dispersion is melt-kneaded with a pressure kneader or the like. Further, the kneaded material is pulverized by a pulverizer such as a hammer mill, a cutter mill, and a jet mill, and the obtained powder is classified by an air classifier or the like to obtain a toner having a desired particle size. If necessary, fine silicon powder, higher fatty acid salts or inorganic oxides may be added to the classified product. The volume average particle diameter (50% volume diameter) of the toner is preferably 3 to 15 μm, and more preferably 5 to 10 μm. In addition, the toner of the present invention has a particularly excellent effect when an image forming method having a roller transfer system is used, and a good image without character omission, which is inevitable with the prior art, can be obtained.

[0019]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the invention. Note that “parts” represents “parts by weight” unless otherwise specified. Example 1 44 parts of styrene, 14 parts of n-butyl acrylate, 2 parts of methacrylic acid, dimethyl silicone oil (trade name KF
96-100cs, manufactured by Shin-Etsu Chemical Co., Ltd., viscosity 100cs)
After dispersing 0.5 part by a multi-disperser (Mitamura Riken) at about 8,000 rpm for 30 minutes,
3 parts of 2,2′-azobisisobutyronitrile was dissolved to obtain an oil phase mixture. The acid value at this time is about 21 mg KO
H / g. On the other hand, as an aqueous phase, 180 parts of a 1% aqueous solution of polyvinyl alcohol (trade name: GM-14, manufactured by Nippon Synthetic Chemical Co., Ltd.) was used.

The oil phase is dispersed in the aqueous phase using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) at a rotational speed of about 6,000.
Stirred for 15 minutes at rpm. After that, the dispersion is agitated,
The mixture was transferred to a stainless steel polymerization can equipped with a thermometer and a nitrogen inlet tube, and heated at 80 ° C. for 8 hours under a nitrogen stream while stirring at about 500 rpm to complete the polymerization reaction. From the obtained reaction solution, polymer particles were separated as a solid content by a centrifugal separator, further washed with water, and vacuum-dried after repeated filtration,
A silicone oil-containing toner binder resin having an average particle size of 100 μm and a Tg of 55 ° C. was obtained.

Comparative Example 1 A resin was produced in the same manner as in Example 1 except that no silicone oil was used.
A binder resin for toner having a μm and a Tg of 55 ° C. was obtained.

Example 2 After mixing 100 parts of the resin obtained in Example 1 with 5 parts of carbon black as a colorant, the obtained mixture is temporarily stored in a tank, and then the mixture is supplied to a kneading machine in a fixed amount. And kneaded. Bridging caused by the resin was not observed in each of the mixing, storage and kneading steps, and stable production was possible. The resin was stored for one week at a temperature of 45 ° C., but no blocking occurred. Comparative Example 2 Using the resin obtained in Comparative Example 1 and performing toner production through exactly the same process as in Example 1, bridging occurred in the storage tank, and a defective feed amount occurred during kneading. Further, when this resin was stored at a temperature of 45 ° C. for one week, aggregates of the resin were found to be slightly generated.

Example 3 A non-magnetic one-component developer was obtained according to the following compounding ratio. Binder resin of Example 1 100 parts Carbon black MA100 (manufactured by Mitsubishi Chemical) 6 parts Bontron S34 (manufactured by Orient Chemical) 2 parts Polypropylene wax 550P (manufactured by Sanyo Chemical) 4 parts After mixing these with a Henschel mixer, biaxial extrusion was performed. The mixture was melted and kneaded with a machine to obtain a toner mass. After coarsely pulverized with a feather mill, finely pulverized with a jet mill,
Then, the 50% volume average particle size was 9 using an airflow classifier.
μm toner particles were obtained. Also, spherical silica fine particles (R97 manufactured by Nippon Aerosil Co., Ltd.) are
2) Mix 0.8 parts with a super mixer and mix with non-magnetic 1
A component-based electrophotographic developer was obtained. The toner was evaluated for printing in a normal environment of 25 ° C. and 50% RH using a commercially available remodeled printer (roller transfer system) using a non-magnetic one-component developing system. A clear image without omission was obtained. In addition, this printing test was performed 25 times.
When the test was performed in a humid environment of 85 ° C. and 85% RH, the voids in the characters did not deteriorate.

Comparative Example 3 A non-magnetic one-component electrophotographic developer was obtained in the same manner as in Example 3, except that the resin obtained in Comparative Example 1 was used instead of the resin obtained in Example 1. Was. When this was evaluated for printing by the printer in the same manner, occurrence of missing characters was slightly observed. On the other hand, in a humid environment, the characters were markedly missing, and could not withstand actual use.

Example 4 A magnetic one-component developer was obtained according to the following compounding ratio. Binder resin of Example 1 100 parts Magnetic powder EPT500 (manufactured by Toda Kogyo) 70 parts Charge control agent T77 (manufactured by Hodogaya Chemical) 1 part Polypropylene wax NP505 (manufactured by Mitsui Chemicals) 4 parts After mixing these with a Henschel mixer, The mixture was melt-kneaded with a twin-screw extruder to obtain a toner mass. After coarsely pulverized with a feather mill, finely pulverized with a jet mill,
Thereafter, the 50% volume average particle size was 8 using an airflow classifier.
μm toner particles were obtained. Further, spherical silica fine particles (R972 manufactured by Nippon Aerosil) were used for 100 parts of the toner.
0.5 part was mixed with a supermixer to obtain a magnetic one-component electrophotographic developer. To evaluate the printing of this toner,
A printer using a commercially available magnetic one-component developing system was modified and used. This printer uses an organic photoreceptor (O
PC) and a roller charging system and a roller transfer system. As a result of the print evaluation, in both the normal environment and the humid environment, the fixability to paper was good, and a clear image without missing characters was obtained.

Comparative Example 4 A one-component magnetic electrophotographic developer was obtained in exactly the same manner as in Example 4, except that the resin obtained in Comparative Example 1 was used instead of the resin obtained in Example 1. When this was similarly evaluated for printing by the above-mentioned printer, some missing characters occurred. On the other hand, in a humid environment, the dropout of characters becomes remarkable,
I can no longer endure actual use.

Example 5 A magnetic one-component electrophotographic developer was obtained in exactly the same manner as in Example 4, except that the formulation was as follows, except that silicone oil was further added to the formulation of Example 4. Binder resin of Example 1 100 parts Magnetic powder EPT500 (manufactured by Toda Kogyo) 70 parts Charge control agent T77 (manufactured by Hodogaya Chemical) 1 part Polypropylene wax NP505 (manufactured by Mitsui Ishika) 4 parts Silicone oil (trade name KF96-100cs, Shin-Etsu) The same printing evaluation was performed by the printer used in Example 4 in the same manner as in Example 4. As in Example 4, the fixability was good in both normal and humid environments, and characters were missing. A clear image with no image was obtained.

Comparative Example 5 A one-component magnetic electrophotographic developer was obtained in exactly the same manner as in Example 5, except that the resin obtained in Comparative Example 1 was used instead of the resin obtained in Example 1. When the same printing evaluation was performed by using the printer, the results were better than the results of Comparative Example 4. However, in the normal environment, some missing characters were observed, and the deterioration was further deteriorated in a humid environment. The level was not practically satisfactory as compared with Example 5.

Example 6 A two-component magnetic developer was obtained according to the following compounding ratio. Binder resin of Example 1 100 parts Carbon black MA0100 (manufactured by Mitsubishi Chemical) 6 parts Bontron S34 (manufactured by Orient Chemical) 2 parts Polypropylene wax NP505 (manufactured by Mitsui Petrochemical) 4 parts These are kneaded and crushed in the same manner as in Example 3. Then, toner particles having a 50% volume average particle diameter of 9 μm were obtained.
0.8 parts of silica fine particles (R972 manufactured by Nippon Aerosil Co., Ltd.) were mixed with 100 parts of the toner using a super mixer to obtain a two-component type electrophotographic developer. A ferrite powder carrier (silicone treatment) having a volume average particle size of 80 μm was mixed with this developer by a V-type mixer to prepare a two-component developer having a toner concentration of 4%. A commercially available electrophotographic developing type copying machine (A4 22
100,000 under normal environment of 24 ° C and 50% RH
When continuous real images of the sheets were taken, no problems such as image density, voids, fog, etc. occurred, and the results were good. Further, the developer was subjected to high temperature and high humidity of 35 ° C., 85% RH,
When similar actual photographing was performed in each of the low-temperature and low-humidity environments of H, it was found that there was no particular tendency for the hollow characters in the characters to deteriorate.

Comparative Example 6 A magnetic two-component developer was obtained in the same manner as in Example 6, except that the resin obtained in Comparative Example 1 was used. When the same actual copying was performed in the same manner with the copying machine used in Example 6, characters were missing. Further, under high temperature and high humidity, the hollow characters became more remarkable, and it became impossible to withstand actual use.

[0031]

As is apparent from the above description, a binder resin having a free acid group in the structure of the present invention and containing an oil component, particularly a binder resin containing a silicone oil at the time of polymerization, is a resin. Even when the particles have a small particle size, bridging does not occur at the time of toner production, and stable productivity can be improved. Even when the Tg of the resin is low, the storage stability is excellent. Furthermore, the toner for electrostatic charge development obtained through at least the step of kneading the oil-containing binder resin and the colorant exhibits good fixability. Further, when such toner is used, it is possible to improve the hollow characters in the characters, which has been a problem of the roller transfer method, and it is possible to obtain a clear and high quality image without the hollow characters especially in a humid environment.

Claims (13)

[Claims] 1. A toner binder resin having a free acid group in its structure and containing an oil component. 2. The binder resin for a toner according to claim 1, wherein an oil is contained during the production of the resin. 3. The copolymer according to claim 1, which is a copolymer of at least one vinyl monomer and a monomer having a polymerizable unsaturated double bond and at least one carboxyl group. Binder resin for toner. 4. The binder resin for a toner according to claim 3, wherein the vinyl monomer contains at least a styrene monomer. 5. The binder resin for a toner according to claim 3, wherein the vinyl monomer contains styrene and at least one monomer selected from the group consisting of acrylates and methacrylates. 6. The binder resin for a toner according to claim 3, wherein the monomer having an unsaturated double bond and a carboxyl group is acrylic acid or methacrylic acid. 7. The toner binder resin according to claim 1, wherein the oil is a silicone oil. 8. The toner binder resin according to claim 1, wherein the viscosity of the oil is from 1 to 10,000 cs. 9. The binder resin for a toner according to claim 1, wherein the viscosity of the oil is from 1 to 1,000 cs. 10. The binder resin for a toner according to claim 1, wherein the oil content is 0.01 to 10 parts by weight based on 100 parts by weight of the resin. 11. The method of claim 1, wherein the at least one vinyl monomer and a monomer having a polymerizable unsaturated double bond and at least one carboxyl group are obtained by suspension polymerization in the presence of silicone oil. The binder resin for a toner according to any one of claims 1 to 10, wherein: 12. An electrostatic charge developing toner manufactured by kneading the resin and the colorant according to claim 1 together with other components as necessary. 13. An electrophotographic image forming method having a roller transfer method, wherein the electrostatic charge developing toner according to claim 12 is used.