JPH08305080A - Resin composition for toner and toner - Google Patents

Abstract

PURPOSE: To prevent the sticking of a toner to a photoreceptor even in the case of use in a copying machine over a long period of time by using a resin compsn. based on a vinyl copolymer contg. low and high mol.wt. polymer components each having the max. value in the mol.wt. distribution within a specified range and contg. polystyrene having a specified wt. average mol.wt. by a specified wt.% of the total amt. of the resin compsn. CONSTITUTION: This resin compsn. is based on a vinyl copolymer contg. a low mol.wt. polymer component having the max. value in the mol.wt. distribution within the range of 2×10<3> -4×10<4> and a high mol.wt. polymer component having the max. value in the mol.wt. distribution within the range of 3×10<5> -8×10<6> and contains polystyrene having a wt. average mol.wt. of 100,000-400,000 by 5-40wt.% of the total amt. of this resin compsn. The vinyl copolymer preferably has units of a styrene monomer or an acrylic ester or methacrylic ester monomer as constituent units. The sticking of a toner using this resin compsn. to a photoreceptor can be prevented even in the case of use over a long time and a stable image is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for a toner used in electrophotography and a toner, more specifically, a toner used in a so-called dry developing method among methods for developing an electrostatic image. Resin composition and toner.

[0002]

2. Description of the Related Art In electrophotography and the like, a dry developing system is often used as a method for developing an electrostatic charge image. In the dry development method, triboelectrically-charged toner is obtained by mixing carriers such as iron powder and glass beads with fine powder obtained by adding a colorant such as carbon black and other additives to a toner resin serving as a binder. (Developer) is used.

In order to obtain a copy, an electrostatic latent image is usually formed on a photosensitive member, and triboelectrically-charged toner is electrically attached to the electrostatic latent image to develop the toner image. Is transferred to a sheet such as paper. Thereafter, the toner image transferred by a heat roll or the like having a releasing property to the toner is fixed to form a permanent visible image.

As a fixing method, a so-called heating roller is used in which the toner image of the sheet to be fixed is passed while being pressed against the surface of the heating roller, the surface of which is formed of a material having releasability for toner. The law is heavily used.

By the way, as for the performance of the above-mentioned toner, the anti-offset property (the phenomenon that the toner adheres to the heating roller for fixing and the paper conveyed next is polluted is unlikely to occur) and the low temperature fixing is performed. Property (toner is firmly adhered to the paper at low temperature, so that toner image can be reliably fixed at low temperature), blocking resistance (toner particles are difficult to aggregate), and image stability (charge amount does not change much) , The image density is uniform).

By the way, in the heating roller method, there is a demand for a toner resin which can be fixed at a lower temperature in order to improve the economical efficiency such as power consumption and the copying speed. Therefore, in a toner using a resin for a toner containing a vinyl-based copolymer as a main component, a method of reducing the molecular weight of the vinyl-based copolymer has been proposed in order to improve low-temperature fixability. However, with such a method, although the low-temperature fixing property of the toner is enhanced, a part of the toner easily migrates to the surface of the heating roller, and an offset phenomenon easily occurs, or the toner easily aggregates. There was a problem.

In order to solve the above problems, there has been proposed a technique in which a toner resin is composed of a resin composed of a low molecular weight polymer component and a high molecular weight polymer component (JP-A-56). -158340, JP-A-58-20
2455 publication). For example, JP-A-56-1583
No. 40 discloses a resin composition for a toner containing a low molecular weight vinyl polymer component having a weight average molecular weight of 50,000 or less and a high molecular weight vinyl polymer component having a weight average molecular weight of 80,000 or more. By using it, the fixability at low temperature is enhanced.

When a resin composition for a toner containing a low molecular weight polymer component and a high molecular weight polymer component is used, offset resistance, low-temperature fixing property, blocking resistance and the like of the resulting toner are improved. Moreover, the charge control ability at a constant level and the image stability due to environmental changes can be enhanced. In recent years, personalization is progressing in the field of copying machines,
There is a strong demand for smaller copying machines. Further, in response to the downsizing of copiers, smaller photoconductors have been required for photocopiers, and organic photoconductors have been mainly used to achieve miniaturization of photoconductors.

However, in a copying machine equipped with a small photosensitive member including an organic photosensitive member, when the conventional toner is used for a long period of time, a part of the toner adheres to the surface of the photosensitive member and the charging property is deteriorated. However, there is a tendency that the problem of deterioration occurs and image fogging occurs. Therefore, even when the copying machine is used for a long period of time, it is possible to reliably prevent the toner from sticking to the photosensitive member, and further improve the above-mentioned fixing property, anti-offset property and toner non-aggregating property. The advent of resin compositions and toners for automobiles is strongly desired.

[0010]

SUMMARY OF THE INVENTION The present invention solves the problems of the conventional resin compositions for toners and toners described above, and can prevent the toners from sticking to the photoconductor even when used for a long period of time. It is an object of the present invention to provide a resin composition for a toner and a toner, which makes it possible to obtain a stable image, is excellent in offset resistance and fixability, and hardly causes aggregation of the toner.

[0011]

The present invention has been made to achieve the above object, and the invention according to claim 1 is a resin composition for a toner, which comprises a vinyl copolymer as a main component. And the maximum value in the molecular weight distribution is 2 × 10 ^3.
A vinyl copolymer containing at least a low molecular weight polymer component in the range of 4 × 10 ⁴ and a high molecular weight polymer component having a maximum in the molecular weight distribution in the range of 3 × 10 ⁵ to 8 × 10 ^6. Main component, weight average molecular weight 100,000-40
This is a resin composition for a toner, characterized in that it contains 5 to 40% by weight of polystyrene based on the whole resin composition.

The invention described in claim 2 is a toner characterized in that it is constituted by using the resin composition for toner of the invention described in claim 1. Hereinafter, the present invention will be described in detail.

The vinyl copolymer in the present invention preferably contains a styrene monomer, an acrylic acid ester or a methacrylic acid ester monomer as a constituent unit. Specific examples of the styrene-based monomer include o-methylstyrene, m-methylstyrene, p in addition to styrene.
-Methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-ter-butylstyrene, pn-hexylstyrene, pn-octylstyrene, p Examples thereof include -n-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, and 3,4-dichlorostyrene.

Specific examples of the acrylic acid ester or methacrylic acid ester monomer include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate and n-acrylate.
Octyl, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, methacrylic acid. In addition to alkyl esters of acrylic acid or methacrylic acid such as stearyl, 2-chloroethyl acrylate,
Phenyl acrylate, methyl α-chloroacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, bisglycidyl methacrylate, polyethylene glycol dimethacrylate, methacryloxyethyl phosphate. And the like, and ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate and the like are particularly preferably used.

Other vinyl monomers in the present invention include acrylic acid such as acrylic acid, methacrylic acid, α-ethylacrylic acid and crotonic acid, and α- or β-alkyl derivatives thereof, fumaric acid, maleic acid, Examples thereof include unsaturated dicarboxylic acids such as citraconic acid and itaconic acid, and monoester and diester derivatives thereof, succinic acid monoacryloyloxyethyl ester, succinic acid monomethacryloyloxyethyl ester, acrylonitrile, methacrylonitrile, and acrylamide.

The vinyl copolymer in the present invention is not particularly limited as long as it is a resin generally used as a toner resin, but the molecular weight distribution measured by gel permeation chromatography (GPC). In the above, the maximum value of the molecular weight distribution of the low molecular weight polymer component is in the range of 2 × 10 ³ to 4 × 10 ⁴ , and the maximum value of the molecular weight distribution of the high molecular weight polymer component is 3 × 10 ⁵ to 8 ×
It must be in the range of 10 ⁶ and may contain a gel component.

If the maximum value of the molecular weight distribution of the low molecular weight polymer component is smaller than the above range, the cohesiveness of the toner may be deteriorated or the toner may be compatibilized with the high molecular weight component and cannot function. If it is larger than the range, the fixability may decrease.

If the maximum value of the molecular weight distribution of the high molecular weight polymer component is smaller than the above range, the offset resistance may be deteriorated, and if it is larger than the above range, the fixing property may be deteriorated.

In the vinyl copolymer containing the low molecular weight polymer and the high molecular weight polymer component, when the content of the high molecular weight polymer component is less than 10% by weight in the vinyl copolymer, However, the offset resistance may be deteriorated. Therefore, the content of the high molecular weight polymer component in the vinyl copolymer is preferably 10% by weight or more, more preferably 20% by weight or more. Further, when the content of the high molecular weight polymer component in the vinyl copolymer is higher than 50% by weight, sufficient fixing performance may not be obtained. Therefore, the high molecular weight polymer component is preferable. Content of 50% by weight or less.

The above vinyl-based copolymer has a glass transition point of 50 ° C. in order to enhance the non-aggregating property of the toner.
The above is desirable. In the resin composition for a toner of the present invention, the weight average molecular weight is 100,000-4 as described above.
The polystyrene in the range of 0,000, preferably 200,000 to 300,000 is blended in an amount of 5 to 40% by weight based on the entire toner resin composition. If the weight average molecular weight of the polystyrene is less than 100,000 or more than 400,000, or if the blending ratio of polystyrene is less than 5% by weight, it is difficult to sufficiently obtain the effect of preventing the toner from sticking to the photoreceptor. Sometimes.
Further, when the polystyrene content exceeds 40% by weight, sufficient fixing performance may not be obtained.

As a method for synthesizing the vinyl-based copolymer,
Suspension polymerization, emulsion polymerization, solution polymerization, bulk polymerization, etc. can be used. The low molecular weight polymer component and the high molecular weight polymer component may be hot melt blended, but in order to disperse more uniformly, it is preferable to disperse them in a solvent and then remove the solvent. More preferably, a method of polymerizing a low molecular weight polymer component in the presence of a high molecular weight polymer component is adopted. The vinyl copolymer and polystyrene may be hot melt blended, but in order to obtain a more uniform resin composition for toner, it is preferable to disperse them in a solvent and then remove the solvent. More preferably, a method of polymerizing the vinyl copolymer in the presence of polystyrene is adopted.

In the resin composition for a toner of the present invention, vinyl acetate, vinyl chloride, ethylene and the like may be copolymerized with the vinyl-based copolymer within the range where the object of the present invention can be achieved. It does not matter even if the polymer of the monomer is blended. Further, a polyester resin or an epoxy resin may be mixed. Further, aliphatic amide, bisaliphatic amide, metal soap, paraffin, etc. may be mixed.

Further, as long as the present invention can be achieved, a dye such as nigrosine or spirone black (produced by Hodogaya Chemical Co., Ltd.) as a charge control agent, or other phthalocyanine-based pigment can be added. Further, carbon black, chrome yellow, aniline blue or the like can be used as the colorant.

Further, low molecular weight polyethylene, polypropylene wax or the like may be added as a release agent, or hydrophobic silica or the like may be added to enhance fluidity. The toner of the present invention is characterized by using the toner resin composition, wherein the toner resin composition contains fine powder containing a colorant such as carbon black described above or other additives, It is composed by mixing carriers such as iron powder and glass beads. Further, magnetic powder may be mixed and used as a magnetic toner.

[0025]

In consideration of the above-mentioned fixing property, anti-offset property, toner non-aggregating property, etc., vinyl type copolymers, particularly styrene-acrylic type copolymers have heretofore been generally used for toner resin compositions. ing. However, as described above, when the toner using the styrene-acrylic copolymer is used for a long time in the copying machine, the toner may adhere to the photosensitive member.

As a result of various studies on the above problems, the inventor of the present application has found that if a specific polystyrene is dispersed in a specific ratio in a resin composition for a toner containing a vinyl-based copolymer as a main component, it is possible to obtain a photosensitive member. The inventors have found that the toner adhesion can be suppressed, and have completed the present invention. That is, the present invention is
It is experimentally confirmed by the inventor of the present application, and the reason why the above problems can be achieved by dispersing polystyrene is not always clear, but the specific polystyrene dispersed in the vinyl copolymer is not clear. It is considered that the particles of (3) act to scrape off the adhered matter on the surface of the photoconductor.

That is, the invention according to claim 1 is a vinyl containing a low molecular weight polymer component and a high molecular weight polymer component which are excellent in offset resistance, low-temperature fixing property, image stability, toner non-aggregation property, and the like. The resin composition for a toner containing a copolymer as a main component is characterized by containing the specific polystyrene to further suppress the adhesion of the toner to the photoreceptor.

Therefore, in the toner of the invention described in claim 2 which uses the resin composition for toner according to the invention of claim 1, the action of the polystyrene effectively fixes the toner to the photoreceptor. To be prevented.

[0029]

The present invention will be clarified by describing non-limiting examples of the present invention. The maximum molecular weights below are the maximums in the molecular weight distribution measured by GPC. In addition, parts mean parts by weight unless otherwise specified.

Example 1 900 g of toluene was placed in a 3 liter separable flask and polystyrene (polystyrene 6 manufactured by Asahi Kasei Corporation) was added.
66R, weight average molecular weight Mw = 200,000) 200 g, and 200 g of a resin having a maximum molecular weight of 800,000 obtained by polymerizing 70 parts of styrene and 30 parts of methacrylic acid butyl ester.
And were added and dissolved. After replacing the gas phase with nitrogen gas, the system was heated to the boiling point of toluene.

With the toluene being refluxed, 300 g of styrene and 100 of methyl methacrylate were stirred under stirring.
g, 2-ethylhexyl acrylate 100 g, and a mixture of 15 g of azobisisobutyronitrile as a polymerization initiator dissolved therein were added dropwise over 6 hours to carry out solution polymerization.

After completion of the dropping, the mixture was aged for 6 hours while stirring at the boiling temperature of toluene. Then, while gradually raising the temperature of the system to 180 ° C., toluene was removed under reduced pressure to obtain a resin. The resin A of the present invention was obtained by cooling and crushing this resin.

Resin A has a molecular weight distribution of 10,000, 1
It has maximum values at 50,000 and 800,000, and glass transition point Tg = 5
It was 7 ° C. Melt blend 100 parts of resin A, 5 parts by weight of carbon black (MA-100 manufactured by Mitsubishi Kasei Co., Ltd.), 1 part of nigrosine, and 3 parts of polypropylene wax (Viscole 660P manufactured by Sanyo Kasei Co., Ltd.), and cool and coarsely pulverize. And further pulverize with a jet mill, about 13-1
A toner powder having an average particle size of 5 μm was produced.

10 g of the above toner was placed in a 100 ml sample bottle, allowed to stand in a constant temperature bath at 50 ° C. for 16 hours, and the degree of coagulation was measured with a powder tester (manufactured by Hosokawa Micron Co.). No cohesiveness was observed.

4 parts by weight of the above toner was mixed with 96 parts of iron powder carrier having an average particle size of about 50 to 80 microns to prepare a developer, and the developer was used to obtain a copy. The electrophotographic copying machine used is a modified Z-52 manufactured by Sharp Corporation. With respect to the above-mentioned copied material, the fixability and the offset degree were evaluated in the following manner, and the adhesion of the toner to the photosensitive member was visually observed.

The fixing temperature is determined by whether the density of the copied image changes when the copy obtained by setting the heat roller of the electrophotographic copying machine at 170 ° C. is rubbed with the sand eraser for the typewriter. did. It was confirmed that with the developer prepared in this example, the density of the copied image did not change, and therefore the developer was sufficiently fixed.

The offset was copied by setting the temperature of the heat roller of the electrophotographic copying machine at 220 ° C., and whether or not the offset phenomenon occurred was observed. In this example, when copying was performed using the above developer, no offset phenomenon was observed. Further, when a running test was carried out to obtain 20,000 copies, toner adhesion to the photoconductor was not observed at all.

Example 2 1200 g of xylene in a 3 liter separable flask
200 g of polystyrene (made by Asahi Kasei Corporation, polystyrene 666R, weight average molecular weight Mw = 200,000),
200 g of a resin having a maximum molecular weight of 2,000,000 obtained by polymerizing 60 parts of styrene, 20 parts of butyl acrylate and 20 parts of methyl methacrylate, and 70 parts of styrene, 10 parts of n-butyl acrylate and 20 parts of methyl methacrylate. Was added to 500 g of a copolymer having a maximum molecular weight of 7,000 obtained by polymerizing. After replacing the gas phase with nitrogen gas, the system was heated to the boiling point of xylene.

The mixture was stirred for 2 hours under the reflux of xylene, and then the xylene was desolvated under reduced pressure while gradually raising the temperature of the system to 180 ° C. to obtain a resin.
The resin B of the present invention was obtained by cooling and pulverizing the obtained resin.

The above resin B has a molecular weight distribution of 700
It has maximum values at 0, 150,000 and 2 million, and has a glass transition point T
It was g = 63 ° C. A developer was prepared and evaluated in the same manner as in Example 1 except that the resin B was used in place of the resin A. As a result, in Example 2 as well, no toner cohesiveness was observed, and the image was sufficiently fixed on the copy. In addition, no offset generation temperature was observed, and no toner adhered to the photoconductor at all in the running test of 20,000 sheets.

Example 3 60 parts of a resin having a maximum molecular weight of 20,000, obtained by polymerizing 70 parts of styrene, 20 parts of methacrylic acid butyl ester and 10 parts of n-butyl acrylate, and polystyrene (made by Asahi Kasei Kogyo KK, Polystyrene 685, weight average molecular weight Mw =
300,000) 7 parts and 70 parts of styrene and 30 parts of methacrylic acid butyl ester were polymerized to obtain a maximum molecular weight of 3
33 parts of the resin of 0,000 was kneaded with a kneader substituted with nitrogen gas at a temperature of 170 ° C. for 10 minutes to obtain a resin. The obtained resin was cooled and pulverized to obtain a resin C of the present invention.

In the molecular weight distribution of Resin C, 20,000 and 30
In all cases, the glass transition point Tg of resin C is 60.
° C. In Example 1, resin C was used instead of resin A
A developer was prepared in the same manner as described above except that was used. As a result, no cohesiveness was observed and it was well fixed. No offset was observed, and no toner adhered to the photoreceptor even after running a test of 20,000 sheets.

Comparative Example 1 A developer was prepared in the same manner as in Example 1 except that 200 g of the resin having a peak molecular weight of 800,000 was not used. As a result, no cohesiveness was observed and the toner was sufficiently fixed. ,
An offset was seen. In the running test of 20,000 sheets, adhesion of toner to the photoconductor was not seen.

Comparative Example 2 A developer was prepared in the same manner as in Example 1 except that polystyrene was not used. As a result, no cohesiveness was observed, the toner was well fixed, and no offset was observed. . However, in the running test of 20,000 sheets, the adhesion of the toner to the photoconductor was found.

Comparative Example 3 A developer was prepared and tested in the same manner as in Example 3 except that 100 g of azobisisobutyronitrile was used as a polymerization initiator instead of 15 g. It has maximum values at 1500, 150,000 and 800,000, glass transition point = 46 ° C), it is well-fixed, no offset is observed, and toner sticking to the photoconductor is also seen in the running test of 20,000 sheets. However, cohesiveness was observed.

Comparative Example 4 A developer was prepared and tested in the same manner as in Example 3 except that the resin having a molecular weight peak of 20,000 was not used. As a result, no offset was observed and no staring property was observed. However, the fixability was poor and the running test could not be performed.

Comparative Example 5 A developer was prepared in the same manner as in Example 3 except that 65 parts by weight was used instead of 7 parts by weight of polystyrene (polystyrene 685, manufactured by Asahi Kasei Kogyo KK, weight average molecular weight Mw = 300,000). As a result of the test, no offset was observed and no cohesiveness was observed, but the fixability was poor and the running test could not be performed.

The structures and evaluation results of Examples 1 to 3 and Comparative Examples 1 to 5 are summarized in Table 1 below. The symbols in Table 1 have the following meanings. LP ... Low molecular weight polymer component HP ... High molecular weight polymer component

[0049]

[Table 1]

[0050]

According to the present invention, the resin composition for a toner according to the present invention contains a vinyl-based copolymer component containing at least the specific low molecular weight polymer component and the high molecular weight polymer component as a main component. Therefore, the fixing performance, the offset resistance, and the non-aggregation property of the toner are improved. Moreover, since the above-mentioned specific polystyrene is blended in the above-mentioned specific ratio, even when it is used in a copying machine for a long time, it is possible to surely prevent the toner from sticking to the photosensitive member and obtain a stable image. You can

Therefore, by constructing a toner using the toner resin composition according to claim 1 as in the toner according to claim 2, the fixing property, the offset resistance and the non-aggregating property are excellent. Since the toner can be provided and the adhesion of the toner to the photoconductor of the copying machine is suppressed, it is possible to reliably prevent the copying machine from being contaminated.

Claims (2)

[Claims] 1. A resin composition for a toner, which comprises a vinyl-based copolymer as a main component, and a low-molecular weight polymer component having a maximum value in the molecular weight distribution in the range of 2 × 10 ³ to 4 × 10 ⁴ . Polystyrene having a weight average molecular weight of 100,000 to 400,000 as a main component, a vinyl-based copolymer containing at least a high molecular weight polymer component having a maximum value in the molecular weight distribution in the range of 3 × 10 ⁵ to 8 × 10 ^6. A resin composition for a toner, comprising 5 to 40% by weight of the entire resin composition. 2. A toner comprising the resin composition for a toner according to claim 1 as a main component.