JPH08305082A - 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. valule in the mol.wt. distribution within a specified range and contg. calcium carbonate having a specified average particle diameter 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 calcium carbonate having 0.1-3μm average particle diameter by 0.1-30wt.% of the total amt. of this resin compsn. The vinyl copolymer preferably has units of a styrene monomer, an acrylic ester or methacrylic ester monomer or other vinyl 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 period of 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. It is a resin composition for a toner, which comprises as a main component calcium carbonate having an average particle diameter of 0.1 to 3 μm in an amount of 0.1 to 30% by weight of the entire 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, or another vinyl monomer as a constitutional unit. Specific examples of the styrene-based monomer include o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4 in addition to styrene.
-Dimethylstyrene, pn-butylstyrene, pt
er-butyl styrene, pn-hexyl styrene, p
-N-octyl styrene, pn-dodecyl styrene,
Examples thereof include 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 commonly used as a toner resin, but it is measured by gel permeation chromatography (GPC). In the molecular weight distribution, 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. ~ 8x
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. The calcium carbonate used in the present invention has an average particle size of 0.1 to 3 μm, preferably 0.3 to 2 μm, and the calcium carbonate accounts for 0.1 to 30% by weight in the resin composition. It is contained in the range, preferably in the range of 1 to 20% by weight.

The average particle size of the calcium carbonate is 0.1 μm.
If it is less than m or the blending ratio is less than 0.1% by weight, the effect of preventing the adhesion of the toner to the photoreceptor may not be sufficiently obtained.

The average particle size of calcium carbonate is 3 μm.
Or when the blending ratio exceeds 30% by weight,
When a toner is formed, 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. More preferably, in the presence of the above calcium carbonate,
A method of polymerizing the vinyl copolymer is adopted.

In the toner resin composition of the present invention, vinyl acetate, vinyl chloride, ethylene and the like may be copolymerized with the vinyl 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, dyes such as nigrosine and spirone black (produced by Hodogaya Chemical Co., Ltd.) as charge control agents and other phthalocyanine pigments 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.

[0027]

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 found that if a calcium carbonate having a specific particle size is dispersed in a specific ratio in a toner resin composition containing a vinyl copolymer as a main component, The inventors have found that it is possible to suppress the adhesion of toner to the photoconductor, and have completed the present invention. That is, the present invention has been experimentally confirmed by the inventor of the present application, and the reason why the above-mentioned problems can be achieved by dispersing calcium carbonate is not always clear, but the dispersion in the vinyl-based copolymer is not clear. It is considered that the above-mentioned calcium carbonate particles that are used 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 and toner non-aggregation property. The resin composition for a toner containing a copolymer as a main component is characterized by containing calcium carbonate having the above-mentioned specific particle diameter 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 calcium carbonate is effective in fixing the toner to the photoreceptor. To be prevented.

[0031]

The present invention will be clarified by describing non-limiting examples of the present invention.

The maximum molecular weights in the following are GP
It is the maximum value in the molecular weight distribution measured by C.
In addition, parts mean parts by weight unless otherwise specified.

Example 1 900 g of toluene was placed in a 3 liter separable flask, 8 g of calcium carbonate having an average particle size of 1.5 μm (Escalon 2000 manufactured by Sankyo Flour Milling Co., Ltd.), 70 parts of styrene and 30 parts of butyl methacrylic acid ester were added. 200 g of a resin having a maximum molecular weight of 800,000 obtained by polymerization was 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.
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 had maximums at 10,000 and 800,000 in the molecular weight distribution and had a glass transition point Tg of 55 ° C. Resin A 100 parts, carbon black (manufactured by Mitsubishi Chemical Corporation, MA-100) 5 parts by weight, nigrosine 1 part,
Polypropylene wax (Sanyo Kasei Co., Viscole 6
60P) 3 parts with melt-blended, cooled and coarsely crushed,
Further, it was finely pulverized with a jet mill to prepare a toner powder having an average particle size of about 13 to 15 μm.

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 an 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 judged by whether the density of the copy image changes when the copy obtained with the heat roller of the electrophotographic copying machine set at 170 ° C. is rubbed with a sand eraser for a typewriter. did. It was confirmed that with the above-mentioned developer prepared in this example, the density of the copied image did not change, and therefore the developer was sufficiently fixed.

The degree of offset was determined by setting the temperature of the heat roller of the electrophotographic copying machine to 220 ° C. and observing whether or not the offset phenomenon occurred. 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, no sticking of toner to the photosensitive member was observed.

Example 2 1200 g xylene in a 3 liter separable flask
80 g of calcium carbonate with an average particle size of 0.3 μm
And 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,
N-Butyl acrylate 10 parts and methyl methacrylate 2
500 parts of a copolymer having a maximum molecular weight of 7,000, obtained by polymerizing 0 part of the same, was added and dissolved. 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 thereafter, the temperature of the system was gradually increased to 180 ° C., and xylene was removed under reduced pressure 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 7,000.
And has a maximum value of 2 million, glass transition point Tg = 60 ° C.
Met. In Example 1, resin B was used instead of resin A
A developer was prepared and evaluated in the same manner as in Example 1 except that was used. As a result, also in Example 2,
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 70 parts of styrene, 20 parts of methacrylic acid butyl ester and 10 parts of n-butyl acrylate were polymerized to obtain 60 parts of a resin having a maximum molecular weight of 20,000, and carbonic acid having an average particle size of 0.7 μm. Kneading 4 parts of calcium and 33 parts of a resin having a maximum molecular weight of 300,000 obtained by polymerizing 70 parts of styrene and 30 parts of methacrylic acid butyl ester with a kneader replaced with nitrogen gas at a temperature of 170 ° C. for 10 minutes. The resin was obtained by cooling, and the obtained resin was cooled and pulverized to obtain Resin C of the present invention.

In the molecular weight distribution of Resin C, 20,000 and 30
It has a maximum value, and the glass transition point Tg of resin C is 59.
° 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 photosensitive member in the running 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 molecular weight peak of 800,000 was not used. As a result, no cohesiveness was observed and the toner was sufficiently fixed. ,
There was an offset. 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 calcium carbonate was not used. As a result, no cohesiveness was observed, fixing was sufficient, and no offset was observed. It was 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 instead of 15 g of the polymerization initiator. There are maximum values at 1500 and 800,000, glass transition point = 46 ° C), sufficient fixing, no offset was observed, and no toner sticking to the photoconductor was observed in the running test of 20,000 sheets. , Cohesiveness was observed.

Comparative Example 4 A developer was prepared in the same manner as in Example 3 except that the resin having a peak molecular weight 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 In Example 3, 42 parts was used instead of 4 parts of calcium carbonate.
A developer was prepared in the same manner except that a part was used, and a test was conducted. As a result, no offset was observed and no cohesiveness was observed, but the fixability was poor and a running test could not be performed.

Comparative Example 6 A developer was prepared and tested in the same manner as in Example 1 except that calcium carbonate having an average particle size of 0.08 μm was used instead of calcium carbonate having an average particle size of 1.5 μm. As a result, no cohesiveness was observed and it was well established,
No offset was seen. However, in the running test of 20,000 sheets, adhesion of toner to the photoconductor was observed.

Comparative Example 7 A developer was prepared in the same manner as in Example 2 except that calcium carbonate having an average particle size of 10 μm was used in place of calcium carbonate having an average particle size of 0.3 μm, and the result was tested. No offset was observed and no cohesiveness was observed, but the fixability was poor and a running test could not be performed.

The structures and evaluation results of Examples 1 to 3 and Comparative Examples 1 to 7 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

[0056]

[Table 1]

[0057]

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 calcium carbonate having the above-mentioned specific particle size is blended in the above-mentioned specific ratio, even when it is used in a copying machine for a long period of time, it is possible to reliably prevent the toner from sticking to the photosensitive member, and to stabilize the toner. Images can be obtained.

Therefore, by constructing a toner using the resin composition for a toner 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 . Calcium carbonate having an average particle size of 0.1 to 3 μm is used as a main component, which is 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 0.1 to 30% 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.