JPH096045A - Binder resin for toner - Google Patents

Abstract

(57) [Summary] [Object] To provide a binder resin for a toner having a well-balanced fixing property and non-offset property of the toner. [Structure] A binder resin for toner comprising a styrene copolymer having a glass transition temperature of 50 to 80 ° C and a softening temperature of 125 to 160 ° C, which is a high molecular weight polymer component constituting the styrene copolymer. Weight average molecular weight is 20
10,000-700,000, weight average molecular weight (Mw)
And the number average molecular weight (Mn) ratio (Mw / Mn) is 1.8.
4, the content ratio is 20 to 70% by weight, and the weight average molecular weight of the low molecular weight polymer component is 6,000 to 30,000.
It is.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binder resin for toner used for developing an electrostatic charge image or a magnetic latent image in an electrophotographic method, an electrostatic recording method, an electrostatic printing method and the like, and a method for producing the same. More specifically, the present invention relates to a binder resin for toner, which can provide a toner having a good balance between fixing property and non-offset property.

[0002]

2. Description of the Related Art In a typical image forming process by an electrophotographic method or an electrostatic printing method, a photoconductive insulating layer is uniformly charged, the insulating layer is exposed, and then a charge on an exposed portion is obtained. To form an electric latent image by dissipating the toner, and a developing step of visualizing the latent image by adhering a finely charged toner to the latent image, and transferring the obtained visible image to a transfer material such as transfer paper. It comprises a transfer step of transferring and a fixing step of permanently fixing by heating or pressing.

Various performances are required for the toner and the binder resin for the toner used in the electrophotographic method or the electrostatic printing method in each of the above steps. For example, in the development process, the toner and the binder resin for the toner maintain a charge amount suitable for a copying machine without being affected by the surrounding environment such as temperature and humidity in order to attach the toner to the electric latent image. I have to do it. Also,
In the fixing step by the heat roller fixing method, the non-offset property that does not adhere to the heat roller and the fixability to paper must be good. Further, it is required to have a blocking resistance so that the toner does not block during storage in a copying machine.

Conventionally, binder resins for toners include:
Styrene-acrylic resins are frequently used, and linear type (non-crosslinked type) resins and crosslinked type resins are used. In the cross-linking type binder resin for toner,
Attempts have been made to widen the molecular weight distribution by crosslinking a resin to improve the fixability and non-offset property as a toner. Further, in the linear type binder resin for toner, a high molecular weight polymer component and a low molecular weight polymer component are mixed to control the glass transition temperature and the molecular weight of both components, and the molecular weight distribution (Mw / Mw / Mn)
Attempts have been made to improve the fixing property and non-offset property of the toner by controlling the toner.

[0005]

However, in the case of a crosslinked type binder resin for a toner, simply cross-linking the resin is inferior in the balance between the fixing property and the non-offset property as a toner and has a sufficient fixing property. It was difficult to obtain a toner. In addition, since the dispersibility of the pigment or the like is poor, it is necessary to disperse the pigment by a high shearing force. As a result, there is a problem that the crosslinked structure is cut and the non-offset property decreases. On the other hand, a toner using a binder resin for a linear toner has good dispersibility of pigments, etc., but, for example, when the fixability is improved, the melt viscosity of the binder resin for a toner is lowered and the toner is not offset. Toner with a good balance between the two
Was hard to get. Therefore, the purpose of the present invention is to
It is an object of the present invention to provide a binder resin for a toner, which has an excellent balance of fixing property and non-offset property as a toner.

[0006]

In view of such circumstances, the inventors of the present invention have earnestly studied the binder resin for toner, and as a result, control the molecular weight and molecular weight distribution of the high molecular weight polymer component constituting the binder resin. It was found that the binder resin for a toner excellent in the balance between the fixing property and the non-offset property as a toner can be obtained in this way, and the present invention has been achieved. That is, the binder resin for toner of the present invention has a glass transition temperature of 50.
A non-crosslinked styrenic copolymer having a softening temperature of 125 to 160 ° C. at -80 ° C., and the styrene copolymer has a weight average molecular weight of 200,000 to 700,000.
0, 20 to 70% by weight of a high molecular weight polymer component having a ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of 1.8 to 4, and a weight average molecular weight of 6,000 to Three
It is characterized in that it consists of 10,000 low molecular weight polymer components.

The binder resin for toner of the present invention comprises a high molecular weight polymer component and a low molecular weight polymer component, and both polymers are composed of a styrene monomer and another copolymerizable vinyl monomer. It is a non-crosslinked styrene-based copolymer, and a styrene-acrylic copolymer is particularly preferable. In the present invention, the styrenic monomer used for the polymerization of the high molecular weight polymer component and the low molecular weight polymer component includes styrene, o-methylstyrene and m.
-Methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn -Octyl styrene, pn-nonyl styrene, pn-densyl styrene, pn-dodecyl styrene, p-phenyl styrene, 3,4-dicyclosyl styrene and the like,
Among them, styrene is preferred. These styrene monomers can be used alone or in combination of two or more.

Other copolymerizable vinyl monomers include ethyl acrylate, methyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate. , Unsaturated carboxylic acids such as methacrylic acid, ethyl methacrylic acid, methyl methacrylic acid, n-butyl methacrylic acid, isobutyl methacrylic acid, propyl methacrylic acid, 2-ethylhexyl methacrylic acid and stearyl methacrylic acid Examples thereof include esters, unsaturated dicarboxylic acid diesters such as dimethyl maleate, diethyl maleate, butyl maleate, dimethyl fumarate, diethyl fumarate, and dibutyl fumarate.

Further, unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid and cinnamic acid, unsaturated dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid, monomethyl maleate, monoethyl maleate, monobutyl maleate and fumaric acid. A carboxylic acid-containing vinyl monomer such as an unsaturated monocarboxylic acid monoester such as monomethyl, monoethyl fumarate or monobutyl fumarate may also be used in combination. The copolymerization ratio of these monomers is not particularly limited, but is preferably selected so that the glass transition temperature of the obtained binder resin for toner is in the range of 50 to 80 ° C. This is because when the glass transition temperature of the binder resin for toner is less than 50 ° C., the blocking occurrence temperature of the toner may be lowered and storage stability may be extremely lowered, and conversely, when it exceeds 80 ° C. This is because the softening temperature becomes high and the fixing property of the toner decreases, and the range is preferably 55 to 70 ° C.

The binder resin for toner of the present invention comprises a high molecular weight polymer component and a low molecular weight polymer component,
The content ratio of the high molecular weight polymer component is in the range of 20 to 70% by weight. This is because if the high molecular weight polymer component is less than 20% by weight, the non-offset property as a toner is inferior, and if it exceeds 70% by weight, the fixability as a toner is inferior. It is in the range of 20 to 60% by weight.

In the present invention, by controlling the molecular weight and the molecular weight distribution of the high molecular weight polymer component constituting the binder resin for toner, it is possible to provide a toner having a well-balanced fixing property and non-offset property. .
That is, the weight average molecular weight of the high molecular weight polymer component is 20
The weight average molecular weight (Mw) and the number average molecular weight (Mn) are in the range (Mw / M).
It is necessary that n) be in the range of 1.8 to 4.0.
This is because when the weight average molecular weight is less than 200,000, the non-offset property as a toner is lowered, and when it exceeds 700,000, the fixability as a toner is lowered, and it is preferable. 300,000 ~
It is in the range of 600,000. This is also because when the Mw / Mn of the high molecular weight polymer component is less than 1.8, the non-offset property as a toner deteriorates, while when it exceeds 4.0, the response to heat is delayed and the toner becomes a toner. This is because the low temperature fixability of No. 1 is deteriorated, and preferably 2.0 to 3.8.
Range.

The low molecular weight polymer component constituting the binder resin for toner of the present invention must have a weight average molecular weight in the range of 6,000 to 30,000. This is because when the weight average molecular weight of the low molecular weight polymer component is less than 6,000, the mechanical strength of the resin is lowered, the toner is likely to be in an excessively pulverized state when electrification occurs, and fog tends to occur in the image. Is. On the contrary, if the weight average molecular weight exceeds 30,000, the fixability as a toner is lowered. Preferably 7,000-2
It is in the range of 0000.

The polymerization of these polymerizable monomers can be carried out by a known polymerization method such as a suspension polymerization method, a solution polymerization method, an emulsion polymerization method or a bulk polymerization method, but there is no problem of odor due to residual solvent, and The suspension polymerization method is preferable from the viewpoints that the heat generation is easily controlled, the amount of the dispersant used is small, and the moisture resistance is not impaired. In particular, the obtained toner binder resin is preferably composed of a uniformly mixed high molecular weight polymer component and low molecular weight polymer component, and suspension polymerization of the high molecular weight polymer component is performed. It is preferable to carry out polymerization by a polymerization method such as a two-stage suspension polymerization method in which suspension polymerization of a low molecular weight polymer component is carried out in the presence of suspended particles of a high molecular weight polymer component.

The method for producing the binder resin for toner of the present invention by the two-step suspension polymerization method will be specifically described below. The suspension polymerization of the high molecular weight polymer component is not particularly limited, and can be performed according to a general suspension polymerization method, and is commonly used in the suspension polymerization together with the above-mentioned monomers. A dispersing agent, a polymerization initiator, a molecular weight modifier and the like can be used, and the reaction is preferably performed at a temperature of 95 to 150 ° C. and a pressure of 0.5 to 7 kg / cm ² .

As the polymerization initiator used for suspension polymerization of the high molecular weight polymer component, a compound having 3 or more t-butylperoxide groups in one molecule or a 10-hour half-life temperature of 90 to 140 ° C. It is possible to use a radical polymerization initiator having one functional group in one molecule. For example, as a compound having three or more t-butyl peroxide groups in one molecule, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane and the like can be mentioned. The 10-hour half-life temperature is 90-140.
Examples of the radical polymerization initiator having one functional group in one molecule at ° C include t-butyl peroxy laurate, t-butyl peroxy 3,5,5-trimethylhexanoate,
Cyclohexanone peroxide, t-butylperoxyisopropyl carbonate, t-butylperoxyacetate, t-butylperoxybenzoate, dicumyl peroxide, t-butylcumyl peroxide, diisopropylbenzene hydroperoxide, di-t-butylperoxide Oxide, p-methane hydroperoxide, 2
-(Carbamoylazo) isobutyronitrile, 2,2-
Organic peroxides such as azobis (2,4,4-trimethylpentane) and 2-phenylazo-2,4-dimethyl-4-methoxyvaleronitrile, and azo compounds. These polymerization initiators can be used alone or in combination of two or more. The amount of the polymerization initiator used may be a very small amount as compared with the amount of the polymerization initiator used in the conventional suspension polymerization, and 0.001 to 0.5 parts by weight based on 100 parts by weight of all the monomers. It is preferably used in the range of parts, and more preferably 0.002 to 0.05 parts by weight.

Next, the low molecular weight polymer component is polymerized by suspension polymerization in the presence of suspension-polymerized high molecular weight polymer suspension particles. The suspension polymerization is not particularly limited, and can be carried out according to a general suspension polymerization method. For example, when the polymerization reaction rate of a high molecular weight polymer becomes about 10 to 90%, a low molecular weight It is preferable to start the polymerization by dissolving and adding the polymerization initiator for the polymer to water or the monomer for the low molecular weight polymer.

The polymerization initiator used for suspension polymerization of the low molecular weight polymer component is not particularly limited,
Usually used peroxides and azo compounds having radical polymerizability can be used. For example, di-t-butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, acetyl peroxide, isobutyryl peroxide Oxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, m-toluoyl peroxide, t-butylperoxyacetate, t-butylperoxide Oxyisobutyrate,
t-butyl peroxypiparate, t-butyl peroxy neodecanoate, cumyl peroxy neodecanoate, t-butyl peroxy 2-ethylhexanoate,
t-butyl peroxy 3,5,5-trimethylhexanoate, t-butyl peroxylylate, t-butyl peroxybenzoate, t-butyl peroxyisopropyl carbonate, azobisisobutyl nitrile, 2,
Examples thereof include 2-azobis- (2,4-dimethylvaleronitrile). Among them, octonyl peroxide, decanonyl, and the like, from the viewpoint of the persistence of the polymerization activity for the monomer and the completion of the polymerization in a relatively short time. Peroxide, lauroyl peroxide, benzoyl peroxide and m-trioil peroxide are preferred. These polymerization initiators can be used alone or in combination of two or more,
The monomer is preferably used in the range of 0.1 to 10 parts by weight, more preferably 0.5 to 100 parts by weight.
The range is 10 parts by weight.

The suspension polymerization is preferably 1 for the monomers.
With about 10 times, more preferably about 2 to 4 times water, a dispersant, a polymerization initiator, and optionally a dispersion aid or a chain transfer agent are added, and the temperature is raised to a predetermined polymerization temperature. The heating is continued until the polymerization rate reaches a predetermined level. Examples of the dispersant used in the suspension polymerization include polyvinyl alcohol, an alkali metal salt of a homopolymer or copolymer of (meth) acrylic acid, carboxytyl cellulose, gelatin, starch, barium sulfate, calcium sulfate, calcium carbonate, Examples thereof include magnesium carbonate and calcium phosphate. Among them, polyvinyl alcohol is preferable, and particularly preferable is partially saponified polyvinyl alcohol having an acetic acid group and a hydroxyl group in a block manner. These dispersants are used in an amount of 0.0
It is preferable to use it in the range of 1 to 5 parts by weight. If the amount of the dispersant is less than 0.01 part by weight, the stability of the suspension polymerization is lowered, and the polymer tends to be solidified by aggregation of formed particles, and conversely, the amount exceeds 5 parts by weight. This is because the toner tends to have a lower environmental dependency, particularly the moisture resistance, and the content is more preferably in the range of 0.05 to 2 parts by weight. If necessary, a dispersing aid such as sodium chloride, potassium chloride, sodium sulfate or potassium sulfate can be used together with these dispersants. further,
In order to adjust the molecular weight, a chain transfer agent such as n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, 2-ethylhexyl thioglycolate, or α-methylstyrene dimer may be used, if necessary. .

The binder resin for toner of the present invention obtained by such a manufacturing method has a softening temperature of 110-1.
It must be in the range of 60 ° C. This is because when the softening temperature is less than 110 ° C., the non-offset property as a toner is poor, and when it exceeds 160 ° C., the fixability as a toner is deteriorated, and preferably 120 to 140 ° C.
Range. Further, it is preferably a non-crosslinked type having a THF insoluble content of 0.5% by weight or less. this is,
When the cross-linking type is such that the THF-insoluble content exceeds 0.5% by weight, the dispersibility of the pigment and the like is poor, and the cross-linking structure tends to be cut by the high shearing force for dispersion and the non-offset property tends to decrease. Because there is.

[0020]

The present invention will be specifically described below with reference to examples. In Examples, the glass transition temperature was determined by a DSC method (heating rate: 10 ° C./min) after the sample was heated to 100 ° C. and melt-quenched. For the softening temperature, a flow tester (CFT-500 manufactured by Shimadzu Corporation) having a nozzle of 1 mmφ × 10 mm was used, and a load of 30 was used.
Under the conditions of Kgf and a temperature rising rate of 3 ° C./min, the temperature when ½ of the sample amount flows out is shown. Weight average molecular weight (Mw), number average molecular weight (Mn), and Mw / Mn are measured values by gel permeation chromatography, using tetrahydrofuran as a solvent and HCL manufactured by Tosoh Corporation.
It was measured using -8020 and calculated by polystyrene conversion.

In the fixing temperature region, an unfixed image obtained by using a copying machine (FP-1570 manufactured by Matsushita Electric Industrial Co., Ltd.) is processed by using a fixing tester capable of freely changing process speed and roller temperature. The image was fixed at a speed of 300 mm / sec, and the obtained fixed image was rubbed 9 times with a sand eraser according to JIS 512, and the image density before and after that was measured using a Macbeth densitometer, and the decrease rate of the image density was 20%. The minimum fixing temperature is less than, and the process speed is 1
The minimum fixing temperature at which the toner migrates to the roller when the toner is fixed using a fixing tester at 00 mm / sec is shown. Also,
For the image fog, the white portion of the image obtained by the evaluation in the fixing temperature region was visually observed.

Example 1 A non-cross-linked styrene-acrylic copolymer having a weight average molecular weight (Mw) of 370,000 and Mw / Mn of 2.
A binder resin for a toner was obtained, which was composed of 20.1% by weight of a high molecular weight polymer component of 0 and 79.9% by weight of a low molecular weight polymer component having a weight average molecular weight (Mw) of 14,000. The obtained binder resin for toner had a glass transition temperature of 64.4 ° C and a softening temperature of 130 ° C. To 93 parts by weight of the obtained binder resin for toner, 4 parts by weight of carbon black (# 40 manufactured by Mitsubishi Kasei Co., Ltd.) and a charge control agent for negative charging ("Bontron S-3 manufactured by Orient Chemical Industry Co., Ltd."
4 ") and 2 parts by weight of a polyolefin wax (660P manufactured by Sanyo Kasei Co., Ltd.) were placed and melt-kneaded at 145 ° C. Then, crush using a jet mill crusher,
By classification, a toner having an average particle size of 13 μm was obtained. The fixing temperature range of the obtained toner was at a practical level in the range of 150 to 200 ° C., and image fogging was not observed.

Example 2 A non-crosslinked styrene-acrylic copolymer having a weight average molecular weight (Mw) of 470,000 and Mw / Mn of 2.
A binder resin for a toner was obtained, which was composed of 33.5% by weight of the high molecular weight polymer component of 8 and 66.5% by weight of the low molecular weight polymer component of which the weight average molecular weight (Mw) was 9,000. The obtained binder resin for toner had a glass transition temperature of 57.0 ° C. and a softening temperature of 125 ° C. To 93 parts by weight of the obtained binder resin for toner, 4 parts by weight of carbon black (# 40 manufactured by Mitsubishi Kasei Co., Ltd.) and a charge control agent for negative charging ("Bontron S-3 manufactured by Orient Chemical Industry Co., Ltd."
4 ") and 2 parts by weight of a polyolefin wax (660P manufactured by Sanyo Kasei Co., Ltd.) were mixed and melt-kneaded at 145 ° C. Then, the toner was pulverized using a jet mill pulverizer and classified to obtain a toner having an average particle diameter of 13 μm. The fixing temperature range of the obtained toner was at a practical level in the range of 140 to 220 ° C., and no image fog was observed.

Example 3 Consisting of a non-crosslinked styrene-acrylic copolymer, having a weight average molecular weight (Mw) of 380,000 and Mw / Mn of 2.
Thus, a binder resin for a toner was obtained, which was composed of 47.5% by weight of the high molecular weight polymer component of No. 4 and 52.5% by weight of the low molecular weight polymer component of which the weight average molecular weight (Mw) was 10,000. The obtained binder resin for toner had a glass transition temperature of 62.0 ° C and a softening temperature of 139 ° C. To 93 parts by weight of the obtained binder resin for toner, 4 parts by weight of carbon black (# 40 manufactured by Mitsubishi Kasei Co., Ltd.) and a charge control agent for negative charging ("Bontron S-3 manufactured by Orient Chemical Industry Co., Ltd."
4 ") and 2 parts by weight of a polyolefin wax (660P manufactured by Sanyo Kasei Co., Ltd.) were mixed and melt-kneaded at 145 ° C. Then, the toner was pulverized using a jet mill pulverizer and classified to obtain a toner having an average particle diameter of 13 μm. The fixing temperature range of the obtained toner was at a practical level in the range of 150 to 210 ° C., and image fog was not recognized.

Example 4 A non-cross-linked styrene-acrylic copolymer having a weight average molecular weight (Mw) of 590,000 and Mw / Mn of 2.
A binder resin for a toner was obtained, which was composed of 50.8% by weight of a high molecular weight polymer component of 9 and 49.2% by weight of a low molecular weight polymer component of 13,000 in weight average molecular weight (Mw). The obtained binder resin for toner had a glass transition temperature of 60.0 ° C. and a softening temperature of 130 ° C. To 93 parts by weight of the obtained binder resin for toner, 4 parts by weight of carbon black (# 40 manufactured by Mitsubishi Kasei Co., Ltd.) and a charge control agent for negative charging ("Bontron S-3 manufactured by Orient Chemical Industry Co., Ltd."
4 ") and 2 parts by weight of a polyolefin wax (660P manufactured by Sanyo Kasei Co., Ltd.) were mixed and melt-kneaded at 145 ° C. Then, the toner was pulverized using a jet mill pulverizer and classified to obtain a toner having an average particle diameter of 13 μm. The fixing temperature range of the obtained toner was at a practical level in the range of 140 to 220 ° C., and no image fog was observed.

Example 5 Consisting of a non-crosslinked styrene-acrylic copolymer, having a weight average molecular weight (Mw) of 600,000 and Mw / Mn of 3.
A binder resin for a toner was obtained which was composed of 53.8% by weight of a high molecular weight polymer component of 6 and 46.2% by weight of a low molecular weight polymer component of 13,000 in weight average molecular weight (Mw). The obtained binder resin for toner had a glass transition temperature of 55.0 ° C and a softening temperature of 130 ° C. To 93 parts by weight of the obtained binder resin for toner, 4 parts by weight of carbon black (# 40 manufactured by Mitsubishi Kasei Co., Ltd.) and a charge control agent for negative charging ("Bontron S-3 manufactured by Orient Chemical Industry Co., Ltd."
4 ") and 2 parts by weight of a polyolefin wax (660P manufactured by Sanyo Kasei Co., Ltd.) were mixed and melt-kneaded at 145 ° C. Then, the toner was pulverized using a jet mill pulverizer and classified to obtain a toner having an average particle diameter of 13 μm. The fixing temperature range of the obtained toner was at a practical level in the range of 150 to 220 ° C., and no image fog was observed.

Example 6 A non-crosslinked styrene-acrylic copolymer having a weight average molecular weight (Mw) of 530,000 and Mw / Mn of 2.
A binder resin for a toner was obtained which was composed of 33.5% by weight of the high molecular weight polymer component of 2 and 66.5% by weight of the low molecular weight polymer component of 20,000 in weight average molecular weight (Mw). The obtained binder resin for toner had a glass transition temperature of 64.0 ° C. and a softening temperature of 136 ° C. To 93 parts by weight of the obtained binder resin for toner, 4 parts by weight of carbon black (# 40 manufactured by Mitsubishi Kasei Co., Ltd.) and a charge control agent for negative charging ("Bontron S-3 manufactured by Orient Chemical Industry Co., Ltd."
4 ") and 2 parts by weight of a polyolefin wax (660P manufactured by Sanyo Kasei Co., Ltd.) were mixed and melt-kneaded at 145 ° C. Then, the toner was pulverized using a jet mill pulverizer and classified to obtain a toner having an average particle diameter of 13 μm. The fixing temperature range of the obtained toner was at a practical level in the range of 150 to 210 ° C., and image fog was not recognized.

Comparative Example 1 A non-crosslinked styrene-acrylic copolymer was used, which had a weight average molecular weight (Mw) of 460,000 and Mw / Mn of 2.
Thus, a binder resin for toner was obtained which was composed of 34.5% by weight of the high molecular weight polymer component of 7 and 65.5% by weight of the low molecular weight polymer component of which the weight average molecular weight (Mw) was 5,000. The obtained binder resin for toner had a glass transition temperature of 62.0 ° C and a softening temperature of 134 ° C. To 93 parts by weight of the obtained binder resin for toner, 4 parts by weight of carbon black (# 40 manufactured by Mitsubishi Kasei Co., Ltd.) and a charge control agent for negative charging ("Bontron S-3 manufactured by Orient Chemical Industry Co., Ltd."
4 ") and 2 parts by weight of a polyolefin wax (660P manufactured by Sanyo Kasei Co., Ltd.) were mixed and melt-kneaded at 145 ° C. Then, the toner was pulverized using a jet mill pulverizer and classified to obtain a toner having an average particle diameter of 13 μm. The fixing temperature range of the obtained toner was at a practical level in the range of 140 to 200 ° C., but fog was observed in the image.

Comparative Example 2 A non-crosslinked styrene-acrylic copolymer was used, which had a weight average molecular weight (Mw) of 380,000 and Mw / Mn of 1.
A binder resin for a toner was obtained which was composed of 20.3% by weight of a high molecular weight polymer component of 6 and 79.7% by weight of a low molecular weight polymer component of 15,000 in weight average molecular weight (Mw). The obtained binder resin for toner had a glass transition temperature of 64.0 ° C and a softening temperature of 130 ° C. To 93 parts by weight of the obtained binder resin for toner, 4 parts by weight of carbon black (# 40 manufactured by Mitsubishi Kasei Co., Ltd.) and a charge control agent for negative charging ("Bontron S-3 manufactured by Orient Chemical Industry Co., Ltd."
4 ") and 2 parts by weight of a polyolefin wax (660P manufactured by Sanyo Kasei Co., Ltd.) were placed and melt-kneaded at 145 ° C. Then, crush using a jet mill crusher,
By classification, a toner having an average particle size of 13 μm was obtained. The fixing temperature range of the obtained toner was 150 to 170 ° C., which was not a practical range. No image fogging was observed.

Comparative Example 3 A non-crosslinked styrene-acrylic copolymer having a weight average molecular weight (Mw) of 450,000 and an Mw / Mn of 4.
A binder resin for toner was obtained, which was composed of 40.2% by weight of the high molecular weight polymer component of 5 and 59.8% by weight of the low molecular weight polymer component of 5,000 in weight average molecular weight (Mw). The obtained binder resin for toner had a glass transition temperature of 66.0 ° C. and a softening temperature of 137 ° C. To 93 parts by weight of the obtained binder resin for toner, 4 parts by weight of carbon black (# 40 manufactured by Mitsubishi Kasei Co., Ltd.) and a charge control agent for negative charging ("Bontron S-3 manufactured by Orient Chemical Industry Co., Ltd."
4 ") and 2 parts by weight of a polyolefin wax (660P manufactured by Sanyo Kasei Co., Ltd.) were mixed and melt-kneaded at 145 ° C. Then, the toner was pulverized using a jet mill pulverizer and classified to obtain a toner having an average particle diameter of 13 μm. The fixing temperature range of the obtained toner was 180 to 230 ° C., which was not a practical range. Fog was also recognized in the image.

[0031]

EFFECT OF THE INVENTION The binder resin for a toner of the present invention can control the molecular weight and the molecular weight distribution of the high molecular weight polymer component constituting the binder resin to provide a toner excellent in the balance between the fixing property and the non-offset property. Can be provided.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoko Harada 2-1, 4-1, Ushikawa-dori, Toyohashi-shi, Aichi Sanryo Rayon Co., Ltd. Toyohashi Plant

Claims (1)

[Claims] 1. A styrene-based copolymer having a glass transition temperature of 50 to 80 ° C. and a softening temperature of 125 to 160 ° C., wherein the styrene-based copolymer has a weight average molecular weight of 2
0,000-700,000, weight average molecular weight (M
20 to 70% by weight of a high molecular weight polymer component having a ratio (Mw / Mn) of w) to number average molecular weight (Mn) of 1.8 to 4,
A binder resin for a toner comprising a low molecular weight polymer component having a weight average molecular weight of 6,000 to 30,000.