JPH0830023A - Resin for toner and its production - Google Patents

Abstract

PURPOSE:To quantitatively and effectively remove acid impurities and to improve electric characteristics by producing a resin by suspension polymn. in the presence of alkali metal carbonate and if necessary, after the polymn., subjecting the resin to heat treatment. CONSTITUTION:This resin for a toner consists of a styrene or styrene/acryl resin produced by suspension polynm. in the presence of a peroxide-based polynm. initiator having benzoyl groups or benzoyl groups containing substituents while using water as a medium. The resin is produced by suspension polymn. in the presence of alkali metal carbonate. If necessary, after the polymn., the resin is heat treated at 50 to 140 deg.C. The styrene or styrene/acryl resin for a toner consists of a homopolymer of styrene monomers or a copolymer of styrene monomers and acryl monomers. If necessary, polyfunctional monomers or other polymerizable monomers can be incorporated into these polymers as structural units.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner resin and a process for producing the same, and more particularly to a styrene-based or styrene / acrylic resin which has a small content of acidic impurities resulting from decomposition of a peroxide-based polymerization initiator and has excellent electrical characteristics. TECHNICAL FIELD The present invention relates to a resin for toner and a method for producing the same.

[0002]

BACKGROUND OF THE INVENTION It is well known that styrene or styrene / acrylic resins are useful as toner resins. This resin is usually obtained by a production method such as an emulsion polymerization method, a bulk polymerization method, or a suspension polymerization method. Among them, the suspension polymerization method is typical. A conventional styrene-based or styrene / acrylic-based toner resin for suspension polymerization is usually prepared by dissolving a styrene-based or styrene-acrylic monomer in which a polymerization initiator is dissolved in water containing a suspension dispersion stabilizer. After being charged and the heat polymerization was completed under stirring,
It is manufactured by being washed, dehydrated and dried. In the production process of this toner resin, a relatively large amount of a polymerization initiator is often used, and it is inevitable that the amount of the polymerization initiator is further increased due to addition of a polymerization initiator for completion of the polymerization. . As this polymerization initiator, an azo-based initiator or a peroxide-based initiator can be used, but the use of the azo-based initiator is limited due to problems such as toxicity, and the peroxide-based initiator is used. Often.

However, when a peroxide type polymerization initiator is used, acidic impurities are by-produced from the decomposition residue. These impurities are divided into the resin and the aqueous medium according to the distribution ratio, but since a large amount of the polymerization initiator is used, a considerable amount of acidic impurities must be left in the resin. The charging characteristics of the toner using this resin, which corresponds to changes in humidity, have a greater effect than expected. As a result, the copy image becomes abnormally dark or light, and it is difficult to obtain a stable image. Conventionally, a styrene or styrene / acrylic-based toner resin for improving this problem is obtained, for example, by adding a hydroxide of an alkali metal to a polymerization system after completion of the polymerization and heat-treating it to remove residual impurities. A resin (Japanese Patent Publication No. 4-73442) is proposed.

[0004]

However, the above-mentioned problems have a problem that they are limited to the treatment after polymerization. That is, treatment with an alkali metal hydroxide during suspension polymerization causes the suspension polymerization system to become unstable due to strong alkalinity, causing aggregation of pearl particles, or the resin being hydrolyzed by heating in a strong alkali. Since it is decomposed, the image characteristics of the toner using this resin deteriorates. Further, although the above is the treatment after the polymerization, special precautions are required not to hydrolyze the resin because a strong alkali is used, and the treatment conditions are limited, such as limiting the heat treatment temperature to a low range. There was a problem that it was difficult to handle.

[0005]

Means for Solving the Problems As a result of investigations to solve the above problems, the present inventor has found that peroxide-based resins, which are often used in styrene-based or styrene / acrylic-based toner resins by suspension polymerization, are used. Typical of polymerization initiators,
When a peroxide-based polymerization initiator having a benzoyl group or a benzoyl group having a substituent is used, benzoic acid or a benzoic acid having a substituent is produced from a decomposition product of the polymerization initiator; Since it has a high compatibility, it is likely to remain in the resin; there is a correlation between the amount of this acidic impurity in the resin and the charging property, and the charging property of the toner deteriorates unless the acidic impurity is kept below a certain amount. I got the knowledge. As a result of further diligent studies based on these findings, the present inventor has less restrictions on the treatment conditions because a strong alkali is not used, and the acidic impurities are quantitatively and effectively removed, and thus the electrical characteristics are excellent. Styrene type or styrene / acrylic type toner
The present invention has been accomplished by finding a resin for use and a manufacturing method thereof.

That is, the present invention is the following <1> to <7>. <1> Styrene-based or styrene / acryl-based toner resin produced by a suspension polymerization method using water as a medium in the presence of a peroxide-based polymerization initiator having a benzoyl group or a substituted benzoyl group In the presence of an alkali metal carbonate, the suspension polymerization is carried out at 50 ° C.
A toner resin, which is heat-treated at 140 ° C. <2> For styrene type or styrene / acrylic type toner produced by a suspension polymerization method using water as a medium in the presence of a peroxide type polymerization initiator having a benzoyl group or a substituted benzoyl group. A resin for a toner, which is obtained by adding alkali metal carbonate after suspension polymerization and heat-treating the resin at 50 ° C to 140 ° C.

<3> The toner resin <1> or <2>
> And a toner comprising a low molecular weight polyolefin wax or its modified product added in the production process of this resin.
Resin composition. <4> A toner comprising the toner resin <1> or <2>, a coloring material and optionally magnetic powder. <5> A toner comprising the resin composition <3>, a coloring material and optionally magnetic powder.

<6> Styrene-based monomer alone or suspension-polymerized styrene-based monomer and acrylic-based monomer in the presence of a peroxide-based polymerization initiator having a benzoyl group or a substituted benzoyl group and an alkali metal carbonate. A process for producing a styrene-based or styrene / acrylic resin, which comprises subjecting the product to heat treatment at 50 ° C. to 140 ° C. after polymerization, if necessary. <7> A styrene-based monomer alone or a suspension-polymerized styrene-based monomer and an acrylic-based monomer in the presence of a peroxide-based polymerization initiator having a benzoyl group or a substituted benzoyl group is treated with an alkali metal carbonate. A method for producing a styrene-based or styrene / acrylic resin, which comprises adding and heating at 50 ° C to 140 ° C.

In the present invention, the alkali metal carbonates include Na ₂ CO ₃ , K ₂ CO ₃ , NaHCO ₃ , and KHC.
O ₃ , Li ₂ CO _{3 and the} like can be mentioned. These may be anhydrous or may have water of crystallization. Of these, preferred are Na ₂ CO ₃ and K ₂ CO ₃ .

In the present invention, the styrene resin or the styrene / acrylic resin for a toner is a homopolymer of a styrene monomer or a copolymer of a styrene monomer and an acrylic monomer, and if necessary, these polymers may be added. It may contain a functional monomer or another polymerizable monomer as a constituent unit.

Examples of the styrene-based monomer include styrene and alkylstyrenes (α-methylstyrene, p-methylstyrene, etc.). Of these, styrene is preferred.

As the acrylic monomer, methyl (meth) acrylate, ethyl (meth) acrylate,
Butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, etc. alkyl (meth) acrylate having 1 to 18 carbon atoms; hydroxylethyl (meth) acrylate, etc. Hydroxyl group-containing (meth) acrylates; dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth)
Examples thereof include amino group-containing (meth) acrylates such as acrylates; nitrile group-containing (meth) acrylic compounds such as acrylonitrile, and (meth) acrylic acid.
Among these, preferred are methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate,
(Meth) acrylic acid and a mixture of two or more thereof.

As the polyfunctional monomer, a polyfunctional monomer having at least two polymerizable double bonds, for example, a divinyl compound (divinylbenzene, divinyltoluene, ethylene glycol diacrylate, 1,6 hexanedio- And a polyvinyl compound having three or more polymerizable double bonds (glycerin,
Examples thereof include trivalent acrylates and trimethacrylates of polyhydric alcohols such as trimethylolpropane. Of these, preferred are divinylbenzene and 1,6 hexanediol diacrylate. A polyfunctional monomer is added as necessary in order to obtain a polymer having a higher molecular weight upon polymerization, and by increasing the molecular weight, the hot offset property at the time of fixing the toner can be improved.

Other polymerizable monomers include vinyl esters (vinyl acetate, vinyl propionate, etc.), aliphatic hydrocarbon vinyl monomers (butadiene, etc.), vinyl ethers.
Tell (vinyl methyl ether, vinyl ethyl ether,
Vinyl isobutyl ether, etc.), vinyl ketone (vinyl methyl ketone, vinyl hexyl ketone, etc.), N-vinyl compound (N-vinylpyrrole, N-vinylcarbazol)
And N-vinylindole, N-vinylpyrrolidone and the like), vinyl halides (vinyl chloride and the like) and the like.

The weight ratio of each monomer in the total polymerizable monomer before suspension polymerization is usually 50 to 100%, preferably 60 to 100%, based on the weight of the total polymerizable monomer, based on the weight of the total polymerizable monomer. The acrylic monomer is usually 5 to 45%, preferably 10 to 40%, and the polyfunctional monomer is usually 3% or less, preferably 1% or less,
Other polymerizable monomers are 10% or less, preferably 5% or less. If the amount of the polyfunctional monomer exceeds 3%, gelation will occur during the polymerization and the cost will be low. Further, it becomes difficult to melt and knead the toner when it is made into toner.

Examples of the peroxide type polymerization initiator having a benzoyl group or a benzoyl group having a substituent include diacyl peroxide type and peroxy ester type initiators. Examples of diacyl peroxide-based compounds include 2,4-dichlorobenzoylper oxide,
Examples thereof include m-tolyl and benzoylperoxide and benzoylperoxide. Examples of peroxy ester type compounds include 1-hexyl per-oxy benzoate, 1-butyl per-oxy-m-toluoyl benzoate, 1-butyl per-oxy benzoate, and bis-t.
-Butyl peroxybenzoate and the like. The amount of the polymerization initiator used is usually 0.1 to 10% by weight, preferably 0.1 to 5% by weight, based on all polymerizable monomers before polymerization.
Is.

The toner resin of the present invention may be one obtained by suspension polymerization of all polymerizable monomers in one step, or one obtained by suspension polymerization of a partially polymerized monomer / resin mixture. It may be one obtained by suspension polymerization of a monomer in which a resin polymerized in advance is dissolved. At this time, it is possible to widen the molecular weight distribution by making the molecular weight of the coexisting resin different from that of the resin generated by the post-polymerization.

The weight average molecular weight (Mw) of the resin for toner of the present invention is tetrahydrofuran (hereinafter abbreviated as THF).
The Mw of the soluble component is usually 1 × 10 ³ to 1 × 10 ⁶ , and preferably 5 × 10 ³ to 1 × 10 ⁵ . When Mw is less than 1 × 10 ³ , the glass transition temperature (Tg) is lowered and the toner blocking property is deteriorated. On the other hand, if it exceeds 1 × 10 ⁶ , the fixing lower limit temperature becomes high in the toner fixing step, which is not preferable. The molecular weight of the toner resin is T as a solvent by gel permeation chromatography (hereinafter abbreviated as GPC).
Measurement is carried out using HF, a calibration curve of molecular weight is prepared with standard polystyrene, converted and displayed. The conditions for measuring the molecular weight by GPC are as follows. Device: HLC-802A (manufactured by Toyo Soda) Column: TSK gel GMH6 2 (manufactured by Toyo Soda) Measuring temperature: 25 ° C. Sample solution: 0.5 wt% THF solution Injection amount: 200 μl Detector: Refractive index detector The molecular weight calibration curve is based on standard polystyrene (molecular weight 842
10,000, 4.48 million, 2.89 million, 1.09 million, 35.55 million, 19
10,000, 964,000, 37,900, 196,000, 91,000,
2.98 thousand, 870, 500).

A composition containing the toner resin of the present invention,
That is, a toner resin composition comprising the toner resin of the present invention and the low molecular weight polyolefin wax added in the production process of the resin or a modified product thereof can be used. Examples of the low molecular weight polyolefin wax or its modified product include (a) polyethylene, polypropylene, and ethylene-α olefin (C3-8) copolymer (for example, ethylene 5
(0% by weight or more, particularly 70% by weight or more); (b) (a) maleic acid derivative (maleic anhydride, maleic acid diethyl ester, di-2-ethyl maleic acid squeezing ester, etc.) adduct; c) an oxide of (a); (d) an ethylenically unsaturated carboxylic acid [(meth) acrylic acid, itaconic acid, etc.] and / or its ester [alkyl (C ₁ -C ₁₈ ) ester, etc.] Copolymers with saturated hydrocarbons (ethylene, propylene, butene-1, etc.); and mixtures of two or more of these. The amount of polyolefin wax or its modified product is usually 30 based on the weight of all polymerizable monomers used.
% Or less, preferably 20% or less. If the amount of the polyolefin wax or its modified product exceeds 30%, the dispersion becomes insufficient.

In this composition, the low molecular weight polyolefin wax or its modified product is preferably uniformly dispersed. As a method for uniformly dispersing the low molecular weight polyolefin wax, the low molecular weight polyolefin wax can be used during the polymerization of the monomer (styrene resin or styrene / styrene /
The method of adding the acrylic resin is preferable. Specifically, a method in which the polyolefin wax is mechanically made into fine particles and then added to the monomer, and the polyolefin wax is dispersed in the resin in advance and then the monomer is added.
There is a method to add to.

In the production of the toner resin of the present invention, the alkali metal carbonate is present in the aqueous medium at the time of suspension polymerization, or is added to the polymerization slurry after the polymerization is substantially completed. Further, it can be added to the resin dried product, but in this case, a method in which the resin dried product is reslurried in water and an alkali metal carbonate is added thereto and stirred can be employed. The alkali metal carbonate may be used in the form of powder, or may be used by dissolving it in water or alcohol.

The amount of the alkali metal carbonate added depends on the amount of the peroxide used as the polymerization initiator. The effect of removing impurities is improved in proportion to the amount used, but if the amount is too large, the alkali metal carbonate adversely affects the charging characteristics. Around the neutralization equivalent of benzoic acid or a benzoic acid having a substituent, which is generated by the decomposition of a peroxide type polymerization initiator of benzoic acids, is a standard amount. When the suspension polymerization is carried out in the presence of an alkali metal carbonate, the alkali metal carbonate is usually added in an amount of 0.0
1 to 10% by weight, preferably 0.1 to 3% by weight is added. When added after suspension polymerization, the alkali metal carbonate is usually added in an amount of 0.01 to 10% by weight, preferably 0.1 to 3% by weight based on the total amount of the suspension after the polymerization, or suspended. After the polymerization, the reaction medium is removed and water is added again to the polymer to add 0.01 to 10% by weight, preferably 0.1 to 3% by weight, to the slurry.

The suspension polymerization can be carried out by dispersing a polymerizable monomer in water containing a dispersion stabilizer and polymerizing it according to a known method. As the dispersion stabilizer, a water-soluble polymer (gelatin, starch, methylcellulose,
Hydroxyethyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid salt, etc.), water-soluble or sparingly soluble inorganic compound (barium sulfate, barium carbonate, calcium carbonate, (Magnesium carbonate, calcium phosphate, talc, bentonite, diatomaceous earth, clay, etc.) and the like. These are usually 0.01 to 10 with respect to water.
%, Preferably 0.1-5%.

In the suspension polymerization, a chain transfer agent may be used if necessary, and known chain transfer agents such as n-
Octyl mercaptan, n-dodecyl mercaptan, t
Mention may be made of dodecyl mercaptan and 2-ethylhexyl thioglycolate.

The suspension polymerization is carried out in a nitrogen stream with stirring. The polymerization temperature is usually 30 to 140 ° C., preferably 60 to
It is 120 ° C. The polymerization time is usually 2 to 20 hours, preferably 4 to 10 hours. After completion of the polymerization, the resin obtained is washed with water to remove impurities. The acid component of the decomposition product of the peroxide type polymerization initiator of benzoic acids is mainly removed in the form of a salt.

In the production of the toner resin of the present invention, a particularly important addition treatment of an alkali carbonate requires a heat treatment step when it is added after the polymerization is substantially completed. That is, this is a step of adding a predetermined amount of alkali metal carbonate and then heat-treating the polymerization system at usually 50 ° C. to 140 ° C., and the heat treatment time is usually 20 minutes to 6 minutes.
The time is preferably 30 minutes to 4 hours. By treating at a high temperature, impurities such as decomposition products of the polymerization initiator in the resin can be effectively removed, and generally a short time is required. 1
When the treatment is performed at a high temperature of 40 ° C. or higher, the pearl-like particles are fused with each other. At a temperature of 50 ° C. or lower, it takes a long time to remove impurities, which is not practically preferable. When the suspension polymerization is carried out in the presence of an alkali metal carbonate in advance and the polymerization temperature is about 50 ° C. or higher, it is often unnecessary to add a heat treatment step after completion of the polymerization. Furthermore, the acid component, which is a decomposition product of the polymerization initiator, can be effectively removed. Washing with water and drying can be carried out by a known method. However, upon washing with water, acid treatment can be carried out to completely remove the residual alkaline component.

The alkali metal carbonate is added to the polymerization system (at the start of polymerization, during the polymerization or after the completion of the polymerization), and the resulting resin is heat-treated at a temperature of 50 ° C. or higher to stimulate the resin melt. It is a feature of the present invention that the acidic impurities that adversely affect the odor and the electrical characteristics of the toner are effectively removed. By this heat treatment, not only the acid component which is the target of the present invention to be removed, but also the unpleasant odor component in the resin is removed together. When an alkali metal carbonate is used, even if it is added before the completion of polymerization, the polymerization system is stable and there is no aggregation of pearl particles, and the decomposition product of the polymerization initiator from the mixed system of resin and monomer is a water solvent. Since it is easily eluted in the system, it is easily dissolved and removed as a salt. Further, even if added after the polymerization is substantially completed, the polymerization system can be maintained at a high temperature and treated without decomposing the resin. Advantageously, it also has the property of being easily dissolved and removed as a salt.

The toner resin of the present invention has a low content of acidic impurities which are decomposition products of the polymerization initiator. That is, the benzoic acid equivalent is usually 1500 PPM or less. 1500p
When it exceeds pm, the toner using this resin is highly dependent on the environment and it is difficult to obtain image stability. In the case of benzoic acid having a substituent (for example, a halogen group), the benzoic acid equivalent is a value converted into benzoic acid excluding the substituent.

The molecular weight distribution (weight average molecular weight Mw / number average molecular weight Mn) of the toner resin of the present invention is usually 10 or more, and preferably 20 or more for electrophotographic toner. When the molecular weight distribution is less than 10, hot offset (H
The difference between the temperature at which F) is generated and the temperature (MF) at the lower limit of fixing becomes small, which is not preferable. Also, the glass transition temperature (T
g) is usually 50 to 80 ° C, preferably 55 to 70 ° C. If the Tg is less than 50 ° C, the preservability after toning becomes poor, and if it exceeds 80 ° C, the MF becomes high and the toner cannot be put to practical use. Tg is a differential scanning calorimeter and the heating rate is 10
It was taken as the intersection of the base line and the endothermic peak curve measured as ° C / min.

The resin composition for the toner of the present invention and for the toner of the present invention can be used as a binder resin for an electrophotographic toner and a binder resin-containing composition. The weight ratio of the constituent components of the toner is usually 50 to 95% of the toner resin of the present invention (which may be used as the toner resin composition of the present invention) based on the toner weight, and a known coloring material (carbon black, Iron black, benzidine yellow, quinacridone, rhodamine B, phthalocyanine, etc.) are usually 5 to 1
0%, magnetic powder (powder of ferromagnetic metal such as iron, cobalt and nickel or compound such as magnetite, hematite and ferrite) is usually 0 to 50%. Furthermore, various additives [charge control agents (metal complexes, nigrosine, etc.),
Lubricants such as polytetrafluoroethylene, low molecular weight polyolefin, fatty acids, or metal salts or amides thereof, etc.] can be included. The amount of these additives is usually 0 to 5% by weight based on the weight of the toner.

The electrophotographic toner is dry-blended with the above-mentioned components, melt-kneaded, coarsely pulverized, and finally atomized using a jet pulverizer or the like, and further classified to have a normal particle size of 5 to 20 μm. Obtained as fine particles. The electrophotographic toner is mixed with carrier particles such as iron powder, glass beads, nickel powder and ferrite, if necessary, and used as a developer for an electric latent image. Further, hydrophobic colloidal silica fine powder can be used to improve the fluidity of the powder. The electrophotographic toner is fixed on a support (paper, polyester film, etc.), and as a fixing method, a known heat roll fixing method can be applied.

[0032]

The present invention will be further described with reference to the following examples, but the present invention is not limited thereto. Unless otherwise specified, all parts in the examples represent parts by weight. Benzoic acid content is gas chromatograph GC-9A
(Shimadzu) using diphenyl ether as an internal standard according to a conventional method.

Example 1 470 parts of ion-exchanged water and 3 parts of polyvinyl alcohol [PVA235 manufactured by Kuraray Co., Ltd.] were placed in a 10 L 4-neck reaction vessel.
Wt% aqueous solution of 50 parts of bicarbonate source - da (NaHCO ₃₎
1.4 parts was added, and a mixed solution of 76 parts of styrene, 24 parts of n-butyl acrylate, and 1.8 parts of benzoylperoxide was added thereto and stirred to obtain a suspension. Then, the reaction vessel was sufficiently replaced with nitrogen, and then the temperature was raised to 80 ° C. to start polymerization. The polymerization was continued at the same temperature for 10 hours, further heated to 95 ° C. and kept at the same temperature for 2 hours to complete the polymerization. The polymerization rate was 99.7%. The polymerized slurry was filtered, washed repeatedly with water, and dried at 55 ° C. for 24 hours using a hot air circulation dryer to obtain a pal resin of the present invention. The measured benzoic acid content in the resin was 950 ppm.

Comparative Example 1 On the other hand, the content of benzoic acid in the resin obtained by polymerizing in exactly the same manner as in Example 1 except that NaHCO ₃ was not added was 3400 ppm.

Comparative Example 2 Also, instead of using the NaHCO ₃ of the present invention, KOH
Polymerization was carried out in exactly the same manner as in Example 1 except that 1.4 parts were added, and during the polymerization, particles in the slurry aggregated and the resin separated. K for simplified production process efficiency
OH could not be used in the raw material charging stage.

Example 2 To a 1 L 4-necked flask, 240 parts of ion-exchanged water, 3.9 parts of calcium tertiary phosphate and 0.07 part of sodium alkylbenzene sulfonate were added, and 60 parts of styrene and methyl acrylate were added thereto. A monomer mixture solution in which a polymerization initiator consisting of 43 parts of ester, 0.07 part of divinylbenzene and 1.8 parts of benzoylperoxide was dissolved was added and stirred to obtain a suspension. After sufficiently replacing the oxygen in the flask with nitrogen, the temperature was raised to 80 ° C. and the polymerization was carried out at the same temperature for 8 hours to substantially complete the polymerization. Then, 1.8 parts of potassium carbonate (K ₂ CO ₃ ) was added to this polymerization slurry system, the temperature was further raised to 95 ° C., and the temperature was kept for 2 hours. The polymerization rate was 99.8%. Next, the polymerized slurry was filtered, repeatedly washed thoroughly with water, and dried at 55 ° C. for 24 hours by using a hot air circulation dryer to obtain a pallet resin of the present invention. The benzoic acid content in the resin was 400 ppm. The melt index (MI) of this resin is 1.1 g / 10 minutes (150 ° C.216
0g) and Tg were 64 ° C.

Examples 3 to 4 Resins of Examples 3 and 4 were obtained by the same method except that the amounts of K ₂ CO ₃ added in Example 2 were 0.9 parts and 0.4 parts, respectively.

Example 5 The benzoic acid content in the resin obtained in the same manner as in Example 2 except that the temperature was 120 ° C. in the heat treatment step was 210 ppm.

Comparative Example 3 Further, a resin of Comparative Example 3 was obtained in exactly the same manner as in Example 2 except that 0.4 part of calcium carbonate (CaCO ₃ ) was added instead of adding K ₂ CO ₃ . The benzoic acid content in the resin was 2500 ppm.

Comparative Example 4 Polymerization was carried out in the same manner as in Example 2 except that K ₂ CO ₃ was not added to obtain a resin of Comparative Example 4. The benzoic acid content in the resin was 3300 ppm.

Example 6 1300 parts of ion-exchanged water and 90 parts of a 3% by weight aqueous solution of polyvinyl alcohol [PVA235 manufactured by Kuraray Co., Ltd.] were added to a 10 L 4-neck reaction vessel, and styrene 490 was added thereto.
Parts, 120 parts of n-butyl acrylate, and styrene and n
-Butyl acrylate ratio is the same as the above-mentioned monomer ratio,
A mixed solution of a resin having a weight average molecular weight of 8,000 and 6.7 parts of benzoylperoxide was stirred to obtain a suspension. After sufficiently replacing the flask with nitrogen, the temperature was raised to 84 ° C., and the polymerization was continued for 7 hours at the same temperature to substantially complete the polymerization. Then, the polymerization slurry system was added with Na ₂ CO.
₃ 5.7 parts was added, the temperature was further raised to 95 ° C., and the temperature was maintained for 3 hours. The polymerization rate was 99.8%. The polymerized slurry obtained was filtered, repeatedly washed thoroughly with water, and dried at 55 ° C. for 24 hours using a hot-air circulating dryer to obtain a pallet-like resin of the present invention. Tg was 61 ° C. This resin is placed in a plastomill at 70 rpm for 10 minutes at a resin temperature of 140
After kneading under the condition of ° C, the molecular weight was measured and the following values were obtained. Weight average molecular weight = 11877 thousand Number average molecular weight = 7.8 thousand Molecular weight distribution (Mw / Mn) = 15 The measured value of the benzoic acid content in the resin was 710 ppm.

Test Example Next, using the resins of Examples 1, 2, 3, 4 and Comparative Example 1, a toner was prepared in the following manner, and then a developer was prepared and used as a charge measurement sample. VISCOL 550P is a low molecular weight polypropylene wax. Release agent Biscole 550P (Sanyo Kasei) 3 parts Charge control agent Spyron Black TRH (Hodogaya Kagaku) 1 part Resin Example and comparative example resin 90 parts Carbon MA100 (Mitsubishi Kasei) 6 parts After mixing the powders, melt kneading at a resin temperature of 140 ° C. for 30 minutes using a Labo Plastomill, then finely pulverizing with a jet pulverizer (Nippon Numatic Co., Ltd.), and disperser.
Classified with a John Separator to obtain an average particle size of 12μ, and the resulting powder is Aerosil R972 (Nippon Aerosil Co., Ltd.)
0.3% was added and mixed uniformly, and three kinds of corresponding toners (T-1, T-1) were prepared for the resins of Examples 1, 2, and 5, respectively.
-2, T-5) and a corresponding toner (TH-1) for Comparative Example 1 were obtained in total of four types of samples. Next, a developer was prepared as follows for measuring the toner charge amount. Preparation of developer: Carrier-iron powder F-on 25 parts of the above toner
1000 parts of 100 (Nippon Iron Powder Co., Ltd.) were mixed to obtain 4 kinds of corresponding developers.

Measurement of toner charge amount: Changes in toner charge amount due to changes in humidity of the above four developers were measured using a Toshiba blow-off charge amount measuring device. The results are shown in Table 1. Measurement conditions: developer at 25 ° C. and humidity at three points (3
(0, 70, 90% RH) for 24 hours, shaker
Stir for 10 minutes using a mixer to charge the toner,
It was measured at the same temperature and humidity.

[0044]

[Table 1]

Measurement of Conductivity of Extract from Resin: The results of measuring the conductivities of the resins prepared in Examples 2, 3, 4 and Comparative Example 4 are shown in Table 2. The measurement sample was prepared as follows. Preparation of measurement sample: Resin 5G with ethylene dichloride 31
Dissolve in 5 g under heating with stirring, and leave overnight. Ion-exchanged water 2
The water-soluble component was extracted with stirring at 00 g, and the aqueous layer was separated.
A total of 4 samples of three corresponding aqueous solutions (R-2, R-3, R-4) for the resins of Examples 2, 3 and 4 and a corresponding aqueous solution (RH-4) for Comparative Example 4 were prepared. Obtained.

[0046]

[Table 2]

[0047]

Since the toner resin of the present invention does not use a strong alkali, there are few restrictions on the processing conditions, and acidic impurities are removed quantitatively and effectively. Therefore, the toner resin of the present invention was used. The toner has excellent electrical characteristics. That is, the toner of the resin of the present invention or the toner of the present invention shows little change in the charge amount with respect to the change in humidity. The stability of the copy image with respect to the humidity change, which is the most important toner performance, is obtained. Further, the unpleasant irritating odor generated by impurities in the resin when the toner is made is extremely small. Therefore, the toner resin of the present invention and the toner resin composition of the present invention are useful as a binder resin and a binder resin-containing composition for an electrophotographic toner.

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Claims (10)

[Claims] 1. A styrene type or styrene / acrylic type toner produced by a suspension polymerization method using water as a medium in the presence of a peroxide type polymerization initiator having a benzoyl group or a substituted benzoyl group. A toner resin, wherein the toner resin is suspension-polymerized in the presence of an alkali metal carbonate, and is optionally heat-treated at 50 ° C. to 140 ° C. after the polymerization. 2. A styrene-based or styrene / acrylic-based toner produced by a suspension polymerization method using water as a medium in the presence of a peroxide-based polymerization initiator having a benzoyl group or a substituted benzoyl group. -In the resin for use, 50 ° C to 140 ° C after addition of an alkali metal carbonate after suspension polymerization
A resin for a toner, which is a resin heat-treated by. 3. The toner resin according to claim 1, wherein the decomposition product of the polymerization initiator remaining in the toner resin has a benzoic acid equivalent of 1500 ppm or less. 4. A toner resin composition comprising the toner resin according to any one of claims 1 to 3 and a low molecular weight polyolefin wax or a modified product thereof added in the process for producing the resin. 5. A toner comprising the resin for toner according to any one of claims 1 to 3, a coloring material and optionally magnetic powder. 6. A toner comprising the resin composition according to claim 4, a coloring material and optionally magnetic powder. 7. A suspension polymerization of a styrene monomer alone or a styrene monomer and an acrylic monomer in the presence of a peroxide polymerization initiator having a benzoyl group or a substituted benzoyl group and an alkali metal carbonate. Is heat-treated at 50 ° C. to 140 ° C. after polymerization, if necessary, for a styrene-based or styrene / acrylic resin production method. 8. The method according to claim 7, wherein the alkali metal carbonate is added in an amount of 0.01 to 10% by weight based on the total amount of the suspension before or during the initiation of the polymerization. 9. An alkali metal carbonate prepared by suspension polymerization of a styrene monomer alone or a styrene monomer and an acrylic monomer in the presence of a peroxide polymerization initiator having a benzoyl group or a benzoyl group having a substituent. A process for producing a styrene-based or styrene / acrylic resin, which comprises adding a salt and performing heat treatment at 50 ° C to 140 ° C. 10. An alkali metal carbonate is added in an amount of 0.01 to 10% by weight based on the total amount of suspension after polymerization, or water is added again to the polymer from which the reaction medium has been removed after suspension polymerization. The method according to claim 9, wherein 0.01 to 10% by weight is added to the slurry.