JPH0816803B2 - Method for producing binder resin for toner - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a binder resin for a toner used in a dry developer used in electrophotography, electrostatic recording, magnetic recording and the like. .

[Prior Art] Conventionally, a number of methods are known as electrophotographic methods, such as US Pat. No. 2,297,691, JP-B-42-23910 and JP-B-43-24748. An electric latent image is formed on the photoconductor by various means using a conductive substance, then the latent image is developed with toner, and the toner image is transferred to a transfer material such as paper as necessary. After that, it is fixed by heating, pressure, heating and pressurizing, solvent vapor or the like to obtain a copy. Further, when there is a step of transferring the toner image, a step for removing the residual toner is usually provided.

A developing method for visualizing an electric latent image using toner is, for example, a magnetic brush method described in U.S. Pat.No. 2,874,063, a cascade developing method described in U.S. Pat. No. 2,618,552 and 2,221,776. And the powder cloud method described in US Pat. No. 3,909,258 and the method using a conductive magnetic toner described in US Pat. No. 3,909,258 are known.

As a toner applied to these developing methods, a fine powder in which a dye / pigment is dispersed in a natural or synthetic resin has been conventionally used. For example, particles obtained by finely pulverizing a dispersion of a coloring material in a binder resin such as polystyrene into about 1 to 30 μm are used as toners. A magnetic toner containing magnetic particles such as magnetite is used. On the other hand, in the case of a system using a so-called two-component developer, the toner is usually used by being mixed with carrier particles such as glass beads and iron powder.

Today, such a recording method has been widely used not only for general copying machines, but also for computer output and microfilm printing. Therefore, the required performance has become higher, and various performances such as smaller size, lighter weight, lower energy, more maintenance-free, and more personal have been simultaneously demanded. In order to satisfy these requirements, the demand for the developer has become more severe in various aspects.

For example, as described above, the range of applications has expanded, and when it is used in general offices and homes, not only is it safe as a substance as a toner, but also attention is paid to the odor generated during fixing. It is needed.

This odor problem is of course an important issue considering the above-mentioned user and manufacturer's standpoints, but in general, it contains a synthetic resin as a main component and utilizes its softening / melting by heating. Considering the method of fixing a developer that can be fixed on a transfer material such as paper, it is technically not easy. Further, in order to solve this problem, it is meaningless to lower the developing characteristics such as image quality and toner durability.

Various methods have been considered in order to simultaneously satisfy these performances. However, in the method of adding an additive, the system becomes complicated, and an unexpected problem often occurs. Therefore, it is desirable to improve the odor of the binder resin itself. For that purpose, it is considered to be good to reduce the residual amount of the odor-causing solvent and the polymerizable monomer in the binder resin, and various methods including the influence on other developing characteristics have been considered so far. Is proposed.

For example, in JP-A-55-155632, occurrence of offset is caused by using a solvent used for obtaining a polymer or a polymer having a polymerizable monomer content of less than 0.1% by weight as a binder resin for toner. Also, it has been proposed to improve storage stability, fluidity and the like.

In JP-A-53-17737, there is a description that the residual of the polymerizable monomer affects the triboelectric charging property, blocking resistance, and fixing property of the toner, and as a binder resin for toner, a polymer is obtained. It has been proposed to reduce the residue of the solvent or polymerizable monomer used in the above.

In JP-A-64-70765, a toner having a residual monomer content of 200 ppm or less is used for the problem that the on-site environment is deteriorated due to the generation of odor during melt-kneading, or odor is generated during copying, which causes discomfort. A resin for use has been proposed. It is described that if the amount of residual monomer exceeds 200 ppm, blocking resistance and vinyl chloride plasticizer resistance decrease, and the problem of odor also remains.

However, especially when the problem of odor is targeted, it is not sufficient to simply reduce the amount of the remaining polymerizable monomer, considering the future expansion of the application range such as electrophotography and electrostatic recording. .

Further, as a method for polymerizing a binder resin for a developer, a solution polymerization method, a bulk polymerization method, a suspension polymerization method, etc. are generally known. As proposed in No. 62-57358, since it is not necessary to remove the solvent and a strong stirring device is not required, the production is easy, and the THF insoluble content that greatly affects the fixing and offset resistance performance of the toner is large. Is a suitable method for polymerizing the binder resin for toner.

However, in the suspension polymerization method, since the resin is obtained in the form of beads, there is no step of removing the solvent or the polymerizable monomer in the molten state of the resin such as solution polymerization, and the purpose is simply to remove water. Only the drying process is performed. As a result, the residual amount of the solvent and the polymerizable monomer tends to increase, and it is necessary to pay particular attention to the above-mentioned odor problem.

[Problems to be Solved by the Invention] An object of the present invention is to provide a method for producing a binder resin having a good odor.

In particular, an object of the present invention is to provide a method for producing a good binder resin with little odor in a binder resin for toner which is polymerized in an aqueous medium.

Another object of the present invention is to provide a method for producing a binder resin that simultaneously satisfies excellent performance in various items.

[Means and Actions for Solving the Problems] That is, the present invention provides at least styrene monomer
In a method for producing a binder resin for a toner by polymerizing a monomer composition containing a polymerizable monomer containing 50% by weight or more and a polymerization initiator, the amount of dissolved oxygen is 2.5 mg / or less and the monomer composition in an aqueous medium. The present invention relates to a method for producing a binder resin for a toner, which comprises subjecting a product to suspension polymerization to produce a styrene-based resin having a benzaldehyde content of 0.01% by weight or less.

As a result of intensive studies on the factors of the binder resin for toner that influence the odor of the toner, the present inventors have found that the amount of the solvent and the polymerizable monomer remaining in the binder resin for toner is as has been found so far. It is of course effective, but more than that, the residual amount of those oxidation products, especially the aldehydes produced by the air oxidation of the polymerizable monomer, has a great influence, and We have confirmed that reducing the residual amount of aldehydes is the best way to prevent the odor of toner.

In particular, in styrene-based polymers or copolymers that are most commonly used as binder resins for toners, benzaldehyde produced by air oxidation of styrene monomer is the most problematic component of odor. You need to be careful.

According to the study by the present inventors, the content of such benzaldehyde in the binder resin for toner needs to be 0.01% by weight or less, and particularly preferably 0.005% by weight or less. When the content of benzaldehyde exceeds 0.01% by weight, the odor of the toner is often noticeable.

From these problems, the present inventors have made earnest studies to reduce the amount of benzaldehyde, and as a result, have found that the object can be achieved by adopting the method described below.

That is, the dissolved oxygen of water used during suspension polymerization is 2.5 mg / or less, preferably 2.0 mg / or less at a measurement temperature of 40 to 45 ° C.
By the following, air oxidation of the polymerizable monomer is suppressed, and as a result, generation of benzaldehyde is suppressed.

That is, conventionally, in the suspension polymerization method, it has been known to replace the atmosphere of the polymerization system with nitrogen for the purpose of reducing wasteful consumption of the polymerization initiator. The purpose is to prevent the decrease in the rate, but it is not sufficient for the purpose of reducing benzaldehyde.
It has been found that it is necessary to adjust the dissolved oxygen in water used during suspension polymerization to a certain level or less in order to achieve the reduction of benzaldehyde. The mechanism of action is considered as follows. That is, in suspension polymerization, the polymerization reaction occurs in the droplets of the polymerizable monomer suspended in water, and the droplets of the polymerizable monomer come into direct contact with water in the place of this polymerization reaction, It is considered to be strongly affected by dissolved oxygen.

As a specific method for reducing the dissolved oxygen, various known techniques can be used, but it is preferable to efficiently install the dissolved oxygen by attaching a nitrogen introducing pipe into the water and flowing nitrogen into the water. It is better to reduce it.

As a result, when the concentration of dissolved oxygen is 2.5 mg / or less in the temperature range of 40 to 45 ° C., benzaldehyde is 0.01 wt% or less in the binder resin for toner, preferably the concentration of dissolved oxygen is 2.0 mg / 0.005w benzaldehyde
t% or less. At the same time, wasteful consumption of the polymerization initiator due to oxygen is reduced, and the residual concentration of the polymerizable monomer can be reduced at the same time.

Also, the suspension of the polymer thus obtained is treated at about 70 ° C.
A method of heating at the above temperature and distilling off residual monomers at the same time as distilling off water may be carried out together.

The concentration of dissolved oxygen in water is measured by the following method. Using a YSI DO meter made by Nikkaki, put the electrode into air or water containing a known amount of oxygen, and turn the O ₂ calibration adjustment knob to adjust the displayed value to the oxygen concentration of the sample.

Next, an electrode is put in and measured while circulating water having a temperature of 40 to 45 ° C. so that there is a flow of about 30 cm / sec. If left standing, move the electrode by hand and measure.

 Read when the displayed value is stable.

The amount of benzaldehyde in the binder resin for toner is determined by the following method using a gas chromatograph.

Make 2.55 mg of DMF as an internal standard and add 100 ml of acetone to make a solvent containing the internal standard. Next, binder resin for toner
200 mg is made up to 10 ml with the above solvent. After ultrasonically shaking for 30 minutes, leave it for 1 hour. Then filter with a 0.5 μm filter. The amount of implanted sample is 4μ.

The conditions for the gas chromatograph are: ・ Capillary column (30m × 0.249mm, DBWAX, film thickness 0.25μ
m) ・ Detector FID, nitrogen pressure 0.45kg / cm ²・ Injection concentration 200 ℃, detector temperature 200 ℃
The column temperature is raised from 50 ° C. to 5 ° C./min for 30 minutes.

・ Preparation of calibration curve Gas chromatographic measurement was performed in the same manner on a standard sample in which the target solution of benzaldehyde was added to the same amount of DMF and acetone solution as the sample solution.
Calculate the weight ratio / area ratio of DMF.

As described above, in the suspension polymerization method, the dissolved oxygen in the water phase was 2.5 m
Although the binder resin for toner which is the object of the present invention can be obtained by controlling the content to be g / or less, crushing property, offset resistance, fixing property, filming property and fusing property to the photoconductor,
To achieve a high degree of image quality, the applicant of the present invention filed Japanese Patent Application No. 62-
Tetrahydrofuran (THF) insoluble matter is contained in an amount of 10 to 70% by weight (preferably 10 to 60% by weight) as proposed in No. 57358, and the THF soluble matter has a Mw / mn in the molecular weight distribution by GPC.
≧ 5, having at least one peak in the region of 2000 to 10,000, having at least one peak or shoulder in the region of molecular weight 15,000 to 100,000, and having a molecular weight of 10,000 or less at 10 to 50% by weight based on the resin. Certain toner binder resins are preferred.

The THF-insoluble matter in the present invention refers to the weight ratio of the polymer component (substantially crosslinked polymer) that becomes insoluble in THF in the resin composition part, and indicates the degree of crosslinking of the resin composition containing the crosslinking component. It can be used as a parameter to indicate. The THF-insoluble matter is defined as a value measured as follows.

That is, 0.5 to 1.0 g of a resin sample (24 mesh pass, 60 mesh on powder) is weighed (W ₁ g), put into a cylindrical filter paper (for example, No.86R made by Toyo Roshi Kaisha, Ltd.), applied to a Soxhlet extractor, and the solvent As an extract, the soluble component extracted with a solvent is evaporated for 6 hours, and then the soluble component extracted with a solvent is evaporated, followed by vacuum drying at 100 ° C. for several hours, and the amount of the THF-soluble resin component is weighed (W ₂ g). The THF insoluble content of the resin is calculated from the following formula.

In the present invention, the peak or / and shoulder molecular weight of a chromatogram by GPC (gel permeation chromatography) is measured under the following conditions.

That is, stabilize the column in a heat chamber at 40 ° C, and add THF as a solvent to the column at this temperature.
(Tetrahydrofuran) is caused to flow at a flow rate of 1 ml per minute, and a THF sample solution of resin adjusted to a sample concentration of 0.05 to 0.6% by weight is injected in an amount of 50 to 200 μm for measurement. In measuring the molecular weight of the sample, the molecular weight distribution of the sample was calculated from the relationship between the logarithmic value and the number of counts of the calibration curve prepared from the monodisperse polystyrene standard sample, and as a standard polystyrene sample for creating the calibration curve, , For example, Pressure Che
mical Co. or Toyo Soda Kogyo Co., Ltd. has a molecular weight of 6 × 10 ² , 2.1 × 10 ³ , 4,5 × 10 ³ , 1.75 × 10 ⁴ , 5, 5. × 10 ⁴ , 1,1 × 1
It is suitable to use those of 0 ⁵ , 3.9 × 10 ⁵ , 8.6 × 10 ⁵ , 2 × 10 ⁶ , 4.48 × 10 ⁶ and at least about 10 standard polystyrene samples. An RI (refractive index) detector is used as the detector.

As the column, in order to accurately measure the molecular weight region of 10 ³ to 2 × 10 ⁶ , it is preferable to combine a plurality of commercially available polystyrene gel garams, for example, μ-st manufactured by Waters.
yragel500,10 ³ , 10 ⁴ , 10 ⁵ union and Showa Denko Shode
x KF-80M, KF-801, 803, 804, 805 combination, KA-
Combination of 802,803,804,805 or TSTge made by Toyo Soda
l G1000H, G2000H, G2500H, G3000H, G4000H, G5000H, G6000
A combination of H, G7000H and GMH is preferred.

The weight% of the binder resin having a molecular weight of 1000 or less of the present invention cuts out the molecular weight of 10,000 or less of the chromatogram by GPC, calculates the weight ratio with the cutout having a molecular weight of 10,000 or more, and uses the weight% of the THF-insoluble matter to calculate the total weight. The weight% with respect to the binder resin is calculated.

As the constituent component of the resin of the present invention, those which are generally used as the resin for toner and various compounds can be used as long as they can achieve the above-mentioned molecular weight distribution. Among them, vinyl monomers are used. Vinyl-based polymers, vinyl-based copolymers, and compositions of the polymers and the copolymers were preferred.

Examples of the vinyl-based monomer (monomer) applicable to the present invention include styrene such as styrene, α-methylstyrene, and p-chlorostyrene and their substitution products; acrylic acid,
Such as methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide etc. A monocarboxylic acid having a double bond or a substituted product thereof; for example, a dicarboxylic acid having a double bond such as maleic acid, butyl maleate, methyl maleate, dimethyl maleate and the like; a substituted product thereof; for example, vinyl chloride, vinyl acetate , Vinyl esters such as vinyl benzoate, etc .; vinyl ketones such as vinyl methyl ketone, vinyl exyl ketone, etc .; such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, etc. Vinyl monomers vinyl ether and the like can be used singly or two or more. Among these, a combination of a styrene polymer and a styrene copolymer is preferable.

The selection of the type of initiator, the type of solvent and the reaction conditions for producing the resin of the present invention are important factors for obtaining the resin of the present invention. Examples of the initiator include benzoyl peroxide, 1,1-di (t-butylperoxy) -3,3,5-
Trimethylcyclohexane, n-butyl-4,4-di (t
-Butylperoxy) valerate, dicumyl peroxide, α, α'-bis (t-butylperoxydiisopropyl) benzene, t-butylperoxycumene, di-t
-Organic peroxides such as butyl peroxide, azo and diazo compounds such as azobisisobutyronitrile and diazoaminoazobenzene can be used.

A part of the binder resin for toner of the present invention can be crosslinked using a crosslinkable monomer.

A compound having two or more polymerizable double bonds is mainly used as the crosslinkable monomer. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; carboxylic acid esters having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate and 1,3-butanediol dimethacrylate, and divinylaniline. , Divinyl ether, divinyl sulfide, divinyl sulfone, and other divinyl compounds and compounds having three or more vinyl groups are used alone or as a mixture. Of these, divinylbenzene is effective.

In the method for producing the binder resin of the present invention, the first resin is prepared by solution polymerization, the first resin is dissolved in a polymerizable monomer, and the polymerizable resin is added in the presence of the resin and a crosslinking agent. It is preferred to suspension polymerize the monomers. The first resin should dissolve 10 to 120 parts by weight, preferably 20 to 100 parts by weight, based on 100 parts by weight of the monomer for suspension polymerization.
Further, in the suspension polymerization, it is preferable to use a crosslinking agent in an amount of about 0.1 to 2.0 wt% with respect to the monomer for suspension polymerization. These conditions allow slight variations depending on the type of initiator and reaction temperature.

A case where the first polymer is dissolved in a monomer and suspension polymerized to obtain the binder resin, a polymer obtained by suspension polymerization without dissolving the first polymer, and a first polymer There is a difference in performance between the case of simply mixing and the case of using as a toner, and it is known that the former brings a good result particularly in fixing property.

The solution polymerization and suspension polymerization related to the present invention will be described below.

As the solvent used in the solution polymerization, xylene, toluene, cumene, cellosolve acetate, isopropyl alcohol, benzene or the like can be used. For styrene monomers, xylene, toluene or cumene are preferred. It is appropriately selected depending on the polymer to be polymerized. Further, the initiator is di-tert-butyl peroxide, tert-butyl peroxybenzoate, benzoyl peroxide, 2,
2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), etc. is 0.1 parts by weight or more (preferably 0.4 to 15 parts by weight) per 100 parts by weight of the monomer.
Used at a concentration of. The reaction temperature varies depending on the solvent used, the initiator, and the polymer to be polymerized, but is 70 ° C.
It is better to do it at ~ 180 ℃. Solvent 1 in solution polymerization
It is preferable to carry out 30 to 400 parts by weight of monomer with respect to 00 parts by weight. Alternatively, it can be obtained by a method by thermal polymerization.

In the suspension polymerization, 100 parts by weight or less (preferably 10 to 90 parts by weight) of the monomer is preferably used with respect to 100 parts by weight of the aqueous solvent. As usable dispersants, polyvinyl alcohol, polyvinyl alcohol partial saponification agent, calcium phosphate, etc. are used, and there is an appropriate amount such as the amount of monomer to the aqueous solvent, but generally 0.05 to 1 part by weight to 100 parts by weight of the aqueous solvent. Used in. Polymerization temperature is 50-95 ℃
Is suitable, but it should be appropriately selected depending on the initiator used and the intended polymer. Further, as the type of the initiator, if it is insoluble or hardly soluble in water, it is possible to use, for example, benzoyl peroxide, tert-butyl peroxyhexanoate, etc., in 100 parts by weight of the monomer. It is used at 0.5 to 10 parts by weight.

[Examples] Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto. In addition, all the parts and% described in the examples are parts by weight and% by weight.

Example 1 200 parts of cumene was placed in a reactor and heated to the reflux temperature. To this, a mixture of 100 parts of styrene monomer and 8 parts of di-tert-butyl peroxide was added dropwise under a cumene reflux for 4 hours. Under cumene reflux (146 ℃ -156 ℃)
Polymerization was completed and the cumene was removed. The obtained polystyrene was dissolved in THF, Mw = 3700, Mw / Mn = 2.64, the molecular weight at which the main peak of GPC was located was 3500, Tg = 57 ° C.

Dissolve the above polystyrene 30 parts in the following monomer mixture,
A mixed solution was prepared.

Partially saponified polyvinyl alcohol in the above mixed solution.
170 parts of water in which 1 part was dissolved was added to give a suspension dispersion. Water 15
Part into a reactor, nitrogen gas is introduced into water through a nitrogen gas introduction tube, and the temperature is raised to 40 to 45 ° C. so that the concentration of dissolved oxygen is 1.5 mg /
Nitrogen gas was flowed so that In this state, the above dispersion liquid was added to the reactor, and a suspension polymerization reaction was carried out at a reaction temperature of 70 to 95 ° C for 9 hours. After completion of the reaction, the reaction product was separated, dehydrated and dried to obtain a composition of polystyrene and a styrene-n-butyl acrylate copolymer. In this composition, the THF insoluble matter and the THF soluble matter were uniformly mixed, and the polystyrene and the styrene-n-butyl acrylate copolymer were uniformly mixed. About 0.5 g of the obtained resin composition (using a resin composition powder of 24 mesh pass, 60 mesh on) was precisely weighed and put into No.86R cylindrical filter paper (diameter 28 mm, length 100 mm) made by Toyo Roshi Kaisha. , THF200m
It was measured by refluxing l once every 4 minutes. The THF-insoluble content of the resin composition was 25%. When the molecular weight distribution of the THF-soluble component was measured, it had peaks at the positions of 40,000 and 34, 000, with Mn = 0.550,000, Mw = 130,000, Mw / Mn = 24, and a molecular weight of 10,000 or less was 25%. there were. Furthermore, the Tg of the resin was 58 ° C.

The content of benzaldehyde was 0.003% or less.
Incidentally, the content of styrene monomer was 0.018%.

Put 10 g of the obtained resin in a 200 cc closed glass container and
After heating at 0 ° C for 10 minutes, the odor was evaluated under heating.

Although a slight odor was felt, it was considered that there is no practical problem as a resin.

Therefore, the above resin was crushed to an average particle size of about 10μ and put in the color cartridge of Canon Copier FC-3 instead of toner, and developed by the copier to form a uniform resin particle layer on the paper surface. After adjusting and modifying the bias, transfer current, etc., the image was developed on the photoreceptor and transferred on paper, and then passed through a fixing device, and the odor generated at that time was observed.

For the odor evaluation, the above copying machine was installed in the center of a small room of about 3 m square, and the fixing of resin particles on the paper by the above method was continuously copied. Sniff the odor while changing When a panel test type evaluation of sensitivity was performed, a very good result was obtained (the results are shown in Table 1). Therefore, even if the present resin is used as it is, it can be applied to the surface treatment of paper by the above means. In addition, it was determined that application to a binder resin for toner is possible as a similar application.

Example 2 200 parts of cumene was placed in a reactor and heated to the reflux temperature. The following mixture was added dropwise under cumene reflux for 4 hours.

Further, the polymerization was completed under cumene reflux (146 to 156 ° C.) to remove cumene. The obtained styrene-α-methylstyrene copolymer had a main peak at the position of molecular weight 4400 in the chart of Mw = 4500, Mw / Mn = 2.8, GPC, and had Tg = 63 ° C.

30 parts of the above styrene-α-methylstyrene copolymer was dissolved in the following monomer mixture to give a mixed solution.

Partially saponified polyvinyl alcohol in the above mixed solution.
170 parts of water in which 1 part was dissolved was added to give a suspension dispersion. 15 parts of water was added, and the concentration of dissolved oxygen was 1.8 mg /
And Similarly, the above dispersion liquid was added to the reactor, and the reaction was carried out at a reaction temperature of 70 to 95 ° C. for 9 hours. After the reaction,
Separately, it was dehydrated and dried to obtain a composition of a styrene-α-methylstyrene copolymer and a styrene-2-ethylhexyl acrylate copolymer.

The THF insoluble content of this composition was 32%. Also, when the molecular weight distribution of the THF-soluble component was measured, it had a peak at the position of the molecular weight of 50 thousand and 42 thousand, and Mn = 0.62 million, Mw = 130,000, Mw / Mn = 2.
The molecular weight of 10,000 or less was 20%. The Tg of the resin is 58.
° C.

The content of benzaldehyde in the resin is 0.004%,
The styrene monomer content was 0.035%.

When the same test as in Example 1 was carried out using the above resin, similarly good results were obtained.

Example 3 200 parts of cumene was placed in the reactor and heated to the reflux temperature. The following mixture was added dropwise under cumene reflux for 4 hours.

Further, the polymerization was completed under cumene reflux (146 to 156 ° C.) to remove cumene. The obtained styrene-methacrylate copolymer had a main peak at the position of Mw = 3900, Mw / Mn = 2.6, and a molecular weight of 4100, and Tg = 60 ° C.

40 parts of the styrene methyl methacrylate copolymer was dissolved in the following monomer mixture to give a mixed solution.

Partially saponified polyvinyl alcohol in the above mixed solution.
170 parts of water in which 1 part was dissolved was added to give a suspension dispersion. 15 parts of water was added and the dissolved oxygen was adjusted to 1.8 mg / m in the same manner as in Example 1. In the same manner, add the above dispersion to the reactor and
The reaction was carried out at 70 to 95 ° C for 9 hours. After completion of the reaction, the reaction product was separated, dehydrated and dried to obtain a composition of a styrene-methyl methacrylate copolymer and a styrene-n-butyl methacrylate copolymer.

The THF insoluble content of this composition was 35%. When the molecular weight distribution of the THF-soluble component was measured, it had peaks at 40,000 and 43,000, Mn = 59,000, Mw = 92,000, Mw / Mn = 16, molecular weight 1
Less than 10,000 was 32%. Furthermore, the Tg of the resin was 60 ° C.

The benzaldehyde content of the above resin was 0.003% lower and the styrene monomer content was 0.021%, and the same good results were obtained in the same odor evaluation as in Example 1.

Example 4 Partially saponified polyvinyl alcohol in the above mixture 0.1
170 parts of water having parts dissolved therein was added to obtain a suspension dispersion liquid. 15 parts of water was added and the dissolved oxygen was adjusted to 1.5 mg / same as in Example 1. In the same manner, add the above dispersion to the reactor and set the reaction temperature.
The reaction was carried out at 70 to 95 ° C for 9 hours. After completion of the reaction, the reaction product was separated, dehydrated and dried to obtain a styrene-n-butyl acrylate copolymer composition.

The THF insoluble content of this composition was 44 wt%. Also THF
When the molecular weight distribution of the soluble component was measured, it had a peak at the position of molecular weight of 20,000, Mn = 80,000, Mw = 28, 000, Mw / Mn = 3.5,
The molecular weight of 10,000 or less was 21 wt%. Furthermore, the Tg of the resin is
It was 56 ° C.

Further, the content of benzaldehyde in the resin was 0.003% or less and the content of styrene monomer was 0.024%. When the same odor evaluation as in Example 1 was carried out, it was found that although the melt-fixability to paper was somewhat poor, Was a good result.

Example 5 150 parts of cumene was placed in the reactor and the temperature was raised to the reflux temperature. The following mixture was added dropwise under cumene reflux for 4 hours.

Further, the polymerization was completed under cumene reflux (146 to 156 ° C.) to remove cumene. The obtained styrene polymer has Mw = 690.
It had a main peak at a position of 0, Mw / Mn = 2.3, and a molecular weight of 7100, and had Tg = 75 ° C.

Dissolve the above polystyrene 30 parts in the following monomer mixture,
A mixed solution was prepared.

Partially saponified polyvinyl alcohol in the above mixed solution.
170 parts of water in which 1 part was dissolved was added to give a suspension dispersion. 15 parts of water was added, the dissolved oxygen was adjusted to 2.3 mg / m in the same manner as in Example 1, the above dispersion liquid was added to the reactor, and the reaction temperature was 70-
The reaction was carried out at 95 ° C for 9 hours. After completion of the reaction, the reaction product was separated, dehydrated and dried to obtain a composition of a styrene polymer and a styrene-n-butyl acrylate copolymer.

The THF insoluble content of this composition was 30%. When the molecular weight distribution of the THF-soluble component was measured, it had peaks at 0.75 million and 43,000, Mn = 0.65 million, Mw = 100,000, Mw / Mn = 15, and a molecular weight of 10,000 or less was 18%. Furthermore, the Tg of the resin is 61 ° C,
The benzaldehyde content in the resin was 0.008% and the styrene monomer content was 0.056%.

When the above resin was subjected to the same odor test as in Example 1, it was determined that the resin was practically acceptable, although a large number of people felt the odor.

Comparative Example 1 200 parts of cumene was placed in a reactor and heated to the reflux temperature. A mixture of 100 parts of a styrene monomer and 8 parts of di-tert-butyl peroxide was added dropwise to the mixture under reflux of cumene over 4 hours. Polymerization was completed under cumene reflux (146 ° C to 156 ° C) to remove cumene. The obtained polystyrene was dissolved in THF, Mw = 3700, Mw / Mn = 2.64, the molecular weight at which the main peak of GPC was located was 3500, Tg = 57 ° C.

Dissolve the above polystyrene 30 parts in the following monomer mixture,
A mixed solution was prepared.

Partially saponified polyvinyl alcohol in the above mixed solution.
170 parts of water in which 1 part was dissolved was added to give a suspension dispersion. Water 15
Parts, and the dissolved oxygen amount is 3.5 mg / same as in Example 15.
And a suspension polymerization reaction was carried out at a reaction temperature of 70 to 95 ° C. for 9 hours.
After completion of the reaction, the reaction product was separated, dehydrated and dried to obtain a composition of polystyrene and a styrene-n-butyl acrylate copolymer.

The benzaldehyde content of the resin composition is 0.019
%, The styrene monomer content was 0.07%, and when the same panel test as in Example 1 was conducted, many people were worried about the odor,
It was judged that it cannot be applied to the surface treatment of paper. It was also judged that it cannot be applied as a binder resin for toner.

Comparative Example 2 200 parts of cumene was placed in a reactor and heated to the reflux temperature. A mixture of 100 parts of a styrene monomer and 8 parts of di-tert-butyl peroxide was added dropwise to the mixture under reflux of cumene over 4 hours. Polymerization was completed under cumene reflux (146 ° C to 156 ° C) to remove cumene. The obtained polystyrene was dissolved in THF, Mw = 3700, Mw / Mn = 2.64, the molecular weight at which the main peak of GPC was located was 3500, Tg = 57 ° C.

Dissolve the above polystyrene 30 parts in the following monomer mixture,
A mixed solution was prepared.

Partially saponified polyvinyl alcohol in the above mixed solution.
170 parts of water in which 1 part was dissolved was added to give a suspension dispersion. Water 15
And the dissolved oxygen concentration is 2.8 m in the same manner as in Example 1.
g / Similarly, add the above dispersion to the reactor,
A suspension polymerization reaction was carried out at a reaction temperature of 70 to 95 ° C. for 6 hours. After completion of the reaction, separate, dehydrate and dry the polystyrene and styrene-
A composition of n-butyl acrylate copolymer was obtained.

Benzaldehyde in the above resin composition was 0.015% and styrene was 0.03%. The result of the panel test similar to that in Example 1 was determined to be unacceptable as in Comparative Example 1.

[Advantages of the Invention] With the widespread use of electrophotography, a good toner is also required against odor at the time of heat fusing and fixing. It was found that the amount of the polymerizable monomer oxide remaining in the binder resin, especially the amount of benzaldehyde, had a great effect, and in order to achieve the reduction, it was necessary to control the amount of dissolved oxygen in the water column during suspension polymerization. We have found that it is essential.

The binder resin for toner synthesized by these measures was extremely good in terms of odor, and it was possible to supply the suspension-polymerized resin, which has no odor problem, for toner.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Manabu Ono 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Tetsuto Kuwashima 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Eiichi Imai 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Innovator Yoshinobu Nagai 1-12-15 Nakano, Nishi-ku, Kobe-shi, Hyogo (56) References Special Kaisho 61-179202 (JP, A)

Claims (2)

[Claims] 1. A method for producing a binder resin for a toner by polymerizing a monomer composition containing a polymerizable monomer containing at least 50% by weight of a styrene monomer and a polymerization initiator, wherein the amount of dissolved oxygen is 2.5 mg. / A method for producing a binder resin for toner, which comprises subjecting a monomer composition to suspension polymerization in the following aqueous medium to produce a styrene resin having a benzaldehyde content of 0.01% by weight or less. 2. The method for producing a binder resin for toner according to claim 1, wherein the amount of dissolved oxygen in the aqueous medium is 2.0 mg / or less.