JPH07191497A - Production of binder resin for toner - Google Patents

Abstract

PURPOSE:To accurately control the mixing ratio of a high mol.wt. polymer to a low mol.wt. polymer and to obtain a toner having good balance of fixing property and anti-offset property by effecting suspension polymn. of the low mol.wt. polymer in the presence of an emulsion of the high mol.wt. polymer and a salting agent. CONSTITUTION:After a high mol.wt. polymer is obtd. by emulsion polymn. method, a low mol.wt. polymer is obtd. by suspension polymn. in the presence of 100 pts.wt. of the emulsion of the high mol.wt. polymer and 0.5-5 pts.wt. of salting agent. Thus, the high mol.wt. polymer and the low mol.wt. polymer are unifformly mixed. Both polymers consist of polymers or copolymers of styrene monomers and other copolymerizable monomers, and especially styrene- acryl copolymers are preferable. As for other copolymerizable vinyl monomers, such monomers that the resin to be produced has >=50 deg.C glass transition temp. is preferably used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a toner resin used in electrophotography, electrostatic printing, etc., and more specifically, controlling the content ratio of a high molecular weight polymer and a low molecular weight polymer. The present invention relates to a method for producing a binder resin for toner, which can accurately perform the above.

[0002]

2. Description of the Related Art A typical image forming process using electrophotography or electrostatic printing is to uniformly charge a photoconductive insulating layer, expose the insulating layer, and then charge the exposed portion. To form an electrical latent image by dissipating the latent image, and visualized by attaching a fine powder toner having an electric charge to the latent image, the obtained visible image on 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.

As the toner and the binder resin for the toner used in such an electrophotographic method or electrostatic printing method, various performances are required in each of the above steps. For example, in the developing process, the toner and the binder resin for the toner retain the charge amount suitable for the 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 process using the heat roller fixing method, the non-offset property that does not adhere to the heat roller and the fixability on paper must be good. Further, blocking resistance that toner does not block during storage in a copying machine is also required.

Conventionally, as a resin for toner, styrene-
Acrylic resins are often used, and linear type resins and crosslinked type resins are used. As a linear type resin, a resin in which a high-molecular weight polymer and a low-molecular weight polymer are mixed to improve fixing property, non-offset property and the like is known. Further, in the case of a cross-linking type resin, the molecular weight distribution is broadened by cross-linking to improve the fixing property and non-offset property of the toner. In particular, research on linear type resins is progressing, and Japanese Patent Publication No. Sho 63-32182 and Japanese Unexamined Patent Publication No. Sho 62-62
As described in Japanese Patent No. 9356 and the like, attempts have been made to improve the fixing property and non-offset property of toner by controlling the high molecular weight region and low molecular weight region of the resin and the molecular weight thereof. It was difficult to obtain a toner having a well-balanced fixing property and non-offset property only by using the control rule.

[0005]

Therefore, various attempts have been made to improve the method for producing a binder resin for a toner. For example, a low molecular weight polymer is produced by a solution polymerization method, after dissolving the high molecular weight polymer produced by the bulk polymerization method in this low molecular weight polymer solution, the solvent is removed by a method such as reduced pressure or spray drying. Method of obtaining a binder resin for toner, in the presence of an emulsion of high molecular weight polymer,
A method of suspension-polymerizing a low molecular weight polymer using a nonionic dispersant has been proposed.

However, in the case of a combination of solution polymerization and bulk polymerization, it is difficult to remove the solvent, resulting in poor productivity, and
The remaining solvent has problems such as odor of toner and image stability. In addition, in the method of suspension polymerizing a low molecular weight polymer in the presence of a high molecular weight polymer emulsion, a part of the high molecular weight polymer flows out at the end of the suspension polymerization of the low molecular weight polymer, It was difficult to obtain a resin having a desired content ratio of the low molecular weight polymer and the low molecular weight polymer.
Therefore, an object of the present invention is to provide a toner which can easily and accurately control the mixing ratio of a high molecular weight polymer and a low molecular weight polymer and can provide a toner having a well-balanced fixing property and non-offset property. To obtain a binder resin for use.

[0007]

In view of such circumstances, the inventors of the present invention have made earnest studies on a method for producing a binder resin for a toner, and as a result, as a result, in the presence of an emulsion of a high molecular weight polymer and a salting-out agent. The present inventors have found that by carrying out suspension polymerization of a molecular weight polymer, it is possible to easily and accurately control the mixing ratio of the high molecular weight polymer and the low molecular weight polymer, and the present invention has been achieved. That is, the method for producing the binder resin for toner of the present invention is
After the high molecular weight polymer is polymerized by the emulsion polymerization method, it is reduced in the presence of 0.5 to 5 parts by weight of a salting-out agent per 100 parts by weight of the emulsion of the high molecular weight polymer and the emulsion of the high molecular weight polymer. It is characterized by polymerizing a molecular weight polymer by suspension polymerization.

The binder resin for toner obtained by the present invention is a mixture of a high molecular weight polymer and a low molecular weight polymer, and each polymer is a styrene monomer or another copolymerizable vinyl monomer. It is a polymer or copolymer composed of a polymer or the like, and is preferably a styrene-acrylic copolymer. In the present invention, examples of the styrene-based monomer used for polymerizing the high molecular weight polymer and the low molecular weight polymer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene and α-methylstyrene. , P-ethylstyrene, 2,4
-Dimethylstyrene, pn-butylstyrene, pt
ert-butyl styrene, pn-hexyl styrene,
pn-octyl styrene, pn-nonyl styrene,
Examples thereof include pn-densyl styrene, pn-dodecyl styrene, p-phenyl styrene and 3,4-dicrosyl styrene, and among them, styrene is preferable. These styrene-based 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 it is preferable to set the glass transition temperature of the obtained resin to a range of 50 ° C. or higher. This is because when the glass transition temperature of the resin is lower than 50 ° C., the storage stability may become extremely low when it is made into a toner.

In the present invention, a high molecular weight polymer is polymerized by an emulsion polymerization method using the above-mentioned monomers, and then a low molecular weight polymer is obtained in the presence of an emulsion of the obtained high molecular weight polymer and a salting-out agent. The binder resin for toner in which a high molecular weight polymer and a low molecular weight polymer are uniformly mixed is produced by polymerizing the combined product by a suspension polymerization method. In the present invention, the emulsion polymerization of the high molecular weight polymer is not particularly limited and can be carried out according to a general emulsion polymerization method, and is generally used in the emulsion polymerization together with the monomers as described above. It is possible to use an emulsifier, a polymerization initiator or the like.

Examples of emulsifiers used include fatty acid salts, alkyl sulfate ester salts, alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkyl sulfosuccinates, alkyl diphenyl ether disulfonates, alkyl phosphates, and polyoxys. Ethylene alkyl sulfate ester salt, polyoxyethylene alkyl allyl sulfate ester salt, naphthalene sulfonic acid formalin condensate, special polycarboxylic acid type polymer surfactant, polyoxyethylene alkyl allyl ether, polyoxyethylene derivative, oxyethylene / oxypropylene Block polymer, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, polio Shiechiren fatty acid esters, polyoxyethylene alkyl amines, alkyl alkanol amides, alkyl amine salts, quaternary ammonium salts, alkyl betaines, and amine oxides, and the like,
An anionic surfactant is preferable from the viewpoint of uniform mixing of the high molecular weight polymer and the low molecular weight polymer.

These emulsifiers may be added so that the monomer for high molecular weight polymer is substantially emulsified and dispersed in water,
0.1 to 100 parts by weight of monomer for high molecular weight polymer
It is preferably used in the range of 2.5 parts by weight, more preferably 0.2 to 1.5 parts by weight. This is because if the amount of the emulsifier used is less than 0.1 parts by weight, the stability of polymerization tends to be poor and agglomerates tend to be generated. This is because there is a tendency for the environmental dependency of (3), especially the humidity resistance, to deteriorate.

In emulsion polymerization of a high molecular weight polymer, the ratio (M / W) of the amount (M) of the monomer for high molecular weight polymer to the amount (W) of water is about 1/2 to 1/10. Carried out in the range of
It is preferable to replace the inside of the reaction system with an inert gas such as nitrogen. The polymer polymerized by emulsion polymerization is
Weight average molecular weight (Mw) is 1 × 10 ^{5 to} 1.5 × 10 ^6.
It is preferably in the range of. This is because when the weight average molecular weight (Mw) is less than 1 × 10 ⁵ , the non-offset property as a toner tends to decrease, and conversely 1.5 × 10 5.
^This is because if it exceeds ⁶ , the fixability as a toner tends to decrease.

In the present invention, by polymerizing a low molecular weight polymer by suspension polymerization in the presence of an emulsion of an emulsion polymerized high molecular weight polymer and a salting-out agent,
It is possible to suppress the outflow of the high molecular weight polymer at the end of the suspension polymerization of the low molecular weight polymer, and it becomes easy to control the content ratio of the low molecular weight polymer and the high molecular weight polymer. It is possible to obtain a binder resin for toner in which the combined material is contained in a desired ratio.

The salting-out agent used in the present invention includes inorganic acids such as hydrochloric acid and sulfuric acid, organic acids such as formic acid and oxalic acid, and inorganic acids or organic acids with sodium, aluminum, alkaline earth metals and the like. Examples thereof include water-soluble metal salts, which can be used alone or in combination of two or more kinds. Among them, magnesium sulfate, aluminum sulfate, sodium sulfate, barium chloride, magnesium chloride, calcium chloride and sodium chloride are particularly preferable. These salting-out agents are used in an amount of 0.5 to 5 parts by weight, preferably 1 to 4 parts by weight, based on 100 parts by weight of the high molecular weight polymer emulsion. This is because if the amount of salting-out agent used is less than 0.5 parts by weight, sufficient salting-out efficiency will not be obtained, and at the end of suspension polymerization, the high-molecular weight polymer will flow out or the polymerization will become unstable and the polymerization will become unstable. On the contrary, when it exceeds 5 parts by weight, the particle size of the resin particles obtained becomes non-uniform, and the resin may not be completely dissolved in the melt-kneading step at the time of toner formation, or depending on the particle size. This is because the content ratio of the high molecular weight polymer and the low molecular weight polymer varies.

The suspension polymerization of the low molecular weight polymer is carried out by sufficiently stirring and mixing the emulsion of the high molecular weight polymer, the salting-out agent, the monomer for the low molecular weight polymer and the dispersant, and then adding the polymerization initiator. The temperature can be raised to carry out polymerization. As the dispersant used in the suspension polymerization, in order to carry out suspension polymerization of a low molecular weight polymer in the presence of an emulsion of a high molecular weight polymer,
The use of a nonionic dispersant can prevent the high molecular weight polymer from being dissolved in the low molecular weight polymer monomer and preventing the viscosity of oil droplets from increasing and the polymerization stability from decreasing. Therefore, it is preferable. Examples of the nonionic dispersant include polyvinyl alcohol, polyethylene oxide, methyl cellulose, ethyl cellulose, gelatin and the like, and among them, polyvinyl alcohol is particularly preferable. Particularly, partially saponified polyvinyl alcohol in which an acetic acid group and a hydroxyl group are present in a block is preferable. Such a dispersant is preferably used in the range of 0.1 to 1 part by weight based on 100 parts by weight of the total amount of the high molecular weight polymer and the low molecular weight polymer. This is because when the amount of the nonionic dispersant used is less than 0.1 part by weight, the stability of the suspension polymerization is lowered and the polymer tends to solidify due to the aggregation of the produced particles. This is because if the amount exceeds the range, the environmental dependency of the toner, particularly the moisture resistance tends to decrease, and more preferably 0.2 to
It is in the range of 0.8 parts by weight.

The suspension polymerization of the low molecular weight polymer is 1 to 10 times, preferably 2 times, that of the low molecular weight polymer monomer.
To about 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 until the polymerization is substantially completed. The heating is continued until the polymerization rate reaches 95% or more. The low molecular weight polymer polymerized by suspension polymerization is
The weight average molecular weight (Mw) is preferably in the range of 3 × 10 ³ to 8 × 10 ⁴ . This is the weight average molecular weight (M
If w) is less than 3 × 10 ³ , the mechanical strength of the resin is lowered, and the toner tends to be in an excessively pulverized state when electrification occurs, and fog tends to occur in the image, and conversely, it exceeds 8 × 10 ⁴ . This is because the fixability as a toner tends to decrease.

In the present invention, the ratio of the high molecular weight polymer and the low molecular weight polymer is not particularly limited, but the high molecular weight polymer is preferably contained in the range of 10 to 50% by weight. . This is because when the high molecular weight polymer is less than 10% by weight, the non-offset property as a toner tends to be poor, and when it exceeds 50 parts by weight, the fixability as a toner tends to be poor.

The polymerization initiator used in the present invention is not particularly limited, and commonly used radically polymerizable peroxides and azo compounds can be used, and examples thereof include potassium sulfate and sulfuric acid. Sodium, di-t
-Butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, acetyl peroxide, isobutyryl peroxide, octanonyl peroxide,
Decanonyl peroxide, lauroyl peroxide,
3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, m-toluoyl peroxide,
t-butyl peroxyacetate, t-butyl peroxyisobutyrate, t-butyl peroxypiperate,
t-butyl peroxy neodecanoate, cumyl peroxy neodecanoate, t-butyl peroxy 2-ethylhexanoate, t-butyl peroxy 3,5,5-trimethylhexanoate, t-butyl peroxy lye Rate, t-butyl peroxybenzoate, t-butyl peroxy isopropyl carbonate, azobisisobutyl nitrile, 2,2-azobis- (2,4-dimethylvaleronitrile) and the like. These polymerization initiators can be used alone or in combination of two or more kinds, and it is preferable to use them in the range of 0.1 to 10 parts by weight, more preferably 0.1 to 100 parts by weight, respectively. It is in the range of 5 to 10 parts by weight. Further, in the present invention, as a chain transfer agent used as necessary for adjusting the molecular weight, n-octyl mercaptan, n-
Dodecyl mercaptan, t-dodecyl mercaptan, 2-ethylhexyl thioglycolate, α-methylstyrene dimer and the like can be mentioned.

[0021]

EXAMPLES The present invention will be specifically described below with reference to examples. In the examples, the weight average molecular weight and the number average molecular weight are measured values by gel permeation chromatography, and were measured by using HCL-8020 manufactured by Tosoh Corporation as a solvent and determined by polystyrene conversion.

Example 1 60 parts by weight of deionized water, potassium sulfate (K ₂ S ₂ O ₈ ).
0.04 parts by weight and 0.4 parts by weight of sodium dialkylsulfosuccinate (Neopex OTP manufactured by Kao Corporation) were charged into the reaction vessel and completely dissolved. Then styrene 32
1 part by weight, and 8 parts by weight of n-butyl acrylate are added to the monomer mixture for high molecular weight polymer, and nitrogen is introduced to replace the nitrogen in the reaction vessel, and then at 80 ° C. in the presence of nitrogen. Emulsion polymerization was carried out for 3 hours. Then, the temperature was raised to 90 ° C. and maintained for 1 hour to complete the polymerization. The weight average molecular weight (Mw) of the obtained high molecular weight polymer was 9.8 × 10 ⁵ .

Then, the content ratio of the high molecular weight polymer and the low molecular weight polymer of the binder resin for toner is set to 10:90, and the emulsion 25 of the obtained high molecular weight polymer is obtained.
Part by weight (10 parts by weight as a solid content) was charged into the reaction vessel. Further, the temperature inside the container is kept at 40 ° C.
6.5%, partially saponified polyalcohol having a degree of polymerization of 2300 (Goshenil GH-23 manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)
A dispersant solution prepared by dissolving 6 parts by weight in 140 parts by weight of deionized water and a salting out solution prepared by dissolving 0.6 parts by weight of sodium sulfate in 10 parts by weight of deionized water were added. Then, a monomer mixture for a low molecular weight polymer consisting of 72 parts by weight of styrene, 18 parts by weight of n-butyl acrylate and 2.7 parts by weight of benzoyl peroxide was added and stirred for 1 hour to uniformly disperse the mixture. . Then, the temperature was raised to 90 ° C. and the suspension polymerization was carried out by maintaining the temperature for 3 hours, followed by washing sufficiently with water and drying to obtain a binder resin for toner in which a high molecular weight polymer and a low molecular weight polymer were uniformly mixed. The obtained binder resin for toner is composed of 9.7% by weight of high molecular weight polymer and 9% of low molecular weight polymer.
0.3% by weight, and the weight average molecular weight is 12.1 ×
10 ⁴ and the number average molecular weight was 1.6 × 10 ⁴ .

93 parts by weight of the obtained binder resin for toner, 4 parts by weight of carbon black, caustic control agent for negative charging 1
% By weight and 2 parts by weight of polyolefin wax were mixed and melt-kneaded at 145.degree. Then, it is pulverized using a jet mill fine pulverizer and classified to have an average particle diameter of 13μ.
m toner was obtained. The obtained toner was good with well-balanced fixing property and non-offset property.

Comparative Example 1 25 parts by weight of the emulsion of the high molecular weight polymer obtained in Example 1 was set with the content ratio of the high molecular weight polymer and the low molecular weight polymer of the binder resin for toner set to 10:90 ( 10 parts by weight as solid content) was charged into the reaction vessel. Further, the inside of the container was kept at a temperature of 40 ° C., and the saponification degree was 86.5
%, 0.6 parts by weight of partially saponified polyalcohol having a degree of polymerization of 2300 (Gosei Niel GH-23 manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was dissolved in 150 parts by weight of deionized water, and a dispersant solution was added. Next, 72 parts by weight of styrene, n-acrylic acid
18 parts by weight of butyl and 2.7 benzoyl peroxide
Then, a monomer mixture for low molecular weight polymer was added, and the mixture was stirred for 1 hour and uniformly dispersed. Then 90
Suspension polymerization was carried out by raising the temperature to 0 ° C. and holding for 3 hours, thoroughly washing with water and drying to obtain a binder resin for toner in which a high molecular weight polymer and a low molecular weight polymer were uniformly mixed. The obtained binder resin for toner was 4.8% by weight of high molecular weight polymer.
And 95.2% by weight of a low molecular weight polymer, having a weight average molecular weight of 7.9 × 10 ⁴ and a number average molecular weight of 9.3 × 10 4.
^{Was 3} .

Using the obtained binder resin for toner, a toner having an average particle diameter of 13 μm was obtained in the same manner as in Example 1. The obtained toner is inferior in non-offset property,
The balance between the fixability and the non-offset property was not sufficient.

Examples 2 to 3 and Comparative Examples 2 to 3 The high molecular weight obtained in Example 1 was set by setting the content ratio of the high molecular weight polymer and the low molecular weight polymer of the binder resin for toner to 10:90. A suspension of a low molecular weight polymer was prepared in the same manner as in Example 1 except that 25 parts by weight of the polymer emulsion (10 parts by weight as a solid content) was used and the amount of sodium sulfate used as a salting-out agent was shown in Table 1. Suspension polymerization was performed. The obtained binder resin for toner was a resin particle having a uniform particle size in Examples 2 and 3 and Comparative Example 2, but was a non-uniform resin particle having a particle size variation in Comparative Example 3.
In addition, Table 1 shows the weight average molecular weight, the number average molecular weight and the content ratio of the high molecular weight polymer of the obtained binder resin for toner.

A toner having an average particle diameter of 13 μm was obtained in the same manner as in Example 1 by using the obtained binder resin for toner. The obtained toners using the binder resin for toners of Examples 2 and 3 were good with well-balanced fixing property and non-offset property. Those using the binder resins for toners of Comparative Examples 2 to 3 were inferior in the non-offset property, and the balance between the fixability and the non-offset property was not sufficient.

[0029]

[Table 1]

Examples 4 to 7 The content ratio of the high molecular weight polymer and the low molecular weight polymer of the binder resin for toner was set as shown in Table 2, and the high molecular weight polymer emulsion obtained in Example 1 and sulfuric acid were obtained. Suspension polymerization of the low molecular weight polymer was performed in the same manner as in Example 1 except that the amounts of sodium and the low molecular weight polymer monomer used were as shown in Table 2. The content ratio of the high molecular weight polymer in the obtained binder resin for toner is shown in Table 2. Using the obtained binder resin for a toner, a toner having an average particle diameter of 13 μm was obtained in the same manner as in Example 1. The obtained toners were all good with well-balanced fixing property and non-offset property.

Comparative Examples 4 to 5 The content ratio of the high molecular weight polymer and the low molecular weight polymer of the binder resin for toner was set as shown in Table 2, and the high molecular weight polymer emulsion obtained in Example 1 and sulfuric acid were obtained. Suspension polymerization of the low molecular weight polymer was carried out in the same manner as in Comparative Example 1 except that the amounts of sodium and the low molecular weight polymer monomer used were as shown in Table 2. It was inferior in properties and solidified during polymerization, and the target binder resin for toner could not be obtained.

[0032]

[Table 2]

Comparative Example 6 Comparative Example 1 except that 10 parts by weight of the high molecular weight polymer obtained by salting out the high molecular weight polymer emulsion obtained in Example 1 and no high molecular weight polymer emulsion were used. 90 parts by weight of a low molecular weight polymer obtained by suspension polymerization in the same manner as above was melt-kneaded at 145 ° C., but a uniform resin mixture was not obtained.

[0034]

The method for producing a binder resin for a toner according to the present invention comprises a suspension of a low molecular weight polymer in the presence of an emulsion of the high molecular weight polymer and a salting-out agent to obtain a low molecular weight polymer and a low molecular weight polymer. The content ratio with the molecular weight polymer can be easily and accurately controlled, and the high molecular weight polymer and the low molecular weight polymer excellent in the balance of fixing property and non-osset property of the toner were contained in an arbitrary ratio. A binder resin for toner can be manufactured.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tajiri Zouun 2-4-1, Ushikawa-dori, Toyohashi-shi, Aichi Sanryu Rayon Co., Ltd. Toyohashi Works (72) Inventor Yoko Harada 4-chome, Ushikawa-dori, Toyohashi-shi, Aichi No. 1 No. 2 Sanryo Rayon Co., Ltd. Toyohashi Works

Claims (1)

[Claims] 1. After polymerizing a high molecular weight polymer by an emulsion polymerization method, the emulsion of the high molecular weight polymer and the emulsion of the high molecular weight polymer per 100 parts by weight of 0.
A method for producing a binder resin for a toner, which comprises polymerizing a low molecular weight polymer by suspension polymerization in the presence of 5 to 5 parts by weight of a salting-out agent.