JPS63178103A - Method for producing resin for toner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a resin for dry toner used in electrophotographic development, and in particular to a method for producing a resin for dry toner that has performance suitable for high-speed copying machines and high-speed recording devices. This invention relates to a method for producing resin.

[Conventional technology]

In recent years, copying by electrophotographic development has been widely used, and along with this, demands for higher performance of the developer have also become extremely high. Under such circumstances, one of the developers currently used is a toner for fusing and fixing using a pressurized heat roller. In this method, a toner that satisfies both low-temperature fixability and offset resistance is desired, and toner resins that satisfy the above characteristics include a low molecular weight polymer that is effective for low-temperature fixability and a toner that is effective for offset resistance. Mixtures of high molecular weight polymers are known to yield favorable results. Further, in this method, uniform mixing of the low molecular weight polymer and the high molecular weight polymer is very important, and various attempts have been made to achieve this uniform mixing.

Among them, a method has recently been developed in which a high molecular weight polymer, which is difficult to obtain by suspension polymerization, is produced by emulsion polymerization, and then a low molecular weight polymer is produced by suspension polymerization using a specific dispersant in the presence of the emulsion (especially JP-A-60-88003) has been proposed. However, in this method, since the emulsifier is used, the emulsifier remains in the toner resin obtained, so it is not preferable in terms of toner performance.
In order to prevent suspension polymerization from becoming unstable due to emulsifiers, it is necessary to use a large amount of nonionic dispersant, and a large amount of nonionic dispersant remains in the toner resin. When used as a toner, moisture resistance, electrical resistance, At present, there are problems such as adverse effects on scattering properties and the like.

[Problem that the invention seeks to solve]

The object of the present invention is to use a suspension polymerization dispersant as an emulsifier when emulsion polymerizing a high molecular weight polymer, and then produce a low molecular weight polymer by suspension polymerization in the presence of the emulsion polymerization latex. , excellent polymerization stability with a small amount of suspension polymerization stabilizer, non-offset properties, and low-temperature fixing properties.

It is an object of the present invention to provide a method for producing a resin for toner using an emulsion-suspension polymerization method that has excellent moisture resistance, charging characteristics, scattering properties, and the like.

[Means for Solving the Problems] The gist of the present invention is to provide a method for producing a toner resin in which a low molecular weight vinyl polymer is produced by a suspension polymerization method in the presence of a high molecular weight vinyl polymer emulsion. , an anionic water-soluble polymer suspension polymer dispersant (I) is used as an emulsifier for a high molecular weight vinyl polymer emulsion, and an anionic water-soluble polymer suspension polymer dispersant (n) is used as an emulsifier for a high molecular weight vinyl polymer emulsion. and a nonionic suspension polymerization dispersant.

The high molecular weight vinyl polymer emulsion used in the present invention is obtained by emulsion polymerization of a vinyl monomer or a mixture thereof using an anionic water-soluble polymer suspension polymer dispersant (1) as an emulsifier.

As the dispersant (1), anionic water-soluble polymer dispersants commonly used in suspension polymerization can be used, including carboxymethylcellulose, vinyl-based dispersants having carboxylic acid metal salts, sulfonic acid metal salts, etc. in the side chain. Polymers, such as unsaturated carboxylic acid metal salts such as (meth)acrylic acid and (meth)
Copolymers with unsaturated carboxylic acid alkyl esters such as acrylic acid alkyl esters, homopolymers of unsaturated carboxylic acid derivatives having sulfonic acid groups in side chains as disclosed in Japanese Patent Publication No. 51-43877, or Examples include copolymers containing the monomers, which are used in the form of a few percent aqueous solution from the viewpoint of workability.

The vinyl monomer used in the emulsion polymerization may be any of those used in toner resins. Specific examples thereof include styrene, α-methylstyrene, p-methyl group, m-methyl group, p-methyl group, p-ethyl group, 2,4-dimethyl group, p-butyl group,
p-hexyl group, p-octyl group, p-nonyl group, p-
Styrene derivatives having a decyl group, p-methoxy group, p-phenyl group, etc., general formula: ca, = CR-COO
R' (wherein R represents hydrogen or a methyl group), R' is a methyl group, an ethyl group, an n-propyl group,
Isopropyl group, n-butyl group, isobutyl group, S-butyl group, t-butyl n-pentyl t>-hexyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, isononyl group, decyl group , dodecyl group, tridecyl, stearyl group, tocosyl group, cyclohexyl group,
Acrylic esters or methacrylic esters such as benzyl group, phenyl group, methoxyethyl group, ethoxyethyl group, butoxyethyl group, phenoxyethyl group, vinyl esters such as vinyl acetate and vinyl propionate, acrylonitrile, methacrylic acid esters, etc. Examples include monomers such as vinyl cyanide compounds such as nitriles.

In the emulsion polymerization, the amount of the dispersant (1) to be used is such that the monomer is substantially emulsified and dispersed in water, and is usually in an amount of 100 parts by weight of the monomer used in the emulsion polymerization. About 0.5 to 2 parts by weight is used. Further, the ratio (M/W) between the amount of monomer (M) and the amount of water (W) during emulsion polymerization is usually about M/W = 1/2 to 1/10.

The polymer obtained by the emulsion polymerization has a high molecular weight, and from the viewpoint of non-offset properties, the weight average molecular weight is preferably about 500,000 or more, particularly preferably about 1,000,000 or more.

During emulsion polymerization, from the viewpoint of polymerizability, it is preferable to carry out a substitution treatment with an inert gas such as nitrogen as much as possible, as in normal emulsion polymerization. Although the method of adding monomers is not particularly limited, in order to obtain a polymer with a high molecular weight, a so-called batch polymerization method in which the entire amount of monomers is added at the same time and polymerized is preferred.

In the present invention, a low molecular weight vinyl polymer is produced by suspension polymerization in the presence of the high molecular weight vinyl polymer emulsion obtained as described above. After sufficiently stirring and mixing the solution, the vinyl monomer or monomer mixture for suspension polymerization, and the suspension polymerization dispersant, an initiator may be added, and the temperature may be raised to carry out polymerization.

As the suspension polymerization dispersant used in suspension polymerization, at least one type selected from anionic and nonionic suspension polymerization dispersants is used. Examples include commonly used nonionic dispersants such as system dispersants and popal.The amount of dispersant (II) added depends on the amount of dispersant (1) added during emulsion polymerization, but is usually It is added in an amount of 0.2 to 1 part by weight per 100 parts by weight of the monomer for turbid polymerization.If the amount added is too large, the dispersion stability may deteriorate, which is not preferable.

Further, in the present invention, an electrolyte such as sodium chloride, potassium chloride, sodium sulfate, potassium sulfate, etc. can be added during suspension polymerization if necessary.

Suspension polymerization in the present invention is carried out by a known method until the polymerization is substantially completed. First, in a reactor equipped with a thermometer, 1 to 10 times, preferably 2 to 4 times, the amount of monomer is added.
Add twice the amount of water, a suspension dispersion stabilizer, and a dispersion aid if necessary, stir, and then add the monomers at room temperature or with heating.
A polymerization initiator and, if necessary, a chain transfer agent are added, and the mixture is heated to a predetermined polymerization temperature to substantially complete polymerization. That is, heating is continued until the polymerization rate reaches at least 95%.

Furthermore, the monomers used in suspension polymerization are the same as those used in emulsion polymerization.

The monomer may be the same as or different from the monomer for emulsion polymerization.

In the present invention, the glass transition temperature (TP) of the resin obtained is 50 to 100°C, particularly 55 to 80°C.
It is preferable that If the TP of the resulting resin is less than 50°C, it becomes difficult to obtain a toner with good blocking properties, and if it exceeds 100°C, the fixing property tends to be low.

In the present invention, a resin exhibiting particularly good toner performance can be obtained when at least 50% of the monomers are styrene or its derivatives.

In general, TP varies slightly depending on the measurement method and measurement conditions, but in the present invention, TP is the baseline and T/nearby of the chart measured with a differential scanning calorimeter (hereinafter referred to as DSC) at a temperature increase rate of 10°C/min. is defined as the intersection of the endothermic curves at .

As the polymerization initiator in the present invention, a known peroxide having radical polymerization activity is used.

Specific examples include di-t-butyl peroxide, t
-butylcumyl peroxide, dicumyl peroxide,
Acetyl peroxide, isobutyryl peroxide, octanonyl peroxide, decanonyl peroxide,
lauroyl peroxide, 3,5,5-)limethylhexanoyl peroxide, benzoyl peroxide, m
-Toluoyl peroxide, t-butyl peroxy acetate, t-butyl peroxy isobutyrate, t-butyl peroxy pivalate, t-butyl peroxy neodecanoate, cumyl peroxy neodecanoate, t
-Butylperoxy 2-ethylhexanoate, t-butylperoxy 3,5.5-)limethylhexanoate, t-butylperoxylaurate, t-butylperoxybenzoate, t-butylperoxyisopropyl carbonate Among them, octanonyl peroxide, decanonyl peroxide, lauroyl peroxide, benzoyl peroxide, m- Toluoyl peroxide and the like are particularly effective in the present invention. These polymerization initiators are used in an amount necessary to complete polymerization in a relatively short period of time, but generally 0.1 to 10 parts by weight, preferably 0.5 parts by weight, per 100 parts by weight of monomers. Between 10 and 10 parts by weight are used.

The present invention is applied when a peroxide is used as at least a part of the polymerization initiator, and an azo compound such as azobisisobutylnitrile or 2,2'-azobis-(2,4-
Chain transfer agents that may be used as necessary in the present invention include cases in which a portion of dimethylvaleronitrile (dimethylvaleronitrile) or the like is used, such as known chain transfer agents, such as n-octylmercaptan,
Examples include n-dodecylmercaptan, t-dodecylmercaptan, 2-ethylhexyl thioglycolate, and α-methylstyrene dimer. If these chain transfer agents remain in the resin, they will cause a bad odor when melted, so if they are used, they should be kept to a minimum.

The conditions for suspension polymerization in the present invention vary depending on the type of monomer to be polymerized and the type and amount of the polymerization initiator, but generally the temperature is 50 to 130°C, preferably 70 to 90°C.
At 0°C, the appropriate time is about 10 to 10 hours. 9
When the temperature exceeds 0℃, the amount of cullet generated tends to increase.
Undesirable.

The present invention will be explained below using examples.

The production of the toner and the evaluation of the toner's fixing properties, non-offset properties, moisture resistance, and scattering properties were carried out by the following methods.

[Manufacture of toner]

90 parts by weight of the resin obtained in the present invention, 5 parts by weight of carbon black
Part by weight and charge control agent (Bontron N manufactured by Orient Chemical Co., Ltd.
-01) Premix 5 parts by weight with a mixing mixer,
The mixture was melt-kneaded in a twin-screw extruder at a temperature of 150° C. for about 5 minutes, cooled, and then pulverized in a jet mill to have an average particle size of 14 μm and classified to produce a toner.

Using this toner, an electrophotographic copying machine (which has been modified in advance to make the surface temperature of the fixing roller variable)
The images were copied onto plain paper using Sharp Corporation's 5F-770) to evaluate fixing properties, non-offset properties, scattering properties, etc.

The developer was produced by removing the toner from a developer bar attached to the main body of the copying machine, supplying the toner obtained in the present invention, and mixing it with a carrier.

[Evaluation of toner fixability]

The lowest temperature of the fixing roller at which the image density does not become less than 95% of the original density after the tape is attached to the image copied on plain paper and peeled off is defined as the minimum fixing temperature.

[Evaluation of non-offset property of toner] When fixing an image on plain paper, the maximum temperature at which the toner does not melt and adhere to the fixing roller is defined as the non-offset upper limit temperature.

[Evaluation of toner scattering property]

After copying 5,000 sheets, the degree of toner scattering on the photoreceptor and the lower part of the copying machine was visually observed and the scattering property was evaluated.

[Evaluation of moisture resistance]

The toner obtained in the present invention was prepared at a temperature of 10°C and a relative humidity of 20°C.
%, temperature 20°C, relative humidity 60%, temperature 35°C, relative humidity 80% in an environmental test room for 90 hours, and the charging ability was measured using a triboelectrostatic measuring device (Blow-off manufactured by Toshiba Chemical) under each atmosphere. The dependence of charging ability on temperature and humidity was evaluated.

[Production method of anionic water-soluble polymer suspension dispersant] Dispersant aqueous solution (A)> In a separable flask with an internal volume of 21 and equipped with a stirrer, a thermometer, and a gas inlet tube, 230 °l of deionized water, Methyl methacrylate 25J', 3-sodium sulfoglovir methacrylate 75/ were charged, and after expelling the air in the system by blowing nitrogen and gas for 30 minutes, it was heated externally in a hot water bath and stirred until the internal temperature was lowered. The temperature was raised to 60°C, and ammonium persulfate was added at 0.5%. P was added.

When stirring was continued for 3 hours at the same temperature, a polymer solution (solid content: about 3% by weight) with a bluish-white appearance was obtained.

Dispersant aqueous solution (B)> In a 2-pull flask with an internal volume of 2 mm equipped with a stirrer, a thermometer, and a gas inlet tube, 2300 I of deionized water, 30 I of methyl methacrylate, and 70 J' of sodium methacrylate were charged, and the mixture was heated for 30 minutes. After expelling the air in the system by blowing in nitrogen gas, the system was heated externally in a hot water bath and raised to an internal temperature of 60° C. while stirring, and 0.5 P of ammonium persulfate was added.

When stirring was continued for 3 hours at the same temperature, a polymer solution (solid content: about 3% by weight) with a bluish-white appearance was obtained.

[Production of high molecular weight vinyl polymer emulsion] Emulsion (A)
〉 In a separable flask with an internal volume of 51 equipped with a stirrer, a thermometer, and a nitrogen inlet tube, 2100 t of deionized water, 127 p of a dispersant aqueous solution (A) (solid content 3.87'), and 300 P% n-butyl styrene were added. Add acrylate 37I,
After thoroughly purging with nitrogen gas while stirring, the internal temperature was lowered to 70°C.
0.75F of potassium persulfate was added, and polymerization was carried out at 70°C for 4 hours in a nitrogen gas atmosphere, resulting in a solid content of 15% by weight.
An emulsion was obtained. The weight average molecular weight (M
w) is 1,300,00 o, number average weight molecular weight (Mn
) was 550.000.

Emulsion (B)> Instead of the dispersant aqueous solution (A), use the same amount of the dispersant aqueous solution (B)
Using the same method as emulsion (A), the solid content was reduced to 10% by weight.
An emulsion was obtained. The weight average molecular weight of the obtained polymer was 1
,010,000, and the number average molecular weight was 480,000.

Emulsion (C)> In place of the aqueous dispersant solution (A), use the same amount of Pellex 0TP (sodium dioctyl sulfosuccinate manufactured by Kako Co., Ltd.) in terms of solid content, and make the same emulsion as in the emulsion (A). Solid content by method 1
A 3% by weight emulsion was obtained.

The weight average molecular weight of the obtained polymer was 1,410,000
, the number average molecular weight was 470,000.

[Example 1] Emulsion (A) 920 P (solid content 138/ ) was placed in a 51 separable flask similar to that used for producing the high molecular weight vinyl polymer emulsion under a nitrogen gas atmosphere. Dispersant aqueous solution (A) 12 F (solid content 0.36 J'),
0.7 P of sodium sulfate and 1020 P of deionized water were added and mixed with stirring. Next, a monomer mixture of 3787' styrene and 94 t of n-butyl acrylate was added and mixed with stirring for 1 hour. After this, 37.8J of benzoyl peroxide
' was added, the internal temperature was raised to 90°C, and polymerization was carried out under a nitrogen atmosphere for 3 hours. The polymerization rate at this time is essentially 100%
Met. Moreover, the polymerization stability was good, and almost no cullet was generated.

The obtained polymer was a clean, uniform granule with a weight average molecular weight of 29,000 and a number average molecular weight of 12,000.
, Tp was 64°C. Furthermore, the fixing properties, non-offset properties, moisture resistance, and scattering properties of the toner were all good.

[Example 2] Emulsion (A) was used instead of emulsion (A) and dispersant aqueous solution (A).
A resin for toner was produced in the same manner as in Example 1 except that B) and the aqueous dispersant solution (B) were used.

The polymerization rate at this time was substantially 100%.

Moreover, the polymerization stability was also good, and almost no cullet was generated. The obtained polymer was a clean, uniform granule with a weight average molecular weight of 260,000. The number average molecular weight was 11,000 and 'r7 was 63°C. Furthermore, the fixing properties, non-offset properties, moisture resistance, and scattering properties of the toner were all good.

[Example 3] Gohsenol KH-20 (Nippon Gosei Kagaku Kogyo Co., Ltd. Group Poval) was used instead of the dispersant aqueous solution (B) used in suspension polymerization.
A toner resin was produced in the same manner as in Example 1 except that 0.4P was used. The polymerization rate at this time is essentially 100%
Met.

Moreover, the polymerization stability was also good. The obtained polymer was a clean, uniform granule with a weight average molecular weight of 260.0.
00, number average molecular weight was 11,000, and TI was 62°C. The fixing properties and non-offset properties of the toner were good, but the moisture resistance and scattering properties were somewhat poor.

[Comparative Example 1] A toner resin was produced in the same manner as in Example 3, except that emulsion (C) was used instead of emulsion (B) and 0.67% of Gohsenol KH-20 was used. The polymerization rate at this time was approximately 9
It was about 3%, and many cullets were generated and adhered to the stirring blade in the form of dumplings, and the obtained polymer also had many coarse particles with uneven particle diameters, while there were also many extremely fine powders.

Furthermore, the toner performance was generally good in fixing properties and non-offset properties, but moisture resistance and scattering properties were significantly poor.

Table 1 *l) The lower the fixing minimum temperature is, the more preferable it is because fixing can be performed with low energy.

*2) The higher the non-offset upper limit temperature is, the better.

*3) The less variation in charging ability due to changes in temperature and humidity, the better the moisture resistance is, which is preferable.

*4) Scattering property 2 〇 Practical △ Practical limit boundary x Not practical [Effects of the invention] As detailed above, the method for producing toner resin of the present invention has a property that is difficult to obtain with conventional emulsion suspension polymerization. The toner resin can be obtained stably even when using an anionic dispersant, which gives good results in toner performance, and by adding a small amount, it has non-offset properties, low-temperature fixing properties, moisture resistance, charging properties, and scattering properties. It becomes possible to obtain a toner with excellent properties such as, etc., and the effect is extremely large.

Claims (1)

[Claims] In a method for producing a toner resin in which a low molecular weight vinyl polymer is produced by suspension polymerization in the presence of a high molecular weight vinyl polymer emulsion, anionic water-soluble Molecular suspension polymerization dispersant (
I) and at least one selected from anionic and nonionic suspension polymerization dispersants as the suspension polymerization dispersant (II) for low molecular weight vinyl polymers. .