JP2001175032A - Toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an odorless toner excellent in blocking resistance and vinyl chloride plasticizer resistance. SOLUTION: The toner is obtained by subjecting at least a binder resin and a colorant to at least kneading and comminution. The binder resin is obtained by polymerizing monomers in the presence of <10 wt.% plasticizer based on the total weight of the monomers and the plasticizer and has styrene and/or its derivative and a (meth)acrylic ester as principal constituent components. The glass transition temperature of the binder resin is 50-100 deg.C and the amount of the residual monomers is <=200 ppm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry toner used for developing electrophotography.

[0002]

2. Description of the Related Art Conventionally, many inventions have been made on resins for dry toners, and various toner properties have been improved. However, there are many residual monomers in conventionally used toner resins or toners.
In particular, there is a problem that the working environment is deteriorated due to the generation of an odor during the melt-kneading process, or the odor is generated at the time of copying, which causes discomfort, and there is a strong demand for improvement.

Under these circumstances, in order to solve this problem, a solid resin obtained by maintaining the polymerization temperature at or above the polymerization temperature for a long time after the polymerization is completed, or by dehydrating and drying after the polymerization is completed, is extruded. There is disclosed a method of removing residual monomers in a molten state using the method. However, these methods have the problem that the steps are complicated and the cost is increased, and there is still a problem of quality deterioration due to melting and kneading, and the appearance of a resin or toner for a toner which is simple in a short time and has very few residual monomers is expected. Have been.

[0004]

The present inventors have conducted intensive studies to achieve the above object, but surprisingly, by reducing the residual monomer in the toner resin to a specific concentration or less, the That the odor of the resin and toner for use is significantly improved, and that the blocking resistance and the PVC plasticizer resistance of the toner are also improved at the same time. As a result, it has been found that the residual monomer in the resin can be removed in a short time, and the present invention has been achieved.

[0005]

The gist of the present invention is to provide a toner obtained by kneading and pulverizing at least a binder resin and a colorant, wherein the binder resin is used for polymerization thereof. Styrene and / or its derivative, (meth) acrylic acid ester obtained by polymerization under the condition that no plasticizer is present in an amount of 10% by weight or more with respect to the total weight of the monomer and the plasticizer is a main component. Wherein the binder resin has a glass transition point of 50 to 100 ° C. and the residual monomer content is 200 ppm or less.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the binder resin used in the toner of the present invention will be described. As the binder resin used in the present invention, a generally known radical polymer that can be produced by suspension polymerization can be used. Specific examples of the monomers used to obtain these resins include styrene, α-methylstyrene, and p-methyl, m-methyl, p-methyl, p-methyl as substituents.
Styrene derivatives having an ethyl group, a 2,4-dimethyl group, a p-butyl group, a p-hexyl group, a p-octyl group, a p-nonyl group, a p-decyl group, a p-methoxy group, a p-phenyl group, etc. In the general formula: CH ₂ ＣＲCR—COOR ′ (where R represents hydrogen or a methyl group),
Is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-
Butyl, n-bentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, isononyl, decyl, dodecyl, tridecyl, stearyl, docosyl, cyclohexyl, benzyl Group,
Phenyl group, methoxyethyl group, ethoxyethyl group, butoxyethyl group, acrylate ester or methacrylic ester such as phenoxyethyl group, vinyl acetate, vinyl acetate such as vinyl propionate, acrylonitrile, methacrylonitrile, etc. Monomers such as acrylic acid or methacrylic acid derivatives can be mentioned, and they may be used alone or as a mixture depending on the purpose.

For example, styrene and / or its derivatives,
A typical example is a monomer mixture containing an alkyl (meth) acrylate as a main component. In the production of the binder resin, various additives can be used together with these monomer mixtures, if necessary.However, the use of a large amount of a plasticizer as an additive means that the resulting toner has a high PVC resistance. It is not preferable because the property is impaired. Further, the glass transition point (T
g) is 50 from the viewpoint of blocking resistance and fixing property.
-100 ° C, especially 55-80 ° C. Generally Tg
Is slightly different depending on the measuring method and measuring conditions, but Tg in the present invention is a base line of a chart measured by a differential scanning calorimeter (hereinafter, referred to as DSC) at a heating rate of 10 ° C./min and an endothermic curve near Tg. Is defined as the intersection of

[0008] In the present invention, the amount of residual monomers in the binder resin must be 200 ppm or less. If the amount of the residual monomer exceeds 200 ppm, the blocking resistance and the PVC plasticizer resistance decrease, and the problem of odor remains unpreferably. This residual monomer amount is preferably 110 pp
m or less, more preferably 90 ppm or less. When the amount of the residual monomer in the binder resin is 20
As a specific method of reducing the content to 0 ppm or less, a monomer mixture constituting the binder resin is synthesized by a polymerization method such as suspension polymerization, and then the dispersion is dispersed while heating to a temperature equal to or higher than the Tg of the obtained resin. Water of 5 to 50% by weight based on the amount of water in the liquid is distilled off as steam. Further, if a larger amount of air or nitrogen is blown in or the dispersion is heated to near the boiling point, the object can be achieved in a shorter time.

In the present invention, the heating temperature for distilling off water as water vapor needs to be higher than Tg of the obtained resin, and if it is lower than Tg, the residual monomers in the resin are trapped in the resin, It is difficult to reduce the amount of residual monomer to 200 ppm or less. In the above method, the amount of water distilled off must be at least 5% by weight based on the amount of water in the resin dispersion after suspension polymerization, and if it is lower than this, the residual monomer in the resin is reduced to 200 ppm or less. Difficult to do. On the other hand, if it exceeds 60% by weight, the effect of reducing the residual monomer is small and problems such as secondary aggregation of the resin and an increase in the amount of cullet tend to occur, which is not preferable.

The suspension polymerization in the present invention is carried out by a known method until the polymerization is substantially completed. First, a reactor equipped with a thermometer is charged with 1 to 10 times, preferably 2 to 4 times, water, a suspension / dispersion stabilizer and, if necessary, a dispersing aid with respect to a monomer, followed by stirring. While heating, a monomer, a polymerization initiator and, if necessary, a chain transfer agent are added and the mixture is heated to a predetermined polymerization temperature, and the polymerization is substantially completed, that is, until the conversion is at least 95%. Keep warm.

As the polymerization initiator in the present invention, those having known radical polymerization activity are used. Specific examples thereof include di-t-butyl peroxide, t-butyl cumyl peroxide, digyl peroxide, acetyl peroxide, isobutyryl peroxide, octonyl peroxide, decanoyl peroxide, lauroyl peroxide, 3 , 5,5-trimethylhexanoyl peroxide, benzoyl peroxide, m-toluoyl peroxide, t-butylperoxyacetate, t-butylperoxyisobutyrate, t-butylperoxypiparate, t-butylperoxide Oxyneo decanoate,
Cumyl peroxy neodecanoate, t-butyl peroxy 2-ethylhexanoate, t-butyl peroxy 3,5,5-trimethylhexanoate, t-butyl peroxy laurate, t-butyl peroxy benzoate And t-butylperoxyisopropyl carbonate. Among them, octonyl peroxide, decanonyl peroxide,
Lauroyl peroxide, benzoyl peroxide, m
-Peroxides such as toluoyl peroxide are particularly effective in the present invention. In addition, azo compounds such as azobisisobutyronitrile and 2,2'-azobis- (2,4-dimethylvaleronitrile) can also be used. These polymerization initiators are used in an amount required to complete the polymerization in a relatively short time, but generally 0.1 to 10 parts by weight, preferably 0.5 to 10 parts by weight, per 100 parts by weight of the monomer. To 5 parts by weight are used. The present invention is applied to the case where a peroxide is used as at least a part of the polymerization initiator, and partially includes an azo compound such as azobisisobutylnitrile and 2,2′azobis- (2,4-dimethylvaleronitrile). The case where they are used in combination is also included.

The chain transfer agent optionally used in the present invention includes known ones such as n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, and 2-ethylhexyl thioglycolate. it can. When these chain transfer agents remain in the resin, they cause odor at the time of melting. Therefore, when used, they should be minimized.

Known suspension and dispersion stabilizers in the present invention are used. Specific examples thereof include polyvinyl alcohol, partially saponified polyvinyl alcohol, sodium or potassium salts of a homopolymer or copolymer of acrylic acid or methacrylic acid, carboxymethyl cellulose, gelatin, water-soluble resins such as starch, barium sulfate, Examples thereof include hardly water-soluble or insoluble inorganic powders such as calcium sulfate, barium carbonate, calcium carbonate, magnesium carbonate, and calcium phosphate. These suspension and dispersion stabilizers are used in an amount necessary to complete the operation without coagulation during polymerization and treatment with an alkali and a solvent (hereinafter referred to as alkali-solvent treatment). Generally, it is used in an amount of 0.01 to 5 parts by weight, preferably 0.05 to 2 parts by weight, based on 100 parts by weight of water. Further, examples of the dispersing aid used in the present invention include electrolytes such as sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate.

The conditions for suspension polymerization in the present invention vary depending on the type of the 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 100 ° C., and the time is About 1 to 10 hours is appropriate. The toner of the present invention contains at least the binder resin as described above and a colorant such as carbon black, and the residual monomer amount of the toner decreases with the reduction of the residual monomer amount of the binder resin used. Is what is done.

The composition ratio of each component in the toner of the present invention is not particularly limited, and may be approximately the same as that of a commonly used toner. For example,
The binder resin and the colorant are in a weight ratio of 60 to 98: 2.
It can be used in the range of about to 40. Further, the toner of the present invention is obtained by, for example, mixing a mixture comprising a binder resin and a colorant with a kneader such as a twin-screw extruder for 150 minutes.
After kneading at a temperature of about ° C., the mixture is finely pulverized and classified using a jet mill or the like to form a toner. The obtained toner particles preferably have an average particle size of about 5 to 15 μm. The toner of the present invention may use additives such as a charge control agent, an anti-offset agent, and magnetic powder in addition to the binder resin and the colorant.

[0016]

Next, the present invention will be described with reference to examples. In the examples, parts are parts by weight unless otherwise specified. Examples 1 to 3, Comparative Example 1 79.7 parts of styrene, 20 parts of n-butyl acrylate,
0.3 parts of divinylbenzene was added to a mixture of 300 parts of water and 0.2 parts of partially saponified polyvinyl alcohol (Gohsenol GH-20 manufactured by Nippon Chemical Industry Co., Ltd.), stirred, and then 3 parts of benzoyl peroxide was added. After the temperature was raised to 85 ° C., suspension polymerization was carried out for 2 hours to complete the polymerization. Thereafter, the temperature was raised to 103 ° C., and as shown in Table 1, water was distilled off at 5%, 20%, 40%, and 50% with respect to the amount of water in the system, respectively. When the residual monomers in the obtained resin were measured by gas chromatography, they were 200 ppm,
They were 110 ppm, 90 ppm and 80 ppm. Also, add 6
The thing which tried to distill 0%, the secondary coagulation was intense on the way,
The operation was stopped because no resin powder for toner was obtained.

5 parts of carbon black (# 30 manufactured by Mitsubishi Kasei Kogyo Co., Ltd.) and a charge control agent (Bontron S-3 manufactured by Orient Chemical Industry Co., Ltd.) were used for 92.5 parts of each resin obtained.
1) 25 parts were kneaded at 150 ° C. for about 5 minutes using a twin-screw extruder, and after cooling, finely pulverized by a jet mill to collect 5 to 15 μm particles to produce a toner. For the manufactured toner,
Each Tg was measured, and blocking resistance, PVC plasticizer resistance, and odor were evaluated. Table 1 shows the obtained results. Comparative Examples 2 to 4 Resin was taken out immediately after completion of suspension polymerization in the same manner as in Examples 1 to 3, resin taken out after polymerization was heated to 92 ° C. and kept for 2 hours, and polymerization Immediately thereafter, the resin was taken out, dried at 50 ° C. for 20 hours, and then dried.
The same evaluation as in Examples 1 to 3 was carried out for those subjected to the residual monomer treatment at 5 ° C. for 5 minutes through an extruder. Table 1 shows the obtained results.

[0018]

[Table 1]

[0019]

As described in detail above, the use of a binder resin having a small amount of residual monomer enables the toner of the present invention to be free from odor and have excellent effects of blocking resistance and PVC plasticizer resistance. To demonstrate.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ryo Funato 4-1-1-60 Sunadabashi, Higashi-ku, Nagoya City, Aichi Prefecture Inside Mitsubishi Rayon Co., Ltd. (72) Keiji Yoshida 4-1-1-60 Sunadabashi, Higashi-ku, Nagoya City, Aichi Prefecture No. Mitsubishi Rayon Co., Ltd.

Claims (4)

[Claims] 1. A toner obtained by kneading and pulverizing at least a binder resin and a colorant, wherein the binder resin has a weight of 10% based on the total weight of a monomer and a plasticizer for the polymerization. Styrene and / or its derivative, (meth) acrylic acid ester, which is obtained by polymerization under the condition that no plasticizer is present in an amount of not less than wt. Transition point 50-100 ° C
Wherein the residual monomer amount is 200 ppm or less. 2. The method according to claim 1, wherein the residual monomer content of the binder resin is 11
2. The toner according to claim 1, wherein the amount is 0 ppm or less. 3. The binder resin having a residual monomer content of 90.
2. The toner according to claim 1, wherein the amount is not more than ppm. 4. The glass transition point of the binder resin is 50 to 50.
The toner according to claim 1, wherein the temperature is 80 ° C. 5.