JP2005025236A - Binder resin and electrophotographic development method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a binder resin which results in toner having no odor and excellent blocking resistance of the toner and resistance against a plasticizer for vinyl chloride, and to provide an electrophotographic development method. <P>SOLUTION: The binder resin to be included in toner comprises styrene and/or its derivative and (meth)acrylate as the main structural components and has 50 to 100°C glass transition temperature and ≤200 ppm residual monomer content. However, the binder resin excludes a polymeric resin produced by polymerizing a monomer in the presence of a plasticizer by ≥10 wt.% with respect to the total weight of the monomer and the plasticizer. The toner containing the above binder resin and a coloring agent is used for electrophotographic development. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a binder resin and an electrophotographic development method.

Conventionally, many inventions have been made on resins for dry toners, and various physical properties of the toner have been improved.
However, there are many residual monomers in the toner resins or toners that have been used in the past, and the workplace environment deteriorates due to the generation of odor at the time of toner production, particularly during melt kneading, or the odor is emitted during copying, causing discomfort. There is a problem of giving, and there is a strong demand for improvement.

  In such a situation, in order to solve this problem, after the polymerization is completed, the polymerization temperature is maintained at a polymerization temperature or higher for a long time, or the solid resin obtained by dehydration and drying after the polymerization is completed using an extruder or the like. A method for removing residual monomer in a molten state is disclosed. However, these methods have complicated processes, increase costs, and leave the problem of quality deterioration due to melt-kneading, etc., and the appearance of toner resins or toners that are simple and have very little residual monomer is expected in a short time. Has been.

  The present inventors have intensively studied to achieve the above object, but surprisingly, by reducing the residual monomer in the toner resin to a specific concentration or less, the odor when the toner resin and the toner are obtained. And the toner blocking resistance and vinyl chloride plasticizer resistance are improved at the same time. Also, by adopting a specific processing step in the resin production method, the residual monomer in the resin can be shortened in a short time. It has been found that can be removed, and the present invention has been achieved.

  The gist of the present invention is a binder resin contained in a toner, wherein the binder resin contains styrene and / or a derivative thereof, (meth) acrylic acid ester as a main component, and A binder resin having a glass transition point of 50 to 100 ° C. and a residual monomer amount of 200 ppm or less (provided that the binder resin is 10% based on the total weight of the monomer and the plasticizer). (Excluding resins which are polymers polymerized in the presence of a plasticizer in an amount of at least% by weight).

First, the binder resin of the present invention will be described. As the binder resin of the present invention, a generally known radical polymer that can be produced by suspension polymerization can be applied. Specific examples of monomers used to obtain these resins include styrene, α-methylstyrene, p-methyl group, m-methyl group, p-methyl group, p-ethyl group, 2, Styrene derivatives having 4-dimethyl group, p-butyl group, p-hexyl group, p-octyl group, p-nonyl group, p-decyl group, p-methoxy group, p-phenyl group, etc., general formula: CH ₂ = CR-COOR ′ (wherein R represents hydrogen or a methyl group), R ′ represents a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, t-butyl group, n-benzyl group, n-hexyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, isononyl group, decyl group, dodecyl group, tridecyl group, stearyl group, docosyl group, Acrylic acid esters or methacrylic acid esters such as chloryl group, benzyl group, phenyl group, methoxyethyl group, ethoxyethyl group, butoxyethyl group, phenoxyethyl group, vinyl esters such as vinyl acetate and vinyl propionate, acrylonitrile And monomers such as acrylic acid or methacrylic acid derivatives such as methacrylonitrile may be used, and the monomers may be used alone or as a mixture depending on the purpose.

For example, styrene and / or a derivative thereof, a monomer mixture containing (meth) acrylic acid alkyl ester as a main constituent component, and the like can be given as representative examples.
Further, the glass transition point (Tg) of the obtained binder resin is preferably 50 to 100 ° C., particularly 55 to 80 ° C. from the viewpoint of blocking resistance and fixability.
In general, Tg varies slightly depending on the measurement method and measurement conditions, but Tg in the present invention is measured between a baseline of the chart measured by a differential scanning calorimeter (hereinafter referred to as DSC) at a rate of temperature increase of 10 ° C./minute and around Tg. Defined as the intersection of endothermic curves.

In the present invention, the amount of residual monomer in the binder resin needs to be 200 ppm or less. When the residual monomer amount exceeds 200 ppm, the blocking resistance and the vinyl chloride plasticizer resistance are lowered, and the problem of odor remains undesirably. This residual monomer amount is preferably in the range of 110 ppm or less, more preferably in the range of 90 ppm or less.
As a specific method of setting the residual monomer amount in the binder resin to 200 ppm or less, a monomer mixture constituting the binder resin is synthesized by a polymerization method such as suspension polymerization, and then the Tg of the resin from which the dispersion can be obtained. While heating at the above temperature, 5 to 50% by weight of water is distilled off as water vapor with respect to the amount of water in the dispersion. Moreover, the objective can be achieved in a shorter time by introducing a larger amount of air, nitrogen, or the like, or by heating to near the boiling point of the dispersion.

In the present invention, the heating temperature for distilling water as water vapor needs to be equal to or higher than the Tg of the obtained resin, and if it is less than Tg, the residual monomer in the resin is trapped in the resin, and the amount of residual monomer It is difficult to adjust the content to 200 ppm or less.
In the above method, the amount of distilled water needs to be 5% by weight or more with respect to the amount of water in the resin dispersion after suspension polymerization, and below this, the residual monomer in the resin is 200 ppm or less. It is difficult to do. Moreover, even if it exceeds 60% by weight, the residual monomer reducing effect is small, and problems such as secondary aggregation of the resin and an increase in the amount of cullet are likely 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, in a reactor equipped with a thermometer, 1 to 10 times, preferably 2 to 4 times, water, a suspension dispersion stabilizer and, if necessary, a dispersion aid are added to the monomer and stirred. While heating, a monomer, a polymerization initiator and, if necessary, a chain transfer agent are added and heated to a predetermined polymerization temperature. The polymerization is substantially completed, that is, until the polymerization rate 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, digamyl 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 peroxypiparate, t-butyl per Oxyneodecanoate, cumylperoxyneodecanoate, t-butylperoxy 2-ethylhexanoate, t-butylperoxy3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-butyl peroxybenzoate, t Butyl peroxy isopropyl carbonate can be mentioned. Among them, octanonyl peroxide, decanonyl peroxide, lauroyl peroxide, benzoyl are preferred because of their long polymerization activity for monomers and the completion of polymerization in a relatively short time. Peroxides such as peroxide and m-toluoyl peroxide are particularly effective in the present invention. In addition, other examples include azo compounds such as azobisisobutyronitrile and 2,2'-azobis- (2,4-dimethylvaleronitrile). These polymerization initiators are used in an amount necessary for completing the polymerization in a relatively short time, but generally 0.1 to 10 parts by weight, preferably 0.5 to 100 parts by weight of the monomer. 5 parts by weight are used. The present invention is applied when a peroxide is used as at least a part of a polymerization initiator, and a part of an azo compound such as azobisisobutylnitrile or 2,2′azobis- (2,4-dimethylvaleronitrile). The case of using together is also included.

  Examples of the chain transfer agent used as necessary in the present invention include n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, 2-ethylhexyl thioglycolate and the like. When these chain transfer agents remain in the resin, they cause a bad odor at the time of melting.

  A well-known thing is used as a suspension dispersion stabilizer in this invention. Specific examples thereof include polyvinyl alcohol, partially saponified polyvinyl alcohol, sodium or potassium salts of homopolymers or copolymers of acrylic acid or methacrylic acid, water-soluble resins such as carboxymethyl cellulose, gelatin, starch, barium sulfate, Mention may be made of poorly water-soluble or insoluble inorganic powders such as calcium sulfate, barium carbonate, calcium carbonate, magnesium carbonate and calcium phosphate. These suspension dispersion stabilizers are used in an amount necessary to complete the operation without solidifying the resin particles produced during polymerization and treatment with alkali and solvent (hereinafter referred to as alkali / solvent treatment). In general, 0.01 to 5 parts by weight, preferably 0.05 to 2 parts by weight is used with respect to 100 parts by weight of water. Examples of the dispersion aid used if necessary 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 monomer to be polymerized and the type and amount of the polymerization initiator. In general, the temperature is 50 to 130 ° C, preferably 70 to 100 ° C, and the time is 1 to 10 ° C. Time is appropriate.
In the present invention, the toner contains at least a binder resin as described above and a colorant such as carbon black, and the amount of residual monomer in the toner decreases as the amount of residual monomer in the binder resin used decreases. It is to be reduced.

The composition ratio of each component in the toner is not particularly limited, and can be set to the same level as that of generally used toner. For example, the binder resin and the colorant can be used in a weight ratio of about 60 to 98: 2 to 40.
The toner is, for example, a mixture of a binder resin and a colorant, etc., kneaded at a temperature of about 150 ° C. using a kneader such as a twin screw extruder, and then finely pulverized and classified using a jet mill or the like. To become toner. The obtained toner particles preferably have an average particle size of about 5 to 15 μm. In addition to the binder resin and the colorant, additives such as a charge control agent, an offset preventing agent, and magnetic powder may be used for the toner.

Next, an Example is shown and this invention is demonstrated. In addition, the number of parts in the examples indicates parts by weight unless otherwise specified.
[Examples 1 to 3, Comparative Example 1]
Add 79.7 parts of styrene, 20 parts of n-butyl acrylate and 0.3 part of divinylbenzene into a mixture of 300 parts of water and 0.2 part of partially saponified polyvinyl alcohol (Nippon Chemical Industry Co., Ltd. Gohsenol GH-20). The mixture was stirred and then 3 parts of benzoyl peroxide was added, and the temperature was raised to 85 ° C., followed by suspension polymerization for 2 hours to complete the polymerization. Then, it heated up to 103 degreeC and as shown in Table 1, 5%, 20%, 40%, and 50% of water were distilled off with respect to the amount of water in a system, respectively. When the residual monomer in the obtained resin was measured by gas chromatography, they were 200 ppm, 110 ppm, 90 ppm and 80 ppm, respectively. In addition, 60% of the water was distilled off, and the secondary agglomeration was severe on the way.

Carbon black (Mitsubishi Kasei Kogyo Co., Ltd. # 30) 5 parts, charge control agent (Orient Chemical Co., Ltd. Bontron S-31) 25 parts biaxially for 92.5 parts of each resin obtained. The mixture was kneaded at 150 ° C. for about 5 minutes in an extruder, cooled, and then finely pulverized with a jet mill, and 5 to 15 μ particles were collected to produce a toner.
Each manufactured toner was measured for Tg to evaluate blocking resistance, polyvinyl chloride resistance, and odor. The obtained results are shown in Table 1.
[Comparative Examples 2 to 4]
After completion of suspension polymerization in the same manner as in Examples 1 to 3, the resin was immediately taken out, the polymer was heated to 92 ° C. after the polymerization and held for 2 hours, and the resin was taken out, and the resin was taken out immediately after the polymerization. The same evaluation as in Examples 1 to 3 was performed on the product which was dried at 50 ° C. for 20 hours and then treated with a residual monomer through an extruder at 150 ° C. for 5 minutes. The obtained results are shown in Table 1.

  As described above in detail, according to the present invention, by using a binder resin with a small amount of residual monomer in the toner, there is no odor and an effect excellent in blocking resistance and PVC plasticizer resistance is exhibited. It is.

Claims (5)

  A binder resin contained in a toner, wherein the binder resin contains styrene and / or a derivative thereof, (meth) acrylic acid ester as a main constituent, and the glass transition point of the binder resin is 50 to 50 Binder resin characterized by being 100 ° C. and having a residual monomer amount of 200 ppm or less. However, the resin which is a polymer obtained by polymerizing the binder resin in the presence of 10% by weight or more of the plasticizer with respect to the total weight of the monomer and the plasticizer is excluded.   The binder resin according to claim 1, wherein the amount of residual monomer is 110 ppm or less.   The binder resin according to claim 1, wherein the amount of residual monomer is 90 ppm or less.   The binder resin according to any one of claims 1 to 3, wherein the glass transition point is 50 to 80 ° C.   5. A developing method comprising developing an electrophotographic image using the toner containing the binder resin according to claim 1 and a colorant.