JPH0252362A - Electrophotographic toner and its production - Google Patents

Abstract

PURPOSE:To obtain a toner contg. pigment such as carbon black, magnetite dispersed uniformly in a binder resin, to increase the image density and to reduce the fogging density by diepersing previously a polyester type agent for treating the surface of the pigment into the binder resin for the toner. CONSTITUTION:After dispersing a treating agent for a pigment into a binder resin, wherein the treating agent comprises a polyester modified in terminal amido group(s) prepd. by amidating at least a terminal of a substantially linear aliphatic polyester expressed by the formula I or II with an amine expressed by the formula III, additional pigment is added further and dispersed uniformly by melting and kneading. In the formulas I, II, and III, m is 2-10; n is 4-10; x is 5-15; l is 2-17; Y is 10-30; each R1 and R2 is H or a 1-4C alkyl group. Thus, the image density is stabilized at high density by the toner, and the fogging density is stabilized at a low level.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a toner for developing electrostatic images formed by electrophotography, electrostatic recording, electrostatic printing, etc. , relates to durable toners with improved image properties.

<Prior art> In general, electrophotography forms an electrical latent image on a photoreceptor,
The latent image is then developed with toner and then fixed.

The developer used in the electrophotographic recording method used here is a two-component developer consisting of a mixture of non-magnetic toner and magnetic particles such as iron powder or ferrite powder to triboelectrically charge the toner, or a magnetic toner. One-component developers are known.

Carbon blanks are generally used as pigments in the toners that make up these two-component developers, but magnetic powders such as magnetite are used in the case of single-component toners, and in both cases, binder resin and The pigment was dispersed by melt-kneading it with the pigment.

<Problems to be Solved by the Invention> When using the above-mentioned conventional technology, if pigments such as carbon black and magnetite are not sufficiently dispersed in the melt-kneading process, carbon black and magnetite are removed from the binder resin during pulverization in the subsequent process. There is a tendency for pigments such as pigments to detach, and furthermore, when the toner is subjected to mechanical stress in the developing device, detachment is particularly likely to proceed, and the detachment of the pigment from the toner in the developing device is This not only causes a decrease in image density, but also increases staining of non-image areas.

Even if the above-mentioned desorption does not occur, problems such as instability of the carbon blank or magnet in the binder arise.

Therefore, it is very important to uniformly disperse carbon black or magnetite in the binder by melt-mixing, and for this purpose, it is necessary to apply a sufficient shear force during kneading to overcome the cohesive force of the carbon blank particles or magnetite particles. Although this is necessary, sufficient shearing force cannot be obtained by mere mechanical melt-kneading as in the past, which inevitably leads to poor dispersion.

In order to solve this problem, Japanese Patent Application Laid-Open No. 57-181553
A method has been proposed in which carbon black is dispersed in the monomer of the resin constituting the binder and then polymerized, but it is difficult to control the polymerization of the resin and it is difficult to obtain desirable characteristic values as a binder resin.

Furthermore, Japanese Patent Application Laid-open No. 60-93452 proposes a method in which an aluminum-based coupling agent is attached to the surface of carbon black to cause a coupling reaction, and then melted and kneaded together with a binder. It is difficult to react with the ring agent, and the liquid coupling agent may form aggregates of carbon black, making it difficult to sufficiently disperse carbon black. Due to this increase, problems arise such as an unavoidable increase in costs.

Means for Solving the Problems> The present invention has been made to solve the problems of the prior art described above, and its outline is as follows.

The present invention uses the following general formula fa) or (b
A pigment surface treatment agent consisting of a terminal amide-modified polyester obtained by amidating at least one end of a substantially linear aliphatic polyester represented by l with an amine represented by general formula (C) is contained. It is something.

(However, R and lh are H or C=1-4 alkyl groups)
In order to produce an actual toner, the pigment surface treatment agent of any of the above formulas is well mixed and dispersed in the binder resin, and then a pigment (charge control agent, etc.) is further added and melt-kneaded. This dramatically improves the dispersibility of the pigment component into the binder resin.

Incidentally, the method of simultaneously mixing the three components of binder resin, pigment, and pigment surface treatment agent and melt-kneading hardly improved the dispersibility.

In this case, the method of dispersing the polyester pigment surface treatment agent in the present invention in the binder resin includes the method of dispersing the polyester pigment surface treatment agent in the polymerization process of the binder resin, and the method of dispersing the polyester pigment surface treatment agent as described above. There is a method of melting and kneading the surface treatment agent with the binder resin and sufficiently dispersing it in the binder resin. In the case of modified polyester, if the condensation product of HOOC-GOOR and IO-pg-o■ (where R1 and R2 are polymethylene groups) is represented by a general formula, it is easy to produce a carboxylic acid type at both ends and an alcohol type at both ends. In addition, the dispersibility of the pigment surface treatment agent in the binder resin is good.

In addition, by using the terminal amide-modified polyester as used in the present invention, it can be modified to an amide as described below.

(However, R3 and R4 are alkyl groups.) (2) In the case of the terminal amide-modified polyester of the general formula (bl), it is a condensate of HOOC-RsOH.

(However, h is a polymethylene group) That is, to talk about each component constituting the present invention, the binder resin is an unsaturated ethylene monomer that is usually used as a binder resin for toner. Due to the force of alcohol formation, the X-rubonic acid on one side reacts with the amine as shown in the formula below.

Can be used. Examples of unsaturated ethylene binder resins include styrene, 0-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, and p-methylstyrene.
Styrenes such as ethylstyrene, 2,4 dimethylstyrene, p-n-butylstyrene, pn-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, and acrylic Methyl acrylate, n-octyl acrylate, dodecyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, methyl methacrylate, methacrylic acid Ethyl, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, methacrylic acid 2
Examples include homopolymers of α-methylstyrene aliphatic monocarboxylic acid esters such as -ethylhexyl, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate.

The pigment surface treatment agent is as shown in the above structural formula, and a specific example thereof is an aliphatic dicarboxylic acid having C=2 to 8 and a linear aliphatic glycol having C=2 to 10, which have approximately the same number of moles. A substantially linear polyester obtained by polycondensation is an amide-modified polyester. Examples of acid components of the polyester in this case include C=2-8 aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, and pimeline. In addition to linear aliphatic dicarboxylic acids such as acid, superic acid, azelaic acid, and sebacic acid, one or more of these can be used.

In addition, as the glycol component, a straight chain aliphatic glycol having 2 to 10 carbon atoms is selected, such as ethylene glycol,
Examples include 1,3-propanediol and 1,4-butanediol. Examples of other aliphatic glycols include 1,5-bentanediol, 1,6-hexanediol, 1,7hebutanediol, 1,8-octanediol, and 1,10-decanediol.

In addition, examples of oxycarboxylic acids include hydroacrylic acid,
Examples include T-oxybutyric acid, 1-hydroxycabronic acid, 1-biloxypalmitic acid, and hydroxystearic acid.

Such aliphatic glycol polyesters are obtained by a melt polycondensation reaction in a conventional manner, and have an intrinsic viscosity of 0.3 or more, preferably 0.5 or more, as measured at 20°C in a mixed solvent of equal weights of phenol/tetrachloroethane. .

When producing the electrophotographic toner of the present invention, a binder resin in which a pigment surface treatment agent is dispersed as described above,
After the pigment and additive components are mixed, a step of melt-kneading using a hot-melt kneader is performed. The bulk toner composition obtained by cross-mixing is then crushed and classified to obtain a toner having a desired particle size. Further, the pigment or dye used in the electrophotographic toner according to the present invention is typically carbon black, nigrosine dye, etc., but is not limited thereto.

<Examples> Examples of the present invention will be described below, but the present invention is not limited by these, and "parts" in the examples mean "parts by weight." In addition, the characteristic values in the examples were measured by the following methods: 1) Softening point ('C) was measured by a Koka type flow tester.

2) Glass transition point ("C) was measured by DSC.

The polyester pigment surface treatment agents used in this example include commercially available Truverse (trade names: all manufactured by IC1) 24000.21000, 20000.17000.
．． Six types of examples using 3000 are given below. Note that all of these numerical values indicate the weight average molecular weight of the surface treatment agent. Further, the binder resin and pigment components such as carbon black or magnetite used in forming the toner are not limited to those in this example.

Example 1゜ Pigment surface treatment agent (trade name: Truverse 24000).

IC1) 3 parts and styrene 80-butyl methacrylate 20 copolymer CM+, / MW: 4.6, M
N: 17000, softening point 140°C, glass conversion point 74°C] and 100 parts were hot-melted and kneaded to obtain a surface-treated binder resin. Carbon blank (REGAL400R, CABOT) is added to 300 parts of this binder resin.
21 parts (manufactured by Orient Chemical Co., Ltd.) and 4.5 parts of a charge control agent (S-34, manufactured by Orient Chemical Co., Ltd.) were melt-kneaded and extruded using a twin-screw extruder, and then pulverized and classified to create the toner of the present invention with a particle size of 12 μm. did.

Comparative Example 1 Styrene-butyl methacrylate copolymer CMu/MW was prepared in Example 1 above without adding a pigment surface treatment agent.
: 4.6, MN: 17000, Softening point 140
A toner was prepared in the same manner as in Example 1 using a binder resin having a glass conversion point of 74° C. and used as a comparative sample.

Example 2゜ Pigment surface treatment agent (trade name: Truverse 21000).

(manufactured by IC1) and toluene to a solid concentration of 10% to obtain a terpolymer of styrene-butyl methacrylate and methyl methacrylate (Mw/Mu: 5.4, M
W: 11,000, softening point: 140° C., glass conversion point: 72° C.] were cross-mixed and dried to obtain a surface-treated binder resin. This binder resin 300
Carbon blank (BPL, manufactured by CABOT) 21
Glossin EX (manufactured by Orient Chemical Co., Ltd.) and charge control agent)
After melt-kneading and extruding 6 parts using a twin-screw extruder, the toner of the present invention having a particle size of 12 μm was prepared by crushing and classifying.

Comparative Example 2゜Styrene-butyl methacrylate-methyl methacrylate 3 was prepared in Example 2 above without adding a pigment surface treatment agent.
Original copolymer (MW/MN: 5.4, M:
11000, softening point 140℃, glass transition point 72℃]
A toner was prepared as a comparative sample using a binder resin in the same manner as in Example 2.

Example 3゜Pigment surface treatment agent (trade name: Truverse 20000゜IC)
1 company) and 3 parts of styrene-butyl methacrylate copolymer (Mw/MW: 4.6, MN: 1700
0.

Softening point: 140°C, glass conversion point: 74°C] 100 parts were hot-melted and kneaded to obtain a binder resin. Carbon blank (REGAL400) was added to 300 parts of this binder resin.
After melt-kneading and extruding 30 parts of a charge control agent (S-34, manufactured by Orient Chemical Co., Ltd.) using a twin-screw extruder, the toner of the present invention with a particle size of 12 μm was prepared by crushing and classifying. did.

Comparative Example 3 Styrene-butyl methacrylate copolymer (MP/MW
: 4.6, MN: 17,000, softening point: 140° C., glass transition point: 74° C.] A binder resin was prepared in the same manner as in Example 3, and used as a comparative sample.

Example 4゜ ■ Pigment surface treatment agent (trade name: Tsuruhaasu 113000).

IC1) 3 parts and styrene-butyl methacrylate copolymer (Mw/MN: 15.4, M: 1 part% 000, softening point 140°C, glass transition point 74°C) 1
00 parts were hot-melted and kneaded to obtain a surface-treated binder resin. To 300 parts of this binder resin, 30 parts of carbon blank (REGAL400R, manufactured by CABOT) and 5 parts of a charge control agent (S-34, manufactured by Orient Chemical Co., Ltd.) were melt-kneaded and extruded using a twin-screw extruder, and then crushed and classified. Particle size 12
A toner of the present invention having a size of μm was prepared.

Comparative Example 4 Styrene-butyl methacrylate copolymer CM+1/Mll without adding the pigment surface treatment agent in Example 4 above
: 15.4, MN: 13000, softening point 140°C
A toner was prepared as a comparative sample in the same manner as in Example 4 using a binder resin having a glass conversion point of 74° C.].

Example 5 Pigment surface treatment agent (trade name: Truverse 3000° IC1
3 parts of styrene-butyl methacrylate copolymer (Mw/MN: 21.3, MN: 9000,
softening point: 140° C., glass conversion point: 74° C.] and 100 parts of the resin were hot-melted and kneaded to obtain a binder resin. Carbon black (REGAL40) was added to 300 parts of this dry binder resin.
0R, manufactured by CABOT) and 30 parts of a charge control agent (S-34
(manufactured by Orient Kagaku Co., Ltd.) were melt-kneaded using a twin-screw extruder, then crushed and classified to prepare a toner of the present invention having a particle size of 12 μm.

Comparative Example 5゜Styrene-butyl methacrylate copolymer (MW/MW
: 21.3, MN: 9000, softening point: 140° C., glass transition point: 74° C.] A toner was prepared in the same manner as in Example 5 and used as a comparative sample.

Example 6゜Pigment surface treatment agent (trade name: Truverse 24000゜IC)
(manufactured by Company I) and 5 parts of styrene-butyl methacrylate copolymer (Mw/MN: 4.6, MN: 17000
, softening point: 140° C., glass conversion point: 74° C.) were hot-melted and kneaded to obtain a surface-treated baingoo resin. Magnetite (EPT-5) is added to 300 parts of this binder resin.
00) and 3 parts of a charge control agent (S-34, manufactured by Orient Chemical Co., Ltd.) were melt-kneaded and extruded using a twin-screw extruder, and then pulverized and classified to prepare a toner of the present invention having a particle size of 12 μm.

Comparative Example 6 Styrene-butyl methacrylate copolymer CM, /MW without adding the pigment surface treatment agent in Example 6 above
: 4.6, MW: 17000, Softening point 140℃
A toner was prepared in the same manner as in Example 6 using a binder resin having a glass conversion point of 74°C] and used as a comparative sample.

Cross-sectional photographs of the six types of kneaded products obtained in the processes of Examples 1 to 6 were taken to observe the dispersion state of pigments, etc., and for comparison, six types of comparative toner mixtures were also photographed in the same manner. Cross-sectional photographs were taken and evaluated. Further, each of the toners obtained in Examples 1 to 6 and Comparative Examples 1 to 6 and a magnetic ferrite carrier were mixed and stirred to obtain a toner concentration of 4.
% by weight of each developer was prepared, placed in a developing device of a commercially available copy machine, and subjected to an actual continuous copying test. The results are listed in Table 1. At this time, a "Macbeth Densitometer" (Macbeth Co., Ltd.) is used to measure image density, and a "Hunter Whiteness Meter" (Nippon Heavy Industries) is used to measure fog density.
was used. The pigment dispersion state was visually evaluated by taking a cross-sectional photograph of the kneaded material using a transmission electron microscope.

As can be seen from Table 1, the comparative toner that does not use a pigment surface treatment agent has a lot of fog and has a poor dispersion state in cross-sectional photographs, whereas the toners of the present invention that use a polyester pigment surface treatment agent The image density is stable at high density, and the fog density is stable at low density.

Table 1 Continuous copying test <Effects of the invention> The present invention obtains a toner in which a pigment such as carbon blank or magnetite is uniformly dispersed in the binder resin by dispersing a polyester pigment surface treatment agent in a toner binder resin in advance. Therefore, it is possible to obtain a copied image with high image density and low fog density.

Agent Patent Attorney Mamoru Takeuchi

Claims (2)

[Claims] (1) A binder resin, a pigment, and at least one end of a substantially linear aliphatic polyester represented by the following general formula (a) or (b), and an amine represented by the general formula (c). An electrophotographic toner characterized by containing a pigment surface treatment agent consisting of a terminal amide-modified polyester that has been amidated with a polyester. , n=4-10, X=5-15) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(b) (However, l=2-17, Y=10-30) ▲Mathematical formulas, chemical formulas, tables, etc. ▼...(c) (However, R_1R_2 is H or an alkyl group with C=1 to 4) (2) The following general formula (a) or (b) in the binder resin
After dispersing a pigment surface treatment agent consisting of a terminal amide-modified polyester in which at least one end of a substantially linear aliphatic polyester represented by is amidated with an amine represented by general formula (c). , an electrophotographic toner characterized by adding a pigment and melting and kneading it to uniformly disperse it ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ... (a) (where m = 2 to 10, n = 4 ~10, X=5-15) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(b) (However, l=2-17, Y=10-30) ▲There are mathematical formulas, chemical formulas, tables, etc.▼・...(c) (However, R_1R_2 is H or an alkyl group with C=1 to 4)