JPH0529903B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention is a toner for developing electrostatic images formed by electrophotography, electrostatic recording, electrostatic printing, etc. Regarding durable toner. <Prior Art> Generally, in electrophotography, an electrical latent image is formed on a photoreceptor, and then the latent image is 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 black is generally used as a pigment in the toners that make up these two-component developers, but in the case of one-component toners, magnetic powder such as magnetite is used, and in both cases, the 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 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.
Desorption of pigment from the toner in the developing device 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, if the carbon black or magnetite is poorly dispersed in the binder, it may cause fogging and unstable image density during the process of continuous copying of multiple sheets using a copying machine. Problems arise. Therefore, it is very important to uniformly disperse carbon black or magnetite in the binder by melt-kneading, and for this purpose, shearing force sufficient to overcome the cohesive force of carbon black particles or magnetite particles is applied during kneading. However, it is not possible to obtain sufficient shearing force by simply mechanical melt-kneading as in the past.
In the end, it was inevitable that poor dispersion would occur. 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 cause the reaction to occur, and the liquid coupling agent may generate aggregates of carbon black, making it difficult to sufficiently disperse the carbon black. Furthermore, the number of toner manufacturing steps increases, resulting in increased costs. This creates problems such as unavoidable problems. <Means for Solving the Problems> The present invention has been made to solve the problems of the conventional techniques described above, and the outline thereof is as described below. In addition to the usual toner components, such as a binder resin, a pigment, and a charge control agent, the present invention uses the following general formula.
A pigment surface consisting of a terminal amide-modified polyester obtained by amidating at least one end of a substantially linear aliphatic polyester represented by (a) or (b) with an amine represented by general formula (c). It contains a processing agent. (However, m = 2 to 10, n = 4 to 10, X = 5 to 15) (However, l = 2 ~ 17, Y = 10 ~ 30) (However, R ₁ R ₂ is H or an alkyl group with C=1 to 4.) Therefore, in order to produce an actual toner, one of the pigment surface treatment agents of the above formulas must be thoroughly mixed and dispersed in the binder resin. After drying, a pigment (charge control agent, etc.) is further added and melt-kneaded to dramatically improve the dispersibility of the pigment component in 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. Both of the above methods can be applied to the present invention because they improve the dispersibility of the pigment in the binder resin, but the former method is applicable to the present invention. Not only is it easier to produce a toner using this method, but the dispersibility of the pigment surface treatment agent in the binder resin is also better. In addition, specific examples of the method for producing the terminal amide-modified polyester, etc. as used in the present invention are as follows: (1) In the case of the terminal amide-modified polyester of general formula (a), HOOC-R ₁ -COOH and HO-R ₂ -OH Condensate (where R ₁ and R ₂ are polymethylene groups) If the product is shown in the general formula: There is. By reacting the carboxylic acid moiety of the products of (), () and () above with the amine of the general formula (c), it can be modified into an amide as described below. (However, R ₃ and R ₄ are alkyl groups.) (2) In the case of the terminal amide-modified polyester of general formula (b) It is a condensate of HOOC-R ₅ -OH. (However, R ₅ is a polymethylene group) In the above, since both terminals are necessarily acid and alcohol, the carboxylic acid and amine on one side are reacted as shown in the following formula. Regarding each component constituting the present invention, the binder resin includes various types of homopolymers or copolymers of unsaturated ethylene monomers, polyester resins, epoxy resins, etc., which are usually used as binder resins for toners. The following can be applied to the present invention. Examples of unsaturated ethylene binder resins include styrene, o-methylstyrene,
m-methylstyrene, p-methylstyrene, α-
Methylstyrene, p-ethylstyrene, 2,4-
Dimethylstyrene, p-n-butylstyrene, p
- Styrenes such as n-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, methyl acrylate, n-octyl acrylate, dodecyl acrylate, acrylic lauryl acid,
2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, methacrylate n-octyl acid,
dodecyl methacrylate, lauryl methacrylate,
Examples include homopolymers of α-methylstyrene aliphatic monocarboxylic acid esters such as 2-ethylhexyl methacrylate, 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 with an amide-modified polyester. Examples of acid components of the polyester in this case include aliphatic dicarboxylic acids with C=2 to 8, 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. Further, as the glycol component, a linear aliphatic glycol having 2 to 10 carbon atoms is selected, such as ethylene glycol, 1.3 propanediol, 1.4 butanediol, and the like. Examples of other aliphatic glycols include 1,5-pentanediol, 1,6-hexanediol, 1,7-
heptanediol, 1,8-octanediol,
One example is 1,10-decanediol. Further, examples of the oxycarboxylic acid include hydroacrylic acid, γ-oxybutyric acid, 1-hydroxycaproic acid, 1-viroxypalmitic acid, and 1-hydroxystearic acid. Such an aliphatic glycol polyester is obtained by a melt polycondensation reaction in a conventional manner, and is prepared in a mixed solvent of equal weight of phenol/tetrachloroethane.
The intrinsic viscosity measured at 20°C is desirably 0.3 or more, particularly 0.5 or more. In producing the electrophotographic toner of the present invention, the binder resin in which the pigment surface treatment agent is dispersed, the pigment, and the additive components are mixed as described above, and then melt-kneaded using a hot melt kneader. administered. The bulk toner composition obtained by kneading is then pulverized 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 Solvers (trade names: all manufactured by ICI) 24000, 21000, 20000, 17000,
Here are six examples using 3000. 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: Solvers 2400,
(manufactured by ICI) and 3 parts of styrene 80-butyl methacrylate 20 copolymer [M _W /M _N : 4.6, M _N : 17000,
A binder resin containing a surface treatment agent was obtained by hot-melting and kneading 100 parts of the resin with a softening point of 140°C and a glass conversion point of 74°C. To 300 parts of this binder resin, 21 parts of carbon black (REGAL400R.CABOT) 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. A toner of the present invention having a particle size of 12 μm was prepared. Comparative Example 1 A styrene-butyl methacrylate copolymer [M _W /M _N : 4.6, M _N : 17000, softening point 140°C, glass transition point 74°C] was prepared in Example 1 above without adding a pigment surface treatment agent. A toner was prepared as a comparison sample using a binder resin in the same manner as in Example 1. Example 2 Pigment surface treatment agent (trade name: Solvers 21000,
(manufactured by ICI) and toluene to a solid concentration of 10% to obtain a terpolymer of styrene-butyl methacrylate and methyl methacrylate [M _W /
M _N :5.4, M _N :11000, softening point 140°C, glass conversion point 72°C] were kneaded and mixed and dried to obtain a binder resin containing a surface treatment agent. To 300 parts of this binder resin, 21 parts of carbon black (manufactured by BPL.CABOT) and 6 parts of a charge control agent (Nigrosine EX. manufactured by Orient Chemical Co., Ltd.) were melt-kneaded and extruded using a twin-screw extruder, and then crushed, classified, and granulated. A toner of the present invention having a diameter of 12 μm was prepared. Comparative Example 2 A terpolymer of styrene-butyl methacrylate-methyl methacrylate [M _W /M _N : 5.4,
M _N : 11000, softening point 140℃, glass transition point 72℃]
A toner was prepared using a binder resin in the same manner as in Example 2 and used as a comparative sample. Example 3 Pigment surface treatment agent (product name: Solvers 20000,
(manufactured by ICI) and 100 parts of styrene-butyl methacrylate copolymer [M _W /M _N : 4.6, M _N : 17000, softening point 140°C, glass conversion point 74°C] were hot-melted and kneaded to form a binder. Resin was obtained. Carbon black (REGAL400R,
A toner of the present invention having a particle size of 12 μm was prepared by melt-kneading and extruding 30 parts of a charge control agent (S-34, manufactured by Orient Chemical Co., Ltd.) using a twin-screw extruder, followed by pulverization and classification. Comparative Example 3 A styrene-butyl methacrylate copolymer [M _W /M _N : 4.6, M _N : 17000, softening point 140°C, glass transition point 74°C] was prepared in Example 3 above without adding a pigment surface treatment agent. A toner was prepared as a comparison sample using a binder resin in the same manner as in Example 3. Example 4 Pigment surface treatment agent (trade name: Solvers 17000,
Surface treatment was carried out by hot melt-kneading 3 parts (manufactured by ICI) and 100 parts of styrene-butyl methacrylate copolymer [M _W /M _N : 15.4, M _N : 13000, softening point 140°C, glass conversion point 74°C]. A compounded binder resin was obtained. To 300 parts of this binder resin, 30 parts of carbon black (REGAL400R.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 pulverized and classified. Particle size
A toner of the present invention having a thickness of 12 μm was prepared. Comparative Example 4 A styrene-butyl methacrylate copolymer [M _W /M _N : 15.4, M _N : 13000, softening point 140°C, glass transition point 74°C] was prepared in Example 4 above without adding a pigment surface treatment agent. A toner was prepared using a binder resin in the same manner as in Example 4 and used as a comparative sample. Example 5 Pigment surface treatment agent (trade name: Solvers 3000,
(manufactured by ICI) and 100 parts of styrene-butyl methacrylate copolymer [M _W /M _N : 21.3, M _N : 9000, softening point 140°C, glass conversion point 74°C] are hot-melted and kneaded to obtain a binder resin. I got it. 300 parts of this binder resin and carbon black (REGAL400R.
CABOT) and 5 parts of a charge control agent (S-34, Orient Chemical Co., Ltd.) were melt-kneaded in 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 A styrene-butyl methacrylate copolymer [M _W /M _N : 21.3, M _N : 9000, softening point 140°C, glass transition point 74°C] was prepared without adding the pigment surface treatment agent in Example 5 above. A toner was prepared as a comparative sample using a binder resin in the same manner as in Example 5. Example 6 Pigment surface treatment agent (product name: Solvers 24000,
Surface treatment was carried out by hot melt-kneading 5 parts (manufactured by ICI) and 100 parts of styrene-butyl methacrylate copolymer [M _W /M _N : 4.6, M _N : 17000, softening point 140°C, glass conversion point 74°C]. A compounded binder resin was obtained. Magnetite (EPT-) is added to 300 parts of this binder resin.
500) 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, followed by pulverization and classification to prepare a toner of the present invention having a particle size of 12 μm. Comparative Example 6 From the styrene-butyl methacrylate copolymer [M _W /M _N : 4.6, M _N : 17000, softening point 140°C, glass transition point 74°C] without adding the pigment surface treatment agent in Example 6 above. A toner was prepared using the same binder resin as in Example 6 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.
Each developer was prepared and placed in the developing device of a commercially available copy machine, and a live continuous copying test was conducted. 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" is used to measure fog density.
(Nippon Denshoku Kogyo) 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 did not use a pigment surface treatment agent had a lot of fog and the dispersion state in cross-sectional photographs was poor, whereas the toners of the present invention that used a polyester pigment surface treatment agent Image density is stable at high density, and fog density is stable at low density.

【table】

[Table] <Effects of the Invention> The present invention enables to obtain a toner in which pigments such as carbon black or magnetite are uniformly dispersed in the binder resin by pre-dispersing a polyester pigment surface treatment agent in the binder resin for toner. , it is possible to obtain a copied image with high image density and low fog density.

Claims (1)

[Scope of 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) are represented by the general formula (c). An electrophotographic toner comprising a pigment surface treatment agent comprising a terminal amide-modified polyester amidated with the amine shown below. (However, m = 2 to 10, n = 4 to 10, X = 5 to 15) (However, l = 2 ~ 17, Y = 10 ~ 30) (However, R ₁ R ₂ is H or a C=1-4 alkyl group) 2 At least a piece of a substantially linear aliphatic polyester represented by the following general formula (a) or (b) in the binder resin It is characterized by dispersing a pigment surface treatment agent made of a polyester modified with amide terminals whose terminals are amidated using an amine represented by the general formula (c), and then further adding a pigment and melt-kneading it to uniformly disperse it. Toner for electrophotography. (However, m = 2 to 10, n = 4 to 10, X = 5 to 15) (However, l = 2 ~ 17, Y = 10 ~ 30) (However, R ₁ R ₂ is H or a C=1-4 alkyl group)