JP3309298B2 - Toner for developing electrostatic images - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for developing an electrostatic latent image formed in electrophotography, electrostatic recording, electrostatic printing, and the like.

[0002]

2. Description of the Related Art Generally, in electrophotography or electrostatic recording, a carrier is used to develop an electrostatic latent image formed on a latent image carrier made of a photoconductive photoreceptor or a dielectric. Develop using a mixed two-component toner or a one-component toner that has been thinned by a blade or the like on a toner supply roller such as a developing sleeve and is appropriately charged and pulverized. After transferring the toner image to the transfer material, the toner image is fixed by heating pressure, solvent vapor, or the like to obtain a copy.

There are various toner fixing methods applied to these developing methods, but a heat roller fixing method is widely used because of its high thermal efficiency and high-speed fixing.
When high-speed fixing is performed by such a heat fixing method, the toner is required to have good low-temperature fixability (or a low fixing minimum temperature). If a low softening resin is contained as the binder resin, a part of the toner image adheres to the surface of the heat roller at the time of fixing, and the toner image is transferred to copy paper to cause background stain. So-called hot offset development or copy paper adheres to the surface of the heat roller and rolls, so-called notch development (especially when the heat roller temperature is low) is likely to occur.

Therefore, means for preventing such development are disclosed in JP-A-51-143333 and JP-A-57-14875.
No. 2, No. 58-97056, No. 60-247
No. 250 and the like propose to add various waxes such as solid silicone varnish, higher fatty acids, higher alcohols and the like as a release agent, all of which are capable of maintaining a satisfactory low-temperature fixability while maintaining sufficient low-temperature fixability. Offset resistance and / or
Further, there is no known material exhibiting winding resistance.

Specifically, conventional polyolefin waxes such as low-molecular-weight polyethylene and low-molecular-weight polypropylene have good offset resistance, but do not have sufficient low-temperature fixability, and have low plant fixing properties such as carnauba wax and candelilla wax. Waxes have good offset resistance and low-temperature fixability, but do not have sufficient winding resistance.Solid silicone varnish, solid silicone oil, amide wax, higher fatty acid, higher alcohol and montan wax have good low-moisture fixability. However, the offset resistance and the notch resistance are not sufficient.

In addition, the conventional release material has a large amount of so-called filming or spent in which the release agent is released from the toner during development and adheres to the photoreceptor or the canderia, so that a high-quality image can be formed stably for a long period of time. Was difficult.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a toner which can be fixed at a low temperature without causing offset development or wrapping around a heat roller at the time of fixing, and has less filming during development. That is.

[0008]

According to the present invention, in a toner comprising at least a binder resin and a colorant, the polymer constituting the binder resin contains a starburst dendrimer. An electrostatic image developing toner is provided. According to the present invention, the number average molecular weight of the starburst dendrimer is 3.0 × 10 ³ or more.
The toner for developing an electrostatic image is characterized by having a particle size of 1.0 × 10 ⁵ . Further, according to the present invention, there is provided an electrostatic image developing toner, wherein the starburst dendrimer is formed from two or more kinds of monomers.

The present invention will be described in detail below. The present inventors have conducted intensive studies in order to achieve the above object, and as a result, have found that a starburst dendrimer is effective. Starburst dendrimers have a characteristic that they exhibit a property of having an apparent cross-linked structure because the basic structure is a block polymer, so that interaction between molecules or within a molecule works greatly.

The property exhibited by the crosslinked structure in the fixing property of the toner is one of the important properties for suppressing the offset to the fixing roller. Until now, in a random polymer, a cross-linked structure has been imparted to a toner by a chemical bond by using a polyfunctional monomer. Although such a method can certainly suppress hot offset to the fixing roller, it cannot cope with future energy saving.

On the other hand, the starburst dendrimer of the present invention can solve this problem. This is because a cross-linking structure by a chemical bond and a cross-linking structure by a physical bond can be arbitrarily set in the molecular structure. In other words, in a conventional toner using a polyfunctional monomer, if a function for suppressing hot offset is provided, fixing energy increases, and energy saving at a low energy is inevitably impossible. In the present invention, as a mechanism for suppressing hot offset, by using the apparent crosslinked structure by physical bonding, it is possible to collapse this apparent crosslinked structure at an arbitrarily set temperature,
Above a certain temperature, hot was suppressed, where a moderate decrease in viscosity was possible. In contrast to the conventional cross-linking structure, which provides the polymer with internal cohesion by chemical bonding by so-called "bolting", in the present invention, instead of "bolting", physical bonding by "high-density springs" is used. Is characterized in that a polymer internal cohesive force is imparted by the method. In other words, since the basic structure is a block polymer, homopolymers in the block interact with each other to cause apparent cross-linking, thereby making it possible to perform energy-saving fixing while suppressing hot offset in fixing. Things.

The number average molecular weight of the starburst dendrimer is preferably from 3.0 × 10 ^{3 to} 1.0 × 10 ⁵ . If the number average molecular weight is less than this, hot offset to the fixing roller is induced, and if it is more than this, the objective energy saving fixing cannot be achieved. Further, the starburst dendrimer is preferably formed from two or more monomers. This is because if one type is used, it is impossible to achieve both hot offset and cold offset after achieving energy-saving fixing.

As the starburst dendrimer used in the present invention, styrene-based starburst dendrimers, olefin-based starburst dendrimers, polyester-based starburst dendrimers, polybutadiene-based starburst dendrimers, and fluorine-based starburst dendrimers are suitable.

In these production methods, first, living polyethylene having one end is obtained by anionic polymerization, isoprene is added thereto to cause a growth reaction, and this end is converted into a styryl-type anion with α-methylstyrene, and this is converted into p-chloroform. First, a diblock macromer is synthesized by reacting methyl. Then, put this macromer in benzene,
Using 2,2-azobisisobutyronitrile as an initiator, ethylene glycol dimethacrylate as a cross-linking agent is added, and microgel polymerization in a micelle formed by a macromer gives a target starburst dendrimer.

The monomers forming the binder resin used in the present invention include styrene, o-methylstyrene and p-methylstyrene.
-Methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert
-Butylstyrene, pn-hexylstyrene, pn
-Octyl styrene, pn-nonyl styrene, pn
Styrenes such as -decylstyrene, pn-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene and 34-dichlorostyrene; ethylenically unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene Vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride; vinyl esters such as vinyl acetate, vinyl propionate and vinyl acetate; methyl acrylate, ethyl acrylate and n-butyl acrylate , Methyl methacrylate, ethyl methacrylate, trifluoroethyl acrylate, hexafluoroisopropyl acrylate, tetrafluoropropyl acrylate, octafluoropropyl acrylate, α-methylene aliphatic carboxylic acid such as heptadecylfluorodecyl acrylate, etc. Vinyl ethers such as vinyl methyl ether; down acids vinyl ketones such as vinyl methyl ketone; N- vinyl indole, can be exemplified N- vinyl compounds such as N- vinylpyrrolidone. These monomers can be used alone or in combination of two or more.

Further, additives such as a colorant and a charge control agent can be used in the toner of the present invention. These include carbon chelate dyes such as carbon black, oil black, nigrosine dyes, metal-containing dyes, aniline dyes, calco oil blue, chrome yellow, ultramarine blue, methylene blue, phthalocyanine blue, rose bengal, and other dyes or pigments. included. The toner of the present invention may contain a fluidizing agent. For example, inorganic oxides such as SiO ₂ and TiO ₂ having a hydrophobic surface, inorganic fine particles such as SiC, metal soaps such as zinc stearate, and others. Can be used.

[0017]

Next, the present invention will be described in more detail by way of examples.

Example 1 Binder resin (styrene-acrylic acid-based starburst dendrimer ) 60 parts by weight (polyester) 35 parts by weight Release agent (carnauba wax) 5 parts by weight Colorant (carbon black) 10 parts by weight 6 parts by weight of a charge control agent (zinc salt of a salicylic acid derivative) is melt-kneaded, cooled, coarsely ground using a hammer mill,
Subsequently, it was pulverized by a pulverizer using an air jet method. The obtained finely pulverized product was classified to have an average particle size of 7.5 μm.
And 0.5 parts by weight of silica fine powder was added to and mixed with 100 parts by weight of the present particles to obtain a toner. 5 parts by weight of the obtained toner was mixed with 95 parts by weight of a ferrite carrier to prepare a developer, and a copying machine (FT-820 manufactured by Ricoh Co., Ltd.) was prepared.
0) was evaluated. The normal fixing roller temperature is 180
The temperature was around 140 ° C., but the toner was evaluated at 140 ° C. because it is an energy-saving fixing toner. The obtained image had high resolution, and no offset to the fixing roller was observed. No photoreceptor filming, carrier spent, poor cleaning, and poor transfer were observed on 100,000 copies.

Example 2 70 parts by weight of binder resin (styrene-methacrylic acid-based starburst dendrimer ) 25 parts by weight of (ester-based polymer) Release agent (carnauba wax) 5 parts by weight Colorant (carbon black) 10 parts by weight of a charge controlling agent (salicylic acid derivative zinc salt) 6 parts by weight was melt-kneaded, cooled, and coarsely ground using a hammer mill.
Subsequently, it was pulverized by a pulverizer using an air jet method. The obtained finely pulverized product was classified to have an average particle size of 8.4 μm.
And 0.3 parts by weight of silica fine powder was added to and mixed with 100 parts by weight of the present particles to obtain a toner. 5 parts by weight of the obtained toner was mixed with 95 parts by weight of a ferrite carrier to prepare a developer, and a copying machine (FT-820 manufactured by Ricoh Co., Ltd.) was prepared.
0) was evaluated. The normal fixing roller temperature is 180
The temperature was around 150 ° C., but the toner was evaluated at 150 ° C. because it is an energy-saving fixing toner. As a result, a high-resolution image was obtained, and no offset to the fixing roller was observed. No photoreceptor filming, carrier spent, poor cleaning, and poor transfer were observed on 100,000 copies.

Example 3 20 parts by weight of binder resin (styrene-methacrylic acid-based polymer) 50 parts by weight of (fluorine-based starburst dendrimer ) 25 parts by weight of (ester-based polymer) Release agent (carnauba wax) 5 parts by weight Colorant (carbon black) 10 parts by weight Charge controlling agent (salicylic acid derivative zinc salt) 6 parts by weight is melt-kneaded, and after cooling, coarsely ground using a hammer mill.
Subsequently, it was pulverized by a pulverizer using an air jet method. The obtained finely pulverized product was classified to have an average particle size of 7.8 μm.
And 0.4 parts by weight of silica fine powder was added to and mixed with 100 parts by weight of the present particles to obtain a toner. 5 parts by weight of the obtained toner was mixed with 95 parts by weight of a ferrite carrier to prepare a developer, and a copying machine (FT-820 manufactured by Ricoh Company) was used.
0) was evaluated. The normal fixing roller temperature is 180
The temperature was around 150 ° C., but the toner was evaluated at 150 ° C. because it is an energy-saving fixing toner. As a result, a high-resolution image was obtained, and no offset to the fixing roller was observed. No photoreceptor filming, carrier spent, poor cleaning, and poor transfer were observed on 100,000 copies.

Comparative Example 1 In Example 1, a styrene-acrylic starburst dend was used.
A developer was prepared in the same manner as in Example 1 except that the immer was replaced with a styrene-acrylic copolymer.
The evaluation was performed in the same manner as described above. The obtained image was an image cold-offset to the fixing roller.

Comparative Example 2 In Example 2, a styrene-methacrylic starburst den
A toner / developer was prepared in the same manner as in Example 2, except that a styrene-methacrylic copolymer was used instead of the drimer . Next, evaluation was performed in the same manner as in Example 1. The obtained image was an image cold-offset to the fixing roller.

[0023]

The toner of the present invention in which the polymer constituting the binder resin is contained as a starburst dendrimer (at this time, the starburst dendrimer has a number average molecular weight of 3.0 × 10 ^{3 to} 1.0 × 10 ^{3). In} the range of ⁵ and preferably from two or more monomers)
Is excellent in that low-temperature fixing is possible without occurrence of offset development or wrapping development around a heat roller at the time of fixing and filming during development is small.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 9/08

Claims (3)

(57) [Claims] 1. A toner for developing an electrostatic image, wherein a polymer constituting at least a binder resin and a colorant contains a starburst dendrimer. 2. The electrostatic image developing toner according to claim 1, wherein the number average molecular weight of the starburst dendrimer is from 3.0 × 10 ^{3 to} 1.0 × 10 ⁵ . 3. The electrostatic image developing toner according to claim 1, wherein the starburst dendrimer is formed from two or more monomers.